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UM10360
LPC17xx User manual
Rev. 01 -- 4 January 2010 User manual
Document information Info Keywords Content LPC1769, LPC1768, LPC1767, LPC1766, LPC1765, LPC1764, LPC1759, LPC1758, LPC1756, LPC1754, LPC1752, LPC1751, ARM, ARM Cortex-M3, 32-bit, USB, Ethernet, CAN, I2S, Microcontroller LPC17xx user manual
Abstract
NXP Semiconductors
UM10360
LPC17xx user manual
Revision history Rev 1 Date 20100104 Description LPC17xx user manual revision. Modifications:
* * * * * *
"Draft" status removed. Editorial updates and typographical corrections throughout the user manual. LPC1758, LPC1767, and LPC1768 have been added to the keywords list on the front cover, the ordering information in section Section 1-4, and the part identification number table in Section 32-7.11. The note about DMA operation in Sleep mode was removed from Section 4-8.1. In Table 8-81, the CLKOUT function was removed from the description of P1.25. In section the Ethernet chapter, in Section 10-16.1 and Section 10-17.2, it has been noted that the external PHY must be initialized and PHY clocks received by the Ethernet block prior to further initialization of the Ethernet block. Also, in Section 10-17.1, under the heading "Ownership of descriptors", the sentence about AHB arbitration was removed. A general and more correct discussion of the subject was added in Section 2-5. The UART fractional baud rate generator is disabled in auto baud mode (see Section 14-14.4.10.1 and Section 15-4.14). In section Section 14-4.12 and Section 15-4.16, the description of the value of the DLL register has been is corrected to read "the value of the DLL register must be greater than 2". *** Motor Control PWM *** The description of RPM calculation in the QEI chapter (see Section 26-4.3), definitions for the formula values are added, and the description improved. The description of the position and index compare registers incorrectly indicated that the less than,equal to, and greater than compare could be selected. It is changed to only indicate "equal to". A description of Flash signature generation has been added in Section 32-10.
* * * *
*
Contact information
For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com
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Chapter 1: LPC17xx Introductory information
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1. Introduction
The LPC17xx is an ARM Cortex-M3 based microcontroller for embedded applications requiring a high level of integration and low power dissipation. The ARM Cortex-M3 is a next generation core that offers system enhancements such as modernized debug features and a higher level of support block integration. High speed versions (LPC1769 and LPC1759) operate at up to a 120 MHz CPU frequency. Other versions operate at up to an 100 MHz CPU frequency. The ARM Cortex-M3 CPU incorporates a 3-stage pipeline and uses a Harvard architecture with separate local instruction and data buses as well as a third bus for peripherals. The ARM Cortex-M3 CPU also includes an internal prefetch unit that supports speculative branches. The peripheral complement of the LPC17xx includes up to 512 kB of flash memory, up to 64 kB of data memory, Ethernet MAC, a USB interface that can be configured as either Host, Device, or OTG, 8 channel general purpose DMA controller, 4 UARTs, 2 CAN channels, 2 SSP controllers, SPI interface, 3 I2C interfaces, 2-input plus 2-output I2S interface, 8 channel 12-bit ADC, 10-bit DAC, motor control PWM, Quadrature Encoder interface, 4 general purpose timers, 6-output general purpose PWM, ultra-low power RTC with separate battery supply, and up to 70 general purpose I/O pins.
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Chapter 1: LPC17xx Introductory information
2. Features
Refer to Section 1-4.1 for details of features on specific part numbers.
* ARM Cortex-M3 processor, running at frequencies of up to 120 MHz on high speed
versions (LPC1769 and LPC1759), up to 100 MHz on other versions. A Memory Protection Unit (MPU) supporting eight regions is included.
* ARM Cortex-M3 built-in Nested Vectored Interrupt Controller (NVIC). * Up to 512 kB on-chip flash program memory with In-System Programming (ISP) and
In-Application Programming (IAP) capabilities. The combination of an enhanced flash memory accelerator and location of the flash memory on the CPU local code/data bus provides high code performance from flash.
* Up to 64 kB on-chip SRAM includes:
- Up to 32 kB of SRAM on the CPU with local code/data bus for high-performance CPU access. - Up to two 16 kB SRAM blocks with separate access paths for higher throughput. These SRAM blocks may be used for Ethernet, USB, and DMA memory, as well as for general purpose instruction and data storage.
* Eight channel General Purpose DMA controller (GPDMA) on the AHB multilayer
matrix that can be used with the SSP, I2S, UART, the Analog-to-Digital and Digital-to-Analog converter peripherals, timer match signals, GPIO, and for memory-to-memory transfers.
* Multilayer AHB matrix interconnect provides a separate bus for each AHB master.
AHB masters include the CPU, General Purpose DMA controller, Ethernet MAC, and the USB interface. This interconnect provides communication with no arbitration delays unless two masters attempt to access the same slave at the same time.
* Split APB bus allows for higher throughput with fewer stalls between the CPU and
DMA. A single level of write buffering allows the CPU to continue without waiting for completion of APB writes if the APB was not already busy.
* Serial interfaces:
- Ethernet MAC with RMII interface and dedicated DMA controller. - USB 2.0 full-speed controller that can be configured for either device, Host, or OTG operation with an on-chip PHY for device and Host functions and a dedicated DMA controller. - Four UARTs with fractional baud rate generation, internal FIFO, IrDA, and DMA support. One UART has modem control I/O and RS-485/EIA-485 support. - Two-channel CAN controller. - Two SSP controllers with FIFO and multi-protocol capabilities. The SSP interfaces can be used with the GPDMA controller. - SPI controller with synchronous, serial, full duplex communication and programmable data length. SPI is included as a legacy peripheral and can be used instead of SSP0. - Three enhanced I2C-bus interfaces, one with an open-drain output supporting the full I2C specification and Fast mode plus with data rates of 1Mbit/s, two with standard port pins. Enhancements include multiple address recognition and monitor mode.
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- I2S (Inter-IC Sound) interface for digital audio input or output, with fractional rate control. The I2S interface can be used with the GPDMA. The I2S interface supports 3-wire data transmit and receive or 4-wire combined transmit and receive connections, as well as master clock output.
* Other peripherals:
- 70 (100 pin package) or 52 (80-pin package) General Purpose I/O (GPIO) pins with configurable pull-up/down resistors, open drain mode, and repeater mode. All GPIOs are located on an AHB bus for fast access, and support Cortex-M3 bit-banding. GPIOs can be accessed by the General Purpose DMA Controller. Any pin of ports 0 and 2 can be used to generate an interrupt. - 12-bit Analog-to-Digital Converter (ADC) with input multiplexing among eight pins, conversion rates up to 200 kHz, and multiple result registers. The 12-bit ADC can be used with the GPDMA controller. - 10-bit Digital-to-Analog Converter (DAC) with dedicated conversion timer and DMA support. - Four general purpose timers/counters, with a total of eight capture inputs and ten compare outputs. Each timer block has an external count input. Specific timer events can be selected to generate DMA requests. - One motor control PWM with support for three-phase motor control. - Quadrature encoder interface that can monitor one external quadrature encoder. - One standard PWM/timer block with external count input. - Real-Time Clock (RTC) with a separate power domain. The RTC is clocked by a dedicated RTC oscillator. The RTC block includes 20 bytes of battery-powered backup registers, allowing system status to be stored when the rest of the chip is powered off. Battery power can be supplied from a standard 3 V Lithium button cell. The RTC will continue working when the battery voltage drops to as low as 2.1 V. An RTC interrupt can wake up the CPU from any reduced power mode. - Watchdog Timer (WDT). The WDT can be clocked from the internal RC oscillator, the RTC oscillator, or the APB clock. - Cortex-M3 system tick timer, including an external clock input option. - Repetitive interrupt timer provides programmable and repeating timed interrupts.
* Standard JTAG test/debug interface as well as Serial Wire Debug and Serial Wire
Trace Port options.
* Emulation trace module supports real-time trace. * Four reduced power modes: Sleep, Deep-sleep, Power-down, and Deep
power-down.
* Single 3.3 V power supply (2.4 V to 3.6 V). Temperature range of -40 C to 85 C. * Four external interrupt inputs configurable as edge/level sensitive. All pins on PORT0
and PORT2 can be used as edge sensitive interrupt sources.
* Non-maskable Interrupt (NMI) input. * Clock output function that can reflect the main oscillator clock, IRC clock, RTC clock,
CPU clock, or the USB clock.
* The Wakeup Interrupt Controller (WIC) allows the CPU to automatically wake up from
any priority interrupt that can occur while the clocks are stopped in deep sleep, Power-down, and Deep power-down modes.
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Chapter 1: LPC17xx Introductory information
* Processor wake-up from Power-down mode via any interrupt able to operate during
Power-down mode (includes external interrupts, RTC interrupt, USB activity, Ethernet wake-up interrupt, CAN bus activity, PORT0/2 pin interrupt, and NMI).
* * * * *
Each peripheral has its own clock divider for further power savings. Brownout detect with separate threshold for interrupt and forced reset. On-chip Power-On Reset (POR). On-chip crystal oscillator with an operating range of 1 MHz to 25 MHz. 4 MHz internal RC oscillator trimmed to 1% accuracy that can optionally be used as a system clock. for a high-frequency crystal. May be run from the main oscillator, the internal RC oscillator, or the RTC oscillator.
* An on-chip PLL allows CPU operation up to the maximum CPU rate without the need
* A second, dedicated PLL may be used for the USB interface in order to allow added
flexibility for the Main PLL settings.
* Versatile pin function selection feature allows many possibilities for using on-chip
peripheral functions.
* Available as 100-pin LQFP (14 x 14 x 1.4 mm) and 80-pin LQFP (12 x 12 x 1.4 mm)
packages.
3. Applications
* * * * * *
eMetering Lighting Industrial networking Alarm systems White goods Motor control
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Chapter 1: LPC17xx Introductory information
4. Ordering information
Table 1. Ordering information Package Name LPC1769FBD100 LPC1768FBD100 LPC1767FBD100 LPC1766FBD100 LPC1765FBD100 LPC1764FBD100 LPC1759FBD80 LPC1758FBD80 LPC1756FBD80 LPC1754FBD80 LPC1752FBD80 LPC1751FBD80 LQFP80 plastic low profile quad flat package; 80 leads; body 12 x 12 x 1.4 mm SOT315-1 LQFP100 plastic low profile quad flat package; 100 leads; body 14 x 14 x 1.4 mm SOT407-1 Description Version Type number
4.1 Part options summary
Table 2. Ordering options for LPC17xx parts Max. CPU speed 120 MHz 100 MHz 100 MHz 100 MHz 100 MHz 100 MHz 120 MHz 100 MHz 100 MHz 100 MHz 100 MHz 100 MHz Flash 512 kB 512 kB 512 kB 256 kB 256 kB 128 kB 512 kB 512 kB 256 kB 128 kB 64 kB 32 kB Total SRAM 64 kB 64 kB 64 kB 64 kB 64 kB 32 kB 64 kB 64 kB 32 kB 32 kB 16 kB 8 kB Ethernet yes yes yes yes no yes no yes no no no no USB Device/Host/OTG Device/Host/OTG no Device/Host/OTG Device/Host/OTG Device Device/Host/OTG Device/Host/OTG Device/Host/OTG Device/Host/OTG Device Device CAN 2 2 no 2 2 2 2 2 2 1 1 1 I2S yes yes yes yes yes no yes yes yes no no no DAC yes yes yes yes yes no yes yes yes yes no no Package 100 pin 100 pin 100 pin 100 pin 100 pin 100 pin 80 pin 80 pin 80 pin 80 pin 80 pin 80 pin Type number LPC1769FBD100 LPC1768FBD100 LPC1767FBD100 LPC1766FBD100 LPC1765FBD100 LPC1764FBD100 LPC1759FBD80 LPC1758FBD80 LPC1756FBD80 LPC1754FBD80 LPC1752FBD80 LPC1751FBD80
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5. Simplified block diagram
Ethernet PHY interface
Xtalin
Trace Port
JTAG interface
USB interface
Trace Module
Test/Debug Interface
ARM Cortex-M3
D-code bus I-code bus
DMA controller
Ethernet 10/100 MAC
USB device, host, OTG
Clocks and Controls
Clock Generation, Power Control, Brownout Detect, and other system functions
Flash Accelerator High Speed GPIO
Multilayer AHB Matrix
SRAM 64 kB ROM 8 kB
AHB to APB bridge APB slave group 0 SSP1 UARTs 0 & 1 CAN 1 & 2 I2C 0 & 1 SPI0 Capture/Compare Timers 0 & 1 Watchdog Timer
AHB to APB bridge APB slave group 1 SSP0 UARTs 2 & 3 I2S I2C2 Repetitive Interrupt Timer Capture/Compare Timers 2 & 3 External Interrupts
PWM1 DAC 12-bit ADC System Control Pin Connect Block Motor Control PWM GPIO Interrupt Ctl Quadrature Encoder 32 kHz oscillator Real Time Clock 20 bytes of backup registers RTC Power Domain Note: shaded peripheral blocks support General Purpose DMA
Fig 1.
LPC1768 simplified block diagram
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Flash 512 kB
RST
System bus
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6. Architectural overview
The ARM Cortex-M3 includes three AHB-Lite buses, one system bus and the I-code and D-code buses which are faster and are used similarly to TCM interfaces: one bus dedicated for instruction fetch (I-code) and one bus for data access (D-code). The use of two core buses allows for simultaneous operations if concurrent operations target different devices. The LPC17xx uses a multi-layer AHB matrix to connect the Cortex-M3 buses and other bus masters to peripherals in a flexible manner that optimizes performance by allowing peripherals on different slaves ports of the matrix to be accessed simultaneously by different bus masters. Details of the multilayer matrix connections are shown in Figure 1-2. APB peripherals are connected to the CPU via two APB busses using separate slave ports from the multilayer AHB matrix. This allows for better performance by reducing collisions between the CPU and the DMA controller. The APB bus bridges are configured to buffer writes so that the CPU or DMA controller can write to APB devices without always waiting for APB write completion.
7. ARM Cortex-M3 processor
The ARM Cortex-M3 is a general purpose 32-bit microprocessor, which offers high performance and very low power consumption. The Cortex-M3 offers many new features, including a Thumb-2 instruction set, low interrupt latency, hardware divide, interruptible/continuable multiple load and store instructions, automatic state save and restore for interrupts, tightly integrated interrupt controller with Wakeup Interrupt Controller, and multiple core buses capable of simultaneous accesses. Pipeline techniques are employed so that all parts of the processing and memory systems can operate continuously. Typically, while one instruction is being executed, its successor is being decoded, and a third instruction is being fetched from memory. The ARM Cortex-M3 processor is described in detail in the Cortex-M3 User Guide that is appended to this manual.
7.1 Cortex-M3 Configuration Options
The LPC17xx uses the r2p0 version of the Cortex-M3 CPU, which includes a number of configurable options, as noted below. System options:
* The Nested Vectored Interrupt Controller (NVIC) is included. The NVIC includes the
SYSTICK timer.
* The Wakeup Interrupt Controller (WIC) is included. The WIC allows more powerful
options for waking up the CPU from reduced power modes.
* A Memory Protection Unit (MPU) is included. * A ROM Table in included. The ROM Table provides addresses of debug components
to external debug systems. Debug related options:
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* A JTAG debug interface is included. * Serial Wire Debug is included. Serial Wire Debug allows debug operations using only
2 wires, simple trace functions can be added with a third wire.
* The Embedded Trace Macrocell (ETM) is included. The ETM provides instruction
trace capabilities.
* The Data Watchpoint and Trace (DWT) unit is included. The DWT allows data
address or data value matches to be trace information or trigger other events. The DWT includes 4 comparators and counters for certain internal events.
* An Instrumentation Trace Macrocell (ITM) is included. Software can write to the ITM in
order to send messages to the trace port.
* The Trace Port Interface Unit (TPIU) is included. The TPIU encodes and provides
trace information to the outside world. This can be on the Serial Wire Viewer pin or the 4-bit parallel trace port.
* A Flash Patch and Breakpoint (FPB) is included. The FPB can generate hardware
breakpoints and remap specific addresses in code space to SRAM as a temporary method of altering non-volatile code. The FPB include 2 literal comparators and 6 instruction comparators.
8. On-chip flash memory system
The LPC17xx contains up to 512 kB of on-chip flash memory. A new two-port flash memory accelerator maximizes performance for use with the two fast AHB-Lite buses. This memory may be used for both code and data storage. Programming of the flash memory may be accomplished in several ways. It may be programmed In System via the serial port. The application program may also erase and/or program the flash while the application is running, allowing a great degree of flexibility for data storage field firmware upgrades, etc.
9. On-chip Static RAM
The LPC17xx contains up to 64 kB of on-chip static RAM memory. Up to 32 kB of SRAM, accessible by the CPU and all three DMA controllers are on a higher-speed bus. Devices containing more than 32 kB SRAM have two additional 16 kB SRAM blocks, each situated on separate slave ports on the AHB multilayer matrix. This architecture allows the possibility for CPU and DMA accesses to be separated in such a way that there are few or no delays for the bus masters.
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10. Block diagram
JTAG interface TEST/DEBUG INTERFACE Ethernet PHY interface USB interface
Xtalin
X32Kin
Debug Port EMULATION TRACE MODULE
DMA controller
ARM Cortex-M3
I-code bus D-code bus
Ethernet 10/100 MAC
USB device, host, OTG
clocks and controls internal power
clock generation, CLK power control, OUT and other system functions Vdd voltage regulator
System bus Flash Accelerator SRAM 32 kB SRAM 16 kB SRAM 16 kB DMAC regs USB regs Ethernet regs HS GPIO Flash 512 kB ROM 8 kB
Multilayer AHB Matrix APB slave group 0 SSP1 UARTs 0 & 1 CAN 1 & 2 I2C 0&1
AHB to APB bridge AHB to APB bridge
APB slave group 1 SSP0 UARTs 2 & 3 I2S I2C2 Capture/compare timers 2 & 3 Repetitive interrupt timer External interrupts DAC System control Motor control PWM Quadrature encoder
SPI0 Capture/compare timers 0 & 1 Watchdog timer PWM1 12-bit ADC Pin connect block GPIO interrupt control 32 kHz oscillator Real Time Clock
Note: shaded peripheral blocks support General Purpose DMA
Vbat ultra-low power Backup registers regulator (20 bytes) RTC Power Domain
Fig 2.
LPC1768 block diagram, CPU and buses
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1. Memory map and peripheral addressing
The ARM Cortex-M3 processor has a single 4 GB address space. The following table shows how this space is used on the LPC17xx.
Table 3. LPC17xx memory usage and details General Use Address range details and description
Address range
0x0000 0000 to 0x1FFF FFFF
On-chip non-volatile memory
0x0000 0000 - 0x0007 FFFF 0x0000 0000 - 0x0003 FFFF 0x0000 0000 - 0x0001 FFFF 0x0000 0000 - 0x0000 FFFF 0x0000 0000 - 0x0000 7FFF
For devices with 512 kB of flash memory. For devices with 256 kB of flash memory. For devices with 128 kB of flash memory. For devices with 64 kB of flash memory. For devices with 32 kB of flash memory. For devices with 32 kB of local SRAM. For devices with 16 kB of local SRAM. For devices with 8 kB of local SRAM. 8 kB Boot ROM with flash services. AHB SRAM - bank 0 (16 kB), present on devices with 32 kB or 64 kB of total SRAM. AHB SRAM - bank 1 (16 kB), present on devices with 64 kB of total SRAM. GPIO. APB0 Peripherals, up to 32 peripheral blocks, 16 kB each. APB1 Peripherals, up to 32 peripheral blocks, 16 kB each. DMA Controller, Ethernet interface, and USB interface. Cortex-M3 related functions, includes the NVIC and System Tick Timer.
On-chip SRAM
0x1000 0000 - 0x1000 7FFF 0x1000 0000 - 0x1000 3FFF 0x1000 0000 - 0x1000 1FFF
Boot ROM 0x2000 0000 to 0x3FFF FFFF On-chip SRAM (typically used for peripheral data) GPIO 0x4000 0000 to 0x5FFF FFFF APB Peripherals
0x1FFF 0000 - 0x1FFF 1FFF 0x2007 C000 - 0x2007 FFFF 0x2008 0000 - 0x2008 3FFF 0x2009 C000 - 0x2009 FFFF 0x4000 0000 - 0x4007 FFFF 0x4008 0000 - 0x400F FFFF
AHB peripherals 0xE000 0000 to 0xE00F FFFF Cortex-M3 Private Peripheral Bus
0x5000 0000 - 0x501F FFFF 0xE000 0000 - 0xE00F FFFF
2. Memory maps
The LPC17xx incorporates several distinct memory regions, shown in the following figures. Figure 2-3 shows the overall map of the entire address space from the user program viewpoint following reset. The interrupt vector area supports address remapping, which is described later in this section.
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0x4010 0000 0x400F C000 0x400C 0000 0x400B C000 0x400B 8000 0x400B 4000 0x400B 0000 0x400A C000 0x400A 8000 0x400A 4000 0x400A 0000 0x4009 C000 0x4009 8000 0x4009 4000 0x4009 0000 0x4008 C000 0x4008 8000 0x4008 0000 15 14 13 11 10 9 8 7 6 5 4 3 2 31
APB1 peripherals system control 30 - 16 reserved QEI motor control PWM reserved reserved I2S reserved I2C2 UART3 UART2 Timer 3 Timer 2 DAC SSP0 1 - 0 reserved
4 GB
LPC1768 memory space 0xFFFF FFFF reserved 0xE010 0000 private peripheral bus reserved 0x5020 0000 AHB periherals reserved 0x4400 0000 peripheral bit band alias addressing reserved APB1 peripherals 0x4200 0000 0x4010 0000 0x4008 0000 0x4000 0000 23 0x2400 0000 AHB SRAM bit band alias addressing 0x2200 0000 reserved GPIO 0x2009 C000 reserved 0x2008 4000 0x2007 C000 0x1FFF 2000 0x1FFF 0000 0x1000 8000 0x1000 0000 AHB SRAM (2 blocks of 16 kB) reserved 8 kB boot ROM reserved 0x200A 0000 18 17 16 15 14 13 12 11 10 9 8 7 6 0x0008 0000 5 4 3 2 1 0 APB0 peripherals 31 - 24 reserved I2C1 22 - 19 reserved CAN2 CAN1 CAN common CAN AF registers CAN AF RAM ADC SSP1 pin connect GPIO interrupts RTC + backup registers SPI I2C0 PWM1 reserved UART1 UART0 TIMER1 TIMER0 WDT 0x5000 0000 2 1 0 0xE000 0000 3 AHB peripherals 127- 4 reserved USB controller reserved GPDMA controller Ethernet controller 0x5000 C000 0x5000 8000 0x5000 4000 0x5000 0000 0x5020 0000
12 repetitive interrupt timer
0x4008 0000 0x4006 0000 0x4005 C000 0x4004 C000 0x4004 8000 0x4004 4000 0x4004 0000 0x4003 C000 0x4003 8000 0x4003 4000 0x4003 0000 0x4002 C000 0x4002 8000 0x4002 4000 0x4002 0000 0x4001 C000 0x4001 8000 0x4001 4000 0x4001 0000 0x4000 C000 0x4000 8000 0x4000 4000 0x4000 0000
1 GB
APB0 peripherals reserved
0.5 GB
I-code/D-code memory space
32 kB local static RAM
Chapter 2: LPC17xx Memory map
reserved 0x0000 0100 0x0000 0000 active interrupt vectors 0 GB 512 kB on-chip flash + 256 byte 0x0000 0000
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Fig 3.
LPC17xx system memory map
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Figure 2-3 and Table 2-4 show different views of the peripheral address space. The AHB peripheral area is 2 megabyte in size, and is divided to allow for up to 128 peripherals. The APB peripheral area is 1 megabyte in size and is divided to allow for up to 64 peripherals. Each peripheral of either type is allocated 16 kilobytes of space. This allows simplifying the address decoding for each peripheral. All peripheral register addresses are word aligned (to 32-bit boundaries) regardless of their size. This eliminates the need for byte lane mapping hardware that would be required to allow byte (8-bit) or half-word (16-bit) accesses to occur at smaller boundaries. An implication of this is that word and half-word registers must be accessed all at once. For example, it is not possible to read or write the upper byte of a word register separately.
3. APB peripheral addresses
The following table shows the APB0/1 address maps. No APB peripheral uses all of the 16 kB space allocated to it. Typically each device's registers are "aliased" or repeated at multiple locations within each 16 kB range.
Table 4. APB0 peripherals and base addresses Base address Peripheral name
APB0 peripheral
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 to 22 23 24 to 31
0x4000 0000 0x4000 4000 0x4000 8000 0x4000 C000 0x4001 0000 0x4001 4000 0x4001 8000 0x4001 C000 0x4002 0000 0x4002 4000 0x4002 8000 0x4002 C000 0x4003 0000 0x4003 4000 0x4003 8000 0x4003 C000 0x4004 0000 0x4004 4000 0x4004 8000 0x4004 C000 to 0x4005 8000 0x4005 C000 0x4006 0000 to 0x4007 C000
Watchdog Timer Timer 0 Timer 1 UART0 UART1 reserved PWM1 I2C0 SPI RTC GPIO interrupts Pin Connect Block SSP1 ADC CAN Acceptance Filter RAM CAN Acceptance Filter Registers CAN Common Registers CAN Controller 1 CAN Controller 2 reserved I2C1 reserved
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APB1 peripherals and base addresses Base address Peripheral name
Table 5.
APB1 peripheral
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 to 30 31
0x4008 0000 0x4008 4000 0x4008 8000 0x4008 C000 0x4009 0000 0x4009 4000 0x4009 8000 0x4009 C000 0x400A 0000 0x400A 4000 0x400A 8000 0x400A C000 0x400B 0000 0x400B 4000 0x400B 8000 0x400B C000 0x400C 0000 to 0x400F 8000 0x400F C000
reserved reserved SSP0 DAC Timer 2 Timer 3 UART2 UART3 I2C2 reserved I2S reserved Repetitive interrupt timer reserved Motor control PWM Quadrature Encoder Interface reserved System control
4. Memory re-mapping
The Cortex-M3 incorporates a mechanism that allows remapping the interrupt vector table to alternate locations in the memory map. This is controlled via the Vector Table Offset Register contained in the Cortex-M3. Refer to Section 6-4 and Section 34-4.3.5 of the Cortex-M3 User Guide appended to this manual for details of the Vector Table Offset feature.
Boot ROM re-mapping
Following a hardware reset, the Boot ROM is temporarily mapped to address 0. This is normally transparent to the user. However, if execution is halted immediately after reset by a debugger, it should correct the mapping for the user. See Section 33-6.
5. AHB arbitration
The Multilayer AHB Matrix arbitrates between several masters. By default, the Cortex-M3 D-code bus has the highest priority, followed by the I-Code bus. All other masters share a lower priority.
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Chapter 2: LPC17xx Memory map
6. Bus fault exceptions
The LPC17xx generates Bus Fault exception if an access is attempted for an address that is in a reserved or unassigned address region. The regions are areas of the memory map that are not implemented for a specific derivative. These include all spaces marked "reserved" in Figure 2-3. For these areas, both attempted data access and instruction fetch generate an exception. In addition, a Bus Fault exception is generated for any instruction fetch that maps to an AHB or APB peripheral address. Within the address space of an existing APB peripheral, an exception is not generated in response to an access to an undefined address. Address decoding within each peripheral is limited to that needed to distinguish defined registers within the peripheral itself. For example, an access to address 0x4000 D000 (an undefined address within the UART0 space) may result in an access to the register defined at address 0x4000 C000. Details of such address aliasing within a peripheral space are not defined in the LPC17xx documentation and are not a supported feature. If software executes a write directly to the flash memory, the flash accelerator will generate a Bus Fault exception. Flash programming must be accomplished by using the specified flash programming interface provided by the Boot Code. Note that the Cortex-M3 core stores the exception flag along with the associated instruction in the pipeline and processes the exception only if an attempt is made to execute the instruction fetched from the disallowed address. This prevents accidental aborts that could be caused by prefetches that occur when code is executed very near a memory boundary.
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1. Introduction
The system control block includes several system features and control registers for a number of functions that are not related to specific peripheral devices. These include:
* * * * *
Reset Brown-Out Detection External Interrupt Inputs Miscellaneous System Controls and Status Code Security vs. Debugging
Each type of function has its own register(s) if any are required and unneeded bits are defined as reserved in order to allow future expansion. Unrelated functions never share the same register addresses
2. Pin description
Table 3-6 shows pins that are associated with System Control block functions.
Table 6. Pin name Pin summary Pin direction Pin description External Interrupt Input 0 - An active low/high level or falling/rising edge general purpose interrupt input. This pin may be used to wake up the processor from Sleep, Deep-sleep, or Power-down modes. External Interrupt Input 1 - See the EINT0 description above. External Interrupt Input 2 - See the EINT0 description above. External Interrupt Input 3 - See the EINT0 description above. External Reset input - A LOW on this pin resets the chip, causing I/O ports and peripherals to take on their default states, and the processor to begin execution at address 0x0000 0000.
EINT0
Input
EINT1 EINT2 EINT3 RESET
Input Input Input Input
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3. Register description
All registers, regardless of size, are on word address boundaries. Details of the registers appear in the description of each function.
Table 7. Name Summary of system control registers Description Access Reset value Address
External Interrupts
EXTINT EXTMODE EXTPOLAR
Reset
External Interrupt Flag Register External Interrupt Mode register External Interrupt Polarity Register Reset Source Identification Register System Control and Status
R/W R/W R/W R/W R/W
0 0 0 see Table 3-8 0
0x400F C140 0x400F C148 0x400F C14C 0x400F C180 0x400F C1A0
RSID SCS
Syscon Miscellaneous Registers
4. Reset
Reset has 4 sources on the LPC17xx: the RESET pin, Watchdog Reset, Power On Reset (POR), and Brown Out Detect (BOD). The RESET pin is a Schmitt trigger input pin. Assertion of chip Reset by any source, once the operating voltage attains a usable level, starts the wake-up timer (see description in Section 4-9 "Wake-up timer" in this chapter), causing reset to remain asserted until the external Reset is de-asserted, the oscillator is running, a fixed number of clocks have passed, and the flash controller has completed its initialization. The reset logic is shown in the following block diagram (see Figure 3-4).
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external reset watchdog reset POR BOD
C Q S
Reset to the on-chip circuitry
Reset to PCON.PD
WAKE-UP TIMER START power-down COUNT 2 n internal RC oscillator write "1" from APB reset APB read of PDBIT in PCON FOSC to other blocks C Q S
EINT0 wake-up EINT1 wake-up EINT2 wake-up EINT3 wake-up RTC wake-up BOD wake-up Ethernet MAC wake-up USB need_clk wake-up CAN wake-up GPIO0 port wake-up GPIO2 port wake-up
Fig 4.
Reset block diagram including the wake-up timer
On the assertion of a reset source external to the Cortex-M3 CPU (POR, BOD reset, External reset, and Watchdog reset), the IRC starts up. After the IRC-start-up time (maximum of 60 s on power-up) and after the IRC provides a stable clock output, the reset signal is latched and synchronized on the IRC clock. Then the following two sequences start simultaneously: 1. The 2-bit IRC wake-up timer starts counting when the synchronized reset is de-asserted. The boot code in the ROM starts when the 2-bit IRC wake-up timer times out. The boot code performs the boot tasks and may jump to the flash. If the flash is not ready to access, the Flash Accelerator will insert wait cycles until the flash is ready. 2. The flash wake-up timer (9-bit) starts counting when the synchronized reset is de-asserted. The flash wakeup-timer generates the 100 s flash start-up time. Once it times out, the flash initialization sequence is started, which takes about 250 cycles. When it's done, the Flash Accelerator will be granted access to the flash. When the internal Reset is removed, the processor begins executing at address 0, which is initially the Reset vector mapped from the Boot Block. At that point, all of the processor and peripheral registers have been initialized to predetermined values. Figure 3-5 shows an example of the relationship between the RESET, the IRC, and the processor status when the LPC17xx starts up after reset. See Section 4-3.2 "Main oscillator" for start-up of the main oscillator if selected by the user code.
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IRC starts
IRC stable
IRC status
RESET
VDD(REG)(3V3) valid threshold
GND 60 s 1 s; IRC stability count boot time boot code executing processor status boot code execution finishes; user code starts user code
supply ramp-up time
Fig 5.
Example of start-up after reset
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4.1 Reset Source Identification Register (RSID - 0x400F C180)
This register contains one bit for each source of Reset. Writing a 1 to any of these bits clears the corresponding read-side bit to 0. The interactions among the four sources are described below.
Table 8. Bit Reset Source Identification register (RSID - address 0x400F C180) bit description Reset value
Symbol Description
0
POR
Assertion of the POR signal sets this bit, and clears all of the other bits in this register. But if another Reset signal (e.g., External Reset) remains asserted after the POR signal is negated, then its bit is set. This bit is not affected by any of the other sources of Reset.
See text
1 2
EXTR WDTR
Assertion of the RESET signal sets this bit. This bit is cleared by POR, but See is not affected by WDT or BOD reset. text This bit is set when the Watchdog Timer times out and the WDTRESET bit See in the Watchdog Mode Register is 1. It is cleared by any of the other text sources of Reset. This bit is set when the VDD(REG)(3V3) voltage reaches a level below the BOD reset trip level (typically 1.85 V under nominal room temperature conditions). If the VDD(REG)(3V3) voltage dips from the normal operating range to below the BOD reset trip level and recovers, the BODR bit will be set to 1. If the VDD(REG)(3V3) voltage dips from the normal operating range to below the BOD reset trip level and continues to decline to the level at which POR is asserted (nominally 1 V), the BODR bit is cleared. If the VDD(REG)(3V3) voltage rises continuously from below 1 V to a level above the BOD reset trip level, the BODR will be set to 1. This bit is not affected by External Reset nor Watchdog Reset.
Note: Only in the case where a reset occurs and the POR = 0, the BODR bit indicates if the VDD(REG)(3V3) voltage was below the BOD reset trip level or not.
3
BODR
See text
31:4 -
Reserved, user software should not write ones to reserved bits. The value NA read from a reserved bit is not defined.
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5. Brown-out detection
The LPC17xx includes a Brown-Out Detector (BOD) that provides 2-stage monitoring of the voltage on the VDD(REG)(3V3) pins. If this voltage falls below the BOD interrupt trip level (typically 2.2 V under nominal room temperature conditions), the BOD asserts an interrupt signal to the NVIC. This signal can be enabled for interrupt in the Interrupt Enable Register in the NVIC in order to cause a CPU interrupt; if not, software can monitor the signal by reading the Raw Interrupt Status Register. The second stage of low-voltage detection asserts Reset to inactivate the LPC17xx when the voltage on the VDD(REG)(3V3) pins falls below the BOD reset trip level (typically 1.85 V under nominal room temperature conditions). This Reset prevents alteration of the flash as operation of the various elements of the chip would otherwise become unreliable due to low voltage. The BOD circuit maintains this reset down below 1 V, at which point the Power-On Reset circuitry maintains the overall Reset. Both the BOD reset interrupt level and the BOD reset trip level thresholds include some hysteresis. In normal operation, this hysteresis allows the BOD reset interrupt level detection to reliably interrupt, or a regularly-executed event loop to sense the condition. But when Brown-Out Detection is enabled to bring the LPC17xx out of Power-down mode (which is itself not a guaranteed operation -- see Section 4-8.7 "Power Mode Control register (PCON - 0x400F C0C0)"), the supply voltage may recover from a transient before the wake-up timer has completed its delay. In this case, the net result of the transient BOD is that the part wakes up and continues operation after the instructions that set Power-down mode, without any interrupt occurring and with the BOD bit in the RSID being 0. Since all other wake-up conditions have latching flags (see Section 3-6.2 "External Interrupt flag register (EXTINT - 0x400F C140)" and Section 27-6.2), a wake-up of this type, without any apparent cause, can be assumed to be a Brown-Out that has gone away.
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6. External interrupt inputs
TheLPC17xx includes four External Interrupt Inputs as selectable pin functions. The logic of an individual external interrupt is represented in Figure 3-6. In addition, external interrupts have the ability to wake up the CPU from Power-down mode. Refer to Section 4-8.8 "Wake-up from Reduced Power Modes" for details.
wakeup enable (one bit of EXTWAKE)
APB Read of EXTWAKE
APB Bus Data
D
Q
EINTi to wakeup timer1
EINTi
GLITCH FILTER
PCLK
EXTPOLARi
interrupt flag (one bit of EXTINT) 1 D S Q
S Q R
S Q R APB read of EXTINT to VIC
EXTMODEi
PCLK reset write 1 to EXTINTi
PCLK
Fig 6.
External interrupt logic
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6.1 Register description
The external interrupt function has four registers associated with it. The EXTINT register contains the interrupt flags. The EXTMODE and EXTPOLAR registers specify the level and edge sensitivity parameters.
Table 9. Name External Interrupt registers Description Access Reset Address value[1]
EXTINT
The External Interrupt Flag Register contains interrupt flags for EINT0, EINT1, EINT2 and EINT3. See Table 3-10. The External Interrupt Mode Register controls whether each pin is edge- or level-sensitive. See Table 3-11.
R/W
0x00
0x400F C140
EXTMODE
R/W
0x00
0x400F C148
EXTPOLAR
The External Interrupt Polarity Register controls R/W which level or edge on each pin will cause an interrupt. See Table 3-12.
0x00
0x400F C14C
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
6.2 External Interrupt flag register (EXTINT - 0x400F C140)
When a pin is selected for its external interrupt function, the level or edge on that pin (selected by its bits in the EXTPOLAR and EXTMODE registers) will set its interrupt flag in this register. This asserts the corresponding interrupt request to the NVIC, which will cause an interrupt if interrupts from the pin are enabled. Writing ones to bits EINT0 through EINT3 in EXTINT register clears the corresponding bits. In level-sensitive mode the interrupt is cleared only when the pin is in its inactive state. Once a bit from EINT0 to EINT3 is set and an appropriate code starts to execute (handling wake-up and/or external interrupt), this bit in EXTINT register must be cleared. Otherwise event that was just triggered by activity on the EINT pin will not be recognized in future. Important: whenever a change of external interrupt operating mode (i.e. active level/edge) is performed (including the initialization of an external interrupt), the corresponding bit in the EXTINT register must be cleared! For details see Section 3-6.3 "External Interrupt Mode register (EXTMODE - 0x400F C148)" and Section 3-6.4 "External Interrupt Polarity register (EXTPOLAR - 0x400F C14C)". For example, if a system wakes up from Power-down using low level on external interrupt 0 pin, its post wake-up code must reset EINT0 bit in order to allow future entry into the Power-down mode. If EINT0 bit is left set to 1, subsequent attempt(s) to invoke Power-down mode will fail. The same goes for external interrupt handling. More details on Power-down mode will be discussed in the following chapters.
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External Interrupt Flag register (EXTINT - address 0x400F C140) bit description Reset value
Table 10. Bit
Symbol Description
0
EINT0
In level-sensitive mode, this bit is set if the EINT0 function is selected for its pin, and the pin is in its active state. In edge-sensitive mode, this bit is set if the EINT0 function is selected for its pin, and the selected edge occurs on the pin. This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active state.[1]
0
1
EINT1
In level-sensitive mode, this bit is set if the EINT1 function is selected for its pin, and the pin is in its active state. In edge-sensitive mode, this bit is set if the EINT1 function is selected for its pin, and the selected edge occurs on the pin. This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active state.[1]
0
2
EINT2
In level-sensitive mode, this bit is set if the EINT2 function is selected for its pin, and the pin is in its active state. In edge-sensitive mode, this bit is set if the EINT2 function is selected for its pin, and the selected edge occurs on the pin. This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active state.[1]
0
3
EINT3
In level-sensitive mode, this bit is set if the EINT3 function is selected for its pin, and the pin is in its active state. In edge-sensitive mode, this bit is set if the EINT3 function is selected for its pin, and the selected edge occurs on the pin. This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active state.[1]
0
31:4 [1]
Reserved, user software should not write ones to reserved bits. The value NA read from a reserved bit is not defined.
Example: e.g. if the EINTx is selected to be low level sensitive and low level is present on
corresponding pin, this bit can not be cleared; this bit can be cleared only when signal on the pin becomes high.
6.3 External Interrupt Mode register (EXTMODE - 0x400F C148)
The bits in this register select whether each EINT pin is level- or edge-sensitive. Only pins that are selected for the EINT function (see Section 8-5) and enabled in the appropriate NVIC register) can cause interrupts from the External Interrupt function (though of course pins selected for other functions may cause interrupts from those functions). Note: Software should only change a bit in this register when its interrupt is disabled in the NVIC (state readable in the ISERn/ICERn registers), and should write the corresponding 1 to EXTINT before enabling (initializing) or re-enabling the interrupt. An extraneous interrupt(s) could be set by changing the mode and not having the EXTINT cleared.
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External Interrupt Mode register (EXTMODE - address 0x400F C148) bit description Value Description Reset value
Table 11. Bit
Symbol
0 1 2 3
EXTMODE0 EXTMODE1 EXTMODE2 EXTMODE3
0 1 0 1 0 1 0 1 -
Level-sensitivity is selected for EINT0. EINT0 is edge sensitive. Level-sensitivity is selected for EINT1. EINT1 is edge sensitive. Level-sensitivity is selected for EINT2. EINT2 is edge sensitive. Level-sensitivity is selected for EINT3. EINT3 is edge sensitive. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 0 0 NA
31:4 -
6.4 External Interrupt Polarity register (EXTPOLAR - 0x400F C14C)
In level-sensitive mode, the bits in this register select whether the corresponding pin is high- or low-active. In edge-sensitive mode, they select whether the pin is rising- or falling-edge sensitive. Only pins that are selected for the EINT function Only pins that are selected for the EINT function (see Section 8-5) and enabled in the appropriate NVIC register) can cause interrupts from the External Interrupt function (though of course pins selected for other functions may cause interrupts from those functions). Note: Software should only change a bit in this register when its interrupt is disabled in the NVIC (state readable in the ISERn/ICERn registers), and should write the corresponding 1 to EXTINT before enabling (initializing) or re-enabling the interrupt. An extraneous interrupt(s) could be set by changing the polarity and not having the EXTINT cleared.
Table 12. Bit External Interrupt Polarity register (EXTPOLAR - address 0x400F C14C) bit description Value Description Reset value
Symbol
0
EXTPOLAR0 0 1
EINT0 is low-active or falling-edge sensitive (depending on EXTMODE0). EINT0 is high-active or rising-edge sensitive (depending on EXTMODE0). EINT1 is low-active or falling-edge sensitive (depending on EXTMODE1). EINT1 is high-active or rising-edge sensitive (depending on EXTMODE1). EINT2 is low-active or falling-edge sensitive (depending on EXTMODE2). EINT2 is high-active or rising-edge sensitive (depending on EXTMODE2).
0
1
EXTPOLAR1 0 1
0
2
EXTPOLAR2 0 1
0
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External Interrupt Polarity register (EXTPOLAR - address 0x400F C14C) bit description Value Description Reset value
Table 12. Bit
Symbol
3
EXTPOLAR3 0 1
EINT3 is low-active or falling-edge sensitive (depending on EXTMODE3). EINT3 is high-active or rising-edge sensitive (depending on EXTMODE3). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
31:4 -
-
NA
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7. Other system controls and status flags
Some aspects of controlling LPC17xx operation that do not fit into peripheral or other registers are grouped here.
7.1 System Controls and Status register (SCS - 0x400F C1A0)
The SCS register contains several control/status bits related to the main oscillator. Since chip operation always begins using the Internal RC Oscillator, and the main oscillator may not be used at all in some applications, it will only be started by software request. This is accomplished by setting the OSCEN bit in the SCS register, as described in Table 3-13. The main oscillator provides a status flag (the OSCSTAT bit in the SCS register) so that software can determine when the oscillator is running and stable. At that point, software can control switching to the main oscillator as a clock source. Prior to starting the main oscillator, a frequency range must be selected by configuring the OSCRANGE bit in the SCS register.
Table 13. Bit System Controls and Status register (SCS - address 0x400F C1A0) bit description Value Description Access Reset value
Symbol
3:0
-
-
Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. Main oscillator range select. R/W The frequency range of the main oscillator is 1 MHz to 20 MHz. The frequency range of the main oscillator is 15 MHz to 25 MHz. Main oscillator enable. R/W
NA
4
OSCRANGE 0 1
0
5
OSCEN 0 1
0
The main oscillator is disabled. The main oscillator is enabled, and will start up if the correct external circuitry is connected to the XTAL1 and XTAL2 pins. Main oscillator status. RO 0 The main oscillator is not ready to be used as a clock source. The main oscillator is ready to be used as a clock source. The main oscillator must be enabled via the OSCEN bit. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
6
OSCSTAT 0 1
31:7 -
-
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1. Summary of clocking and power control functions
This section describes the generation of the various clocks needed by the LPC17xx and options of clock source selection, as well as power control and wake-up from reduced power modes. Functions described in the following subsections include:
* * * * * * * *
Oscillators Clock source selection PLLs Clock dividers APB dividers Power control Wake-up timer External clock output
USB PLL settings (PLL1...)
USB PLL select (PLL1CON)
USB PLL (PLL1)
main PLL settings (PLL0...) CPU PLL select (PLL0CON)
usb_clk
USB Clock Divider USB clock divider setting USBCLKCFG[3:0]
osc_clk rtc_clk irc_osc
sysclk
Main PLL (PLL0)
pllclk
CPU Clock Divider
cclk
system clock select CLKSRCSEL[1:0]
CPU clock divider setting CCLKCFG[7:0] Peripheral Clock Divider
pclk1 pclk2 pclk4 pclk8 wd_clk
watchdog clock select WDCLKSEL[1:0]
PCLK_WDT
Fig 7.
Clock generation for the LPC17xx
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2. Register description
All registers, regardless of size, are on word address boundaries. Details of the registers appear in the description of each function.
Table 14. Name Summary of system control registers Description Access Reset value Address
Clock source selection
CLKSRCSEL PLL0CON PLL0CFG PLL0STAT PLL0FEED PLL1CON PLL1CFG PLL1STAT PLL1FEED
Clock dividers
Clock Source Select Register PLL0 Control Register PLL0 Configuration Register PLL0 Status Register PLL0 Feed Register PLL1 Control Register PLL1 Configuration Register PLL1 Status Register PLL1 Feed Register CPU Clock Configuration Register USB Clock Configuration Register Peripheral Clock Selection register 0. Peripheral Clock Selection register 1. Power Control Register Power Control for Peripherals Register Clock Output Configuration Register
R/W R/W R/W RO WO R/W R/W RO WO R/W R/W R/W R/W R/W R/W R/W
0 0 0 0 NA 0 0 0 NA 0 0 0 0 0 0x03BE 0
0x400F C10C 0x400F C080 0x400F C084 0x400F C088 0x400F C08C 0x400F C0A0 0x400F C0A4 0x400F C0A8 0x400F C0AC 0x400F C104 0x400F C108 0x400F C1A8 0x400F C1AC 0x400F C0C0 0x400F C0C4 0x400F C1C8
Phase Locked Loop (PLL0, Main PLL)
Phase Locked Loop (PLL1, USB PLL)
CCLKCFG USBCLKCFG PCLKSEL0 PCLKSEL1
Power control
PCON PCONP
Utility
CLKOUTCFG
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3. Oscillators
The LPC17xx includes three independent oscillators. These are the Main Oscillator, the Internal RC Oscillator, and the RTC oscillator. Each oscillator can be used for more than one purpose as required in a particular application. This can be seen in Figure 4-7. Following Reset, the LPC17xx will operate from the Internal RC Oscillator until switched by software. This allows systems to operate without any external crystal, and allows the boot loader code to operate at a known frequency.
3.1 Internal RC oscillator
The Internal RC Oscillator (IRC) may be used as the clock source for the watchdog timer, and/or as the clock that drives PLL0 and subsequently the CPU. The precision of the IRC does not allow for use of the USB interface, which requires a much more precise time base in order to comply with the USB specification. Also, the IRC should not be used with the CAN1/2 block if the CAN baud rate is higher than 100 kbit/s.The nominal IRC frequency is 4 MHz. Upon power-up or any chip reset, the LPC17xx uses the IRC as the clock source. Software may later switch to one of the other available clock sources.
3.2 Main oscillator
The main oscillator can be used as the clock source for the CPU, with or without using PLL0. The main oscillator operates at frequencies of 1 MHz to 25 MHz. This frequency can be boosted to a higher frequency, up to the maximum CPU operating frequency, by the Main PLL (PLL0). The oscillator output is called OSC_CLK. The clock selected as the PLL0 input is PLLCLKIN and the ARM processor clock frequency is referred to as CCLK for purposes of rate equations, etc. elsewhere in this document. The frequencies of PLLCLKIN and CCLK are the same value unless the PLL0 is active and connected. Refer to Section 4-5 "PLL0 (Phase Locked Loop 0)" for details. The on-board oscillator in the LPC17xx can operate in one of two modes: slave mode and oscillation mode. In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF (CC in Figure 4-8, drawing a), with an amplitude between 200 mVrms and 1000 mVrms. This corresponds to a square wave signal with a signal swing of between 280 mV and 1.4 V. The XTAL2 pin in this configuration can be left unconnected. External components and models used in oscillation mode are shown in Figure 4-8, drawings b and c, and in Table 4-15 and Table 4-16. Since the feedback resistance is integrated on chip, only a crystal and the capacitances CX1 and CX2 need to be connected externally in case of fundamental mode oscillation (the fundamental frequency is represented by L, CL and RS). Capacitance CP in Figure 4-8, drawing c, represents the parallel package capacitance and should not be larger than 7 pF. Parameters FC, CL, RS and CP are supplied by the crystal manufacturer.
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LPC17xx
LPC17xx
XTAL1
XTAL2
XTAL1
XTAL2 L
CC Xtal Clock CX1 CX2
<=>
CL RS
CP
a)
b)
c)
Fig 8.
Oscillator modes and models: a) slave mode of operation, b) oscillation mode of operation, c) external crystal model used for CX1/X2 evaluation Table 15. Recommended values for CX1/X2 in oscillation mode (crystal and external components parameters) low frequency mode (OSCRANGE = 0, see Table 3-13) Crystal load capacitance CL Maximum crystal series resistance RS External load capacitors CX1, CX2
Fundamental oscillation frequency FOSC
1 MHz - 5 MHz
10 pF 20 pF 30 pF
< 300 < 300 < 300 < 300 < 200 < 100 < 160 < 60 < 80
18 pF, 18 pF 39 pF, 39 pF 57 pF, 57 pF 18 pF, 18 pF 39 pF, 39 pF 57 pF, 57 pF 18 pF, 18 pF 39 pF, 39 pF 18 pF, 18 pF
5 MHz - 10 MHz
10 pF 20 pF 30 pF
10 MHz - 15 MHz 15 MHz - 20 MHz
Table 16.
10 pF 20 pF 10 pF
Recommended values for CX1/X2 in oscillation mode (crystal and external components parameters) high frequency mode (OSCRANGE = 1, see Table 3-13) Crystal load capacitance CL Maximum crystal series resistance RS External load capacitors CX1, CX2
Fundamental oscillation frequency FOSC
15 MHz - 20 MHz 20 MHz - 25 MHz
10 pF 20 pF 10 pF 20 pF
< 180 < 100 < 160 < 80
18 pF, 18 pF 39 pF, 39 pF 18 pF, 18 pF 39 pF, 39 pF
Since chip operation always begins using the Internal RC Oscillator, and the main oscillator may not be used at all in some applications, it will only be started by software request. This is accomplished by setting the OSCEN bit in the SCS register, as described in Table 3-13. The main oscillator provides a status flag (the OSCSTAT bit in the SCS register) so that software can determine when the oscillator is running and stable. At that
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point, software can control switching to the main oscillator as a clock source. Prior to starting the main oscillator, a frequency range must be selected by configuring the OSCRANGE bit in the SCS register.
3.3 RTC oscillator
The RTC oscillator provides a 1 Hz clock to the RTC and a 32 kHz clock output that can be used as the clock source for PLL0 and CPU and/or the watchdog timer.
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4. Clock source selection multiplexer
Several clock sources may be chosen to drive PLL0 and ultimately the CPU and on-chip peripheral devices. The clock sources available are the main oscillator, the RTC oscillator, and the Internal RC oscillator. The clock source selection can only be changed safely when PLL0 is not connected. For a detailed description of how to change the clock source in a system using PLL0 see Section 4-5.13 "PLL0 setup sequence". Note the following restrictions regarding the choice of clock sources:
* The IRC oscillator should not be used (via PLL0) as the clock source for the USB
subsystem.
* The IRC oscillator should not be used (via PLL0) as the clock source for the CAN
controllers if the CAN baud rate is higher than 100 kbit/s.
4.1 Clock Source Select register (CLKSRCSEL - 0x400F C10C)
The CLKSRCSEL register contains the bits that select the clock source for PLL0.
Table 17. Bit Clock Source Select register (CLKSRCSEL - address 0x400F C10C) bit description Value Description Reset value
Symbol
1:0
CLKSRC 00 01 10 11
Selects the clock source for PLL0 as follows: Selects the Internal RC oscillator as the PLL0 clock source (default). Selects the main oscillator as the PLL0 clock source. Selects the RTC oscillator as the PLL0 clock source. Reserved, do not use this setting.
0
Warning: Improper setting of this value, or an incorrect sequence of changing this value may result in incorrect operation of the device.
31:2
-
0
Reserved, user software should not write ones to reserved bits. NA The value read from a reserved bit is not defined.
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5. PLL0 (Phase Locked Loop 0)
PLL0 accepts an input clock frequency in the range of 32 kHz to 50 MHz. The clock source is selected in the CLKSRCSEL register (see Section 4-4). The input frequency is multiplied up to a high frequency, then divided down to provide the actual clock used by the CPU, peripherals, and optionally the USB subsystem. Note that the USB subsystem has its own dedicated PLL (see Section 4-6). PLL0 can produce a clock up to the maximum allowed for the CPU, which is 120 MHz on high speed versions (LPC1769 and LPC1759), and 100 MHz on other versions.
5.1 PLL0 operation
The PLL input, in the range of 32 kHZ to 50 MHz, may initially be divided down by a value "N", which may be in the range of 1 to 256. This input division provides a greater number of possibilities in providing a wide range of output frequencies from the same input frequency. Following the PLL input divider is the PLL multiplier. This can multiply the input divider output through the use of a Current Controlled Oscillator (CCO) by a value "M", in the range of 6 through 512, plus additional values listed in Table 4-21. The resulting frequency must be in the range of 275 MHz to 550 MHz. The multiplier works by dividing the CCO output by the value of M, then using a phase-frequency detector to compare the divided CCO output to the multiplier input. The error value is used to adjust the CCO frequency. There are additional dividers at the output of PLL0 to bring the frequency down to what is needed for the CPU, peripherals, and potentially the USB subsystem. PLL0 output dividers are described in the Clock Dividers section following the PLL0 description. A block diagram of PLL0 is shown in Figure 4-9 PLL activation is controlled via the PLL0CON register. PLL0 multiplier and divider values are controlled by the PLL0CFG register. These two registers are protected in order to prevent accidental alteration of PLL0 parameters or deactivation of the PLL. Since all chip operations, including the Watchdog Timer, could be dependent on PLL0 if so configured (for example when it is providing the chip clock), accidental changes to the PLL0 setup values could result in unexpected or fatal behavior of the microcontroller. The protection is accomplished by a feed sequence similar to that of the Watchdog Timer. Details are provided in the description of the PLL0FEED register. PLL0 is turned off and bypassed following a chip Reset and by entering Power-down mode. PLL0 must be configured, enabled, and connected to the system by software. It is important that the setup procedure described in Section 4-5.13 "PLL0 setup sequence" is followed or PLL0 might not operate at all!
5.1.1 PLL0 and startup/boot code interaction
When there is no valid user code (determined by the checksum word) in the user flash or the ISP enable pin (P2.10) is pulled low on startup, the ISP mode will be entered and the boot code will setup the PLL with the IRC. Therefore it can not be assumed that the PLL is disabled when the user opens a debug session to debug the application code. The user startup code must follow the steps described in this chapter to disconnect the PLL.
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5.2 PLL0 register description
PLL0 is controlled by the registers shown in Table 4-18. More detailed descriptions follow. Warning: Improper setting of PLL0 values may result in incorrect operation of the device!
Table 18. Name PLL0 registers Description Access Reset Address value[1]
PLL0CON
PLL0 Control Register. Holding register for R/W updating PLL0 control bits. Values written to this register do not take effect until a valid PLL0 feed sequence has taken place. PLL0 Configuration Register. Holding register for R/W updating PLL0 configuration values. Values written to this register do not take effect until a valid PLL0 feed sequence has taken place. PLL0 Status Register. Read-back register for RO PLL0 control and configuration information. If PLL0CON or PLL0CFG have been written to, but a PLL0 feed sequence has not yet occurred, they will not reflect the current PLL0 state. Reading this register provides the actual values controlling the PLL0, as well as the PLL0 status. PLL0 Feed Register. This register enables loading of the PLL0 control and configuration information from the PLL0CON and PLL0CFG registers into the shadow registers that actually affect PLL0 operation. WO
0
0x400F C080
PLL0CFG
0
0x400F C084
PLL0STAT
0
0x400F C088
PLL0FEED
NA
0x400F C08C
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
PLLC PLLE PLOCK pd refclk pllclkin NSEL [7:0] MSEL [14:0] N-DIVIDER
PHASEFREQUENCY DETECTOR
FILTER
CCO
pllclk
M-DIVIDER
/2
Fig 9.
PLL0 block diagram
5.3 PLL0 Control register (PLL0CON - 0x400F C080)
The PLL0CON register contains the bits that enable and connect PLL0. Enabling PLL0 allows it to attempt to lock to the current settings of the multiplier and divider values. Connecting PLL0 causes the processor and most chip functions to run from the PLL0
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output clock. Changes to the PLL0CON register do not take effect until a correct PLL0 feed sequence has been given (see Section 4-5.8 "PLL0 Feed register (PLL0FEED 0x400F C08C)").
Table 19. Bit PLL Control register (PLL0CON - address 0x400F C080) bit description Description Reset value
Symbol
0
PLLE0
PLL0 Enable. When one, and after a valid PLL0 feed, this bit will activate 0 PLL0 and allow it to lock to the requested frequency. See PLL0STAT register, Table 4-22. PLL0 Connect. Setting PLLC0 to one after PLL0 has been enabled and locked, then followed by a valid PLL0 feed sequence causes PLL0 to become the clock source for the CPU, AHB peripherals, and used to derive the clocks for APB peripherals. The PLL0 output may potentially be used to clock the USB subsystem if the frequency is 48 MHz. See PLL0STAT register, Table 4-22. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0
1
PLLC0
31:2
-
NA
PLL0 must be set up, enabled, and Lock established before it may be used as a clock source. When switching from the oscillator clock to the PLL0 output or vice versa, internal circuitry synchronizes the operation in order to ensure that glitches are not generated. Hardware does not insure that PLL0 is locked before it is connected or automatically disconnect PLL0 if lock is lost during operation. In the event of loss of lock on PLL0, it is likely that the oscillator clock has become unstable and disconnecting PLL0 will not remedy the situation.
5.4 PLL0 Configuration register (PLL0CFG - 0x400F C084)
The PLL0CFG register contains PLL0 multiplier and divider values. Changes to the PLL0CFG register do not take effect until a correct PLL feed sequence has been given (see Section 4-5.8 "PLL0 Feed register (PLL0FEED - 0x400F C08C)"). Calculations for the PLL frequency, and multiplier and divider values are found in the Section 4-5.10 "PLL0 frequency calculation".
Table 20. Bit PLL0 Configuration register (PLL0CFG - address 0x400F C084) bit description Description Reset value
Symbol
14:0
MSEL0
PLL0 Multiplier value. Supplies the value "M" in PLL0 frequency calculations. The value stored here is M - 1. Supported values for M are 6 through 512 and those listed in Table 4-21.
Note: Not all values of M are needed, and therefore some are not supported by hardware. For details on selecting values for MSEL0 see Section 4-5.10 "PLL0 frequency calculation".
0
15
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
23:16 NSEL0
PLL0 Pre-Divider value. Supplies the value "N" in PLL0 frequency 0 calculations. The value stored here is N - 1. Supported values for N are 1 through 32.
Note: For details on selecting the right value for NSEL0 see Section 4-5.10 "PLL0 frequency calculation".
31:24 -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
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Multiplier values for PLL0 with a 32 kHz input Pre-divide (N) FCCO Multiplier (M) Pre-divide (N) FCCO
Table 21. Multiplier (M)
4272 4395 4578 4725 4807 5127 5188 5400 5493 5859 6042 6075 6104 6409 6592 6750 6836 6866 6958 7050 7324 7425 7690 7813 7935 8057 8100 8545 8789 9155 9613 10254 10376 10986 11719
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2
279.9698 288.0307 300.0238 309.6576 315.0316 336.0031 340.0008 353.8944 359.9892 383.9754 395.9685 398.1312 400.0317 420.0202 432.0133 442.3680 448.0041 449.9702 455.9995 462.0288 479.9857 486.6048 503.9718 512.0328 520.0282 528.0236 530.8416 280.0026 287.9980 299.9910 314.9988 336.0031 340.0008 359.9892 384.0082
12085 12207 12817 12817 13184 13184 13672 13733 13733 13916 14099 14420 14648 15381 15381 15564 15625 15869 16113 16479 17578 18127 18311 19226 19775 20508 20599 20874 21149 21973 23071 23438 23804 24170
2 2 2 3 2 3 2 2 3 2 2 3 2 2 3 3 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
396.0013 399.9990 419.9875 279.9916 432.0133 288.0089 448.0041 450.0029 300.0020 455.9995 461.9960 315.0097 479.9857 504.0046 336.0031 340.0008 512.0000 519.9954 527.9908 359.9892 383.9973 395.9904 400.0099 419.9984 431.9915 448.0041 449.9920 455.9995 462.0070 480.0075 503.9937 512.0109 520.0063 528.0017
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5.5 PLL0 Status register (PLL0STAT - 0x400F C088)
The read-only PLL0STAT register provides the actual PLL0 parameters that are in effect at the time it is read, as well as PLL0 status. PLL0STAT may disagree with values found in PLL0CON and PLL0CFG because changes to those registers do not take effect until a proper PLL0 feed has occurred (see Section 4-5.8 "PLL0 Feed register (PLL0FEED 0x400F C08C)").
Table 22. Bit PLL Status register (PLL0STAT - address 0x400F C088) bit description Description Reset value
Symbol
14:0 15
MSEL0 -
Read-back for the PLL0 Multiplier value. This is the value currently 0 used by PLL0, and is one less than the actual multiplier. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Read-back for the PLL0 Pre-Divider value. This is the value currently used by PLL0, and is one less than the actual divider. NA 0
23:16 NSEL0 24
PLLE0_STAT Read-back for the PLL0 Enable bit. This bit reflects the state of the 0 PLEC0 bit in PLL0CON (see Table 4-19) after a valid PLL0 feed. When one, PLL0 is currently enabled. When zero, PLL0 is turned off. This bit is automatically cleared when Power-down mode is entered.
25
PLLC0_STAT Read-back for the PLL0 Connect bit. This bit reflects the state of the PLLC0 bit in PLL0CON (see Table 4-19) after a valid PLL0 feed. When PLLC0 and PLLE0 are both one, PLL0 is connected as the clock source for the CPU. When either PLLC0 or PLLE0 is zero, PLL0 is bypassed. This bit is automatically cleared when Power-down mode is entered.
0
26
PLOCK0
Reflects the PLL0 Lock status. When zero, PLL0 is not locked. When one, PLL0 is locked onto the requested frequency. See text for details. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
31:27 -
NA
5.6 PLL0 Interrupt: PLOCK0
The PLOCK0 bit in the PLL0STAT register reflects the lock status of PLL0. When PLL0 is enabled, or parameters are changed, PLL0 requires some time to establish lock under the new conditions. PLOCK0 can be monitored to determine when PLL0 may be connected for use. The value of PLOCK0 may not be stable when the PLL reference frequency (FREF, the frequency of REFCLK, which is equal to the PLL input frequency divided by the pre-divider value) is less than 100 kHz or greater than 20 MHz. In these cases, the PLL may be assumed to be stable after a start-up time has passed. This time is 500 s when FREF is greater than 400 kHz and 200 / FREF seconds when FREF is less than 400 kHz PLOCK0 is connected to the interrupt controller. This allows for software to turn on PLL0 and continue with other functions without having to wait for PLL0 to achieve lock. When the interrupt occurs, PLL0 may be connected, and the interrupt disabled. PLOCK0 appears as interrupt 32 in Table 6-50. Note that PLOCK0 remains asserted whenever PLL0 is locked, so if the interrupt is used, the interrupt service routine must disable the PLOCK0 interrupt prior to exiting.
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5.7 PLL0 Modes
The combinations of PLLE0 and PLLC0 are shown in Table 4-23.
Table 23. PLL control bit combinations
PLLC0 PLLE0 PLL Function
0 0 1 1
0 1 0 1
PLL0 is turned off and disconnected. PLL0 outputs the unmodified clock input. PLL0 is active, but not yet connected. PLL0 can be connected after PLOCK0 is asserted. Same as 00 combination. This prevents the possibility of PLL0 being connected without also being enabled. PLL0 is active and has been connected as the system clock source.
5.8 PLL0 Feed register (PLL0FEED - 0x400F C08C)
A correct feed sequence must be written to the PLL0FEED register in order for changes to the PLL0CON and PLL0CFG registers to take effect. The feed sequence is: 1. Write the value 0xAA to PLL0FEED. 2. Write the value 0x55 to PLL0FEED. The two writes must be in the correct sequence, and there must be no other register access in the same address space (0x400F C000 to 0x400F FFFF) between them. Because of this, it may be necessary to disable interrupts for the duration of the PLL0 feed operation, if there is a possibility that an interrupt service routine could write to another register in that space. If either of the feed values is incorrect, or one of the previously mentioned conditions is not met, any changes to the PLL0CON or PLL0CFG register will not become effective.
Table 24. Bit PLL Feed register (PLL0FEED - address 0x400F C08C) bit description Description Reset value
Symbol
7:0 31:8
PLL0FEED The PLL0 feed sequence must be written to this register in order for PLL0 configuration and control register changes to take effect. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
5.9 PLL0 and Power-down mode
Power-down mode automatically turns off and disconnects PLL0. Wake-up from Power-down mode does not automatically restore PLL0 settings, this must be done in software. Typically, a routine to activate PLL0, wait for lock, and then connect PLL0 can be called at the beginning of any interrupt service routine that might be called due to the wake-up. It is important not to attempt to restart PLL0 by simply feeding it when execution resumes after a wake-up from Power-down mode. This would enable and connect PLL0 at the same time, before PLL lock is established.
5.10 PLL0 frequency calculation
PLL0 equations use the following parameters:
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PLL frequency parameter Description
Table 25. Parameter
FIN FCCO N M FREF
the frequency of PLLCLKIN from the Clock Source Selection Multiplexer. the frequency of the PLLCLK (output of the PLL Current Controlled Oscillator) PLL0 Pre-divider value from the NSEL0 bits in the PLL0CFG register (PLL0CFG NSEL0 field + 1). N is an integer from 1 through 32. PLL0 Multiplier value from the MSEL0 bits in the PLL0CFG register (PLL0CFG MSEL0 field + 1). Not all potential values are supported. See below. PLL internal reference frequency, FIN divided by N.
The PLL0 output frequency (when PLL0 is both active and connected) is given by: FCCO = (2 x M x FIN) / N PLL inputs and settings must meet the following:
* FIN is in the range of 32 kHz to 50 MHz. * FCCO is in the range of 275 MHz to 550 MHz.
The equation can be solved for other PLL parameters: M = (FCCO x N) / (2 x FIN) N = (2 x M x FIN) / FCCO FIN = (FCCO x N) / (2 x M) Allowed values for M: At higher oscillator frequencies, in the MHz range, values of M from 6 through 512 are allowed. This supports the entire useful range of both the main oscillator and the IRC. For lower frequencies, specifically when the RTC is used to clock PLL0, a set of 65 additional M values have been selected for supporting baud rate generation, CAN/USB operation, and obtaining integer MHz frequencies. These values are shown in Table 4-26.
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Additional Multiplier Values for use with a Low Frequency Clock Input Low Frequency PLL Multipliers
Table 26.
4272 5127 6042 6750 7324 8057 9613 12085 13733 15381 16479 19775 21973
4395 5188 6075 6836 7425 8100 10254 12207 13916 15564 17578 20508 23071
4578 5400 6104 6866 7690 8545 10376 12817 14099 15625 18127 20599 23438
4725 5493 6409 6958 7813 8789 10986 13184 14420 15869 18311 20874 23804
4807 5859 6592 7050 7935 9155 11719 13672 14648 16113 19226 21149 24170
5.11 Procedure for determining PLL0 settings
PLL0 parameter determination can be simplified by using a spreadsheet available from NXP. To determine PLL0 parameters by hand, the following general procedure may be used: 1. Determine if the application requires use of the USB interface, and whether it will be clocked from PLL0. The USB requires a 50% duty cycle clock of 48 MHz within a very small tolerance, which means that FCCO must be an even integer multiple of 48 MHz (i.e. an integer multiple of 96 MHz), within a very small tolerance. 2. Choose the desired processor operating frequency (CCLK). This may be based on processor throughput requirements, need to support a specific set of UART baud rates, etc. Bear in mind that peripheral devices may be running from a lower clock frequency than that of the processor (see Section 4-7 "Clock dividers" on page 55 and Section 4-8 "Power control" on page 59). Find a value for FCCO that is close to a multiple of the desired CCLK frequency, bearing in mind the requirement for USB support in [1] above, and that lower values of FCCO result in lower power dissipation. 3. Choose a value for the PLL input frequency (FIN). This can be a clock obtained from the main oscillator, the RTC oscillator, or the on-chip RC oscillator. For USB support, the main oscillator should be used. Bear in mind that if PLL1 rather than PLL0 is used to clock the USB subsystem, this affects the choice of the main oscillator frequency. 4. Calculate values for M and N to produce a sufficiently accurate FCCO frequency. The desired M value -1 will be written to the MSEL0 field in PLL0CFG. The desired N value -1 will be written to the NSEL0 field in PLL0CFG. In general, it is better to use a smaller value for N, to reduce the level of multiplication that must be accomplished by the CCO. Due to the difficulty in finding the best values in some cases, it is recommended to use a spreadsheet or similar method to show many possibilities at once, from which an overall best choice may be selected. A spreadsheet is available from NXP for this purpose.
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5.12 Examples of PLL0 settings
The following table gives a summary of examples that illustrate selecting PLL0 values based on different system requirements.
Table 27. Example Summary of PLL0 examples Description
1
* The PLL0 clock source is 10 MHz. * PLL0 is not used as the USB clock source, or the USB interface is not used. * The desired CPU clock is 100 MHz.
2
* The PLL0 clock source is 4 MHz. * PLL0 is used as the USB clock source. * The desired CPU clock is 60 MHz.
3
* The PLL0 clock source is the 32.768 kHz RTC clock. * PLL0 is not used as the USB clock source, or the USB interface is not used. * The desired CPU clock is 72 MHz.
Example 1 Assumptions:
* The USB interface will not be used in the application, or will be clocked by PLL1. * The desired CPU rate is 100 MHz. * An external 10 MHz crystal or clock source will be used as the system clock source.
Calculations: M = (FCCO x N) / (2 x FIN) A smaller value for the PLL pre-divide (N) as well as a smaller value of the multiplier (M), both result in better PLL operational stability and lower output jitter. Lower values of FCCO also save power. So, the process of determining PLL setup parameters involves looking for the smallest N and M values giving the lowest FCCO value that will support the required CPU and/or USB clocks. It is usually easier to work backward from the desired output clock rate and determine a target FCCO rate, then find a way to obtain that FCCO rate from the available input clock. Potential precise values of FCCO are integer multiples of the desired CPU clock. In this example, it is clear that the smallest frequency for FCCO that can produce the desired CPU clock rate and is within the PLL0 operating range of 275 to 550 MHz is 300 MHz (3 x 100 MHz). Assuming that the PLL pre-divide is 1 (N = 1), the equation above gives M = ((300 x 106 x 1) / (2 x 10 x 106) = 300 / 20 = 15. Since the result is an integer, there is no need to look any further for a good set of PLL0 configuration values. The value written to PLL0CFG would be 0x0E (N - 1 = 0; M - 1 = 14 gives 0x0E). The PLL output must be further divided in order to produce the CPU clock. This is accomplished using a separate divider that is described later in this chapter, see Section 4-7.1.
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Example 2 Assumptions:
* The USB interface will be used in the application and will be clocked from PLL0. * The desired CPU rate is 60 MHz. * An external 4 MHz crystal or clock source will be used as the system clock source.
This clock source could be the Internal RC oscillator (IRC). Calculations: M = (FCCO x N) / (2 x FIN) Because supporting USB requires a precise 48 MHz clock with a 50% duty cycle, that need must be addressed first. Potential precise values of FCCO are integer multiples of the 2 x the 48 MHz USB clock. The 2 x insures that the clock has a 50% duty cycle, which would not be the case for a division of the PLL output by an odd number. The possibilities for the FCCO rate when the USB is used are 288 MHz, 384 MHz, and 480 MHz. The smallest frequency for FCCO that can produce a valid USB clock rate and is within the PLL0 operating range is 288 MHz (3 x 2 x 48 MHz). Start by assuming N = 1, since this produces the smallest multiplier needed for PLL0. So, M = ((288 x 106) x 1) / (2 x (4 x 106)) = 288 / 8 = 36. The result is an integer, which is necessary to obtain a precise USB clock. The value written to PLL0CFG would be 0x23 (N - 1 = 0; M - 1 = 35 = 0x23). The potential CPU clock rate can be determined by dividing FCCO by the desired CPU frequency: 288 x 106 / 60 x 106 = 4.8. The nearest integer value for the CPU Clock Divider is then 5, giving us 57.6 MHz as the nearest value to the desired CPU clock rate. If it is important to obtain exactly 60 MHz, an FCCO rate must be found that can be divided down to both 48 MHz and 60 MHz. As previously noted, the possibilities for the FCCO rate when the USB is used are 288 MHz, 384 MHz, and 480 MHz. Of these, only is 480 MHz is also evenly divisible by 60. Divided by 10, this gives the 48 MHz with a 50% duty cycle needed by the USB subsystem. Divided by 8, it gives 60 MHz for the CPU clock. PLL0 settings for 480 MHz are N = 1 and M = 60. The PLL output must be further divided in order to produce both the CPU clock and the USB clock. This is accomplished using separate dividers that are described later in this chapter. See Section 4-7.1 and Section 4-7.2.
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Example 3 Assumptions:
* The USB interface will not be used in the application, or will be clocked by PLL1. * The desired CPU rate is 72 MHz * The 32.768 kHz RTC clock source will be used as the system clock source
Calculations: M = (FCCO x N) / (2 x FIN) The smallest integer multiple of the desired CPU clock rate that is within the PLL0 operating range is 288 MHz (4 x 72 MHz). Using the equation above and assuming that N = 1, M = ((288 x 106) x 1) / (2 x 32,768) = 4,394.53125. This is not an integer, so the CPU frequency will not be exactly 72 MHz with this setting. Since this example is less obvious, it may be useful to make a table of possibilities for different values of N (see below).
Table 28. N M Potential values for PLL example M Rounded FREF in Hz (FIN / N) FCCO in MHz (FREF x M) CCLK in MHz % Error (FCCO / 4) (CCLK-72) / 72
1 2 3 4 5
4394.53125 8789.0625 13183.59375 17578.125 21972.65625
4395 8789 13184 17578 21973
32768 16384 10922.67 8192 6553.6
288.0307 287.9980 288.0089 287.9980 288.0045
72.0077 71.9995 72.0022 71.9995 72.0011
0.0107 -0.0007 0.0031 -0.0007 0.0016
Beyond N = 5, the value of M is out of range or not supported, so the table stops at that point. In the third column of the table, the calculated M value is rounded to the nearest integer. If this results in CCLK being above the maximum operating frequency, it is allowed if it is not more than 1/2 % above the maximum frequency. In general, larger values of FREF result in a more stable PLL when the input clock is a low frequency. Even the first table entry shows a very small error of just over 1 hundredth of a percent, or 107 parts per million (ppm). If that is not accurate enough in the application, the second case gives a much smaller error of 7 ppm. There are no allowed combinations that give a smaller error than that. Remember that when a frequency below about 1 MHz is used as the PLL0 clock source, not all multiplier values are available. As it turns out, all of the rounded M values found in Table 4-28 of this example are supported, which may be confirmed in Table 4-26. If PLL0 calculations suggest use of unsupported multiplier values, those values must be disregarded and other values examined to find the best fit. The value written to PLL0CFG for the second table entry would be 0x12254 (N - 1 = 1 = 0x1; M - 1 = 8788 = 0x2254). The PLL output must be further divided in order to produce the CPU clock. This is accomplished using a separate divider that is described later in this chapter, see Section 4-7.1.
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5.13 PLL0 setup sequence
The following sequence must be followed step by step in order to have PLL0 initialized and running: 1. Disconnect PLL0 with one feed sequence if PLL0 is already connected. 2. Disable PLL0 with one feed sequence. 3. Change the CPU Clock Divider setting to speed up operation without PLL0, if desired. 4. Write to the Clock Source Selection Control register to change the clock source if needed. 5. Write to the PLL0CFG and make it effective with one feed sequence. The PLL0CFG can only be updated when PLL0 is disabled. 6. Enable PLL0 with one feed sequence. 7. Change the CPU Clock Divider setting for the operation with PLL0. It is critical to do this before connecting PLL0. 8. Wait for PLL0 to achieve lock by monitoring the PLOCK0 bit in the PLL0STAT register, or using the PLOCK0 interrupt, or wait for a fixed time when the input clock to PLL0 is slow (i.e. 32 kHz). The value of PLOCK0 may not be stable when the PLL reference frequency (FREF, the frequency of REFCLK, which is equal to the PLL input frequency divided by the pre-divider value) is less than 100 kHz or greater than 20 MHz. In these cases, the PLL may be assumed to be stable after a start-up time has passed. This time is 500 s when FREF is greater than 400 kHz and 200 / FREF seconds when FREF is less than 400 kHz. 9. Connect PLL0 with one feed sequence. It is very important not to merge any steps above. For example, do not update the PLL0CFG and enable PLL0 simultaneously with the same feed sequence.
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6. PLL1 (Phase Locked Loop 1)
PLL1 receives its clock input from the main oscillator only and can be used to provide a fixed 48 MHz clock only to the USB subsystem. This is an option in addition to the possibility of generating the USB clock from PLL0. PLL1 is disabled and powered off on reset. If PLL1 is left disabled, the USB clock can be supplied by PLL0 if everything is set up to provide 48 MHz through that route. If PLL1 is enabled and connected via the PLL1CON register (see Section 4-6.2), it is automatically selected to drive the USB subsystem (see Figure 4-7). PLL1 activation is controlled via the PLL1CON register. PLL1 multiplier and divider values are controlled by the PLL1CFG register. These two registers are protected in order to prevent accidental alteration of PLL1 parameters or deactivation of PLL1. The protection is accomplished by a feed sequence similar to that of the Watchdog Timer. Details are provided in the description of the PLL1FEED register. PLL1 accepts an input clock frequency in the range of 10 MHz to 25 MHz only. The input frequency is multiplied up to the range of 48 MHz for the USB clock using a Current Controlled Oscillator (CCO). The multiplier can be an integer value from 1 to 32 (for USB, the multiplier value cannot be higher than 4. The CCO operates in the range of 156 MHz to 320 MHz, so there is an additional divider in the loop to keep the CCO within its frequency range while PLL1 is providing the desired output frequency. The output divider may be set to divide by 2, 4, 8, or 16 to produce the output clock. Since the minimum output divider value is 2, it is insured that the output of PLL1 has a 50% duty cycle. A block diagram of PLL1 is shown in Figure 4-10.
6.1 PLL1 register description
PLL1 is controlled by the registers shown in Table 4-29. More detailed descriptions follow. Writes to any unused bits are ignored. A read of any unused bits will return a logic zero. Warning: Improper setting of PLL1 values may result in incorrect operation of the USB subsystem!
Table 29. Name PLL1 registers Description Access Reset Address value[1]
PLL1CON
PLL1 Control Register. Holding register for R/W updating PLL1 control bits. Values written to this register do not take effect until a valid PLL1 feed sequence has taken place.
0
0x400F C0A0
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PLL1 registers Description Access Reset Address value[1]
Table 29. Name
PLL1CFG
PLL1 Configuration Register. Holding register for updating PLL1 configuration values. Values written to this register do not take effect until a valid PLL1 feed sequence has taken place.
R/W
0
0x400F C0A4
PLL1STAT
PLL1 Status Register. Read-back register for RO PLL1 control and configuration information. If PLL1CON or PLL1CFG have been written to, but a PLL1 feed sequence has not yet occurred, they will not reflect the current PL1L state. Reading this register provides the actual values controlling PLL1, as well as PLL1 status. PLL1 Feed Register. This register enables loading of PLL1 control and configuration information from the PLL1CON and PLL1CFG registers into the shadow registers that actually affect PLL1 operation. WO
0
0x400F C0A8
PLL1FEED
NA
0x400F C0AC
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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PLLC CLOCK SYNCHRONIZATION
0 PSEL[1:0]
direct
PD PLLE 0 bypass
PD
FOSC PHASEFREQUENCY DETECTOR CCO FCCO
1 0
CD 0 0 1 1 CCLK
PLOCK
/2P
PD FOUT CD DIV-BY-M MSEL<4:0> MSEL[4:0]
Fig 10. PLL1 block diagram
6.2 PLL1 Control register (PLL1CON - 0x400F C0A0)
The PLL1CON register contains the bits that enable and connect PLL1. Enabling PLL1 allows it to attempt to lock to the current settings of the multiplier and divider values. Connecting PLL1 causes the USB subsystem to run from the PLL1 output clock. Changes to the PLL1CON register do not take effect until a correct PLL feed sequence has been given (see Section 4-6.6 and Section 4-6.3).
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PLL1 Control register (PLL1CON - address 0x400F C0A0) bit description Description Reset value
Table 30. Bit
Symbol
0
PLLE1
PLL1 Enable. When one, and after a valid PLL1 feed, this bit will activate PLL1 and allow it to lock to the requested frequency. See PLL1STAT register, Table 4-32. PLL1 Connect. Setting PLLC to one after PLL1 has been enabled and locked, then followed by a valid PLL1 feed sequence causes PLL1 to become the clock source for the USB subsystem via the USB clock divider. See PLL1STAT register, Table 4-32. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
PLLC1
0
31:2
-
NA
PLL1 must be set up, enabled, and lock established before it may be used as a clock source for the USB subsystem. The hardware does not insure that the PLL is locked before it is connected nor does it automatically disconnect the PLL if lock is lost during operation.
6.3 PLL1 Configuration register (PLL1CFG - 0x400F C0A4)
The PLL1CFG register contains the PLL1 multiplier and divider values. Changes to the PLL1CFG register do not take effect until a correct PLL1 feed sequence has been given (see Section 4-6.6). Calculations for the PLL1 frequency, and multiplier and divider values are found in Section 4-6.9.
Table 31. Bit PLL Configuration register (PLL1CFG - address 0x400F C0A4) bit description Description Reset value
Symbol
4:0
MSEL1
PLL1 Multiplier value. Supplies the value "M" in the PLL1 frequency calculations.
Note: For details on selecting the right value for MSEL1 see Section 4-5.10.
0
6:5
PSEL1
PLL1 Divider value. Supplies the value "P" in the PLL1 frequency calculations.
Note: For details on selecting the right value for PSEL1 see Section 4-5.10.
0
31:7
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
6.4 PLL1 Status register (PLL1STAT - 0x400F C0A8)
The read-only PLL1STAT register provides the actual PLL1 parameters that are in effect at the time it is read, as well as the PLL1 status. PLL1STAT may disagree with values found in PLL1CON and PLL1CFG because changes to those registers do not take effect until a proper PLL1 feed has occurred (see Section 4-6.6 "PLL1 Feed register (PLL1FEED - 0x400F C0AC)").
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PLL1 Status register (PLL1STAT - address 0x400F C0A8) bit description Description Reset value
Table 32. Bit
Symbol
4:0 6:5 7 8
MSEL1 PSEL1 -
Read-back for the PLL1 Multiplier value. This is the value currently 0 used by PLL1. Read-back for the PLL1 Divider value. This is the value currently used by PLL1. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 NA 0
PLLE1_STAT Read-back for the PLL1 Enable bit. When one, PLL1 is currently activated. When zero, PLL1 is turned off. This bit is automatically cleared when Power-down mode is activated.
9
PLLC1_STAT Read-back for the PLL1 Connect bit. When PLLC and PLLE are 0 both one, PLL1 is connected as the clock source for the microcontroller. When either PLLC or PLLE is zero, PLL1 is bypassed and the oscillator clock is used directly by the microcontroller. This bit is automatically cleared when Power-down mode is activated. PLOCK1 Reflects the PLL1 Lock status. When zero, PLL1 is not locked. When one, PLL1 is locked onto the requested frequency. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 NA
10
31:11 -
6.4.1 PLL1 modes
The combinations of PLLE1 and PLLC1 are shown in Table 4-33.
Table 33. PLLC1 PLL1 control bit combinations PLLE1 PLL1 Function
0 0 1 1
0 1 0 1
PLL1 is turned off and disconnected. PLL1 is active, but not yet connected. PLL1 can be connected after PLOCK1 is asserted. Same as 00 combination. This prevents the possibility of PLL1 being connected without also being enabled. PLL1 is active and has been connected. The clock for the USB subsystem is sourced from PLL1.
6.5 PLL1 Interrupt: PLOCK1
The PLOCK1 bit in the PLL1STAT register reflects the lock status of PLL1. When PLL1 is enabled, or parameters are changed, the PLL requires some time to establish lock under the new conditions. PLOCK1 can be monitored to determine when the PLL may be connected for use. PLOCK1 is connected to the interrupt controller. This allows for software to turn on the PLL and continue with other functions without having to wait for the PLL to achieve lock. When the interrupt occurs, the PLL may be connected, and the interrupt disabled. PLOCK1 appears as interrupt 48 in Table 6-50. Note that PLOCK1 remains asserted whenever PLL1 is locked, so if the interrupt is used, the interrupt service routine must disable the PLOCK1 interrupt prior to exiting.
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6.6 PLL1 Feed register (PLL1FEED - 0x400F C0AC)
A correct feed sequence must be written to the PLL1FEED register in order for changes to the PLL1CON and PLL1CFG registers to take effect. The feed sequence is: 1. Write the value 0xAA to PLL1FEED. 2. Write the value 0x55 to PLL1FEED. The two writes must be in the correct sequence, and there must be no other register access in the same address space (0x400F C000 to 0x400F FFFF) between them. Because of this, it may be necessary to disable interrupts for the duration of the PLL feed operation, if there is a possibility that an interrupt service routine could write to another register in that space. If either of the feed values is incorrect, or one of the previously mentioned conditions is not met, any changes to the PLL1CON or PLL1CFG register will not become effective.
Table 34. Bit PLL1 Feed register (PLL1FEED - address 0x400F C0AC) bit description Description Reset value
Symbol
7:0 31:8
PLL1FEED -
The PLL1 feed sequence must be written to this register in order for PLL1 configuration and control register changes to take effect. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
6.7 PLL1 and Power-down mode
Power-down mode automatically turns off and disconnects activated PLL(s). Wake-up from Power-down mode does not automatically restore PLL settings, this must be done in software. Typically, a routine to activate the PLL, wait for lock, and then connect the PLL can be called at the beginning of any interrupt service routine that might be called due to the wake-up. It is important not to attempt to restart a PLL by simply feeding it when execution resumes after a wake-up from Power-down mode. This would enable and connect the PLL at the same time, before PLL lock is established. If activity on the USB data lines is not selected to wake the microcontroller from Power-down mode (see Section 4-8.8 for details of wake up from reduced modes), both the Main PLL (PLL0) and the USB PLL (PLL1) will be automatically be turned off and disconnected when Power-down mode is invoked, as described above. However, if the USB activity interrupt is enabled and USB_NEED_CLK = 1 (see Table 11-190 for a description of USB_NEED_CLK), it is not possible to go into Power-down mode and any attempt to set the PD bit will fail, leaving the PLLs in the current state.
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6.8 PLL1 frequency calculation
The PLL1 equations use the following parameters:
Table 35. Element Elements determining PLL frequency Description
FOSC FCCO USBCLK M P
the frequency from the crystal oscillator the frequency of the PLL1 current controlled oscillator the PLL1 output frequency (48 MHz for USB) PLL1 Multiplier value from the MSEL1 bits in the PLL1CFG register PLL1 Divider value from the PSEL1 bits in the PLL1CFG register
The PLL1 output frequency (when the PLL is both active and connected) is given by: USBCLK = M x FOSC or USBCLK = FCCO / (2 x P)
The CCO frequency can be computed as: FCCO = USBCLK x 2 x P or FCCO = FOSC x M x 2 x P
The PLL1 inputs and settings must meet the following criteria:
* FOSC is in the range of 10 MHz to 25 MHz. * USBCLK is 48 MHz. * FCCO is in the range of 156 MHz to 320 MHz. 6.9 Procedure for determining PLL1 settings
The PLL1 configuration for USB may be determined as follows: 1. The desired PLL1 output frequency is USBCLK = 48 MHz. 2. Choose an oscillator frequency (FOSC). USBCLK must be the whole (non-fractional) multiple of FOSC meaning that the possible values for FOSC are 12 MHz, 16 MHz, and 24 MHz. 3. Calculate the value of M to configure the MSEL1 bits. M = USBCLK / FOSC. In this case, the possible values for M = 2, 3, or 4 (FOSC = 24 MHz, 16 MHz, or 12 MHz). The value written to the MSEL1 bits in PLL1CFG is M - 1 (see Table 4-37). 4. Find a value for P to configure the PSEL1 bits, such that FCCO is within its defined frequency limits of 156 MHz to 320 MHz. FCCO is calculated using FCCO = USBCLK x 2 x P. It follows that P = 2 is the only P value to yield FCCO in the allowed range. The value written to the PSEL1 bits in PLL1CFG is `01' for P = 2 (see Table 4-36).
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Table 36. PLL1 Divider values Values allowed for using PLL1 with USB are highlighted. PSEL1 Bits (PLL1CFG bits [6:5]) Value of P
00
01
1
2
10 11
4 8
Table 37. PLL1 Multiplier values Values allowed for using PLL1 with USB are highlighted. MSEL1 Bits (PLL1CFG bits [4:0]) Value of M
00000
00001 00010 00011
1
2 3 4
... 11110 11111
... 31 32
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7. Clock dividers
The output of the PLL0 must be divided down for use by the CPU and the USB subsystem (if used with PLL0, see Section 4-6). Separate dividers are provided such that the CPU frequency can be determined independently from the USB subsystem, which always requires 48 MHz with a 50% duty cycle for proper operation.
USB PLL settings (PLL1...)
USB PLL select (PLL1CON)
osc_clk
USB PLL (PLL1)
main PLL settings (PLL0...) CPU PLL select (PLL0CON)
usb_clk
USB Clock Divider USB clock divider setting USBCLKCFG[3:0] CPU Clock Divider CPU clock divider setting CCLKCFG[7:0]
sysclk
Main PLL (PLL0)
pllclk
cclk
Fig 11. PLLs and clock dividers
7.1 CPU Clock Configuration register (CCLKCFG - 0x400F C104)
The CCLKCFG register controls the division of the PLL0 output before it is used by the CPU. When PLL0 is bypassed, the division may be by 1. When PLL0 is running, the output must be divided in order to bring the CPU clock frequency (CCLK) within operating limits. An 8-bit divider allows a range of options, including slowing CPU operation to a low rate for temporary power savings without turning off PLL0. Note: when the USB interface is used in an application, CCLK must be at least 18 MHz in order to support internal operations of the USB subsystem.
Table 38. Bit CPU Clock Configuration register (CCLKCFG - address 0x400F C104) bit description Value Description Reset value
Symbol
7:0
CCLKSEL 0 to 1 2 3 4 : 255
Selects the divide value for creating the CPU clock (CCLK) from the PLL0 output. Not allowed, the CPU clock will always be greater than 100 MHz. PLL0 output is divided by 3 to produce the CPU clock. PLL0 output is divided by 4 to produce the CPU clock. PLL0 output is divided by 5 to produce the CPU clock. : PLL0 output is divided by 256 to produce the CPU clock. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00
31:8
-
NA
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The CCLK is derived from the PLL0 output signal, divided by CCLKSEL + 1. Having CCLKSEL = 1 results in CCLK being one half the PLL0 output, CCLKSEL = 3 results in CCLK being one quarter of the PLL0 output, etc.
7.2 USB Clock Configuration register (USBCLKCFG - 0x400F C108)
This register is used only if the USB PLL (PLL1) is not connected (via the PLLC1 bit in PLL1CON). If PLL1 is connected, its output is automatically used as the USB clock source, and PLL1 must be configured to supply the correct 48 MHz clock to the USB subsystem. If PLL1 is not connected, the USB subsystem will be driven by PLL0 via the USB clock divider. The USBCLKCFG register controls the division of the PLL0 output before it is used by the USB subsystem.The PLL0 output must be divided in order to bring the USB clock frequency to 48 MHz with a 50% duty cycle. A 4-bit divider allows obtaining the correct USB clock from any even multiple of 48 MHz (i.e. any multiple of 96 MHz) within the PLL operating range. Remark: The Internal RC oscillator should not be used to drive PLL0 when the USB is using PLL0 as a clock source because a more precise clock is needed for USB specification compliance (see Table 4-17).
Table 39. Bit USB Clock Configuration register (USBCLKCFG - address 0x400F C108) bit description Value Description Reset value
Symbol
3:0
USBSEL
Selects the divide value for creating the USB clock from the PLL0 output. Only the values shown below can produce even number multiples of 48 MHz from the PLL0 output.
Warning: Improper setting of this value will result in incorrect operation of the USB interface.
0
5 7 9 31:4 -
PLL0 output is divided by 6. PLL0 output must be 288 MHz. PLL0 output is divided by 8. PLL0 output must be 384 MHz. PLL0 output is divided by 10. PLL0 output must be 480 MHz. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
7.3 Peripheral Clock Selection registers 0 and 1 (PCLKSEL0 0x400F C1A8 and PCLKSEL1 - 0x400F C1AC)
A pair of bits in a Peripheral Clock Selection register controls the rate of the clock signal that will be supplied to the corresponding peripheral as specified in Table 4-40, Table 4-41 and Table 4-42. Remark: The peripheral clock for the RTC block is fixed at CCLK/8.
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Peripheral Clock Selection register 0 (PCLKSEL0 - address 0x400F C1A8) bit description Description Reset value
Table 40. Bit
Symbol
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 25:24 27:26 29:28 31:30
[1]
PCLK_WDT PCLK_TIMER0 PCLK_TIMER1 PCLK_UART0 PCLK_UART1 PCLK_PWM1 PCLK_I2C0 PCLK_SPI PCLK_SSP1 PCLK_DAC PCLK_ADC PCLK_CAN1 PCLK_CAN2 PCLK_ACF
Peripheral clock selection for WDT. Peripheral clock selection for TIMER0. Peripheral clock selection for TIMER1. Peripheral clock selection for UART0. Peripheral clock selection for UART1. Reserved. Peripheral clock selection for PWM1. Peripheral clock selection for Reserved. Peripheral clock selection for SSP1. Peripheral clock selection for DAC. Peripheral clock selection for ADC. Peripheral clock selection for Peripheral clock selection for CAN1.[1] CAN2.[1] filtering.[1] I2C0. Peripheral clock selection for SPI.
00 00 00 00 00 NA 00 00 00 NA 00 00 00 00 00 00
Peripheral clock selection for CAN acceptance
PCLK_CAN1 and PCLK_CAN2 must have the same PCLK divide value when the CAN function is used.
Table 41. Bit
Peripheral Clock Selection register 1 (PCLKSEL1 - address 0x400F C1AC) bit description Description Reset value
Symbol
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 25:24 27:26 29:28 31:30
PCLK_QEI PCLK_GPIOINT PCLK_PCB PCLK_I2C1 PCLK_SSP0 PCLK_TIMER2 PCLK_TIMER3 PCLK_UART2 PCLK_UART3 PCLK_I2C2 PCLK_I2S PCLK_RIT PCLK_SYSCON PCLK_MC
Peripheral clock selection for the Quadrature Encoder Interface. Peripheral clock selection for GPIO interrupts. Peripheral clock selection for the Pin Connect block. Peripheral clock selection for I2C1. Reserved. Peripheral clock selection for SSP0. Peripheral clock selection for TIMER2. Peripheral clock selection for TIMER3. Peripheral clock selection for UART2. Peripheral clock selection for UART3. Peripheral clock selection for Reserved. Peripheral clock selection for Repetitive Interrupt Timer. Peripheral clock selection for the System Control block. Peripheral clock selection for the Motor Control PWM. I2C2. Peripheral clock selection for I2S.
00 00 00 00 NA 00 00 00 00 00 00 00 NA 00 00 00
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Peripheral Clock Selection register bit values Reset value
Table 42.
PCLKSEL0 and PCLKSEL1 Function individual peripheral's clock select options
00 01 10 11
PCLK_peripheral = CCLK/4 PCLK_peripheral = CCLK PCLK_peripheral = CCLK/2 PCLK_peripheral = CCLK/8, except for CAN1, CAN2, and CAN filtering when "11" selects = CCLK/6.
00
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8. Power control
The LPC17xx supports a variety of power control features: Sleep mode, Deep Sleep mode, Power-down mode, and Deep Power-down mode. The CPU clock rate may also be controlled as needed by changing clock sources, re-configuring PLL values, and/or altering the CPU clock divider value. This allows a trade-off of power versus processing speed based on application requirements. In addition, Peripheral Power Control allows shutting down the clocks to individual on-chip peripherals, allowing fine tuning of power consumption by eliminating all dynamic power use in any peripherals that are not required for the application. Entry to any reduced power mode begins with the execution of either a WFI (Wait For Interrupt) or WFE (Wait For Exception) instruction by the Cortex-M3. The Cortex-M3 internally supports two reduced power modes: Sleep and Deep Sleep. These are selected by the SLEEPDEEP bit in the cortex-M3 System Control Register. Power-down and Deep Power-down modes are selected by bits in the PCON register. See Table 4-44. The same register contains flags that indicate whether entry into each reduced power mode actually occurred. The LPC17xx also implements a separate power domain in order to allow turning off power to the bulk of the device while maintaining operation of the Real Time Clock. Reduced power modes have some limitation during debug, see Section 33-5 for more information.
8.1 Sleep mode
Note: Sleep mode on the LPC17xx corresponds to the Idle mode on LPC2xxx series devices. The name is changed because ARM has incorporated portions of reduced power mode control into the Cortex-M3. LPC17xx documentation uses the Cortex-M3 terminology where applicable. When Sleep mode is entered, the clock to the core is stopped, and the SMFLAG bit in PCON is set, see Table 4-44.Resumption from the Sleep mode does not need any special sequence but re-enabling the clock to the ARM core. In Sleep mode, execution of instructions is suspended until either a Reset or an interrupt occurs. Peripheral functions continue operation during Sleep mode and may generate interrupts to cause the processor to resume execution. Sleep mode eliminates dynamic power used by the processor itself, memory systems and related controllers, and internal buses. Wake-up from Sleep mode will occur whenever any enabled interrupt occurs.
8.2 Deep Sleep mode
Note: Deep Sleep mode on the LPC17xx corresponds to the Sleep mode on LPC23xx and LPC24xx series devices. The name is changed because ARM has incorporated portions of reduced power mode control into the Cortex-M3. LPC17xx documentation uses the Cortex-M3 terminology where applicable. When the chip enters the Deep Sleep mode, the main oscillator is powered down, nearly all clocks are stopped, and the DSFLAG bit in PCON is set, see Table 4-44. The IRC remains running and can be configured to drive the Watchdog Timer, allowing the
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Watchdog to wake up the CPU. The 32 kHz RTC oscillator is not stopped and RTC interrupts may be used as a wake-up source. The flash is left in the standby mode allowing a quick wake-up. The PLLs are automatically turned off and disconnected. The CCLK and USBCLK clock dividers automatically get reset to zero. The processor state and registers, peripheral registers, and internal SRAM values are preserved throughout Deep Sleep mode and the logic levels of chip pins remain static. The Deep Sleep mode can be terminated and normal operation resumed by either a Reset or certain specific interrupts that are able to function without clocks. Since all dynamic operation of the chip is suspended, Deep Sleep mode reduces chip power consumption to a very low value. On the wake-up of Deep Sleep mode, if the IRC was used before entering Deep Sleep mode, a 2-bit IRC timer starts counting and the code execution and peripherals activities will resume after the timer expires (4 cycles). If the main external oscillator was used, the 12-bit main oscillator timer starts counting and the code execution will resume when the timer expires (4096 cycles). The user must remember to re-configure any required PLLs and clock dividers after the wake-up. Wake-up from Deep Sleep mode can be brought about by NMI, External Interrupts EINT0 through EINT3, GPIO interrupts, the Ethernet Wake-on-LAN interrupt, Brownout Detect, an RTC Alarm interrupt, a Watchdog Timer timeout, a USB input pin transition (USB activity interrupt), or a CAN input pin transition, when the related interrupt is enabled. Wake-up will occur whenever any enabled interrupt occurs.
8.3 Power-down mode
Power-down mode does everything that Deep Sleep mode does, but also turns off the flash memory. Entry to Power-down mode causes the PDFLAG bit in PCON to be set, see Table 4-44. This saves more power, but requires waiting for resumption of flash operation before execution of code or data access in the flash memory can be accomplished. When the chip enters Power-down mode, the IRC, the main oscillator, and all clocks are stopped. The RTC remains running if it has been enabled and RTC interrupts may be used to wake up the CPU. The flash is forced into Power-down mode. The PLLs are automatically turned off and disconnected. The CCLK and USBCLK clock dividers automatically get reset to zero. Upon wake-up from Power-down mode, if the IRC was used before entering Power-down mode, after IRC-start-up time (about 60 s), the 2-bit IRC timer starts counting and expiring in 4 cycles. Code execution can then be resumed immediately following the expiration of the IRC timer if the code was running from SRAM. In the meantime, the flash wake-up timer measures flash start-up time of about 100 s. When it times out, access to the flash is enabled. The user must remember to re-configure any required PLLs and clock dividers after the wake-up. Wake-up from Power-down mode can be brought about by NMI, External Interrupts EINT0 through EINT3, GPIO interrupts, the Ethernet Wake-on-LAN interrupt, Brownout Detect, an RTC Alarm interrupt, a USB input pin transition (USB activity interrupt), or a CAN input pin transition, when the related interrupt is enabled.
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8.4 Deep Power-down mode
In Deep Power-down mode, power is shut off to the entire chip with the exception of the Real-Time Clock, the RESET pin, the WIC, and the RTC backup registers. Entry to Deep Power-down mode causes the DPDFLAG bit in PCON to be set, see Table 4-44. To optimize power conservation, the user has the additional option of turning off or retaining power to the 32 kHz oscillator. It is also possible to use external circuitry to turn off power to the on-chip regulator via the VDD(REG)(3V3) pins after entering Deep Power-down mode.Power to the on-chip regulator must be restored before device operation can be restarted. Wake-up from Deep Power-down mode will occur when an external reset signal is applied, or the RTC interrupt is enabled and an RTC interrupt is generated.
8.5 Peripheral power control
A Power Control for Peripherals feature allows individual peripherals to be turned off if they are not needed in the application, resulting in additional power savings. This is detailed in the description of the PCONP register.
8.6 Register description
The Power Control function uses registers shown in Table 4-43. More detailed descriptions follow.
Table 43. Name Power Control registers Description Access Reset value[1] Address
PCON
Power Control Register. This register contains control bits that enable some reduced power operating modes of the LPC17xx. See Table 4-44. Power Control for Peripherals Register. This register contains control bits that enable and disable individual peripheral functions, allowing elimination of power consumption by peripherals that are not needed.
R/W
0x00
0x400F C0C0
PCONP
R/W
0x400F C0C4
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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8.7 Power Mode Control register (PCON - 0x400F C0C0)
Controls for some reduced power modes and other power related controls are contained in the PCON register, as described in Table 4-44.
Table 44. Bit Power Mode Control register (PCON - address 0x400F C0C0) bit description Description Reset value
Symbol
0 1 2
PM0 PM1 BODRPM
Power mode control bit 0. This bit controls entry to the Power-down mode. See Section 4-8.7.1 below for details. Power mode control bit 1. This bit controls entry to the Deep Power-down mode. See Section 4-8.7.1 below for details.
0 0
Brown-Out Reduced Power Mode. When BODRPM is 1, the 0 Brown-Out Detect circuitry will be turned off when chip Power-down mode or Deep Sleep mode is entered, resulting in a further reduction in power usage. However, the possibility of using Brown-Out Detect as a wake-up source from the reduced power mode will be lost. When 0, the Brown-Out Detect function remains active during Power-down and Deep Sleep modes. See the System Control Block chapter for details of Brown-Out detection.
3
BOGD
Brown-Out Global Disable. When BOGD is 1, the Brown-Out Detect circuitry is fully disabled at all times, and does not consume power. When 0, the Brown-Out Detect circuitry is enabled. See the System Control Block chapter for details of Brown-Out detection.
0
4
BORD
Brown-Out Reset Disable. When BORD is 1, the BOD will not reset the device when the VDD(REG)(3V3) voltage dips goes below the BOD reset trip level. The Brown-Out interrupt is not affected. When BORD is 0, the BOD reset is enabled. See the Section 3-5 for details of Brown-Out detection.
0
7:3 8 9 10 11
SMFLAG DSFLAG PDFLAG
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Sleep Mode entry flag. Set when the Sleep mode is successfully entered. Cleared by software writing a one to this bit.
NA 0 [1][2]
Deep Sleep entry flag. Set when the Deep Sleep mode is successfully 0 [1][2] entered. Cleared by software writing a one to this bit. Power-down entry flag. Set when the Power-down mode is successfully entered. Cleared by software writing a one to this bit. 0 [1][2] 0 [1][3] NA
DPDFLAG Deep Power-down entry flag. Set when the Deep Power-down mode is successfully entered. Cleared by software writing a one to this bit. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
31:12 [1] [2] [3]
Only one of these flags will be valid at a specific time. Hardware reset only for a power-up of core power or by a brownout detect event. Hardware reset only for a power-up event on Vbat.
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8.7.1 Encoding of Reduced Power Modes
The PM1and PM0 bits in PCON allow entering reduced power modes as needed. The encoding of these bits allows backward compatibility with devices that previously only supported Sleep and Power-down modes. Table 4-45 below shows the encoding for the three reduced power modes supported by the LPC17xx.
Table 45. PM1, PM0 Encoding of reduced power modes Description
00 01 10 11
Execution of WFI or WFE enters either Sleep or Deep Sleep mode as defined by the SLEEPDEEP bit in the Cortex-M3 System Control Register. Execution of WFI or WFE enters Power-down mode if the SLEEPDEEP bit in the Cortex-M3 System Control Register is 1. Reserved, this setting should not be used. Execution of WFI or WFE enters Deep Power-down mode if the SLEEPDEEP bit in the Cortex-M3 System Control Register is 1.
8.8 Wake-up from Reduced Power Modes
Any enabled interrupt can wake up the CPU from Sleep mode. Certain interrupts can wake up the processor if it is in either Deep Sleep mode or Power-down mode. Interrupts that can occur during Deep Sleep or Power-down mode will wake up the CPU if the interrupt is enabled. After wake-up, execution will continue to the appropriate interrupt service routine. These interrupts are NMI, External Interrupts EINT0 through EINT3, GPIO interrupts, Ethernet Wake-on-LAN interrupt, Brownout Detect, RTC Alarm, CAN Activity Interrupt, and USB Activity Interrupt. In addition, the watchdog timer can wake up the part from Deep Sleep mode if the watchdog timer is being clocked by the IRC oscillator. For the wake-up process to take place the corresponding interrupt must be enabled in the NVIC. For pin-related peripheral functions, the related functions must also be mapped to pins. The CAN Activity Interrupt is generated by activity on the CAN bus pins, and the USB Activity Interrupt is generated by activity on the USB bus pins. These interrupts are only useful to wake up the CPU when it is on Deep Sleep or Power-down mode, when the peripheral functions are powered up, but not active. Typically, if these interrupts are used, their flags should be polled just before enabling the interrupt and entering the desired reduced power mode. This can save time and power by avoiding an immediate wake-up. Upon wake-up, the interrupt service can turn off the related activity interrupt, do any application specific setup, and exit to await a normal peripheral interrupt.
8.9 Power Control for Peripherals register (PCONP - 0x400F C0C4)
The PCONP register allows turning off selected peripheral functions for the purpose of saving power. This is accomplished by gating off the clock source to the specified peripheral blocks. A few peripheral functions cannot be turned off (i.e. the Watchdog timer, the Pin Connect block, and the System Control block). Some peripherals, particularly those that include analog functions, may consume power that is not clock dependent. These peripherals may contain a separate disable control that turns off additional circuitry to reduce power. Information on peripheral specific power saving features may be found in the chapter describing that peripheral.
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Each bit in PCONP controls one peripheral as shown in Table 4-46. If a peripheral control bit is 1, that peripheral is enabled. If a peripheral control bit is 0, that peripheral's clock is disabled (gated off) to conserve power. For example if bit 19 is 1, the I2C1 interface is enabled. If bit 19 is 0, the I2C1 interface is disabled. Important: valid read from a peripheral register and valid write to a peripheral register is possible only if that peripheral is enabled in the PCONP register!
Table 46. Bit Power Control for Peripherals register (PCONP - address 0x400F C0C4) bit description Description Reset value
Symbol
0 1 2 3 4 5 6 7 8 9 10 11 12
PCTIM0 PCTIM1 PCUART0 PCUART1 PCPWM1 PCI2C0 PCSPI PCRTC PCSSP1 PCADC
Reserved. Timer/Counter 0 power/clock control bit. Timer/Counter 1 power/clock control bit. UART0 power/clock control bit. UART1 power/clock control bit. Reserved. PWM1 power/clock control bit. The I2C0 interface power/clock control bit. The SPI interface power/clock control bit. The RTC power/clock control bit. The SSP 1 interface power/clock control bit. Reserved. A/D converter (ADC) power/clock control bit.
Note: Clear the PDN bit in the AD0CR before clearing this bit, and set this bit before setting PDN.
NA 1 1 1 1 NA 1 1 1 1 1 NA 0
13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
PCCAN1 PCCAN2 PCRIT PCQEI PCI2C1 PCSSP0 PCTIM2 PCTIM3 PCUART2 PCUART3 PCI2C2 PCI2S -
CAN Controller 1 power/clock control bit. CAN Controller 2 power/clock control bit. Reserved. Repetitive Interrupt Timer power/clock control bit. Quadrature Encoder Interface power/clock control bit. The I2C1 interface power/clock control bit. Reserved. The SSP0 interface power/clock control bit. Timer 2 power/clock control bit. Timer 3 power/clock control bit. UART 2 power/clock control bit. UART 3 power/clock control bit. I2C I2S interface 2 power/clock control bit. interface power/clock control bit.
0 0 NA 0 0 0 1 NA 1 0 0 0 0 1 0 NA
PCMCPWM Motor Control PWM
Reserved.
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Power Control for Peripherals register (PCONP - address 0x400F C0C4) bit description Description Reset value
Table 46. Bit
Symbol
29 30 31
PCGPDMA PCENET PCUSB
GPDMA function power/clock control bit. Ethernet block power/clock control bit. USB interface power/clock control bit.
0 0 0
Note that the DAC peripheral does not have a control bit in PCONP. To enable the DAC, its output must be selected to appear on the related pin, P0.26, by configuring the PINSEL1 register. See Section 8-5.2 "Pin Function Select Register 1 (PINSEL1 0x4002 C004)".
8.10 Power control usage notes
After every reset, the PCONP register contains the value that enables selected interfaces and peripherals controlled by the PCONP to be enabled. Therefore, apart from proper configuring via peripheral dedicated registers, the user's application might have to access the PCONP in order to start using some of the on-board peripherals. Power saving oriented systems should have 1s in the PCONP register only in positions that match peripherals really used in the application. All other bits, declared to be "Reserved" or dedicated to the peripherals not used in the current application, must be cleared to 0.
8.11 Power domains
The LPC17xx provides two independent power domains that allow the bulk of the device to have power removed while maintaining operation of the Real Time Clock. The VBAT pin supplies power only to the RTC domain. The RTC requires a minimum of power to operate, which can be supplied by an external battery. Whenever the device core power is present, that power is used to operate the RTC, causing no power drain from a battery when main power is available.
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Chapter 4: LPC17xx Clocking and power control
9. Wake-up timer
The LPC17xx begins operation at power-up and when awakened from Power-down mode by using the 4 MHz IRC oscillator as the clock source. This allows chip operation to begin quickly. If the main oscillator or one or both PLLs are needed by the application, software will need to enable these features and wait for them to stabilize before they are used as a clock source. When the main oscillator is initially activated, the wake-up timer allows software to ensure that the main oscillator is fully functional before the processor uses it as a clock source and starts to execute instructions. This is important at power-on, all types of Reset, and whenever any of the aforementioned functions are turned off for any reason. Since the oscillator and other functions are turned off during Power-down mode, any wake-up of the processor from Power-down mode makes use of the Wake-up Timer. The Wake-up Timer monitors the crystal oscillator as the means of checking whether it is safe to begin code execution. When power is applied to the chip, or some event caused the chip to exit Power-down mode, some time is required for the oscillator to produce a signal of sufficient amplitude to drive the clock logic. The amount of time depends on many factors, including the rate of VDD(REG)(3V3) ramp (in the case of power on), the type of crystal and its electrical characteristics (if a quartz crystal is used), as well as any other external circuitry (e.g. capacitors), and the characteristics of the oscillator itself under the existing ambient conditions. Once a clock is detected, the Wake-up Timer counts a fixed number of clocks (4,096), then sets the flag (OSCSTAT bit in the SCS register) that indicates that the main oscillator is ready for use. Software can then switch to the main oscillator and start any required PLLs. Refer to the Main Oscillator description in this chapter for details.
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Chapter 4: LPC17xx Clocking and power control
10. External clock output pin
For system test and development purposes, any one of several internal clocks may be brought out on the CLKOUT function available on the P1.27 pin, as shown in Figure 4-12. Clocks that may be observed via CLKOUT are the CPU clock (cclk), the main oscillator (osc_clk), the internal RC oscillator (irc_osc), the USB clock (usb_clk), and the RTC clock (rtc_clk).
CLKOUTCFG[3:0]
cclk osc_clk irc_osc usb_clk rtc_clk
000 001 010 011 100
CLKOUTCFG[7:4]
CLKOUTCFG[8]
CLKOUT Divider
Clock Enable Syncronizer
CLKOUT
CLKOUTCFG[9]
Fig 12. CLKOUT selection
10.1 Clock Output Configuration register (CLKOUTCFG - 0x400F C1C8)
The CLKOUTCFG register controls the selection of the internal clock that appears on the CLKOUT pin and allows dividing the clock by an integer value up to 16. The divider can be used to produce a system clock that is related to one of the on-chip clocks. For most clock sources, the division may be by 1. When the CPU clock is selected and is higher than approximately 50 MHz, the output must be divided in order to bring the frequency within the ability of the pin to switch with reasonable logic levels. Note: The CLKOUT multiplexer is designed to switch cleanly, without glitches, between the possible clock sources. The divider is also designed to allow changing the divide value without glitches.
Table 47. Bit Clock Output Configuration register (CLKOUTCFG - 0x400F C1C8) bit description Value Description Reset value
Symbol
3:0
CLKOUTSEL 0000 0001 0010 0011 0100
Selects the clock source for the CLKOUT function. Selects the CPU clock as the CLKOUT source. Selects the main oscillator as the CLKOUT source. Selects the Internal RC oscillator as the CLKOUT source (default). Selects the USB clock as the CLKOUT source. Selects the RTC oscillator as the CLKOUT source.
0
others Reserved, do not use these settings.
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Clock Output Configuration register (CLKOUTCFG - 0x400F C1C8) bit description Value Description Reset value
Table 47. Bit
Symbol
7:4
CLKOUTDIV 0000 0001 0010 ... 1111
Integer value to divide the output clock by, minus one. Clock is divided by 1. Clock is divided by 2. Clock is divided by 3. ... Clock is divided by 16.
0
8
CLKOUT_EN
CLKOUT enable control, allows switching the CLKOUT 0 source without glitches. Clear to stop CLKOUT on the next falling edge. Set to enable CLKOUT. Used in concert with the CLKOUT_EN bit below. CLKOUT activity indication. Reads as 1 when CLKOUT is 0 enabled. Read as 0 when CLKOUT has been disabled via the CLKOUT_EN bit and the clock has completed being stopped. Reserved, user software should not write ones to reserved NA bits. The value read from a reserved bit is not defined.
9
CLKOUT_ACT
31:10 -
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Chapter 5: LPC17xx Flash accelerator
Rev. 01 -- 4 January 2010 User manual
1. Introduction
The flash accelerator block in the LPC17xx allows maximization of the performance of the Cortex-M3 processor when it is running code from flash memory, while also saving power. The flash accelerator also provides speed and power improvements for data accesses to the flash memory.
2. Flash accelerator blocks
The flash accelerator is divided into several functional blocks:
* AHB-Lite bus interface, accessible by the Cortex-M3 I-code and D-code buses, as
well as by the General Purpose DMA Controller
* An array of eight 128-bit buffers * Flash accelerator control logic, including address compare and flash control * A flash memory interface
Figure 5-13 shows a simplified diagram of the flash accelerator blocks and data paths.
DCode bus Cortex-M3 CPU ICode bus
Bus Matrix Combined AHB
Flash Accelerator
AHB-Lite bus interface Buffer Array Flash Interface Flash Memory
DMA General Purpose Master Port DMA Controller
Flash Accelerator Control
Fig 13. Simplified block diagram of the flash accelerator showing potential bus connections
In the following descriptions, the term "fetch" applies to an explicit flash read request from the CPU. "Prefetch" is used to denote a flash read of instructions beyond the current processor fetch address.
2.1 Flash memory bank
There is one bank of flash memory controlled by the LPC17xx flash accelerator. Flash programming operations are not controlled by the flash accelerator, but are handled as a separate function. A Boot ROM contains flash programming algorithms that may be called as part of the application program, and a loader that may be run to allow programming of the flash memory.
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2.2 Flash programming Issues
Since the flash memory does not allow accesses during programming and erase operations, it is necessary for the flash accelerator to force the CPU to wait if a memory access to a flash address is requested while the flash memory is busy with a programming operation. Under some conditions, this delay could result in a Watchdog time-out. The user will need to be aware of this possibility and take steps to insure that an unwanted Watchdog reset does not cause a system failure while programming or erasing the flash memory. In order to preclude the possibility of stale data being read from the flash memory, the LPC17xx flash accelerator buffers are automatically invalidated at the beginning of any flash programming or erase operation. Any subsequent read from a flash address will cause a new fetch to be initiated after the flash operation has completed.
3. Register description
The flash accelerator is controlled by the register shown in Table 5-48. More detailed descriptions follow.
Table 48. Name Summary of flash accelerator registers Description Access Reset Address value[1]
FLASHCFG
[1]
Flash Accelerator Configuration Register. R/W Controls flash access timing. See Table 5-49.
0x303A 0x400F C000
Reset Value reflects the data stored in defined bits only. It does not include reserved bits content.
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Chapter 5: LPC17xx Flash accelerator
4. Flash Accelerator Configuration register (FLASHCFG - 0x400F C000)
Configuration bits select the flash access time, as shown in Table 5-49. The lower bits of FLASHCFG control internal flash accelerator functions and should not be altered. Following reset, flash accelerator functions are enabled and flash access timing is set to a default value of 4 clocks. Changing the FLASHCFG register value causes the flash accelerator to invalidate all of the holding latches, resulting in new reads of flash information as required. This guarantees synchronization of the flash accelerator to CPU operation.
Table 49. Bit Flash Accelerator Configuration register (FLASHCFG - address 0x400F C000) bit description Value Description Reset value
Symbol
11:0
-
-
Reserved, user software should not change these bits from the reset value.
0x03A
15:12 FLASHTIM
Flash access time. The value of this field plus 1 gives the number of CPU clocks used 0x3 for a flash access.
Warning: improper setting of this value may result in incorrect operation of the device. Important Note: Frequency values shown below are estimates at this time.
0000 0001 0010 0011 0100 0101 Other 31:16 -
Flash accesses use 1 CPU clock. Use for up to 20 MHz CPU clock. Flash accesses use 2 CPU clocks. Use for up to 40 MHz CPU clock. Flash accesses use 3 CPU clocks. Use for up to 60 MHz CPU clock. Flash accesses use 4 CPU clocks. Use for up to 80 MHz CPU clock. Flash accesses use 5 CPU clocks. Use for up to 100 MHz CPU clock. Use for up to 120 Mhz for LPC1759 and LPC1769 only. Flash accesses use 6 CPU clocks. This "safe" setting will work under any conditions. Intended for potential future higher speed devices. Reserved. The value read from a reserved bit is not defined. NA
5. Operation
Simply put, the flash accelerator attempts to have the next Cortex-M3 instruction that will be needed in its latches in time to prevent CPU fetch stalls. The LPC17xx uses one bank of flash memory. The flash accelerator includes an array of eight 128-bit buffers to store both instructions and data in a configurable manner. Each 128-bit buffer in the array can include four 32-bit instructions, eight 16-bit instructions or some combination of the two. During sequential code execution, a buffer typically contains the current instruction and the entire flash line that contains that instruction, or one flash line of data containing a previously requested address. Buffers are marked according to how they are used (as instruction or data buffers), and when they have been accessed. This information is used to carry out the buffer replacement strategy. The Cortex-M3 provides a separate bus for instruction access (I-code) and data access (D-code) in the code memory space. These buses, plus the General Purpose DMA Controllers's master port, are arbitrated by the AHB multilayer matrix. Any access to the flash memory's address space is presented to the flash accelerator.
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Chapter 5: LPC17xx Flash accelerator
If a flash instruction fetch and a flash data access from the CPU occur at the same time, the multilayer matrix gives precedence to the data access. This is because a stalled data access always slows down execution, while a stalled instruction fetch often does not. When the flash data access is concluded, any flash fetch or prefetch that had been in progress is re-initiated. Branches and other program flow changes cause a break in the sequential flow of instruction fetches described above. Buffer replacement strategy in the flash accelerator attempts to maximize the chances that potentially reusable information is retained until it is needed again. If an attempt is made to write directly to the flash memory without using the normal flash programming interface (via Boot ROM function calls), the flash accelerator generates an error condition. The CPU treats this error as a data abort. The GPDMA handles error conditions as described in Section 31-4.1.6.3. When an Instruction Fetch is not satisfied by existing contents of the buffer array, nor has a prefetch been initiated for that flash line, the CPU will be stalled while a fetch is initiated for the related 128-bit flash line. If a prefetch has been initiated but not yet completed, the CPU is stalled for a shorter time since the required flash access is already in progress. Typically, a flash prefetch is begun whenever an access is made to a just prefetched address, or to a buffer whose immediate successor is not already in another buffer. A prefetch in progress may be aborted by a data access, in order to minimize CPU stalls. A prefetched flash line is latched within the flash memory, but the flash accelerator does not capture the line in a buffer until the CPU presents an address that is contained within the prefetched flash line. If the core presents an instruction address that is not already buffered and is not contained in the prefetched flash line, the prefetched line will be discarded. Some special cases include the possibility that the CPU will request a data access to an address already contained in an instruction buffer. In this case, the data will be read from the buffer as if it was a data buffer. The reverse case, if the CPU requests an instruction address that can be satisfied from an existing data buffer, causes the instruction to be supplied from the data buffer, and the buffer to be changed into an instruction buffer. This causes the buffer to be handled differently when the flash accelerator is determining which buffer is to be overwritten next.
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Chapter 6: LPC17xx Nested Vectored Interrupt Controller (NVIC)
Rev. 01 -- 4 January 2010 User manual
1. Features
* * * * * * * *
Nested Vectored Interrupt Controller that is an integral part of the ARM Cortex-M3 Tightly coupled interrupt controller provides low interrupt latency Controls system exceptions and peripheral interrupts In the LPC17xx, the NVIC supports 35 vectored interrupts 32 programmable interrupt priority levels, with hardware priority level masking Relocatable vector table Non-Maskable Interrupt Software interrupt generation
2. Description
The Nested Vectored Interrupt Controller (NVIC) is an integral part of the Cortex-M3. The tight coupling to the CPU allows for low interrupt latency and efficient processing of late arriving interrupts. Refer to the Cortex-M3 User Guide Section 34-4.2 for details of NVIC operation.
3. Interrupt sources
Table 6-50 lists the interrupt sources for each peripheral function. Each peripheral device may have one or more interrupt lines to the Vectored Interrupt Controller. Each line may represent more than one interrupt source, as noted. Exception numbers relate to where entries are stored in the exception vector table. Interrupt numbers are used in some other contexts, such as software interrupts. In addition, the NVIC handles the Non-Maskable Interrupt (NMI). In order for NMI to operate from an external signal, the NMI function must be connected to the related device pin (P2.10 / EINT0n / NMI). When connected, a logic 1 on the pin will cause the NMI to be processed. For details, refer to the Cortex-M3 User Guide that is an appendix to this User Manual.
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Chapter 6: LPC17xx Nested Vectored Interrupt Controller (NVIC)
Table 50.
Connection of interrupt sources to the Vectored Interrupt Controller Flag(s)
Interrupt Exception Vector Function ID Number Offset
0 1 2 3 4 5
16 17 18 19 20 21
0x40 0x44 0x48 0x4C 0x50 0x54
WDT Timer 0 Timer 1 Timer 2 Timer 3 UART0
Watchdog Interrupt (WDINT) Match 0 - 1 (MR0, MR1) Capture 0 - 1 (CR0, CR1) Match 0 - 2 (MR0, MR1, MR2) Capture 0 - 1 (CR0, CR1) Match 0-3 Capture 0-1 Match 0-3 Capture 0-1 Rx Line Status (RLS) Transmit Holding Register Empty (THRE) Rx Data Available (RDA) Character Time-out Indicator (CTI) End of Auto-Baud (ABEO) Auto-Baud Time-Out (ABTO)
6
22
0x58
UART1
Rx Line Status (RLS) Transmit Holding Register Empty (THRE) Rx Data Available (RDA) Character Time-out Indicator (CTI) Modem Control Change End of Auto-Baud (ABEO) Auto-Baud Time-Out (ABTO)
7
23
0x5C
UART 2
Rx Line Status (RLS) Transmit Holding Register Empty (THRE) Rx Data Available (RDA) Character Time-out Indicator (CTI) End of Auto-Baud (ABEO) Auto-Baud Time-Out (ABTO)
8
24
0x60
UART 3
Rx Line Status (RLS) Transmit Holding Register Empty (THRE) Rx Data Available (RDA) Character Time-out Indicator (CTI) End of Auto-Baud (ABEO) Auto-Baud Time-Out (ABTO)
9 10 11 12 13
25 26 27 28 29
0x64 0x68 0x6C 0x70 0x74
PWM1 I2C0 I2C1 I2C2 SPI
Match 0 - 6 of PWM1 Capture 0-1 of PWM1 SI (state change) SI (state change) SI (state change) SPI Interrupt Flag (SPIF) Mode Fault (MODF)
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Table 50.
Connection of interrupt sources to the Vectored Interrupt Controller Flag(s)
Interrupt Exception Vector Function ID Number Offset
14
30
0x78
SSP0
Tx FIFO half empty of SSP0 Rx FIFO half full of SSP0 Rx Timeout of SSP0 Rx Overrun of SSP0
15
31
0x7C
SSP 1
Tx FIFO half empty Rx FIFO half full Rx Timeout Rx Overrun
16 17 18 19 20 21 22 23 24 25 26 27 28
32 33 34 35 36 37 38 39 40 41 42 43 44
0x80 0x84 0x88 0x8C 0x90 0x94 0x98 0x9C 0xA0 0xA4 0xA8 0xAC 0xB0
PLL0 (Main PLL) RTC External Interrupt External Interrupt External Interrupt External Interrupt ADC BOD USB CAN GPDMA I2S Ethernet
PLL0 Lock (PLOCK0) Counter Increment (RTCCIF) Alarm (RTCALF) External Interrupt 0 (EINT0) External Interrupt 1 (EINT1) External Interrupt 2 (EINT2) External Interrupt 3 (EINT3).
Note: EINT3 channel is shared with GPIO interrupts
A/D Converter end of conversion Brown Out detect USB_INT_REQ_LP, USB_INT_REQ_HP, USB_INT_REQ_DMA CAN Common, CAN 0 Tx, CAN 0 Rx, CAN 1 Tx, CAN 1 Rx IntStatus of DMA channel 0, IntStatus of DMA channel 1 irq, dmareq1, dmareq2 WakeupInt, SoftInt, TxDoneInt, TxFinishedInt, TxErrorInt, TxUnderrunInt, RxDoneInt, RxFinishedInt, RxErrorInt, RxOverrunInt. RITINT IPER[2:0], IPW[2:0], ICAP[2:0], FES INX_Int, TIM_Int, VELC_Int, DIR_Int, ERR_Int, ENCLK_Int, POS0_Int, POS1_Int, POS2_Int, REV_Int, POS0REV_Int, POS1REV_Int, POS2REV_Int PLL1 Lock (PLOCK1)
29 30 31
45 46 47
0xB4 0xB8 0xBC
Repetitive Interrupt Timer Motor Control PWM Quadrature Encoder
32 33 34
48 49 50
0xC0 0xC4 0xC8
PLL1 (USB PLL)
USB Activity Interrupt USB_NEED_CLK CAN Activity Interrupt CAN1WAKE, CAN2WAKE
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4. Vector table remapping
The Cortex-M3 incorporates a mechanism that allows remapping the interrupt vector table to alternate locations in the memory map. This is controlled via the Vector Table Offset Register (VTOR) contained in the Cortex-M3. The vector table may be located anywhere within the bottom 1 GB of Cortex-M3 address space. The vector table should be located on a 256 word (1024 byte) boundary to insure alignment on LPC17xx family devices. Refer to Section 34-4.3.5 of the Cortex-M3 User Guide appended to this manual for details of the Vector Table Offset feature. ARM describes bit 29 of the VTOR (TBLOFF) as selecting a memory region, either code or SRAM. For simplicity, this bit can be thought as simply part of the address offset since the split between the "code" space and the "SRAM" space occurs at the location corresponding to bit 29 in a memory address. Examples: To place the vector table at the beginning of the "local" static RAM, starting at address 0x1000 0000, place the value 0x1000 0000 in the VTOR register. This indicates address 0x1000 0000 in the code space, since bit 29 of the VTOR equals 0. To place the vector table at the beginning of the AHB static RAM, starting at address 0x2007 C000, place the value 0x2007 C000 in the VTOR register. This indicates address 0x2007 C000 in the SRAM space, since bit 29 of the VTOR equals 1.
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5. Register description
The following table summarizes the registers in the NVIC as implemented in the LPC17xx. The Cortex-M3 User Guide Section 34-4.2 provides a functional description of the NVIC.
Table 51. Name NVIC register map Description Access Reset value Address
ISER0 to Interrupt Set-Enable Registers. These 2 registers allow enabling ISER1 interrupts and reading back the interrupt enables for specific peripheral functions. ICER0 to Interrupt Clear-Enable Registers. These 2 registers allow disabling ICER1 interrupts and reading back the interrupt enables for specific peripheral functions. ISPR0 to Interrupt Set-Pending Registers. These 2 registers allow changing ISPR1 the interrupt state to pending and reading back the interrupt pending state for specific peripheral functions. ICPR0 to Interrupt Clear-Pending Registers. These 2 registers allow ICPR1 changing the interrupt state to not pending and reading back the interrupt pending state for specific peripheral functions. IABR0 to Interrupt Active Bit Registers. These 2 registers allow reading the IABR1 current interrupt active state for specific peripheral functions. IPR0 to IPR8 Interrupt Priority Registers. These 9 registers allow assigning a priority to each interrupt. Each register contains the 5-bit priority fields for 4 interrupts.
RW
0
ISER0 - 0xE000 E100 ISER1 - 0xE000 E104
RW
0
ICER0 - 0xE000 E180 ICER1 - 0xE000 E184
RW
0
ISPR0 - 0xE000 E200 ISPR1 - 0xE000 E204
RW
0
ICPR0 - 0xE000 E280 ICPR1 - 0xE000 E284
RO RW
0 0
IABR0 - 0xE000 E300 IABR1 - 0xE000 E304 IPR0 - 0xE000 E400 IPR1 - 0xE000 E404 IPR2 - 0xE000 E408 IPR3 - 0xE000 E40C IPR4 - 0xE000 E410 IPR5 - 0xE000 E414 IPR6 - 0xE000 E418 IPR7 - 0xE000 E41C IPR8 - 0xE000 E420
STIR
Software Trigger Interrupt Register. This register allows software to WO generate an interrupt.
0
STIR - 0xE000 EF00
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5.1 Interrupt Set-Enable Register 0 register (ISER0 - 0xE000 E100)
The ISER0 register allows enabling the first 32 peripheral interrupts, or for reading the enabled state of those interrupts. The remaining interrupts are enabled via the ISER1 register (Section 6-5.2). Disabling interrupts is done through the ICER0 and ICER1 registers (Section 6-5.3 and Section 6-5.4).
Table 52. Bit Interrupt Set-Enable Register 0 register (ISER0 - 0xE000 E100) Function
Name
0
ISE_WDT
Watchdog Timer Interrupt Enable. Write: writing 0 has no effect, writing 1 enables the interrupt. Read: 0 indicates that the interrupt is disabled, 1 indicates that the interrupt is enabled.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ISE_TIMER0 ISE_TIMER1 ISE_TIMER2 ISE_TIMER3 ISE_UART0 ISE_UART1 ISE_UART2 ISE_UART3 ISE_PWM ISE_I2C0 ISE_I2C1 ISE_I2C2 ISE_SPI ISE_SSP0 ISE_SSP1 ISE_PLL0 ISE_RTC ISE_EINT0 ISE_EINT1 ISE_EINT2 ISE_EINT3 ISE_ADC ISE_BOD ISE_USB ISE_CAN ISE_DMA ISE_I2S ISE_ENET ISE_RIT ISE_MCPWM ISE_QEI
Timer 0 Interrupt Enable. See functional description for bit 0. Timer 1. Interrupt Enable. See functional description for bit 0. Timer 2 Interrupt Enable. See functional description for bit 0. Timer 3 Interrupt Enable. See functional description for bit 0. UART0 Interrupt Enable. See functional description for bit 0. UART1 Interrupt Enable. See functional description for bit 0. UART2 Interrupt Enable. See functional description for bit 0. UART3 Interrupt Enable. See functional description for bit 0. PWM1 Interrupt Enable. See functional description for bit 0. I2C0 Interrupt Enable. See functional description for bit 0. I2C1 Interrupt Enable. See functional description for bit 0. I2C2 Interrupt Enable. See functional description for bit 0. SPI Interrupt Enable. See functional description for bit 0. SSP0 Interrupt Enable. See functional description for bit 0. SSP1 Interrupt Enable. See functional description for bit 0. PLL0 (Main PLL) Interrupt Enable. See functional description for bit 0. Real Time Clock (RTC) Interrupt Enable. See functional description for bit 0. External Interrupt 0 Interrupt Enable. See functional description for bit 0. External Interrupt 1 Interrupt Enable. See functional description for bit 0. External Interrupt 2 Interrupt Enable. See functional description for bit 0. External Interrupt 3 Interrupt Enable. See functional description for bit 0. ADC Interrupt Enable. See functional description for bit 0. BOD Interrupt Enable. See functional description for bit 0. USB Interrupt Enable. See functional description for bit 0. CAN Interrupt Enable. See functional description for bit 0. GPDMA Interrupt Enable. See functional description for bit 0. I2S Interrupt Enable. See functional description for bit 0. Ethernet Interrupt Enable. See functional description for bit 0. Repetitive Interrupt Timer Interrupt Enable. See functional description for bit 0. Motor Control PWM Interrupt Enable. See functional description for bit 0. Quadrature Encoder Interface Interrupt Enable. See functional description for bit 0.
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5.2 Interrupt Set-Enable Register 1 register (ISER1 - 0xE000 E104)
The ISER1 register allows enabling the second group of peripheral interrupts, or for reading the enabled state of those interrupts. Disabling interrupts is done through the ICER0 and ICER1 registers (Section 6-5.3 and Section 6-5.4).
Table 53. Bit Interrupt Set-Enable Register 1 register (ISER1 - 0xE000 E104) Function
Name
0
ISE_PLL1
PLL1 (USB PLL) Interrupt Enable. Write: writing 0 has no effect, writing 1 enables the interrupt. Read: 0 indicates that the interrupt is disabled, 1 indicates that the interrupt is enabled.
1 2
ISE_USBACT ISE_CANACT
USB Activity Interrupt Enable. See functional description for bit 0. CAN Activity Interrupt Enable. See functional description for bit 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
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5.3 Interrupt Clear-Enable Register 0 (ICER0 - 0xE000 E180)
The ICER0 register allows disabling the first 32 peripheral interrupts, or for reading the enabled state of those interrupts. The remaining interrupts are disabled via the ICER1 register (Section 6-5.4). Enabling interrupts is done through the ISER0 and ISER1 registers (Section 6-5.1 and Section 6-5.2).
Table 54. Bit Interrupt Clear-Enable Register 0 (ICER0 - 0xE000 E180) Function
Name
0
ICE_WDT
Watchdog Timer Interrupt Disable. Write: writing 0 has no effect, writing 1 disables the interrupt. Read: 0 indicates that the interrupt is disabled, 1 indicates that the interrupt is enabled.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ICE_TIMER0 ICE_TIMER1 ICE_TIMER2 ICE_TIMER3 ICE_UART0 ICE_UART1 ICE_UART2 ICE_UART3 ICE_PWM ICE_I2C0 ICE_I2C1 ICE_I2C2 ICE_SPI ICE_SSP0 ICE_SSP1 ICE_PLL0 ICE_RTC ICE_EINT0 ICE_EINT1 ICE_EINT2 ICE_EINT3 ICE_ADC ICE_BOD ICE_USB ICE_CAN ICE_DMA ICE_I2S ICE_ENET ICE_RIT ICE_MCPWM ICE_QEI
Timer 0 Interrupt Disable. See functional description for bit 0. Timer 1. Interrupt Disable. See functional description for bit 0. Timer 2 Interrupt Disable. See functional description for bit 0. Timer 3 Interrupt Disable. See functional description for bit 0. UART0 Interrupt Disable. See functional description for bit 0. UART1 Interrupt Disable. See functional description for bit 0. UART2 Interrupt Disable. See functional description for bit 0. UART3 Interrupt Disable. See functional description for bit 0. PWM1 Interrupt Disable. See functional description for bit 0. I2C0 Interrupt Disable. See functional description for bit 0. I2C1 Interrupt Disable. See functional description for bit 0. I2C2 Interrupt Disable. See functional description for bit 0. SPI Interrupt Disable. See functional description for bit 0. SSP0 Interrupt Disable. See functional description for bit 0. SSP1 Interrupt Disable. See functional description for bit 0. PLL0 (Main PLL) Interrupt Disable. See functional description for bit 0. Real Time Clock (RTC) Interrupt Disable. See functional description for bit 0. External Interrupt 0 Interrupt Disable. See functional description for bit 0. External Interrupt 1 Interrupt Disable. See functional description for bit 0. External Interrupt 2 Interrupt Disable. See functional description for bit 0. External Interrupt 3 Interrupt Disable. See functional description for bit 0. ADC Interrupt Disable. See functional description for bit 0. BOD Interrupt Disable. See functional description for bit 0. USB Interrupt Disable. See functional description for bit 0. CAN Interrupt Disable. See functional description for bit 0. GPDMA Interrupt Disable. See functional description for bit 0. I2S Interrupt Disable. See functional description for bit 0. Ethernet Interrupt Disable. See functional description for bit 0. Repetitive Interrupt Timer Interrupt Disable. See functional description for bit 0. Motor Control PWM Interrupt Disable. See functional description for bit 0. Quadrature Encoder Interface Interrupt Disable. See functional description for bit 0.
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5.4 Interrupt Clear-Enable Register 1 register (ICER1 - 0xE000 E184)
The ICER1 register allows disabling the second group of peripheral interrupts, or for reading the enabled state of those interrupts. Enabling interrupts is done through the ISER0 and ISER1 registers (Section 6-5.1 and Section 6-5.2).
Table 55. Bit Interrupt Clear-Enable Register 1 register (ICER1 - 0xE000 E184) Function
Name
0
ICE_PLL1
PLL1 (USB PLL) Interrupt Disable. Write: writing 0 has no effect, writing 1 disables the interrupt. Read: 0 indicates that the interrupt is disabled, 1 indicates that the interrupt is enabled.
1 2
ICE_USBACT ICE_CANACT
USB Activity Interrupt Disable. See functional description for bit 0. CAN Activity Interrupt Disable. See functional description for bit 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
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5.5 Interrupt Set-Pending Register 0 register (ISPR0 - 0xE000 E200)
The ISPR0 register allows setting the pending state of the first 32 peripheral interrupts, or for reading the pending state of those interrupts. The remaining interrupts can have their pending state set via the ISPR1 register (Section 6-5.6). Clearing the pending state of interrupts is done through the ICPR0 and ICPR1 registers (Section 6-5.7 and Section 6-5.8).
Table 56. Bit Interrupt Set-Pending Register 0 register (ISPR0 - 0xE000 E200) Function
Name
0
ISP_WDT
Watchdog Timer Interrupt Pending set. Write: writing 0 has no effect, writing 1 changes the interrupt state to pending. Read: 0 indicates that the interrupt is not pending, 1 indicates that the interrupt is pending.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ISP_TIMER0 ISP_TIMER1 ISP_TIMER2 ISP_TIMER3 ISP_UART0 ISP_UART1 ISP_UART2 ISP_UART3 ISP_PWM ISP_I2C0 ISP_I2C1 ISP_I2C2 ISP_SPI ISP_SSP0 ISP_SSP1 ISP_PLL0 ISP_RTC ISP_EINT0 ISP_EINT1 ISP_EINT2 ISP_EINT3 ISP_ADC ISP_BOD ISP_USB ISP_CAN ISP_DMA ISP_I2S ISP_ENET ISP_RIT ISP_MCPWM ISP_QEI
Timer 0 Interrupt Pending set. See functional description for bit 0. Timer 1. Interrupt Pending set. See functional description for bit 0. Timer 2 Interrupt Pending set. See functional description for bit 0. Timer 3 Interrupt Pending set. See functional description for bit 0. UART0 Interrupt Pending set. See functional description for bit 0. UART1 Interrupt Pending set. See functional description for bit 0. UART2 Interrupt Pending set. See functional description for bit 0. UART3 Interrupt Pending set. See functional description for bit 0. PWM1 Interrupt Pending set. See functional description for bit 0. I2C0 Interrupt Pending set. See functional description for bit 0. I2C1 Interrupt Pending set. See functional description for bit 0. I2C2 Interrupt Pending set. See functional description for bit 0. SPI Interrupt Pending set. See functional description for bit 0. SSP0 Interrupt Pending set. See functional description for bit 0. SSP1 Interrupt Pending set. See functional description for bit 0. PLL0 (Main PLL) Interrupt Pending set. See functional description for bit 0. Real Time Clock (RTC) Interrupt Pending set. See functional description for bit 0. External Interrupt 0 Interrupt Pending set. See functional description for bit 0. External Interrupt 1 Interrupt Pending set. See functional description for bit 0. External Interrupt 2 Interrupt Pending set. See functional description for bit 0. External Interrupt 3 Interrupt Pending set. See functional description for bit 0. ADC Interrupt Pending set. See functional description for bit 0. BOD Interrupt Pending set. See functional description for bit 0. USB Interrupt Pending set. See functional description for bit 0. CAN Interrupt Pending set. See functional description for bit 0. GPDMA Interrupt Pending set. See functional description for bit 0. I2S Interrupt Pending set. See functional description for bit 0. Ethernet Interrupt Pending set. See functional description for bit 0. Repetitive Interrupt Timer Interrupt Pending set. See functional description for bit 0. Motor Control PWM Interrupt Pending set. See functional description for bit 0. Quadrature Encoder Interface Interrupt Pending set. See functional description for bit 0.
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5.6 Interrupt Set-Pending Register 1 register (ISPR1 - 0xE000 E204)
The ISPR1 register allows setting the pending state of the second group of peripheral interrupts, or for reading the pending state of those interrupts. Clearing the pending state of interrupts is done through the ICPR0 and ICPR1 registers (Section 6-5.7 and Section 6-5.8).
Table 57. Bit Interrupt Set-Pending Register 1 register (ISPR1 - 0xE000 E204) Function
Name
0
ISP_PLL1
PLL1 (USB PLL) Interrupt Pending set. Write: writing 0 has no effect, writing 1 changes the interrupt state to pending. Read: 0 indicates that the interrupt is not pending, 1 indicates that the interrupt is pending.
1 2
ISP_USBACT ISP_CANACT
USB Activity Interrupt Pending set. See functional description for bit 0. CAN Activity Interrupt Pending set. See functional description for bit 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
31:3 -
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5.7 Interrupt Clear-Pending Register 0 register (ICPR0 - 0xE000 E280)
The ICPR0 register allows clearing the pending state of the first 32 peripheral interrupts, or for reading the pending state of those interrupts. The remaining interrupts can have their pending state cleared via the ICPR1 register (Section 6-5.8). Setting the pending state of interrupts is done through the ISPR0 and ISPR1 registers (Section 6-5.5 and Section 6-5.6).
Table 58. Bit Interrupt Clear-Pending Register 0 register (ICPR0 - 0xE000 E280) Function
Name
0
ICP_WDT
Watchdog Timer Interrupt Pending clear. Write: writing 0 has no effect, writing 1 changes the interrupt state to not pending. Read: 0 indicates that the interrupt is not pending, 1 indicates that the interrupt is pending.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ICP_TIMER0 ICP_TIMER1 ICP_TIMER2 ICP_TIMER3 ICP_UART0 ICP_UART1 ICP_UART2 ICP_UART3 ICP_PWM ICP_I2C0 ICP_I2C1 ICP_I2C2 ICP_SPI ICP_SSP0 ICP_SSP1 ICP_PLL0 ICP_RTC ICP_EINT0 ICP_EINT1 ICP_EINT2 ICP_EINT3 ICP_ADC ICP_BOD ICP_USB ICP_CAN ICP_DMA ICP_I2S ICP_ENET ICP_RIT ICP_MCPWM ICP_QEI
Timer 0 Interrupt Pending clear. See functional description for bit 0. Timer 1. Interrupt Pending clear. See functional description for bit 0. Timer 2 Interrupt Pending clear. See functional description for bit 0. Timer 3 Interrupt Pending clear. See functional description for bit 0. UART0 Interrupt Pending clear. See functional description for bit 0. UART1 Interrupt Pending clear. See functional description for bit 0. UART2 Interrupt Pending clear. See functional description for bit 0. UART3 Interrupt Pending clear. See functional description for bit 0. PWM1 Interrupt Pending clear. See functional description for bit 0. I2C0 Interrupt Pending clear. See functional description for bit 0. I2C1 Interrupt Pending clear. See functional description for bit 0. I2C2 Interrupt Pending clear. See functional description for bit 0. SPI Interrupt Pending clear. See functional description for bit 0. SSP0 Interrupt Pending clear. See functional description for bit 0. SSP1 Interrupt Pending clear. See functional description for bit 0. PLL0 (Main PLL) Interrupt Pending clear. See functional description for bit 0. Real Time Clock (RTC) Interrupt Pending clear. See functional description for bit 0. External Interrupt 0 Interrupt Pending clear. See functional description for bit 0. External Interrupt 1 Interrupt Pending clear. See functional description for bit 0. External Interrupt 2 Interrupt Pending clear. See functional description for bit 0. External Interrupt 3 Interrupt Pending clear. See functional description for bit 0. ADC Interrupt Pending clear. See functional description for bit 0. BOD Interrupt Pending clear. See functional description for bit 0. USB Interrupt Pending clear. See functional description for bit 0. CAN Interrupt Pending clear. See functional description for bit 0. GPDMA Interrupt Pending clear. See functional description for bit 0. I2S Interrupt Pending clear. See functional description for bit 0. Ethernet Interrupt Pending clear. See functional description for bit 0. Repetitive Interrupt Timer Interrupt Pending clear. See functional description for bit 0. Motor Control PWM Interrupt Pending clear. See functional description for bit 0. Quadrature Encoder Interface Interrupt Pending clear. See functional description for bit 0.
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5.8 Interrupt Clear-Pending Register 1 register (ICPR1 - 0xE000 E284)
The ICPR1 register allows clearing the pending state of the second group of peripheral interrupts, or for reading the pending state of those interrupts. Setting the pending state of interrupts is done through the ISPR0 and ISPR1 registers (Section 6-5.5 and Section 6-5.6).
Table 59. Bit Interrupt Set-Pending Register 1 register (ISPR1 - 0xE000 E204) Function
Name
0
ICP_PLL1
PLL1 (USB PLL) Interrupt Pending clear. Write: writing 0 has no effect, writing 1 changes the interrupt state to not pending. Read: 0 indicates that the interrupt is not pending, 1 indicates that the interrupt is pending.
1 2
ICP_USBACT ICP_CANACT
USB Activity Interrupt Pending clear. See functional description for bit 0. CAN Activity Interrupt Pending clear. See functional description for bit 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
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5.9 Interrupt Active Bit Register 0 (IABR0 - 0xE000 E300)
The IABR0 register is a read-only register that allows reading the active state of the first 32 peripheral interrupts. This allows determining which peripherals are asserting an interrupt to the NVIC, and may also be pending if there are enabled. The remaining interrupts can have their active state read via the IABR1 register (Section 6-5.10).
Table 60. Bit Interrupt Active Bit Register 0 (IABR0 - 0xE000 E300) Function
Name
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
IAB_WDT IAB_TIMER0 IAB_TIMER1 IAB_TIMER2 IAB_TIMER3 IAB_UART0 IAB_UART1 IAB_UART2 IAB_UART3 IAB_PWM IAB_I2C0 IAB_I2C1 IAB_I2C2 IAB_SPI IAB_SSP0 IAB_SSP1 IAB_PLL0 IAB_RTC IAB_EINT0 IAB_EINT1 IAB_EINT2 IAB_EINT3 IAB_ADC IAB_BOD IAB_USB IAB_CAN IAB_DMA IAB_I2S IAB_ENET IAB_RIT IAB_MCPWM IAB_QEI
Watchdog Timer Interrupt Active. Read: 0 indicates that the interrupt is not active, 1 indicates that the interrupt is active. Timer 0 Interrupt Active. See functional description for bit 0. Timer 1. Interrupt Active. See functional description for bit 0. Timer 2 Interrupt Active. See functional description for bit 0. Timer 3 Interrupt Active. See functional description for bit 0. UART0 Interrupt Active. See functional description for bit 0. UART1 Interrupt Active. See functional description for bit 0. UART2 Interrupt Active. See functional description for bit 0. UART3 Interrupt Active. See functional description for bit 0. PWM1 Interrupt Active. See functional description for bit 0. I2C0 Interrupt Active. See functional description for bit 0. I2C1 Interrupt Active. See functional description for bit 0. I2C2 Interrupt Active. See functional description for bit 0. SPI Interrupt Active. See functional description for bit 0. SSP0 Interrupt Active. See functional description for bit 0. SSP1 Interrupt Active. See functional description for bit 0. PLL0 (Main PLL) Interrupt Active. See functional description for bit 0. Real Time Clock (RTC) Interrupt Active. See functional description for bit 0. External Interrupt 0 Interrupt Active. See functional description for bit 0. External Interrupt 1 Interrupt Active. See functional description for bit 0. External Interrupt 2 Interrupt Active. See functional description for bit 0. External Interrupt 3 Interrupt Active. See functional description for bit 0. ADC Interrupt Active. See functional description for bit 0. BOD Interrupt Active. See functional description for bit 0. USB Interrupt Active. See functional description for bit 0. CAN Interrupt Active. See functional description for bit 0. GPDMA Interrupt Active. See functional description for bit 0. I2S Interrupt Active. See functional description for bit 0. Ethernet Interrupt Active. See functional description for bit 0. Repetitive Interrupt Timer Interrupt Active. See functional description for bit 0. Motor Control PWM Interrupt Active. See functional description for bit 0. Quadrature Encoder Interface Interrupt Active. See functional description for bit 0.
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5.10 Interrupt Active Bit Register 1 (IABR1 - 0xE000 E304)
The IABR1 register is a read-only register that allows reading the active state of the second group of peripheral interrupts. This allows determining which peripherals are asserting an interrupt to the NVIC, and may also be pending if there are enabled.
Table 61. Bit Interrupt Active Bit Register 1 (IABR1 - 0xE000 E304) Function
Name
0 1 2
IAB_PLL1 IAB_USBACT IAB_CANACT
PLL1 (USB PLL) Interrupt Active. Read: 0 indicates that the interrupt is not active, 1 indicates that the interrupt is active. USB Activity Interrupt Active. See functional description for bit 0. CAN Activity Interrupt Active. See functional description for bit 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
31:3 -
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5.11 Interrupt Priority Register 0 (IPR0 - 0xE000 E400)
The IPR0 register controls the priority of the first 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 62. Bit Interrupt Priority Register 0 (IPR0 - 0xE000 E400) Function
Name
2:0 7:3 10:8
Unimplemented IP_WDT Unimplemented
These bits ignore writes, and read as 0. Watchdog Timer Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. Timer 0 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. Timer 1 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. Timer 2 Interrupt Priority. See functional description for bits 7-3.
15:11 IP_TIMER0 18:16 Unimplemented 23:19 IP_TIMER1 26:24 Unimplemented 31:27 IP_TIMER2
5.12 Interrupt Priority Register 1 (IPR1 - 0xE000 E404)
The IPR1 register controls the priority of the second group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 63. Bit Interrupt Priority Register 1 (IPR1 - 0xE000 E404) Function
Name
2:0 7:3 10:8
Unimplemented IP_TIMER3 Unimplemented
These bits ignore writes, and read as 0. Timer 3 Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. UART0 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. UART1 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. UART2 Interrupt Priority. See functional description for bits 7-3.
15:11 IP_UART0 18:16 Unimplemented 23:19 IP_UART1 26:24 Unimplemented 31:27 IP_UART2
5.13 Interrupt Priority Register 2 (IPR2 - 0xE000 E408)
The IPR2 register controls the priority of the third group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 64. Bit Interrupt Priority Register 2 (IPR2 - 0xE000 E408) Function
Name
2:0 7:3 10:8
Unimplemented IP_UART3 Unimplemented
These bits ignore writes, and read as 0. UART3 Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. PWM Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. I2C0 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. I2C1 Interrupt Priority. See functional description for bits 7-3.
15:11 IP_PWM 18:16 Unimplemented 23:19 IP_I2C0 26:24 Unimplemented 31:27 IP_I2C1
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5.14 Interrupt Priority Register 3 (IPR3 - 0xE000 E40C)
The IPR3 register controls the priority of the fourth group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 65. Bit Interrupt Priority Register 3 (IPR3 - 0xE000 E40C) Function
Name
2:0 7:3 10:8
Unimplemented IP_I2C2 Unimplemented
These bits ignore writes, and read as 0. I2C2 Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. SPI Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. SSP0 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. SSP1 Interrupt Priority. See functional description for bits 7-3.
15:11 IP_SPI 18:16 Unimplemented 23:19 IP_SSP0 26:24 Unimplemented 31:27 IP_SSP1
5.15 Interrupt Priority Register 4 (IPR4 - 0xE000 E410)
The IPR4 register controls the priority of the fifth group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 66. Bit Interrupt Priority Register 4 (IPR4 - 0xE000 E410) Function
Name
2:0 7:3 10:8
Unimplemented IP_PLL0 Unimplemented
These bits ignore writes, and read as 0. PLL0 (Main PLL) Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. Real Time Clock (RTC) Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. External Interrupt 0 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. External Interrupt 1 Interrupt Priority. See functional description for bits 7-3.
15:11 IP_RTC 18:16 Unimplemented 23:19 IP_EINT0 26:24 Unimplemented 31:27 IP_EINT1
5.16 Interrupt Priority Register 5 (IPR5 - 0xE000 E414)
The IPR5 register controls the priority of the sixth group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 67. Bit Interrupt Priority Register 5 (IPR5 - 0xE000 E414) Function
Name
2:0 7:3 10:8
Unimplemented IP_EINT2 Unimplemented
These bits ignore writes, and read as 0. External Interrupt 2 Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. External Interrupt 3 Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. ADC Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. BOD Interrupt Priority. See functional description for bits 7-3.
15:11 IP_EINT3 18:16 Unimplemented 23:19 IP_ADC 26:24 Unimplemented 31:27 IP_BOD
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5.17 Interrupt Priority Register 6 (IPR6 - 0xE000 E418)
The IPR6 register controls the priority of the seventh group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 68. Bit Interrupt Priority Register 6 (IPR6 - 0xE000 E418) Function
Name
2:0 7:3 10:8
Unimplemented IP_USB Unimplemented
These bits ignore writes, and read as 0. USB Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. CAN Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. GPDMA Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. I2S Interrupt Priority. See functional description for bits 7-3.
15:11 IP_CAN 18:16 Unimplemented 23:19 IP_DMA 26:24 Unimplemented 31:27 IP_I2S
5.18 Interrupt Priority Register 7 (IPR7 - 0xE000 E41C)
The IPR7 register controls the priority of the eighth group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 69. Bit Interrupt Priority Register 7 (IPR7 - 0xE000 E41C) Function
Name
2:0 7:3 10:8
Unimplemented IP_ENET Unimplemented
These bits ignore writes, and read as 0. Ethernet Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. Repetitive Interrupt Timer Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. Motor Control PWM Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. Quadrature Encoder Interface Interrupt Priority. See functional description for bits 7-3.
15:11 IP_RIT 18:16 Unimplemented 23:19 IP_MCPWM 26:24 Unimplemented 31:27 IP_QEI
5.19 Interrupt Priority Register 8 (IPR8 - 0xE000 E420)
The IPR8 register controls the priority of the ninth and last group of 4 peripheral interrupts. Each interrupt can have one of 32 priorities, where 0 is the highest priority.
Table 70. Bit Interrupt Priority Register 8 (IPR8 - 0xE000 E420) Function
Name
2:0 7:3 10:8
Unimplemented IP_PLL1 Unimplemented
These bits ignore writes, and read as 0. PLL1 (USB PLL) Interrupt Priority. 0 = highest priority. 31 (0x1F) = lowest priority. These bits ignore writes, and read as 0. USB Activity Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0. CAN Activity Interrupt Priority. See functional description for bits 7-3. These bits ignore writes, and read as 0.
15:11 IP_USBACT 18:16 Unimplemented 23:19 IP_CANACT 31:24 Unimplemented
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5.20 Software Trigger Interrupt Register (STIR - 0xE000 EF00)
The STIR register provides an alternate way for software to generate an interrupt, in addition to using the ISPR registers. This mechanism can only be used to generate peripheral interrupts, not system exceptions. By default, only privileged software can write to the STIR register. Unprivileged software can be given this ability if privileged software sets the USERSETMPEND bit in the CCR register (see Section 34-4.3.8).
Table 71. Bit Software Trigger Interrupt Register (STIR - 0xE000 EF00) Function
Name
8:0 31:9
INTID -
Writing a value to this field generates an interrupt for the specified the interrupt number (see Table 6-50). The range allowed for the LPC17xx is 0 to 111. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
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1. LPC17xx pin configuration
100
1
76 75 51 50 61 60 41 40
002aae158 002aad945_1
25 26
Fig 14. LPC176x LQFP100 pin configuration
1
20 21
Fig 15. LPC175x LQFP80 pin configuration
1.1 LPC17xx pin description
I/O pins on the LPC17xx are 5V tolerant and have input hysteresis unless indicated in the table below. Crystal pins, power pins, and reference voltage pins are not 5V tolerant. In addition, when pins are selected to be A to D converter inputs, they are no longer 5V tolerant and must be limited to the voltage at the ADC positive reference pin (VREFP).
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Table 72. Symbol
Pin description LQFP 100 LQFP 80 Type Description
P0[0] to P0[31]
I/O
Port 0: Port 0 is a 32-bit I/O port with individual direction controls for each bit. The operation of port 0 pins depends upon the pin function selected via the pin connect block. Pins 12, 13, 14, and 31 of this port are not available. P0[0] -- General purpose digital input/output pin. RD1 -- CAN1 receiver input. TXD3 -- Transmitter output for UART3. SDA1 -- I2C1 data input/output (this pin is not fully compliant with the I2C-bus specification, see Section 19-4 for details). P0[1] -- General purpose digital input/output pin. TD1 -- CAN1 transmitter output. RXD3 -- Receiver input for UART3. SCL1 -- I2C1 clock input/output (this pin is not fully compliant with the I2C-bus specification, see Section 19-4 for details). P0[2] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. TXD0 -- Transmitter output for UART0. AD0[7] -- A/D converter 0, input 7. P0[3] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. RXD0 -- Receiver input for UART0. AD0[6] -- A/D converter 0, input 6. P0[4] -- General purpose digital input/output pin. I2SRX_CLK -- Receive Clock. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification. RD2 -- CAN2 receiver input. CAP2[0] -- Capture input for Timer 2, channel 0. P0[5] -- General purpose digital input/output pin. I2SRX_WS -- Receive Word Select. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. TD2 -- CAN2 transmitter output. CAP2[1] -- Capture input for Timer 2, channel 1. P0[6] -- General purpose digital input/output pin. I2SRX_SDA -- Receive data. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. SSEL1 -- Slave Select for SSP1. MAT2[0] -- Match output for Timer 2, channel 0. P0[7] -- General purpose digital input/output pin. I2STX_CLK -- Transmit Clock. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification. SCK1 -- Serial Clock for SSP1. MAT2[1] -- Match output for Timer 2, channel 1.
P0[0] / RD1 / TXD3 / SDA1
46
37
I/O I O I/O
P0[1] / TD1 / RXD3 / SCL1
47
38
I/O O I I/O
P0[2] / TXD0 / AD0[7]
98
79
I/O O I
P0[3] / RXD0 / AD0[6]
99
80
I/O I I
P0[4] / I2SRX_CLK / RD2 / CAP2[0]
81
-
I/O I/O I I
P0[5] / I2SRX_WS / 80 TD2 / CAP2[1]
-
I/O I/O
O I P0[6] / I2SRX_SDA / SSEL1 / MAT2[0] 79 64 I/O I/O I/O O P0[7] / I2STX_CLK / SCK1 / MAT2[1] 78 63 I/O I/O I/O O
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P0[8] / I2STX_WS / 77 MISO1 / MAT2[2]
62
I/O I/O
P0[8] -- General purpose digital input/output pin. I2STX_WS -- Transmit Word Select. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. MISO1 -- Master In Slave Out for SSP1. MAT2[2] -- Match output for Timer 2, channel 2. P0[9] -- General purpose digital input/output pin. I2STX_SDA -- Transmit data. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. MOSI1 -- Master Out Slave In for SSP1. MAT2[3] -- Match output for Timer 2, channel 3. P0[10] -- General purpose digital input/output pin. TXD2 -- Transmitter output for UART2. SDA2 -- I2C2 data input/output (this is not an open-drain pin). MAT3[0] -- Match output for Timer 3, channel 0. P0[11] -- General purpose digital input/output pin. RXD2 -- Receiver input for UART2. SCL2 -- I2C2 clock input/output (this is not an open-drain pin). MAT3[1] -- Match output for Timer 3, channel 1. P0[15] -- General purpose digital input/output pin. TXD1 -- Transmitter output for UART1. SCK0 -- Serial clock for SSP0. SCK -- Serial clock for SPI. P0[16] -- General purpose digital input/output pin. RXD1 -- Receiver input for UART1. SSEL0 -- Slave Select for SSP0. SSEL -- Slave Select for SPI. P0[17] -- General purpose digital input/output pin. CTS1 -- Clear to Send input for UART1. MISO0 -- Master In Slave Out for SSP0. MISO -- Master In Slave Out for SPI. P0[18] -- General purpose digital input/output pin. DCD1 -- Data Carrier Detect input for UART1. MOSI0 -- Master Out Slave In for SSP0. MOSI -- Master Out Slave In for SPI. P0[19] -- General purpose digital input/output pin. DSR1 -- Data Set Ready input for UART1. SDA1 -- I2C1 data input/output (this pin is not fully compliant with the I2C-bus specification, see Section 19-4 for details).
I/O O P0[9] / I2STX_SDA / MOSI1 / MAT2[3] 76 61 I/O I/O I/O O P0[10] / TXD2 / SDA2 / MAT3[0] 48 39 I/O O I/O O P0[11] / RXD2 / SCL2 / MAT3[1] 49 40 I/O I I/O O P0[15] / TXD1 / SCK0 / SCK 62 47 I/O O I/O I/O P0[16] / RXD1 / SSEL0 / SSEL 63 48 I/O I I/O I/O P0[17] / CTS1 / MISO0 / MISO 61 46 I/O I I/O I/O P0[18] / DCD1 / MOSI0 / MOSI 60 45 I/O I I/O I/O P0[19] / DSR1 / SDA1 59
-
I/O I I/O
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P0[20] / DTR1 / SCL1
58
-
I/O O I/O
P0[20] -- General purpose digital input/output pin. DTR1 -- Data Terminal Ready output for UART1. Can also be configured to be an RS-485/EIA-485 output enable signal. SCL1 -- I2C1 clock input/output (this pin is not fully compliant with the I2C-bus specification, see Section 19-4 for details). P0[21] -- General purpose digital input/output pin. RI1 -- Ring Indicator input for UART1. RD1 -- CAN1 receiver input. P0[22] -- General purpose digital input/output pin. RTS1 -- Request to Send output for UART1. Can also be configured to be an RS-485/EIA-485 output enable signal. TD1 -- CAN1 transmitter output. P0[23] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. AD0[0] -- A/D converter 0, input 0. I2SRX_CLK -- Receive Clock. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification. CAP3[0] -- Capture input for Timer 3, channel 0. P0[24] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. AD0[1] -- A/D converter 0, input 1. I2SRX_WS -- Receive Word Select. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. CAP3[1] -- Capture input for Timer 3, channel 1. P0[25] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. AD0[2] -- A/D converter 0, input 2. I2SRX_SDA -- Receive data. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. TXD3 -- Transmitter output for UART3. P0[26] -- General purpose digital input/output pin. When configured as an ADC input or DAC output, the digital section of the pad is disabled. AD0[3] -- A/D converter 0, input 3. AOUT -- D/A converter output. RXD3 -- Receiver input for UART3. P0[27] -- General purpose digital input/output pin. Open-drain 5 V tolerant digital I/O pad, compatible with I2C-bus specifications for 100 kHz standard mode, 400 kHz Fast Mode, and 1 MHz Fast Mode Plus. This pad requires an external pull-up to provide output functionality. When power is switched off, this pin connected to the I2C-bus is floating and does not disturb the I2C lines. Open-drain configuration applies to all functions on this pin. SDA0 -- I2C0 data input/output. Open-drain output (for I2C-bus compliance). USB_SDA -- USB port I2C serial data (OTG transceiver).
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P0[21] / RI1 / RD1
57
-
I/O I I
P0[22] / RTS1 / TD1 56
44
I/O O O
P0[23] / AD0[0] / I2SRX_CLK / CAP3[0]
9
-
I/O I I/O I
P0[24] / AD0[1] / I2SRX_WS / CAP3[1]
8
-
I/O I I/O
I P0[25] / AD0[2] / I2SRX_SDA / TXD3 7 7 I/O I I/O O P0[26] / AD0[3] / AOUT / RXD3 6 6 I/O I O I P0[27] / SDA0 / USB_SDA 25 I/O
I/O I/O
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P0[28] / SCL0 / USB_SCL
24
-
I/O
P0[28] -- General purpose digital input/output pin. Open-drain 5 V tolerant digital I/O pad, compatible with I2C-bus specifications for 100 kHz standard mode, 400 kHz Fast Mode, and 1 MHz Fast Mode Plus. This pad requires an external pull-up to provide output functionality. When power is switched off, this pin connected to the I2C-bus is floating and does not disturb the I2C lines. Open-drain configuration applies to all functions on this pin. SCL0 -- I2C0 clock input/output. Open-drain output (for I2C-bus compliance). USB_SCL -- USB port I2C serial clock (OTG transceiver). P0[29] -- General purpose digital input/output pin. Pad provides digital I/O and USB functions. It is designed in accordance with the USB specification, revision 2.0 (Full-speed and Low-speed mode only). USB_D+ -- USB bidirectional D+ line. P0[30] -- General purpose digital input/output pin. Pad provides digital I/O and USB functions. It is designed in accordance with the USB specification, revision 2.0 (Full-speed and Low-speed mode only). USB_D- -- USB bidirectional D- line. Port 1: Port 1 is a 32-bit I/O port with individual direction controls for each bit. The operation of port 1 pins depends upon the pin function selected via the pin connect block. Pins 2, 3, 5, 6, 7, 11, 12, and 13 of this port are not available. P1[0] -- General purpose digital input/output pin. ENET_TXD0 -- Ethernet transmit data 0. P1[1] -- General purpose digital input/output pin. ENET_TXD1 -- Ethernet transmit data 1. P1[4] -- General purpose digital input/output pin. ENET_TX_EN -- Ethernet transmit data enable. P1[8] -- General purpose digital input/output pin. ENET_CRS -- Ethernet carrier sense. P1[9] -- General purpose digital input/output pin. ENET_RXD0 -- Ethernet receive data. P1[10] -- General purpose digital input/output pin. ENET_RXD1 -- Ethernet receive data. P1[14] -- General purpose digital input/output pin. ENET_RX_ER -- Ethernet receive error. P1[15] -- General purpose digital input/output pin. ENET_REF_CLK -- Ethernet reference clock. P1[16] -- General purpose digital input/output pin. ENET_MDC -- Ethernet MIIM clock. P1[17] -- General purpose digital input/output pin. ENET_MDIO -- Ethernet MIIM data input and output.
I/O I/O P0[29] / USB_D+ 29 22 I/O
I/O P0[30] / USB_D- 30 23 I/O
I/O P1[0] to P1[31] I/O
P1[0] / ENET_TXD0 P1[1] / ENET_TXD1 P1[4] / ENET_TX_EN P1[8] / ENET_CRS P1[9] / ENET_RXD0 P1[10] / ENET_RXD1 P1[14] / ENET_RX_ER P1[15] / ENET_REF_CLK P1[16] / ENET_MDC P1[17] / ENET_MDIO
95 94 93 92 91 90 89 88 87 86
76 75 74 73 72 71 70 69 -
I/O O I/O O I/O O I/O I I/O I I/O I I/O I I/O I I/O O I/O I/O
-
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P1[18] / 32 USB_UP_LED / PWM1[1] / CAP1[0]
25
I/O O
P1[18] -- General purpose digital input/output pin. USB_UP_LED -- USB GoodLink LED indicator. It is LOW when device is configured (non-control endpoints enabled). It is HIGH when the device is not configured or during global suspend. PWM1[1] -- Pulse Width Modulator 1, channel 1 output. CAP1[0] -- Capture input for Timer 1, channel 0. P1[19] -- General purpose digital input/output pin. MCOA0 -- Motor control PWM channel 0, output A. USB_PPWR -- Port Power enable signal for USB port. CAP1[1] -- Capture input for Timer 1, channel 1. P1[20] -- General purpose digital input/output pin. MCI0 -- Motor control PWM channel 0 input. Also Quadrature Encoder Interface PHA input. PWM1[2] -- Pulse Width Modulator 1, channel 2 output. SCK0 -- Serial clock for SSP0. P1[21] -- General purpose digital input/output pin. MCABORT -- Motor control PWM, active low fast abort. PWM1[3] -- Pulse Width Modulator 1, channel 3 output. SSEL0 -- Slave Select for SSP0. P1[22] -- General purpose digital input/output pin. MCOB0 -- Motor control PWM channel 0, output B. USB_PWRD -- Power Status for USB port (host power switch). MAT1[0] -- Match output for Timer 1, channel 0. P1[23] -- General purpose digital input/output pin. MCI1 -- Motor control PWM channel 1 input. Also Quadrature Encoder Interface PHB input. PWM1[4] -- Pulse Width Modulator 1, channel 4 output. MISO0 -- Master In Slave Out for SSP0. P1[24] -- General purpose digital input/output pin. MCI2 -- Motor control PWM channel 2 input. Also Quadrature Encoder Interface INDEX input. PWM1[5] -- Pulse Width Modulator 1, channel 5 output. MOSI0 -- Master Out Slave in for SSP0. P1[25] -- General purpose digital input/output pin. MCOA1 -- Motor control PWM channel 1, output A. MAT1[1] -- Match output for Timer 1, channel 1. P1[26] -- General purpose digital input/output pin. MCOB1 -- Motor control PWM channel 1, output B. PWM1[6] -- Pulse Width Modulator 1, channel 6 output. CAP0[0] -- Capture input for Timer 0, channel 0.
O I P1[19] / MCOA0 / USB_PPWR / CAP1[1] 33 26 I/O O O I P1[20] / MCI0 / PWM1[2] / SCK0 34 27 I/O I O I/O P1[21] / MCABORT / PWM1[3] / SSEL0 35
-
I/O O O I/O
P1[22] / MCOB0 / USB_PWRD / MAT1[0]
36
28
I/O O I O
P1[23] / MCI1 / PWM1[4] / MISO0
37
29
I/O I O I/O
P1[24] / MCI2 / PWM1[5] / MOSI0
38
30
I/O I O I/O
P1[25] / MCOA1 / MAT1[1]
39
31
I/O O O
P1[26] / MCOB1 / 40 PWM1[6] / CAP0[0]
32
I/O O O I
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P1[27] / CLKOUT / USB_OVRCR / CAP0[1]
43
-
I/O O I I
P1[27] -- General purpose digital input/output pin. CLKOUT -- Clock output pin. USB_OVRCR -- USB port Over-Current status. CAP0[1] -- Capture input for Timer 0, channel 1. P1[28] -- General purpose digital input/output pin. MCOA2 -- Motor control PWM channel 2, output A. PCAP1[0] -- Capture input for PWM1, channel 0. MAT0[0] -- Match output for Timer 0, channel 0. P1[29] -- General purpose digital input/output pin. MCOB2 -- Motor control PWM channel 2, output B. PCAP1[1] -- Capture input for PWM1, channel 1. MAT0[1] -- Match output for Timer 0, channel 0. P1[30] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. VBUS -- Monitors the presence of USB bus power. Note: This signal must be HIGH for USB reset to occur. AD0[4] -- A/D converter 0, input 4. P1[31] -- General purpose digital input/output pin. When configured as an ADC input, digital section of the pad is disabled. SCK1 -- Serial Clock for SSP1. AD0[5] -- A/D converter 0, input 5. Port 2: Port 2 is a 32-bit I/O port with individual direction controls for each bit. The operation of port 2 pins depends upon the pin function selected via the pin connect block. Pins 14 through 31 of this port are not available. P2[0] -- General purpose digital input/output pin. PWM1[1] -- Pulse Width Modulator 1, channel 1 output. TXD1 -- Transmitter output for UART1. P2[1] -- General purpose digital input/output pin. PWM1[2] -- Pulse Width Modulator 1, channel 2 output. RXD1 -- Receiver input for UART1. P2[2] -- General purpose digital input/output pin. PWM1[3] -- Pulse Width Modulator 1, channel 3 output. CTS1 -- Clear to Send input for UART1. TRACEDATA[3] -- Trace data, bit 3. P2[3] -- General purpose digital input/output pin. PWM1[4] -- Pulse Width Modulator 1, channel 4 output. DCD1 -- Data Carrier Detect input for UART1. TRACEDATA[2] -- Trace data, bit 2.
P1[28] / MCOA2 / 44 PCAP1[0] / MAT0[0]
35
I/O O I O
P1[29] / MCOB2 / PCAP1[1] / MAT0[1]
45
36
I/O O I O
P1[30] / VBUS / AD0[4]
21
18
I/O I I
P1[31] / SCK1 / AD0[5]
20
17
I/O I/O I
P2[0] to P2[31]
I/O
P2[0] / PWM1[1] / TXD1
75
60
I/O O O
P2[1] / PWM1[2] / RXD1
74
59
I/O O I
P2[2] / PWM1[3] / CTS1 / TRACEDATA[3]
73
58
I/O O I O
P2[3] / PWM1[4] / DCD1 / TRACEDATA[2]
70
55
I/O O I O
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P2[4] / PWM1[5] / DSR1 / TRACEDATA[1]
69
54
I/O O I O
P2[4] -- General purpose digital input/output pin. PWM1[5] -- Pulse Width Modulator 1, channel 5 output. DSR1 -- Data Set Ready input for UART1. TRACEDATA[1] -- Trace data, bit 1. P2[5] -- General purpose digital input/output pin. PWM1[6] -- Pulse Width Modulator 1, channel 6 output. DTR1 -- Data Terminal Ready output for UART1. Can also be configured to be an RS-485/EIA-485 output enable signal. TRACEDATA[0] -- Trace data, bit 0. P2[6] -- General purpose digital input/output pin. PCAP1[0] -- Capture input for PWM1, channel 0. RI1 -- Ring Indicator input for UART1. TRACECLK -- Trace Clock. P2[7] -- General purpose digital input/output pin. RD2 -- CAN2 receiver input. RTS1 -- Request to Send output for UART1. Can also be configured to be an RS-485/EIA-485 output enable signal. P2[8] -- General purpose digital input/output pin. TD2 -- CAN2 transmitter output. TXD2 -- Transmitter output for UART2. ENET_MDC -- Ethernet MIIM clock. P2[9] -- General purpose digital input/output pin. USB_CONNECT -- Signal used to switch an external 1.5 k resistor under software control. Used with the SoftConnect USB feature. RXD2 -- Receiver input for UART2. ENET_MDIO -- Ethernet MIIM data input and output. P2[10] -- General purpose digital input/output pin. 5 V tolerant pad with 5 ns glitch filter providing digital I/O functions with TTL levels and hysteresis. Note: A LOW on this pin while RESET is LOW forces the on-chip bootloader to take over control of the part after a reset and go into ISP mode. See Section 32-1.
P2[5] / PWM1[6] / DTR1 / TRACEDATA[0]
68
53
I/O O O O
P2[6] / PCAP1[0] / RI1 / TRACECLK
67
52
I/O I I O
P2[7] / RD2 / RTS1
66
51
I/O I O
P2[8] / TD2 / 65 TXD2 / ENET_MDC
50
I/O O O O
P2[9] / USB_CONNECT / RXD2 / ENET_MDIO
64
49
I/O O I I/O
P2[10] / EINT0 / NMI
53
41
I/O
I I P2[11] / EINT1 / I2STX_CLK 52 I/O I I/O
EINT0 -- External interrupt 0 input. NMI -- Non-maskable interrupt input. P2[11] -- General purpose digital input/output pin. 5 V tolerant pad with 5 ns glitch filter providing digital I/O functions with TTL levels and hysteresis. EINT1 -- External interrupt 1 input. I2STX_CLK -- Transmit Clock. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification.
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
P2[12] / EINT2 / I2STX_WS
51
-
I/O I I/O
P2[12] -- General purpose digital input/output pin. 5 V tolerant pad with 5 ns glitch filter providing digital I/O functions with TTL levels and hysteresis. EINT2 -- External interrupt 2 input. I2STX_WS -- Transmit Word Select. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. P2[13] -- General purpose digital input/output pin. 5 V tolerant pad with 5 ns glitch filter providing digital I/O functions with TTL levels and hysteresis. EINT3 -- External interrupt 3 input. I2STX_SDA -- Transmit data. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. Port 3: Port 3 is a 32-bit I/O port with individual direction controls for each bit. The operation of port 3 pins depends upon the pin function selected via the pin connect block. Pins 0 through 24, and 27 through 31 of this port are not available. P3[25] -- General purpose digital input/output pin. MAT0[0] -- Match output for Timer 0, channel 0. PWM1[2] -- Pulse Width Modulator 1, output 2. P3[26] -- General purpose digital input/output pin. STCLK -- System tick timer clock input. MAT0[1] -- Match output for Timer 0, channel 1. PWM1[3] -- Pulse Width Modulator 1, output 3. Port 4: Port 4 is a 32-bit I/O port with individual direction controls for each bit. The operation of port 4 pins depends upon the pin function selected via the pin connect block. Pins 0 through 27, 30, and 31 of this port are not available. P4[28] -- General purpose digital input/output pin. RX_MCLK -- I2S receive master clock. MAT2[0] -- Match output for Timer 2, channel 0. TXD3 -- Transmitter output for UART3. P4[29] -- General purpose digital input/output pin. TX_MCLK -- I2S transmit master clock. MAT2[1] -- Match output for Timer 2, channel 1. RXD3 -- Receiver input for UART3. TDO -- Test Data out for JTAG interface. SWO -- Serial wire trace output. TDI -- Test Data in for JTAG interface. TMS -- Test Mode Select for JTAG interface. SWDIO -- Serial wire debug data input/output. TRST -- Test Reset for JTAG interface. TCK -- Test Clock for JTAG interface. SWDCLK -- Serial wire clock. RTCK -- JTAG interface control signal.
(c) NXP B.V. 2010. All rights reserved.
P2[13] / EINT3 / I2STX_SDA
50
-
I/O I I/O
P3[0] to P3[31]
I/O
P3[25] / MAT0[0] / PWM1[2]
27
-
I/O O O
P3[26] / STCLK / 26 MAT0[1] / PWM1[3]
-
I/O I O O
P4[0] to P4[31]
I/O
P4[28] / RX_MCLK / MAT2[0] / TXD3
82
65
I/O I O O
P4[29] TX_MCLK / MAT2[1] / RXD3
85
68
I/O I O I
TDO / SWO TDI TMS / SWDIO TRST TCK / SWDCLK RTCK
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1 2 3 4 5 100
1 2 3 4 5
O O I I I/O I I I I/O
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Chapter 7: LPC17xx Pin configuration
Table 72. Symbol
Pin description ...continued LQFP 100 LQFP 80 Type Description
RSTOUT RESET
14 17
11 14
O I
RSTOUT -- This is a 3.3 V pin. A LOW on this pin indicates that the LPC17xx is in a Reset state. External reset input: A LOW on this pin resets the device, causing I/O ports and peripherals to take on their default states, and processor execution to begin at address 0. This is a 5 V tolerant pad with a 20 ns glitch filter, TTL levels and hysteresis.
XTAL1 XTAL2 RTCX1 RTCX2 VSS
22[1] 23[1] 16[1] 18[1]
19[1] 20[1] 13[1] 15[1]
I O I O
Input to the oscillator circuit and internal clock generator circuits. Output from the oscillator amplifier. Input to the RTC oscillator circuit. Output from the RTC oscillator circuit.
ground: 0 V reference.
31, 41, 24, 33, I 55, 72, 43, 57, 83, 97[1] 66, 78[1] 11[1] 9[1] I
VSSA VDD(3V3) VDD(REG)(3V3) VDDA
analog ground: 0 V reference. This should be the same voltage as VSS, but should be isolated to minimize noise and error. 3.3 V supply voltage: This is the power supply voltage for I/O other than pins in the Vbat domain. 3.3 V voltage regulator supply voltage: This is the supply voltage for the on-chip voltage regulator only. analog 3.3 V pad supply voltage: This can be connected to the same supply as VDD(3V3) but should be isolated to minimize noise and error. This voltage is used to power the ADC and DAC. Note: this pin should be tied to 3.3v if the ADC and DAC are not used. ADC positive reference voltage: This should be nominally the same voltage as VDDA but should be isolated to minimize noise and error. The voltage level on this pin is used as a reference for ADC and DAC. Note: this pin should be tied to 3.3v if the ADC and DAC are not used. ADC negative reference voltage: This should be the same voltage as VSS but should be isolated to minimize noise and error. Level on this pin is used as a reference for ADC and DAC. RTC domain power supply: 3.3 V on this pin supplies the power to the RTC peripheral.
28, 54, 21, 42, I 71, 96[1] 56, 77[1] 42, 84[1] 34, 67[1] I 10[1] 8[1] I
VREFP
12[1]
10[1]
I
VREFN
15[1]
12[1]
I
VBAT n.c.
[1]
19[1] 13
16[1] -
I -
not connected
Pad provides special analog functionality.
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1. How to read this chapter
Table 8-73 shows the functions of the PINSEL registers in the LPC17xx.
Table 73. Register Summary of PINSEL registers Controls Table
PINSEL0 PINSEL1 PINSEL2 PINSEL3 PINSEL4 PINSEL5 PINSEL6 PINSEL7 PINSEL8 PINSEL9 PINSEL10
P0[15:0] P0 [31:16] P1 [15:0] (Ethernet) P1 [31:16] P2 [15:0] P2 [31:16] P3 [15:0] P3 [31:16] P4 [15:0] P4 [31:16] Trace port enable
Table 8-78 Table 8-79 Table 8-80 Table 8-81 Table 8-82 not used not used Table 8-83 not used Table 8-84 Table 8-85
2. Description
The pin connect block allows most pins of the microcontroller to have more than one potential function. Configuration registers control the multiplexers to allow connection between the pin and the on chip peripherals. Peripherals should be connected to the appropriate pins prior to being activated and prior to any related interrupt(s) being enabled. Activity of any enabled peripheral function that is not mapped to a related pin should be considered undefined. Selection of a single function on a port pin excludes other peripheral functions available on the same pin. However, the GPIO input stays connected and may be read by software or used to contribute to the GPIO interrupt feature.
3. Pin function select register values
The PINSEL registers control the functions of device pins as shown below. Pairs of bits in these registers correspond to specific device pins.
Table 74. Pin function select register bits Value after Reset
PINSEL0 to Function PINSEL9 Values
00 01 10 11
UM10360_1
Primary (default) function, typically GPIO port First alternate function Second alternate function Third alternate function
00
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Chapter 8: LPC17xx Pin connect block
The direction control bit in the GPIO registers is effective only when the GPIO function is selected for a pin. For other functions, direction is controlled automatically. Each derivative typically has a different pinout and therefore a different set of functions possible for each pin. Details for a specific derivative may be found in the appropriate data sheet. Multiple connections Since a particular peripheral function may be allowed on more than one pin, it is in principle possible to configure more than one pin to perform the same function. If a peripheral output function is configured to appear on more than one pin, it will in fact be routed to those pins. If a peripheral input function is configured to appear on more than one pin for some reason, the peripheral will receive its input from the lowest port number. For instance, any pin of port 0 will take precedence over any pin of a higher numbered port, and pin 0 of any port will take precedence over a higher numbered pin of the same port.
4. Pin mode select register values
The PINMODE registers control the input mode of all ports. This includes the use of the on-chip pull-up/pull-down resistor feature and a special open drain operating mode. The on-chip pull-up/pull-down resistor can be selected for every port pin regardless of the function on this pin with the exception of the I2C pins for the I2C0 interface and the USB pins (see Section 8-5.10). Three bits are used to control the mode of a port pin, two in a PINMODE register, and an additional one in a PINMODE_OD register. Bits are reserved for unused pins as in the PINSEL registers.
Table 75. Pin Mode Select register Bits Value after Reset
PINMODE0 to Function PINMODE9 Values
00 01 10 11
Pin has an on-chip pull-up resistor enabled. Repeater mode (see text below). Pin has neither pull-up nor pull-down resistor enabled. Pin has an on-chip pull-down resistor enabled.
00
Repeater mode enables the pull-up resistor if the pin is at a logic high and enables the pull-down resistor if the pin is at a logic low. This causes the pin to retain its last known state if it is configured as an input and is not driven externally. The state retention is not applicable to the Deep Power-down mode. Repeater mode may typically be used to prevent a pin from floating (and potentially using significant power if it floats to an indeterminate state) if it is temporarily not driven. The PINMODE_OD registers control the open drain mode for ports. The open drain mode causes the pin to be pulled low normally if it is configured as an output and the data value is 0. If the data value is 1, the output drive of the pin is turned off, equivalent to changing the pin direction. This combination simulates an open drain output.
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Chapter 8: LPC17xx Pin connect block
Open Drain Pin Mode Select register Bits Value after Reset
Table 76.
PINMODE_OD0 to Function PINMODE_OD4 Values
0 1
Pin is in the normal (not open drain) mode. Pin is in the open drain mode.
00
Function of PINMODE in open drain mode Normally the value of PINMODE applies to a pin only when it is in the input mode. When a pin is in the open drain mode, caused by a 1 in the corresponding bit of one of the PINMODE_OD registers, the input mode still does not apply when the pin is outputting a 0. However, when the pin value is 1, PINMODE applies since this state turns off the pin's output driver. For example, this allows for the possibility of configuring a pin to be open drain with an on-chip pullup. A pullup in this case which is only on when the pin is not being pulled low by the pin's own output.
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Chapter 8: LPC17xx Pin connect block
5. Register description
The Pin Control Module contains 11 registers as shown in Table 8-77 below.
Table 77. Name Pin Connect Block Register Map Description Access Reset Value[1] Address
PINSEL0 PINSEL1 PINSEL2 PINSEL3 PINSEL4 PINSEL7 PINSEL8 PINSEL9 PINSEL10 PINMODE0 PINMODE1 PINMODE2 PINMODE3 PINMODE4 PINMODE5 PINMODE6 PINMODE7 PINMODE9 PINMODE_OD0 PINMODE_OD1 PINMODE_OD2 PINMODE_OD3 PINMODE_OD4 I2CPADCFG
[1]
Pin function select register 0. Pin function select register 1. Pin function select register 2. Pin function select register 3. Pin function select register 4 Pin function select register 7 Pin function select register 8 Pin function select register 9 Pin function select register 10 Pin mode select register 0 Pin mode select register 1 Pin mode select register 2 Pin mode select register 3. Pin mode select register 4 Pin mode select register 5 Pin mode select register 6 Pin mode select register 7 Pin mode select register 9 Open drain mode control register 0 Open drain mode control register 1 Open drain mode control register 2 Open drain mode control register 3 Open drain mode control register 4 I2C Pin Configuration register
R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0x4002 C000 0x4002 C004 0x4002 C008 0x4002 C00C 0x4002 C010 0x4002 C01C 0x4002 C020 0x4002 C024 0x4002 C028 0x4002 C040 0x4002 C044 0x4002 C048 0x4002 C04C 0x4002 C050 0x4002 C054 0x4002 C058 0x4002 C05C 0x4002 C064 0x4002 C068 0x4002 C06C 0x4002 C070 0x4002 C074 0x4002 C078 0x4002 C07C
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
Pin control module register reset values On external reset, watchdog reset, power-on-reset (POR), and BOD reset, all registers in this module are reset to '0'.
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Chapter 8: LPC17xx Pin connect block
5.1 Pin Function Select register 0 (PINSEL0 - 0x4002 C000)
The PINSEL0 register controls the functions of the lower half of Port 0. The direction control bit in FIO0DIR register is effective only when the GPIO function is selected for a pin. For other functions, the direction is controlled automatically.
Table 78. Pin function select register 0 (PINSEL0 - address 0x4002 C000) bit description Function when Function when 01 00 Function when 10 Function when 11 Reset value
PINSEL0 Pin name
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 29:24 31:30
[1]
P0.0 P0.1 P0.2 P0.3 P0.4[1] P0.5[1] P0.6 P0.7 P0.8 P0.9 P0.10 P0.11 P0.15
GPIO Port 0.0 GPIO Port 0.1 GPIO Port 0.2 GPIO Port 0.3 GPIO Port 0.4 GPIO Port 0.5 GPIO Port 0.6 GPIO Port 0.7 GPIO Port 0.8 GPIO Port 0.9 GPIO Port 0.10 GPIO Port 0.11 Reserved GPIO Port 0.15
RD1 TD1 TXD0 RXD0 I2SRX_CLK I2SRX_WS I2SRX_SDA I2STX_CLK I2STX_WS I2STX_SDA TXD2 RXD2 Reserved TXD1
TXD3 RXD3 AD0.7 AD0.6 RD2 TD2 SSEL1 SCK1 MISO1 MOSI1 SDA2 SCL2 Reserved SCK0
SDA1 SCL1 Reserved Reserved CAP2.0 CAP2.1 MAT2.0 MAT2.1 MAT2.2 MAT2.3 MAT3.0 MAT3.1 Reserved SCK
00 00 00 00 00 00 00 00 00 00 00 00 0 00
Not available on 80-pin package.
5.2 Pin Function Select Register 1 (PINSEL1 - 0x4002 C004)
The PINSEL1 register controls the functions of the upper half of Port 0. The direction control bit in the FIO0DIR register is effective only when the GPIO function is selected for a pin. For other functions the direction is controlled automatically.
Table 79. Pin function select register 1 (PINSEL1 - address 0x4002 C004) bit description Function when 10 Function when 11 Reset value
PINSEL1 Pin name Function when Function 00 when 01
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 25:24
UM10360_1
P0.16 P0.17 P0.18 P0.19[1] P0.20[1] P0.21[1] P0.22 P0.23[1] P0.24[1] P0.25 P0.26 P0.28[1][2]
GPIO Port 0.16 GPIO Port 0.17 GPIO Port 0.18 GPIO Port 0.19 GPIO Port 0.20 GPIO Port 0.21 GPIO Port 0.22 GPIO Port 0.23 GPIO Port 0.24 GPIO Port 0.25 GPIO Port 0.26 GPIO Port 0.28
RXD1 CTS1 DCD1 DSR1 DTR1 RI1 RTS1 AD0.0 AD0.1 AD0.2 AD0.3 SDA0 SCL0
SSEL0 MISO0 MOSI0 Reserved Reserved Reserved Reserved I2SRX_CLK I2SRX_WS I2SRX_SDA AOUT USB_SDA USB_SCL
SSEL MISO MOSI SDA1 SCL1 RD1 TD1 CAP3.0 CAP3.1 TXD3 RXD3 Reserved Reserved
00 00 00 00 00 00 00 00 00 00 00 00 00
P0.27[1][2] GPIO Port 0.27
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Chapter 8: LPC17xx Pin connect block
Pin function select register 1 (PINSEL1 - address 0x4002 C004) bit description Function when 10 Function when 11 Reset value
Table 79.
PINSEL1 Pin name Function when Function 00 when 01
27:26 29:28 31:30
[1] [2]
P0.29 P0.30 -
GPIO Port 0.29 GPIO Port 0.30 Reserved
USB_D+ USB_D- Reserved
Reserved Reserved Reserved
Reserved Reserved Reserved
00 00 00
Not available on 80-pin package. Pins P027] and P0[28] are open-drain for I2C-bus compliance.
5.3 Pin Function Select register 2 (PINSEL2 - 0x4002 C008)
The PINSEL2 register controls the functions of the lower half of Port 1, which contains the Ethernet related pins. The direction control bit in the FIO1DIR register is effective only when the GPIO function is selected for a pin. For other functions, the direction is controlled automatically.
Table 80. Pin function select register 2 (PINSEL2 - address 0x4002 C008) bit description Function when Function when 00 01 Function when 10 Function when 11 Reset value
PINSEL2 Pin name
1:0 3:2 7:4 9:8 15:10 17:16 19:18 21:20 27:22 29:28 31:30
P1.0 P1.1 P1.4 P1.8 P1.9 P1.10 P1.14 P1.15
GPIO Port 1.0 GPIO Port 1.1 Reserved GPIO Port 1.4 Reserved GPIO Port 1.8 GPIO Port 1.9 GPIO Port 1.10 Reserved GPIO Port 1.14 GPIO Port 1.15
ENET_TXD0 ENET_TXD1 Reserved ENET_TX_EN Reserved ENET_CRS ENET_RXD0 ENET_RXD1 Reserved ENET_RX_ER
Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
00 00 0 00 0 00 00 00 0 00 00
ENET_REF_CLK Reserved
5.4 Pin Function Select Register 3 (PINSEL3 - 0x4002 C00C)
The PINSEL3 register controls the functions of the upper half of Port 1. The direction control bit in the FIO1DIR register is effective only when the GPIO function is selected for a pin. For other functions, direction is controlled automatically.
Table 81. Pin function select register 3 (PINSEL3 - address 0x4002 C00C) bit description Function when Function when 00 01 Function when 10 Function when 11 Reset value
PINSEL3 Pin name
1:0 3:2 5:4 7:6 9:8 11:10 13:12
UM10360_1
P1.16[1] P1.17[1] P1.18 P1.19 P1.20 P1.21[1] P1.22
GPIO Port 1.16 ENET_MDC GPIO Port 1.17 ENET_MDIO GPIO Port 1.18 USB_UP_LED GPIO Port 1.19 MCOA0 GPIO Port 1.20 MCI0 GPIO Port 1.21 MCABORT GPIO Port 1.22 MCOB0
Reserved Reserved PWM1.1 USB_PPWR PWM1.2 PWM1.3 USB_PWRD
Reserved Reserved CAP1.0 CAP1.1 SCK0 SSEL0 MAT1.0
00 00 00 00 00 00 00
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Chapter 8: LPC17xx Pin connect block
Pin function select register 3 (PINSEL3 - address 0x4002 C00C) bit description Function when Function when 00 01 Function when 10 Function when 11 Reset value
Table 81.
PINSEL3 Pin name
15:14 17:16 19:18 21:20 23:22 25:24 27:26 29:28 31:30
[1]
P1.23 P1.24 P1.25 P1.26 P1.27[1] P1.28 P1.29 P1.30 P1.31
GPIO Port 1.23 MCI1 GPIO Port 1.24 MCI2 GPIO Port 1.25 MCOA1 GPIO Port 1.26 MCOB1 GPIO Port 1.27 CLKOUT GPIO Port 1.28 MCOA2 GPIO Port 1.29 MCOB2 GPIO Port 1.30 Reserved GPIO Port 1.31 Reserved
PWM1.4 PWM1.5 Reserved PWM1.6 PCAP1.0 PCAP1.1 VBUS SCK1
MISO0 MOSI0 MAT1.1 CAP0.0 MAT0.0 MAT0.1 AD0.4 AD0.5
00 00 00 00 00 00 00 00 00
USB_OVRCR CAP0.1
Not available on 80-pin package.
5.5 Pin Function Select Register 4 (PINSEL4 - 0x4002 C010)
The PINSEL4 register controls the functions of the lower half of Port 2. The direction control bit in the FIO2DIR register is effective only when the GPIO function is selected for a pin. For other functions, direction is controlled automatically.
Table 82. Pin function select register 4 (PINSEL4 - address 0x4002 C010) bit description Function when Function when 01 Function 00 when 10 Function when Reset 11 value
PINSEL4 Pin name
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 25:24 27:26 31:28
[1] [2]
P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P2.8 P2.9 P2.10 P2.11[1] P2.12[1] P2.13[1] -
GPIO Port 2.0 GPIO Port 2.1 GPIO Port 2.2 GPIO Port 2.3 GPIO Port 2.4 GPIO Port 2.5 GPIO Port 2.6 GPIO Port 2.7 GPIO Port 2.8 GPIO Port 2.9 GPIO Port 2.10 GPIO Port 2.11 GPIO Port 2.12 GPIO Port 2.13 Reserved
PWM1.1 PWM1.2 PWM1.3 PWM1.4 PWM1.5 PWM1.6 PCAP1.0 RD2 TD2 USB_CONNECT EINT0 EINT1 EINT2 EINT3 Reserved
TXD1 RXD1 CTS1 DCD1 DSR1 DTR1 RI1 RTS1 TXD2 RXD2 NMI Reserved Reserved Reserved Reserved
Reserved Reserved Reserved
[2]
00 00 00 00 00 00 00 00 00 00 00 00 00 00 0
Reserved [2] Reserved [2] Reserved Reserved Reserved ENET_MDC ENET_MDIO Reserved I2STX_CLK I2STX_WS I2STX_SDA Reserved
[2] [2]
Not available on 80-pin package. These pins support a debug trace function when selected via a development tool or by writing to the PINSEL10 register. See Section 8-5.8 "Pin Function Select Register 10 (PINSEL10 - 0x4002 C028)" for details.
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5.6 Pin Function Select Register 7 (PINSEL7 - 0x4002 C01C)
The PINSEL7 register controls the functions of the upper half of Port 3. The direction control bit in the FIO3DIR register is effective only when the GPIO function is selected for a pin. For other functions, direction is controlled automatically.
Table 83. Pin function select register 7 (PINSEL7 - address 0x4002 C01C) bit description Function when Function 00 when 01 Function when 10 Function when 11 Reset value
PINSEL7 Pin name
17:0 19:18 21:20 31:22
[1]
P3.25[1] P3.26[1] -
Reserved GPIO Port 3.25 GPIO Port 3.26 Reserved
Reserved Reserved STCLK Reserved
Reserved MAT0.0 MAT0.1 Reserved
Reserved PWM1.2 PWM1.3 Reserved
0 00 00 0
Not available on 80-pin package.
5.7 Pin Function Select Register 9 (PINSEL9 - 0x4002 C024)
The PINSEL9 register controls the functions of the upper half of Port 4. The direction control bit in the FIO4DIR register is effective only when the GPIO function is selected for a pin. For other functions, direction is controlled automatically.
Table 84. Pin function select register 9 (PINSEL9 - address 0x4002 C024) bit description Function when Function 00 when 01 Function when 10 Function when 11 Reset value
PINSEL9 Pin name
23:0 25:24 27:26 31:28
P4.28 P4.29 -
Reserved GPIO Port 4.28 GPIO Port 4.29 Reserved
Reserved RX_MCLK TX_MCLK Reserved
Reserved MAT2.0 MAT2.1 Reserved
Reserved TXD3 RXD3 Reserved
00 00 00 00
5.8 Pin Function Select Register 10 (PINSEL10 - 0x4002 C028)
Only bit 3 of this register is used to control the Trace function on pins P2.2 through P2.6.
Table 85. Bit Pin function select register 10 (PINSEL10 - address 0x4002 C028) bit description Value Description Reset value
Symbol
2:0 3
GPIO/TRACE
0 1
Reserved. Software should not write 1 to these bits. NA TPIU interface pins control. TPIU interface is disabled. TPIU interface is enabled. TPIU signals are available on the pins hosting them regardless of the PINSEL4 content. Reserved. Software should not write 1 to these bits. NA 0
31:4
-
-
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5.9 Pin Mode select register 0 (PINMODE0 - 0x4002 C040)
This register controls pull-up/pull-down resistor configuration for Port 0 pins 0 to 15.
Table 86. Pin Mode select register 0 (PINMODE0 - address 0x4002 C040) bit description Value Description Reset value
PINMODE0 Symbol
1:0
P0.00MODE 00 01 10 11
Port 0 pin 0 on-chip pull-up/down resistor control. P0.0 pin has a pull-up resistor enabled. P0.0 pin has repeater mode enabled. P0.0 pin has neither pull-up nor pull-down. P0.0 has a pull-down resistor enabled. Port 0 pin 1 control, see P0.00MODE. Port 0 pin 2 control, see P0.00MODE. Port 0 pin 3 control, see P0.00MODE. Port 0 pin 4 control, see P0.00MODE. Port 0 pin 5 control, see P0.00MODE. Port 0 pin 6 control, see P0.00MODE. Port 0 pin 7 control, see P0.00MODE. Port 0 pin 8 control, see P0.00MODE. Port 0 pin 9control, see P0.00MODE. Port 0 pin 10 control, see P0.00MODE. Port 0 pin 11 control, see P0.00MODE. Reserved. Port 0 pin 15 control, see P0.00MODE.
00
3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 29:24 31:30
[1]
P0.01MODE P0.02MODE P0.03MODE P0.04MODE[1] P0.05MODE[1] P0.06MODE P0.07MODE P0.08MODE P0.09MODE P0.10MODE P0.11MODE P0.15MODE
00 00 00 00 00 00 00 00 00 00 00 NA 00
Not available on 80-pin package.
5.10 Pin Mode select register 1 (PINMODE1 - 0x4002 C044)
This register controls pull-up/pull-down resistor configuration for Port 1 pins 16 to 26. For details see Section 8-4 "Pin mode select register values".
Table 87. Pin Mode select register 1 (PINMODE1 - address 0x4002 C044) bit description Description Reset value
PINMODE1 Symbol
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18
P0.16MODE P0.17MODE P0.18MODE P0.19MODE[1] P0.20MODE[1] P0.21MODE[1] P0.22MODE P0.23MODE[1] P0.24MODE[1] P0.25MODE
Port 1 pin 16 control, see P0.00MODE. Port 1 pin 17 control, see P0.00MODE. Port 1 pin 18 control, see P0.00MODE. Port 1 pin 19 control, see P0.00MODE. Port 1 pin 20control, see P0.00MODE. Port 1 pin 21 control, see P0.00MODE. Port 1 pin 22 control, see P0.00MODE. Port 1 pin 23 control, see P0.00MODE. Port 1 pin 24 control, see P0.00MODE. Port 1 pin 25 control, see P0.00MODE.
00 00 00 00 00 00 00 00 00 00
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Pin Mode select register 1 (PINMODE1 - address 0x4002 C044) bit description Description Reset value
Table 87.
PINMODE1 Symbol
21:20 29:22 31:30
[1] [2]
P0.26MODE -
Port 1 pin 26 control, see P0.00MODE. Reserved. Reserved.
[2]
00 NA NA
Not available on 80-pin package. The pin mode cannot be selected for pins P0[27] to P0[30]. Pins P0[27] and P0[28] are dedicated I2C open-drain pins without pull-up/down. Pins P0[29] and P0[30] are USB specific pins without configurable pull-up or pull-down resistors. Pins P0[29] and P0[30] also must have the same direction since they operate as a unit for the USB function, see Section 9-5.1 "GPIO port Direction register FIOxDIR (FIO0DIR to FIO4DIR- 0x2009 C000 to 0x2009 C080)".
5.11 Pin Mode select register 2 (PINMODE2 - 0x4002 C048)
This register controls pull-up/pull-down resistor configuration for Port 1 pins 0 to 15. For details see Section 8-4 "Pin mode select register values".
Table 88. Pin Mode select register 2 (PINMODE2 - address 0x4002 C048) bit description Description Reset value
PINMODE2 Symbol
1:0 3:2 7:4 9:8 15:10 17:16 19:18 21:20 27:22 29:28 31:30
P1.00MODE P1.01MODE P1.04MODE P1.08MODE P1.09MODE P1.10MODE P1.14MODE P1.15MODE
Port 1 pin 0 control, see P0.00MODE. Port 1 pin 1 control, see P0.00MODE. Reserved. Port 1 pin 4 control, see P0.00MODE. Reserved. Port 1 pin 8 control, see P0.00MODE. Port 1 pin 9 control, see P0.00MODE. Port 1 pin 10 control, see P0.00MODE. Reserved. Port 1 pin 14 control, see P0.00MODE. Port 1 pin 15 control, see P0.00MODE.
00 00 NA 00 NA 00 00 00 NA 00 00
5.12 Pin Mode select register 3 (PINMODE3 - 0x4002 C04C)
This register controls pull-up/pull-down resistor configuration for Port 1 pins 16 to 31. For details see Section 8-4 "Pin mode select register values".
Table 89. Pin Mode select register 3 (PINMODE3 - address 0x4002 C04C) bit description Description Reset value
PINMODE3 Symbol
1:0 3:2 5:4 7:6 9:8 11:10 13:12
UM10360_1
P1.16MODE[1] P1.17MODE[1] P1.18MODE P1.19MODE P1.20MODE P1.21MODE[1] P1.22MODE
Port 1 pin 16 control, see P0.00MODE. Port 1 pin 17 control, see P0.00MODE. Port 1 pin 18 control, see P0.00MODE. Port 1 pin 19 control, see P0.00MODE. Port 1 pin 20 control, see P0.00MODE. Port 1 pin 21 control, see P0.00MODE. Port 1 pin 22 control, see P0.00MODE.
00 00 00 00 00 00 00
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Pin Mode select register 3 (PINMODE3 - address 0x4002 C04C) bit description Description Reset value
Table 89.
PINMODE3 Symbol
15:14 17:16 19:18 21:20 23:22 25:24 27:26 29:28 31:30
[1]
P1.23MODE P1.24MODE P1.25MODE P1.26MODE P1.27MODE[1] P1.28MODE P1.29MODE P1.30MODE P1.31MODE
Port 1 pin 23 control, see P0.00MODE. Port 1 pin 24 control, see P0.00MODE. Port 1 pin 25 control, see P0.00MODE. Port 1 pin 26 control, see P0.00MODE. Port 1 pin 27 control, see P0.00MODE. Port 1 pin 28 control, see P0.00MODE. Port 1 pin 29 control, see P0.00MODE. Port 1 pin 30 control, see P0.00MODE. Port 1 pin 31 control, see P0.00MODE.
00 00 00 00 00 00 00 00 00
Not available on 80-pin package.
5.13 Pin Mode select register 4 (PINMODE4 - 0x4002 C050)
This register controls pull-up/pull-down resistor configuration for Port 2 pins 0 to 15. For details see Section 8-4 "Pin mode select register values".
Table 90. Pin Mode select register 4 (PINMODE4 - address 0x4002 C050) bit description Symbol Description Reset value
PINMODE4
1:0 3:2 5:4 7:6 9:8 11:10 13:12 15:14 17:16 19:18 21:20 23:22 25:24 27:26 31:28
[1]
P2.00MODE P2.01MODE P2.02MODE P2.03MODE P2.04MODE P2.05MODE P2.06MODE P2.07MODE P2.08MODE P2.09MODE P2.10MODE P2.11MODE[1] P2.12MODE[1] P2.13MODE[1] -
Port 2 pin 0 control, see P0.00MODE. Port 2 pin 1 control, see P0.00MODE. Port 2 pin 2 control, see P0.00MODE. Port 2 pin 3 control, see P0.00MODE. Port 2 pin 4 control, see P0.00MODE. Port 2 pin 5 control, see P0.00MODE. Port 2 pin 6 control, see P0.00MODE. Port 2 pin 7 control, see P0.00MODE. Port 2 pin 8 control, see P0.00MODE. Port 2 pin 9 control, see P0.00MODE. Port 2 pin 10 control, see P0.00MODE. Port 2 pin 11 control, see P0.00MODE. Port 2 pin 12 control, see P0.00MODE. Port 2 pin 13 control, see P0.00MODE. Reserved.
00 00 00 00 00 00 00 00 00 00 00 00 00 00 NA
Not available on 80-pin package.
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5.14 Pin Mode select register 7 (PINMODE7 - 0x4002 C05C)
This register controls pull-up/pull-down resistor configuration for Port 3 pins 16 to 31. For details see Section 8-4 "Pin mode select register values".
Table 91. Pin Mode select register 7 (PINMODE7 - address 0x4002 C05C) bit description Description Reset value
PINMODE7 Symbol
17:0 19:18 21:20 31:22
[1]
P3.25MODE[1] P3.26MODE[1] -
Reserved Port 3 pin 25 control, see P0.00MODE. Port 3 pin 26 control, see P0.00MODE. Reserved.
NA 00 00 NA
Not available on 80-pin package.
5.15 Pin Mode select register 9 (PINMODE9 - 0x4002 C064)
This register controls pull-up/pull-down resistor configuration for Port 4 pins 16 to 31. For details see Section 8-4 "Pin mode select register values".
Table 92. Pin Mode select register 9 (PINMODE9 - address 0x4002 C064) bit description Description Reset value
PINMODE9 Symbol
23:0 25:24 27:26 31:28
P4.28MODE P4.29MODE -
Reserved. Port 4 pin 28 control, see P0.00MODE. Port 4 pin 29 control, see P0.00MODE. Reserved.
NA 00 00 NA
5.16 Open Drain Pin Mode select register 0 (PINMODE_OD0 - 0x4002 C068)
This register controls the open drain mode for Port 0 pins. For details see Section 8-4 "Pin mode select register values".
Table 93. Open Drain Pin Mode select register 0 (PINMODE_OD0 - address 0x4002 C068) bit description Value Description Reset value
PINMODE Symbol _OD0
0
P0.00OD[3] 0 1
Port 0 pin 0 open drain mode control. P0.0 pin is in the normal (not open drain) mode. P0.0 pin is in the open drain mode. Port 0 pin 1 open drain mode control, see P0.00OD Port 0 pin 2 open drain mode control, see P0.00OD Port 0 pin 3 open drain mode control, see P0.00OD Port 0 pin 4 open drain mode control, see P0.00OD Port 0 pin 5 open drain mode control, see P0.00OD Port 0 pin 6 open drain mode control, see P0.00OD Port 0 pin 7 open drain mode control, see P0.00OD Port 0 pin 8 open drain mode control, see P0.00OD Port 0 pin 9 open drain mode control, see P0.00OD
0
1 2 3 4 5 6 7 8 9
P0.01OD[3] P0.02OD P0.03OD P0.04OD P0.05OD P0.06OD P0.07OD P0.08OD P0.09OD
0 0 0 0 0 0 0 0 0
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Open Drain Pin Mode select register 0 (PINMODE_OD0 - address 0x4002 C068) bit description Value Description Reset value
Table 93.
PINMODE Symbol _OD0
10 11 14:12 15 16 17 18 19 20 21 22 23 24 25 26 28:27 29 30 31
[1] [2]
P0.10OD[3] P0.11OD[3] P0.15OD P0.16OD P0.17OD P0.18OD P0.19OD[3] P0.20OD[3] P0.21OD P0.22OD P0.23OD P0.24OD P0.25OD P0.26OD [2]
Port 0 pin 10 open drain mode control, see P0.00OD Port 0 pin 11 open drain mode control, see P0.00OD Reserved. Port 0 pin 15 open drain mode control, see P0.00OD Port 0 pin 16 open drain mode control, see P0.00OD Port 0 pin 17 open drain mode control, see P0.00OD Port 0 pin 18 open drain mode control, see P0.00OD Port 0 pin 19 open drain mode control, see P0.00OD Port 0 pin 20open drain mode control, see P0.00OD Port 0 pin 21 open drain mode control, see P0.00OD Port 0 pin 22 open drain mode control, see P0.00OD Port 0 pin 23 open drain mode control, see P0.00OD Port 0 pin 24open drain mode control, see P0.00OD Port 0 pin 25 open drain mode control, see P0.00OD Port 0 pin 26 open drain mode control, see P0.00OD Reserved. Port 0 pin 29 open drain mode control, see P0.00OD Port 0 pin 30 open drain mode control, see P0.00OD Reserved.
0 0 NA 0 0 0 0 0 0 0 0 0 0 0 0 NA 0 0 NA
P0.29OD P0.30OD Not available on 80-pin package.
Port 0 pins 27 and 28 should be set up using the I2CPADCFG register if they are used for an I2C-bus. Bits 27 and 28 of PINMODE_OD0 do not have any affect on these pins, they are special open drain I2C-bus compatible pins. Port 0 bits 1:0, 11:10, and 20:19 may potentially be used for I2C-buses using standard port pins. If so, they should be configured for open drain mode via the related bits in PINMODE_OD0.
[3]
5.17 Open Drain Pin Mode select register 1 (PINMODE_OD1 0x4002 C06C)
This register controls the open drain mode for Port 1 pins. For details see Section 8-4 "Pin mode select register values".
Table 94. Open Drain Pin Mode select register 1 (PINMODE_OD1 - address 0x4002 C06C) bit description Value Description Reset value
PINMODE Symbol _OD1
0
P1.00OD 0 1
Port 1 pin 0 open drain mode control. P1.0 pin is in the normal (not open drain) mode. P1.0 pin is in the open drain mode. Port 1 pin 1 open drain mode control, see P1.00OD Reserved. Port 1 pin 4 open drain mode control, see P1.00OD
0
1 3:2 4
P1.01OD P1.04OD
0 NA 0
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Chapter 8: LPC17xx Pin connect block
Open Drain Pin Mode select register 1 (PINMODE_OD1 - address 0x4002 C06C) bit description Value Description Reset value
Table 94.
PINMODE Symbol _OD1
7:5 8 9 10 13:11 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
[1]
P1.08OD P1.09OD P1.10OD P1.14OD P1.15OD P1.16OD[1] P1.17OD[1] P1.18OD P1.19OD P1.20OD P1.21OD[1] P1.22OD P1.23OD P1.24OD P1.25OD P1.26OD P1.27OD[1] P1.28OD P1.29OD P1.30OD P1.31OD
Not available on 80-pin package.
Reserved. Port 1 pin 8 open drain mode control, see P1.00OD Port 1 pin 9 open drain mode control, see P1.00OD Port 1 pin 10 open drain mode control, see P1.00OD Reserved. Port 1 pin 14 open drain mode control, see P1.00OD Port 1 pin 15 open drain mode control, see P1.00OD Port 1 pin 16 open drain mode control, see P1.00OD Port 1 pin 17 open drain mode control, see P1.00OD Port 1 pin 18 open drain mode control, see P1.00OD Port 1 pin 19 open drain mode control, see P1.00OD Port 1 pin 20open drain mode control, see P1.00OD Port 1 pin 21 open drain mode control, see P1.00OD Port 1 pin 22 open drain mode control, see P1.00OD Port 1 pin 23 open drain mode control, see P1.00OD Port 1 pin 24open drain mode control, see P1.00OD Port 1 pin 25 open drain mode control, see P1.00OD Port 1 pin 26 open drain mode control, see P1.00OD Port 1 pin 27 open drain mode control, see P1.00OD Port 1 pin 28 open drain mode control, see P1.00OD Port 1 pin 29 open drain mode control, see P1.00OD Port 1 pin 30 open drain mode control, see P1.00OD Port 1 pin 31 open drain mode control.
NA 0 0 0 NA 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
5.18 Open Drain Pin Mode select register 2 (PINMODE_OD2 - 0x4002 C070)
This register controls the open drain mode for Port 2 pins. For details see Section 8-4 "Pin mode select register values".
Table 95. Open Drain Pin Mode select register 2 (PINMODE_OD2 - address 0x4002 C070) bit description Value Description Reset value
PINMODE Symbol _OD2
0
P2.00OD 0 1
Port 2 pin 0 open drain mode control. P2.0 pin is in the normal (not open drain) mode. P2.0 pin is in the open drain mode. Port 2 pin 1 open drain mode control, see P2.00OD Port 2 pin 2 open drain mode control, see P2.00OD Port 2 pin 3 open drain mode control, see P2.00OD Port 2 pin 4 open drain mode control, see P2.00OD
0
1 2 3 4
UM10360_1
P2.01OD P2.02OD P2.03OD P2.04OD
0 0 0 0
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Chapter 8: LPC17xx Pin connect block
Open Drain Pin Mode select register 2 (PINMODE_OD2 - address 0x4002 C070) bit description Value Description Reset value
Table 95.
PINMODE Symbol _OD2
5 6 7 8 9 10 11 12 13 31:14
[1]
P2.05OD P2.06OD P2.07OD P2.08OD P2.09OD P2.10OD P2.11OD[1] P2.12OD[1] P2.13OD[1] -
Port 2 pin 5 open drain mode control, see P2.00OD Port 2 pin 6 open drain mode control, see P2.00OD Port 2 pin 7 open drain mode control, see P2.00OD Port 2 pin 8 open drain mode control, see P2.00OD Port 2 pin 9 open drain mode control, see P2.00OD Port 2 pin 10 open drain mode control, see P2.00OD Port 2 pin 11 open drain mode control, see P2.00OD Port 2 pin 12 open drain mode control, see P2.00OD Port 2 pin 13 open drain mode control, see P2.00OD Reserved.
0 0 0 0 0 0 0 0 0 NA
Not available on 80-pin package.
5.19 Open Drain Pin Mode select register 3 (PINMODE_OD3 - 0x4002 C074)
This register controls the open drain mode for Port 3 pins. For details see Section 8-4 "Pin mode select register values".
Table 96. Open Drain Pin Mode select register 3 (PINMODE_OD3 - address 0x4002 C074) bit description Value Description Reset value
PINMODE Symbol _OD3
24:0 25
P3.25OD[1] 0 1
Reserved. Port 3 pin 0 open drain mode control. P3.25 pin is in the normal (not open drain) mode. P3.25 pin is in the open drain mode. Port 3 pin 26 open drain mode control, see P3.25OD Reserved.
NA 0
26 31:27
[1]
P3.26OD[1] -
0 NA
Not available on 80-pin package.
5.20 Open Drain Pin Mode select register 4 (PINMODE_OD4 - 0x4002 C078)
This register controls the open drain mode for Port 4 pins. For details see Section 8-4 "Pin mode select register values".
Table 97. Open Drain Pin Mode select register 4 (PINMODE_OD4 - address 0x4002 C078) bit description Value Description Reset value
PINMODE Symbol _OD4
27:0
-
Reserved.
NA
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Chapter 8: LPC17xx Pin connect block
Open Drain Pin Mode select register 4 (PINMODE_OD4 - address 0x4002 C078) bit description Value Description Reset value
Table 97.
PINMODE Symbol _OD4
28
P4.28OD 0 1
Port 4 pin 28 open drain mode control. P4.28 pin is in the normal (not open drain) mode. P4.28 pin is in the open drain mode. Port 4 pin 29 open drain mode control, see P4.28OD Reserved.
0
29 31:30
P4.28OD -
0 NA
5.21 I2C Pin Configuration register (I2CPADCFG - 0x4002 C07C)
The I2CPADCFG register allows configuration of the I2C pins for the I2C0 interface only, in order to support various I2C-bus operating modes. For use in standard or Fast Mode I2C, the 4 bits in I2CPADCFG should be 0, the default value for this register. For Fast Mode Plus, the SDADRV0 and SCLDRV0 bits should be 1. For non-I2C use of these pins, it may be desirable to turn off I2C filtering and slew rate control by setting SDAI2C0 and SCLI2C0 to 1. See Table 8-98 below.
Table 98. I2C Pin Configuration register (I2CPADCFG - address 0x4002 C07C) bit description Value Description Reset value
I2CPADCFG Symbol
0
SDADRV0 0 1
Drive mode control for the SDA0 pin, P0.27. The SDA0 pin is in the standard drive mode. The SDA0 pin is in Fast Mode Plus drive mode.
0
1
SDAI2C0 0 1
I2C mode control for the SDA0 pin, P0.27.
The SDA0 pin has control enabled.
0
I2C
glitch filtering and slew rate
The SDA0 pin has I2C glitch filtering and slew rate control disabled. Drive mode control for the SCL0 pin, P0.28. 0 The SCL0 pin is in the standard drive mode. The SCL0 pin is in Fast Mode Plus drive mode.
2
SCLDRV0 0 1
3
SCLI2C0 0 1
I2C mode control for the SCL0 pin, P0.28.
The SCL0 pin has control enabled.
0
I2C
glitch filtering and slew rate
The SCL0 pin has I2C glitch filtering and slew rate control disabled. Reserved. NA
31:4
-
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
GPIOs are configured using the following registers: 1. Power: always enabled. 2. Pins: See Section 8-3 for GPIO pins and their modes. 3. Wake-up: GPIO ports 0 and 2 can be used for wake-up if needed, see (Section 4-8.8). 4. Interrupts: Enable GPIO interrupts in IO0/2IntEnR (Table 9-113) or IO0/2IntEnF (Table 9-115). Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register.
2. Features
2.1 Digital I/O ports * Accelerated GPIO functions:
- GPIO registers are located on a peripheral AHB bus for fast I/O timing. - Mask registers allow treating sets of port bits as a group, leaving other bits unchanged. - All GPIO registers are byte, half-word, and word addressable. - Entire port value can be written in one instruction. - GPIO registers are accessible by the GPDMA.
* Bit-level set and clear registers allow a single instruction set or clear of any number of
bits in one port.
* All GPIO registers support Cortex-M3 bit-banding. * GPIO registers are accessible by the GPDMA controller to allow DMA of data to or
from GPIOs, synchronized to any DMA request.
* Direction control of individual port bits. * All I/Os default to input with pullup after reset. 2.2 Interrupt generating digital ports * Port 0 and Port 2 can provide a single interrupt for any combination of port pins. * Each port pin can be programmed to generate an interrupt on a rising edge, a falling
edge, or both.
* Edge detection is asynchronous, so it may operate when clocks are not present, such
as during Power-down mode. With this feature, level triggered interrupts are not needed.
* Each enabled interrupt contributes to a wake-up signal that can be used to bring the
part out of Power-down mode.
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
* Registers provide a software view of pending rising edge interrupts, pending falling
edge interrupts, and overall pending GPIO interrupts.
* GPIO0 and GPIO2 interrupts share the same position in the NVIC with External
Interrupt 3.
3. Applications
* * * * *
General purpose I/O Driving LEDs or other indicators Controlling off-chip devices Sensing digital inputs, detecting edges Bringing the part out of Power-down mode
4. Pin description
Table 99. Pin Name GPIO pin description Type Description
P0[30:0][1]; P1[31:0][2]; P2[13:0]; P3[26:25]; P4[29:28]
Input/ Output
General purpose input/output. These are typically shared with other peripherals functions and will therefore not all be available in an application. Packaging options may affect the number of GPIOs available in a particular device. Some pins may be limited by requirements of the alternate functions of the pin. For example, the pins containing the I2C0 functions are open-drain for any function selected on that pin. Details may be found in Section 7-1.1.
[1] [2]
P0[14:12] are not available. P1[2], P1[3], P1[7:5], P1[13:11] are not available.
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5. Register description
Due to compatibility requirements with the LPC2300 series ARM7-based products, the LPC17xx implements portions of five 32-bit General Purpose I/O ports. Details on a specific GPIO port usage can be found in Section 8-3. The registers in Table 9-100 represent the enhanced GPIO features available on all of the GPIO ports. These registers are located on an AHB bus for fast read and write timing. They can all be accessed in byte, half-word, and word sizes. A mask register allows access to a group of bits in a single GPIO port independently from other bits in the same port.
Table 100. GPIO register map (local bus accessible registers - enhanced GPIO features) Generic Name Description Access Reset PORTn Register value[1] Name & Address
FIODIR
Fast GPIO Port Direction control register. This register individually controls the direction of each port pin.
R/W
0
FIO0DIR - 0x2009 C000 FIO1DIR - 0x2009 C020 FIO2DIR - 0x2009 C040 FIO3DIR - 0x2009 C060 FIO4DIR - 0x2009 C080 FIO0MASK - 0x2009 C010 FIO1MASK - 0x2009 C030 FIO2MASK - 0x2009 C050 FIO3MASK - 0x2009 C070 FIO4MASK - 0x2009 C090 FIO0PIN - 0x2009 C014 FIO1PIN - 0x2009 C034 FIO2PIN - 0x2009 C054 FIO3PIN - 0x2009 C074 FIO4PIN - 0x2009 C094
FIOMASK Fast Mask register for port. Writes, sets, clears, and reads to R/W port (done via writes to FIOPIN, FIOSET, and FIOCLR, and reads of FIOPIN) alter or return only the bits enabled by zeros in this register. FIOPIN Fast Port Pin value register using FIOMASK. The current state R/W of digital port pins can be read from this register, regardless of pin direction or alternate function selection (as long as pins are not configured as an input to ADC). The value read is masked by ANDing with inverted FIOMASK. Writing to this register places corresponding values in all bits enabled by zeros in FIOMASK.
Important: if an FIOPIN register is read, its bit(s) masked with 1 in the FIOMASK register will be read as 0 regardless of the physical pin state.
0
0
FIOSET
Fast Port Output Set register using FIOMASK. This register R/W controls the state of output pins. Writing 1s produces highs at the corresponding port pins. Writing 0s has no effect. Reading this register returns the current contents of the port output register. Only bits enabled by 0 in FIOMASK can be altered. Fast Port Output Clear register using FIOMASK. This register WO controls the state of output pins. Writing 1s produces lows at the corresponding port pins. Writing 0s has no effect. Only bits enabled by 0 in FIOMASK can be altered.
0
FIO0SET - 0x2009 C018 FIO1SET - 0x2009 C038 FIO2SET - 0x2009 C058 FIO3SET - 0x2009 C078 FIO4SET - 0x2009 C098 FIO0CLR - 0x2009 C01C FIO1CLR - 0x2009 C03C FIO2CLR - 0x2009 C05C FIO3CLR - 0x2009 C07C FIO4CLR - 0x2009 C09C
FIOCLR
0
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
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Table 101. GPIO interrupt register map Generic Name Description Access Reset value[1] PORTn Register Name & Address
IntEnR IntEnF IntStatR IntStatF IntClr IntStatus
[1]
GPIO Interrupt Enable for Rising edge. GPIO Interrupt Enable for Falling edge. GPIO Interrupt Status for Rising edge. GPIO Interrupt Status for Falling edge. GPIO Interrupt Clear. GPIO overall Interrupt Status.
R/W R/W RO RO WO RO
0 0 0 0 0 0
IO0IntEnR - 0x4002 8090 IO2IntEnR - 0x4002 80B0 IO0IntEnR - 0x4002 8094 IO2IntEnR - 0x4002 80B4 IO0IntStatR - 0x4002 8084 IO2IntStatR - 0x4002 80A4 IO0IntStatF - 0x4002 8088 IO2IntStatF - 0x4002 80A8 IO0IntClr - 0x4002 808C IO2IntClr - 0x4002 80AC IOIntStatus - 0x4002 8080
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
5.1 GPIO port Direction register FIOxDIR (FIO0DIR to FIO4DIR- 0x2009 C000 to 0x2009 C080)
This word accessible register is used to control the direction of the pins when they are configured as GPIO port pins. Direction bit for any pin must be set according to the pin functionality. Note that GPIO pins P0.29 and P0.30 are shared with the USB_D+ and USB_D- pins and must have the same direction. If either FIO0DIR bit 29 or 30 are configured as zero, both P0.29 and P0.30 will be inputs. If both FIO0DIR bits 29 and 30 are ones, both P0.29 and P0.30 will be outputs.
Table 102. Fast GPIO port Direction register FIO0DIR to FIO4DIR - addresses 0x2009 C000 to 0x2009 C080) bit description Bit Symbol Value Description Reset value
31:0
FIO0DIR FIO1DIR FIO2DIR FIO3DIR FIOI4DIR
Fast GPIO Direction PORTx control bits. Bit 0 in FIOxDIR controls pin Px.0, bit 31 in FIOxDIR controls pin Px.31. 0 1 Controlled pin is input. Controlled pin is output.
0x0
Aside from the 32-bit long and word only accessible FIODIR register, every fast GPIO port can also be controlled via several byte and half-word accessible registers listed in Table 9-103, too. Next to providing the same functions as the FIODIR register, these additional registers allow easier and faster access to the physical port pins.
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Table 103. Fast GPIO port Direction control byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset value PORTn Register Address & Name
FIOxDIR0
Fast GPIO Port x Direction 8 (byte) control register 0. Bit 0 in R/W FIOxDIR0 register corresponds to pin Px.0 ... bit 7 to pin Px.7. Fast GPIO Port x Direction 8 (byte) control register 1. Bit 0 in R/W FIOxDIR1 register corresponds to pin Px.8 ... bit 7 to pin Px.15. Fast GPIO Port x Direction 8 (byte) control register 2. Bit 0 in R/W FIOxDIR2 register corresponds to pin Px.16 ... bit 7 to pin Px.23. Fast GPIO Port x Direction 8 (byte) control register 3. Bit 0 in R/W FIOxDIR3 register corresponds to pin Px.24 ... bit 7 to pin Px.31. Fast GPIO Port x Direction control Lower half-word register. Bit 0 in FIOxDIRL register corresponds to pin Px.0 ... bit 15 to pin Px.15. Fast GPIO Port x Direction control Upper half-word register. Bit 0 in FIOxDIRU register corresponds to Px.16 ... bit 15 to Px.31.
0x00
FIO0DIR0 - 0x2009 C000 FIO1DIR0 - 0x2009 C020 FIO2DIR0 - 0x2009 C040 FIO3DIR0 - 0x2009 C060 FIO4DIR0 - 0x2009 C080 FIO0DIR1 - 0x2009 C001 FIO1DIR1 - 0x2009 C021 FIO2DIR1 - 0x2009 C041 FIO3DIR1 - 0x2009 C061 FIO4DIR1 - 0x2009 C081 FIO0DIR2 - 0x2009 C002 FIO1DIR2 - 0x2009 C022 FIO2DIR2 - 0x2009 C042 FIO3DIR2 - 0x2009 C062 FIO4DIR2 - 0x2009 C082 FIO0DIR3 - 0x2009 C003 FIO1DIR3 - 0x2009 C023 FIO2DIR3 - 0x2009 C043 FIO3DIR3 - 0x2009 C063 FIO4DIR3 - 0x2009 C083
FIOxDIR1
0x00
FIO0DIR2
0x00
FIOxDIR3
0x00
FIOxDIRL
16 (half-word) 0x0000 FIO0DIRL - 0x2009 C000 R/W FIO1DIRL - 0x2009 C020 FIO2DIRL - 0x2009 C040 FIO3DIRL - 0x2009 C060 FIO4DIRL - 0x2009 C080 16 (half-word) 0x0000 FIO0DIRU - 0x2009 C002 R/W FIO1DIRU - 0x2009 C022 FIO2DIRU - 0x2009 C042 FIO3DIRU - 0x2009 C062 FIO4DIRU - 0x2009 C082
FIOxDIRU
5.2 GPIO port output Set register FIOxSET (FIO0SET to FIO4SET - 0x2009 C018 to 0x2009 C098)
This register is used to produce a HIGH level output at the port pins configured as GPIO in an OUTPUT mode. Writing 1 produces a HIGH level at the corresponding port pins. Writing 0 has no effect. If any pin is configured as an input or a secondary function, writing 1 to the corresponding bit in the FIOxSET has no effect. Reading the FIOxSET register returns the value of this register, as determined by previous writes to FIOxSET and FIOxCLR (or FIOxPIN as noted above). This value does not reflect the effect of any outside world influence on the I/O pins.
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Access to a port pin via the FIOxSET register is conditioned by the corresponding bit of the FIOxMASK register (see Section 9-5.5).
Table 104. Fast GPIO port output Set register (FIO0SET to FIO4SET - addresses 0x2009 C018 to 0x2009 C098) bit description Bit Symbol Value Description Reset value
31:0
FIO0SET FIO1SET FIO2SET 0 FIO3SET FIO4SET 1
Fast GPIO output value Set bits. Bit 0 in FIOxSET controls pin Px.0, bit 31 in FIOxSET controls pin Px.31. Controlled pin output is unchanged. Controlled pin output is set to HIGH.
0x0
Aside from the 32-bit long and word only accessible FIOxSET register, every fast GPIO port can also be controlled via several byte and half-word accessible registers listed in Table 9-105, too. Next to providing the same functions as the FIOxSET register, these additional registers allow easier and faster access to the physical port pins.
Table 105. Fast GPIO port output Set byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset value PORTn Register Address & Name
FIOxSET0
Fast GPIO Port x output Set register 0. Bit 0 in FIOxSET0 register corresponds to pin Px.0 ... bit 7 to pin Px.7. Fast GPIO Port x output Set register 1. Bit 0 in FIOxSET1 register corresponds to pin Px.8 ... bit 7 to pin Px.15. Fast GPIO Port x output Set register 2. Bit 0 in FIOxSET2 register corresponds to pin Px.16 ... bit 7 to pin Px.23. Fast GPIO Port x output Set register 3. Bit 0 in FIOxSET3 register corresponds to pin Px.24 ... bit 7 to pin Px.31.
8 (byte) R/W
0x00
FIO0SET0 - 0x2009 C018 FIO1SET0 - 0x2009 C038 FIO2SET0 - 0x2009 C058 FIO3SET0 - 0x2009 C078 FIO4SET0 - 0x2009 C098 FIO0SET1 - 0x2009 C019 FIO1SET1 - 0x2009 C039 FIO2SET1 - 0x2009 C059 FIO3SET1 - 0x2009 C079 FIO4SET1 - 0x2009 C099 FIO0SET2 - 0x2009 C01A FIO1SET2 - 0x2009 C03A FIO2SET2 - 0x2009 C05A FIO3SET2 - 0x2009 C07A FIO4SET2 - 0x2009 C09A FIO0SET3 - 0x2009 C01B FIO1SET3 - 0x2009 C03B FIO2SET3 - 0x2009 C05B FIO3SET3 - 0x2009 C07B FIO4SET3 - 0x2009 C09B
FIOxSET1
8 (byte) R/W
0x00
FIOxSET2
8 (byte) R/W
0x00
FIOxSET3
8 (byte) R/W
0x00
FIOxSETL
Fast GPIO Port x output Set 16 (half-word) 0x0000 FIO0SETL - 0x2009 C018 Lower half-word register. Bit 0 R/W FIO1SETL - 0x2009 C038 in FIOxSETL register FIO2SETL - 0x2009 C058 corresponds to pin Px.0 ... bit FIO3SETL - 0x2009 C078 15 to pin Px.15. FIO4SETL - 0x2009 C098 Fast GPIO Port x output Set 16 (half-word) 0x0000 FIO0SETU - 0x2009 C01A Upper half-word register. Bit 0 R/W FIO1SETU - 0x2009 C03A in FIOxSETU register FIO2SETU - 0x2009 C05A corresponds to Px.16 ... bit FIO3SETU - 0x2009 C07A 15 to Px.31. FIO4SETU - 0x2009 C09A
FIOxSETU
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5.3 GPIO port output Clear register FIOxCLR (FIO0CLR to FIO4CLR0x2009 C01C to 0x2009 C09C)
This register is used to produce a LOW level output at port pins configured as GPIO in an OUTPUT mode. Writing 1 produces a LOW level at the corresponding port pin and clears the corresponding bit in the FIOxSET register. Writing 0 has no effect. If any pin is configured as an input or a secondary function, writing to FIOxCLR has no effect. Access to a port pin via the FIOxCLR register is conditioned by the corresponding bit of the FIOxMASK register (see Section 9-5.5).
Table 106. Fast GPIO port output Clear register (FIO0CLR to FIO4CLR- addresses 0x2009 C01C to 0x2009 C09C) bit description Bit Symbol Value Description Reset value
31:0
FIO0CLR FIO1CLR FIO2CLR 0 FIO3CLR FIO4CLR 1
Fast GPIO output value Clear bits. Bit 0 in FIOxCLR controls pin 0x0 Px.0, bit 31 controls pin Px.31. Controlled pin output is unchanged. Controlled pin output is set to LOW.
Aside from the 32-bit long and word only accessible FIOxCLR register, every fast GPIO port can also be controlled via several byte and half-word accessible registers listed in Table 9-107, too. Next to providing the same functions as the FIOxCLR register, these additional registers allow easier and faster access to the physical port pins.
Table 107. Fast GPIO port output Clear byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset value PORTn Register Address & Name
FIOxCLR0
Fast GPIO Port x output Clear register 0. Bit 0 in FIOxCLR0 register corresponds to pin Px.0 ... bit 7 to pin Px.7. Fast GPIO Port x output Clear register 1. Bit 0 in FIOxCLR1 register corresponds to pin Px.8 ... bit 7 to pin Px.15. Fast GPIO Port x output Clear register 2. Bit 0 in FIOxCLR2 register corresponds to pin Px.16 ... bit 7 to pin Px.23.
8 (byte) WO
0x00
FIO0CLR0 - 0x2009 C01C FIO1CLR0 - 0x2009 C03C FIO2CLR0 - 0x2009 C05C FIO3CLR0 - 0x2009 C07C FIO4CLR0 - 0x2009 C09C FIO0CLR1 - 0x2009 C01D FIO1CLR1 - 0x2009 C03D FIO2CLR1 - 0x2009 C05D FIO3CLR1 - 0x2009 C07D FIO4CLR1 - 0x2009 C09D FIO0CLR2 - 0x2009 C01E FIO1CLR2 - 0x2009 C03E FIO2CLR2 - 0x2009 C05E FIO3CLR2 - 0x2009 C07E FIO4CLR2 - 0x2009 C09E
FIOxCLR1
8 (byte) WO
0x00
FIOxCLR2
8 (byte) WO
0x00
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Table 107. Fast GPIO port output Clear byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset value PORTn Register Address & Name
FIOxCLR3
Fast GPIO Port x output Clear register 3. Bit 0 in FIOxCLR3 register corresponds to pin Px.24 ... bit 7 to pin Px.31. Fast GPIO Port x output Clear Lower half-word register. Bit 0 in FIOxCLRL register corresponds to pin Px.0 ... bit 15 to pin Px.15.
8 (byte) WO
0x00
FIO0CLR3 - 0x2009 C01F FIO1CLR3 - 0x2009 C03F FIO2CLR3 - 0x2009 C05F FIO3CLR3 - 0x2009 C07F FIO4CLR3 - 0x2009 C09F
FIOxCLRL
16 (half-word) WO
0x0000 FIO0CLRL - 0x2009 C01C FIO1CLRL - 0x2009 C03C FIO2CLRL - 0x2009 C05C FIO3CLRL - 0x2009 C07C FIO4CLRL - 0x2009 C09C 0x0000 FIO0CLRU - 0x2009 C01E FIO1CLRU - 0x2009 C03E FIO2CLRU - 0x2009 C05E FIO3CLRU - 0x2009 C07E FIO4CLRU - 0x2009 C09E
FIOxCLRU Fast GPIO Port x output Clear Upper half-word register. Bit 0 in FIOxCLRU register corresponds to pin Px.16 ... bit 15 to Px.31.
16 (half-word) WO
5.4 GPIO port Pin value register FIOxPIN (FIO0PIN to FIO4PIN- 0x2009 C014 to 0x2009 C094)
This register provides the value of port pins that are configured to perform only digital functions. The register will give the logic value of the pin regardless of whether the pin is configured for input or output, or as GPIO or an alternate digital function. As an example, a particular port pin may have GPIO input, GPIO output, UART receive, and PWM output as selectable functions. Any configuration of that pin will allow its current logic state to be read from the corresponding FIOxPIN register. If a pin has an analog function as one of its options, the pin state cannot be read if the analog configuration is selected. Selecting the pin as an A/D input disconnects the digital features of the pin. In that case, the pin value read in the FIOxPIN register is not valid. Writing to the FIOxPIN register stores the value in the port output register, bypassing the need to use both the FIOxSET and FIOxCLR registers to obtain the entire written value. This feature should be used carefully in an application since it affects the entire port. Access to a port pin via the FIOxPIN register is conditioned by the corresponding bit of the FIOxMASK register (see Section 9-5.5). Only pins masked with zeros in the Mask register (see Section 9-5.5) will be correlated to the current content of the Fast GPIO port pin value register.
Table 108. Fast GPIO port Pin value register (FIO0PIN to FIO4PIN- addresses 0x2009 C014 to 0x2009 C094) bit description Bit Symbol Value Description Reset value
31:0
FIO0VAL FIO1VAL FIO2VAL FIO3VAL FIO4VAL
Fast GPIO output value Set bits. Bit 0 in FIOxCLR corresponds to pin Px.0, bit 31 in FIOxCLR corresponds to pin Px.31. 0 1 Controlled pin output is set to LOW. Controlled pin output is set to HIGH.
0x0
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Aside from the 32-bit long and word only accessible FIOxPIN register, every fast GPIO port can also be controlled via several byte and half-word accessible registers listed in Table 9-109, too. Next to providing the same functions as the FIOxPIN register, these additional registers allow easier and faster access to the physical port pins.
Table 109. Fast GPIO port Pin value byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset value PORTn Register Address & Name
FIOxPIN0
Fast GPIO Port x Pin value register 0. Bit 0 in FIOxPIN0 register corresponds to pin Px.0 ... bit 7 to pin Px.7. Fast GPIO Port x Pin value register 1. Bit 0 in FIOxPIN1 register corresponds to pin Px.8 ... bit 7 to pin Px.15. Fast GPIO Port x Pin value register 2. Bit 0 in FIOxPIN2 register corresponds to pin Px.16 ... bit 7 to pin Px.23. Fast GPIO Port x Pin value register 3. Bit 0 in FIOxPIN3 register corresponds to pin Px.24 ... bit 7 to pin Px.31. Fast GPIO Port x Pin value Lower half-word register. Bit 0 in FIOxPINL register corresponds to pin Px.0 ... bit 15 to pin Px.15.
8 (byte) R/W
0x00
FIO0PIN0 - 0x2009 C014 FIO1PIN0 - 0x2009 C034 FIO2PIN0 - 0x2009 C054 FIO3PIN0 - 0x2009 C074 FIO4PIN0 - 0x2009 C094 FIO0PIN1 - 0x2009 C015 FIO1PIN1 - 0x2009 C035 FIO2PIN1 - 0x2009 C055 FIO3PIN1 - 0x2009 C075 FIO4PIN1 - 0x2009 C095 FIO0PIN2 - 0x2009 C016 FIO1PIN2 - 0x2009 C036 FIO2PIN2 - 0x2009 C056 FIO3PIN2 - 0x2009 C076 FIO4PIN2 - 0x2009 C096 FIO0PIN3 - 0x2009 C017 FIO1PIN3 - 0x2009 C037 FIO2PIN3 - 0x2009 C057 FIO3PIN3 - 0x2009 C077 FIO4PIN3 - 0x2009 C097
FIOxPIN1
8 (byte) R/W
0x00
FIOxPIN2
8 (byte) R/W
0x00
FIOxPIN3
8 (byte) R/W
0x00
FIOxPINL
16 (half-word) 0x0000 FIO0PINL - 0x2009 C014 R/W FIO1PINL - 0x2009 C034 FIO2PINL - 0x2009 C054 FIO3PINL - 0x2009 C074 FIO4PINL - 0x2009 C094
FIOxPINU
Fast GPIO Port x Pin value 16 (half-word) 0x0000 FIO0PINU - 0x2009 C016 Upper half-word register. Bit 0 R/W FIO1PINU - 0x2009 C036 in FIOxPINU register FIO2PINU - 0x2009 C056 corresponds to pin Px.16 ... bit FIO3PINU - 0x2009 C076 15 to Px.31. FIO4PINU - 0x2009 C096
5.5 Fast GPIO port Mask register FIOxMASK (FIO0MASK to FIO4MASK 0x2009 C010 to 0x2009 C090)
This register is used to select port pins that will and will not be affected by write accesses to the FIOxPIN, FIOxSET or FIOxCLR register. Mask register also filters out port's content when the FIOxPIN register is read.
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A zero in this register's bit enables an access to the corresponding physical pin via a read or write access. If a bit in this register is one, corresponding pin will not be changed with write access and if read, will not be reflected in the updated FIOxPIN register. For software examples, see Section 9-6.
Table 110. Fast GPIO port Mask register (FIO0MASK to FIO4MASK - addresses 0x2009 C010 to 0x2009 C090) bit description Bit Symbol Value Description Reset value
31:0 FIO0MASK FIO1MASK FIO2MASK FIO3MASK FIO4MASK
Fast GPIO physical pin access control. 0 Controlled pin is affected by writes to the port's FIOxSET, FIOxCLR, and FIOxPIN register(s). Current state of the pin can be read from the FIOxPIN register. Controlled pin is not affected by writes into the port's FIOxSET, FIOxCLR and FIOxPIN register(s). When the FIOxPIN register is read, this bit will not be updated with the state of the physical pin.
0x0
1
Aside from the 32-bit long and word only accessible FIOxMASK register, every fast GPIO port can also be controlled via several byte and half-word accessible registers listed in Table 9-111, too. Next to providing the same functions as the FIOxMASK register, these additional registers allow easier and faster access to the physical port pins.
Table 111. Fast GPIO port Mask byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset PORTn Register value Address & Name
FIOxMASK0
Fast GPIO Port x Mask register 0. Bit 0 in FIOxMASK0 register corresponds to pin Px.0 ... bit 7 to pin Px.7. Fast GPIO Port x Mask register 1. Bit 0 in FIOxMASK1 register corresponds to pin Px.8 ... bit 7 to pin Px.15.
8 (byte) R/W
0x0
FIO0MASK0 - 0x2009 C010 FIO1MASK0 - 0x2009 C030 FIO2MASK0 - 0x2009 C050 FIO3MASK0 - 0x2009 C070 FIO4MASK0 - 0x2009 C090 FIO0MASK1 - 0x2009 C011 FIO1MASK1 - 0x2009 C031 FIO2MASK1 - 0x2009 C051 FIO3MASK1 - 0x2009 C071 FIO4MASK1 - 0x2009 C091 FIO0MASK2 - 0x2009 C012 FIO1MASK2 - 0x2009 C032 FIO2MASK2 - 0x2009 C052 FIO3MASK2 - 0x2009 C072 FIO4MASK2 - 0x2009 C092
FIOxMASK1
8 (byte) R/W
0x0
FIOxMASK2
Fast GPIO Port x Mask 8 (byte) register 2. Bit 0 in R/W FIOxMASK2 register corresponds to pin Px.16 ... bit 7 to pin Px.23.
0x0
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Table 111. Fast GPIO port Mask byte and half-word accessible register description Generic Register name Description Register length (bits) & access Reset PORTn Register value Address & Name
FIOxMASK3
Fast GPIO Port x Mask 8 (byte) register 3. Bit 0 in R/W FIOxMASK3 register corresponds to pin Px.24 ... bit 7 to pin Px.31. Fast GPIO Port x Mask Lower half-word register. Bit 0 in FIOxMASKL register corresponds to pin Px.0 ... bit 15 to pin Px.15. Fast GPIO Port x Mask Upper half-word register. Bit 0 in FIOxMASKU register corresponds to pin Px.16 ... bit 15 to Px.31. 16 (half-word) R/W
0x0
FIO0MASK3 - 0x2009 C013 FIO1MASK3 - 0x2009 C033 FIO2MASK3 - 0x2009 C053 FIO3MASK3 - 0x2009 C073 FIO4MASK3 - 0x2009 C093 FIO0MASKL - 0x2009 C010 FIO1MASKL - 0x2009 C030 FIO2MASKL - 0x2009 C050 FIO3MASKL - 0x2009 C070 FIO4MASKL - 0x2009 C090 FIO0MASKU - 0x2009 C012 FIO1MASKU - 0x2009 C032 FIO2MASKU - 0x2009 C052 FIO3MASKU - 0x2009 C072 FIO4MASKU - 0x2009 C092
FIOxMASKL
0x0
FIOxMASKU
16 (half-word) R/W
0x0
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5.6 GPIO interrupt registers
The following registers configure the pins of Port 0 and Port 2 to generate interrupts.
5.6.1 GPIO overall Interrupt Status register (IOIntStatus - 0x4002 8080)
This read-only register indicates the presence of interrupt pending on all of the GPIO ports that support GPIO interrupts. Only status one bit per port is required.
Table 112. GPIO overall Interrupt Status register (IOIntStatus - address 0x4002 8080) bit description Bit Symbol Value Description Reset value
0
P0Int 0 1
Port 0 GPIO interrupt pending. There are no pending interrupts on Port 0. There is at least one pending interrupt on Port 0. Reserved. The value read from a reserved bit is not defined. Port 2 GPIO interrupt pending. 0 1 There are no pending interrupts on Port 2. There is at least one pending interrupt on Port 2. Reserved. The value read from a reserved bit is not defined.
0
1 2
P2Int
-
NA 0
31:2
-
-
NA
5.6.2 GPIO Interrupt Enable for port 0 Rising Edge (IO0IntEnR - 0x4002 8090)
Each bit in these read-write registers enables the rising edge interrupt for the corresponding port 0 pin.
Table 113. GPIO Interrupt Enable for port 0 Rising Edge (IO0IntEnR - 0x4002 8090) bit description Bit Symbol Value Description Reset value
0
P0.0ER 0 1
Enable rising edge interrupt for P0.0. Rising edge interrupt is disabled on P0.0. Rising edge interrupt is enabled on P0.0. Enable rising edge interrupt for P0.1. Enable rising edge interrupt for P0.2. Enable rising edge interrupt for P0.3. Enable rising edge interrupt for P0.4. Enable rising edge interrupt for P0.5. Enable rising edge interrupt for P0.6. Enable rising edge interrupt for P0.7. Enable rising edge interrupt for P0.8. Enable rising edge interrupt for P0.9. Enable rising edge interrupt for P0.10. Enable rising edge interrupt for P0.11. Reserved Enable rising edge interrupt for P0.15. Enable rising edge interrupt for P0.16.
0
1 2 3 4 5 6 7 8 9 10 11 15 16
P0.1ER P0.2ER P0.3ER P0.4ER[1] P0.5ER[1] P0.6ER P0.7ER P0.8ER P0.9ER P0.10ER P0.11ER P0.15ER P0.16ER
0 0 0 0 0 0 0 0 0 0 0 NA 0 0
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Table 113. GPIO Interrupt Enable for port 0 Rising Edge (IO0IntEnR - 0x4002 8090) bit description Bit Symbol Value Description Reset value
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
[1]
P0.17ER P0.18ER P0.19ER[1] P0.20ER[1] P0.21ER[1] P0.22ER P0.23ER[1] P0.24ER[1] P0.25ER P0.26ER P0.27ER[1] P0.28ER[1] P0.29ER P0.30ER -
Enable rising edge interrupt for P0.17. Enable rising edge interrupt for P0.18. Enable rising edge interrupt for P0.19. Enable rising edge interrupt for P0.20. Enable rising edge interrupt for P0.21. Enable rising edge interrupt for P0.22. Enable rising edge interrupt for P0.23. Enable rising edge interrupt for P0.24. Enable rising edge interrupt for P0.25. Enable rising edge interrupt for P0.26. Enable rising edge interrupt for P0.27. Enable rising edge interrupt for P0.28. Enable rising edge interrupt for P0.29. Enable rising edge interrupt for P0.30. Reserved.
0 0 0 0 0 0 0 0 0 0 0 0 0 0 NA
Not available on 80-pin package.
5.6.3 GPIO Interrupt Enable for port 2 Rising Edge (IO2IntEnR - 0x4002 80B0)
Each bit in these read-write registers enables the rising edge interrupt for the corresponding port 2 pin.
Table 114. GPIO Interrupt Enable for port 2 Rising Edge (IO2IntEnR - 0x4002 80B0) bit description Bit Symbol Value Description Reset value
0
P2.0ER 0 1
Enable rising edge interrupt for P2.0. Rising edge interrupt is disabled on P2.0. Rising edge interrupt is enabled on P2.0. Enable rising edge interrupt for P2.1. Enable rising edge interrupt for P2.2. Enable rising edge interrupt for P2.3. Enable rising edge interrupt for P2.4. Enable rising edge interrupt for P2.5. Enable rising edge interrupt for P2.6. Enable rising edge interrupt for P2.7. Enable rising edge interrupt for P2.8. Enable rising edge interrupt for P2.9. Enable rising edge interrupt for P2.10. Enable rising edge interrupt for P2.11.
0
1 2 3 4 5 6 7 8 9 10 11
P2.1ER P2.2ER P2.3ER P2.4ER P2.5ER P2.6ER P2.7ER P2.8ER P2.9ER P2.10ER P2.11ER[1]
0 0 0 0 0 0 0 0 0 0 0
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
Table 114. GPIO Interrupt Enable for port 2 Rising Edge (IO2IntEnR - 0x4002 80B0) bit description Bit Symbol Value Description Reset value
12 13
P2.12ER[1] P2.13ER[1]
Enable rising edge interrupt for P2.12. Enable rising edge interrupt for P2.13. Reserved.
0 0 NA
31:14 [1]
Not available on 80-pin package.
5.6.4 GPIO Interrupt Enable for port 0 Falling Edge (IO0IntEnF - 0x4002 8094)
Each bit in these read-write registers enables the falling edge interrupt for the corresponding GPIO port 0 pin.
Table 115. GPIO Interrupt Enable for port 0 Falling Edge (IO0IntEnF - address 0x4002 8094) bit description Bit Symbol Value Description Reset value
0
P0.0EF 0 1
Enable falling edge interrupt for P0.0 Falling edge interrupt is disabled on P0.0. Falling edge interrupt is enabled on P0.0. Enable falling edge interrupt for P0.1. Enable falling edge interrupt for P0.2. Enable falling edge interrupt for P0.3. Enable falling edge interrupt for P0.4. Enable falling edge interrupt for P0.5. Enable falling edge interrupt for P0.6. Enable falling edge interrupt for P0.7. Enable falling edge interrupt for P0.8. Enable falling edge interrupt for P0.9. Enable falling edge interrupt for P0.10. Enable falling edge interrupt for P0.11. Reserved. Enable falling edge interrupt for P0.15. Enable falling edge interrupt for P0.16. Enable falling edge interrupt for P0.17. Enable falling edge interrupt for P0.18. Enable falling edge interrupt for P0.19. Enable falling edge interrupt for P0.20. Enable falling edge interrupt for P0.21. Enable falling edge interrupt for P0.22. Enable falling edge interrupt for P0.23. Enable falling edge interrupt for P0.24. Enable falling edge interrupt for P0.25. Enable falling edge interrupt for P0.26. Enable falling edge interrupt for P0.27.
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1 2 3 4 5 6 7 8 9 10 11 15 16 17 18 19 20 21 22 23 24 25 26 27
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P0.1EF P0.2EF P0.3EF P0.4EF[1] P0.5EF[1] P0.6EF P0.7EF P0.8EF P0.9EF P0.10EF P0.11EF P0.15EF P0.16EF P0.17EF P0.18EF P0.19EF[1] P0.20EF[1] P0.21EF[1] P0.22EF P0.23EF[1] P0.24EF[1] P0.25EF P0.26EF P0.27EF[1]
0 0 0 0 0 0 0 0 0 0 0 NA 0 0 0 0 0 0 0 0 0 0 0 0 0
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Table 115. GPIO Interrupt Enable for port 0 Falling Edge (IO0IntEnF - address 0x4002 8094) bit description Bit Symbol Value Description Reset value
28 29 30 31
[1]
P0.28EF[1] P0.29EF P0.30EF -
Enable falling edge interrupt for P0.28. Enable falling edge interrupt for P0.29. Enable falling edge interrupt for P0.30. Reserved.
0 0 0 NA
Not available on 80-pin package.
5.6.5 GPIO Interrupt Enable for port 2 Falling Edge (IO2IntEnF - 0x4002 80B4)
Each bit in these read-write registers enables the falling edge interrupt for the corresponding GPIO port 2 pin.
Table 116. GPIO Interrupt Enable for port 2 Falling Edge (IO2IntEnF - 0x4002 80B4) bit description Bit Symbol Value Description Reset value
0
P2.0EF 0 1
Enable falling edge interrupt for P2.0 Falling edge interrupt is disabled on P2.0. Falling edge interrupt is enabled on P2.0. Enable falling edge interrupt for P2.1. Enable falling edge interrupt for P2.2. Enable falling edge interrupt for P2.3. Enable falling edge interrupt for P2.4. Enable falling edge interrupt for P2.5. Enable falling edge interrupt for P2.6. Enable falling edge interrupt for P2.7. Enable falling edge interrupt for P2.8. Enable falling edge interrupt for P2.9. Enable falling edge interrupt for P2.10. Enable falling edge interrupt for P2.11. Enable falling edge interrupt for P2.12. Enable falling edge interrupt for P2.13. Reserved.
0
1 2 3 4 5 6 7 8 9 10 11 12 13
P2.1EF P2.2EF P2.3EF P2.4EF P2.5EF P2.6EF P2.7EF P2.8EF P2.9EF P2.10EF P2.11EF[1] P2.12EF[1] P2.13EF[1]
0 0 0 0 0 0 0 0 0 0 0 0 0 NA
31:14 [1]
Not available on 80-pin package.
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
5.6.6 GPIO Interrupt Status for port 0 Rising Edge Interrupt (IO0IntStatR 0x4002 8084)
Each bit in these read-only registers indicates the rising edge interrupt status for port 0.
Table 117. GPIO Interrupt Status for port 0 Rising Edge Interrupt (IO0IntStatR - 0x4002 8084) bit description Bit Symbol Value Description Reset value
0
P0.0REI 0 1
Status of Rising Edge Interrupt for P0.0 A rising edge has not been detected on P0.0. Interrupt has been generated due to a rising edge on P0.0. Status of Rising Edge Interrupt for P0.1. Status of Rising Edge Interrupt for P0.2. Status of Rising Edge Interrupt for P0.3. Status of Rising Edge Interrupt for P0.4. Status of Rising Edge Interrupt for P0.5. Status of Rising Edge Interrupt for P0.6. Status of Rising Edge Interrupt for P0.7. Status of Rising Edge Interrupt for P0.8. Status of Rising Edge Interrupt for P0.9. Status of Rising Edge Interrupt for P0.10. Status of Rising Edge Interrupt for P0.11. Reserved. Status of Rising Edge Interrupt for P0.15. Status of Rising Edge Interrupt for P0.16. Status of Rising Edge Interrupt for P0.17. Status of Rising Edge Interrupt for P0.18. Status of Rising Edge Interrupt for P0.19. Status of Rising Edge Interrupt for P0.20. Status of Rising Edge Interrupt for P0.21. Status of Rising Edge Interrupt for P0.22. Status of Rising Edge Interrupt for P0.23. Status of Rising Edge Interrupt for P0.24. Status of Rising Edge Interrupt for P0.25. Status of Rising Edge Interrupt for P0.26. Status of Rising Edge Interrupt for P0.27. Status of Rising Edge Interrupt for P0.28. Status of Rising Edge Interrupt for P0.29. Status of Rising Edge Interrupt for P0.30. Reserved.
0
1 2 3 4 5 6 7 8 9 10 11 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
[1]
P0.1REI P0.2REI P0.3REI P0.4REI[1] P0.5REI[1] P0.6REI P0.7REI P0.8REI P0.9REI P0.10REI P0.11REI P0.15REI P0.16REI P0.17REI P0.18REI P0.19REI[1] P0.20REI[1] P0.21REI[1] P0.22REI P0.23REI[1] P0.24REI[1] P0.25REI P0.26REI P0.27REI[1] P0.28REI[1] P0.29REI P0.30REI -
0 0 0 0 0 0 0 0 0 0 0 NA 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 NA
14:12 -
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
5.6.7 GPIO Interrupt Status for port 2 Rising Edge Interrupt (IO2IntStatR 0x4002 80A4)
Each bit in these read-only registers indicates the rising edge interrupt status for port 2.
Table 118. GPIO Interrupt Status for port 2 Rising Edge Interrupt (IO2IntStatR - 0x4002 80A4) bit description Bit Symbol Value Description Reset value
0
P2.0REI 0 1
Status of Rising Edge Interrupt for P2.0 A rising edge has not been detected on P2.0. Interrupt has been generated due to a rising edge on P2.0. Status of Rising Edge Interrupt for P2.1. Status of Rising Edge Interrupt for P2.2. Status of Rising Edge Interrupt for P2.3. Status of Rising Edge Interrupt for P2.4. Status of Rising Edge Interrupt for P2.5. Status of Rising Edge Interrupt for P2.6. Status of Rising Edge Interrupt for P2.7. Status of Rising Edge Interrupt for P2.8. Status of Rising Edge Interrupt for P2.9. Status of Rising Edge Interrupt for P2.10. Status of Rising Edge Interrupt for P2.11. Status of Rising Edge Interrupt for P2.12. Status of Rising Edge Interrupt for P2.13. Reserved.
0
1 2 3 4 5 6 7 8 9 10 11 12 13
P2.1REI P2.2REI P2.3REI P2.4REI P2.5REI P2.6REI P2.7REI P2.8REI P2.9REI P2.10REI P2.11REI[1] P2.12REI[1] P2.13REI[1]
0 0 0 0 0 0 0 0 0 0 0 0 0 NA
31:14 [1]
Not available on 80-pin package.
5.6.8 GPIO Interrupt Status for port 0 Falling Edge Interrupt (IO0IntStatF 0x4002 8088)
Each bit in these read-only registers indicates the falling edge interrupt status for port 0.
Table 119. GPIO Interrupt Status for port 0 Falling Edge Interrupt (IO0IntStatF - 0x4002 8088) bit description Bit Symbol Value Description Reset value
0
P0.0FEI 0 1
Status of Falling Edge Interrupt for P0.0 A falling edge has not been detected on P0.0. Interrupt has been generated due to a falling edge on P0.0. Status of Falling Edge Interrupt for P0.1. Status of Falling Edge Interrupt for P0.2. Status of Falling Edge Interrupt for P0.3. Status of Falling Edge Interrupt for P0.4. Status of Falling Edge Interrupt for P0.5. Status of Falling Edge Interrupt for P0.6. Status of Falling Edge Interrupt for P0.7.
0
1 2 3 4 5 6 7
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P0.1FEI P0.2FEI P0.3FEI P0.4FEI[1] P0.5FEI[1] P0.6FEI P0.7FEI
0 0 0 0 0 0 0
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
Table 119. GPIO Interrupt Status for port 0 Falling Edge Interrupt (IO0IntStatF - 0x4002 8088) bit description Bit Symbol Value Description Reset value
8 9 10 11 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
[1]
P0.8FEI P0.9FEI P0.10FEI P0.11FEI P0.15FEI P0.16FEI P0.17FEI P0.18FEI P0.19FEI[1] P0.20FEI[1] P0.21FEI[1] P0.22FEI P0.23FEI[1] P0.24FEI[1] P0.25FEI P0.26FEI P0.27FEI[1] P0.28FEI[1] P0.29FEI P0.30FEI -
Status of Falling Edge Interrupt for P0.8. Status of Falling Edge Interrupt for P0.9. Status of Falling Edge Interrupt for P0.10. Status of Falling Edge Interrupt for P0.11. Reserved. Status of Falling Edge Interrupt for P0.15. Status of Falling Edge Interrupt for P0.16. Status of Falling Edge Interrupt for P0.17. Status of Falling Edge Interrupt for P0.18. Status of Falling Edge Interrupt for P0.19. Status of Falling Edge Interrupt for P0.20. Status of Falling Edge Interrupt for P0.21. Status of Falling Edge Interrupt for P0.22. Status of Falling Edge Interrupt for P0.23. Status of Falling Edge Interrupt for P0.24. Status of Falling Edge Interrupt for P0.25. Status of Falling Edge Interrupt for P0.26. Status of Falling Edge Interrupt for P0.27. Status of Falling Edge Interrupt for P0.28. Status of Falling Edge Interrupt for P0.29. Status of Falling Edge Interrupt for P0.30. Reserved.
0 0 0 0 NA 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 NA
14:12 -
Not available on 80-pin package.
5.6.9 GPIO Interrupt Status for port 2 Falling Edge Interrupt (IO2IntStatF 0x4002 80A8)
Each bit in these read-only registers indicates the falling edge interrupt status for port 2.
Table 120. GPIO Interrupt Status for port 2 Falling Edge Interrupt (IO2IntStatF - 0x4002 80A8) bit description Bit Symbol Value Description Reset value
0
P2.0FEI 0 1
Status of Falling Edge Interrupt for P2.0 A falling edge has not been detected on P2.0. Interrupt has been generated due to a falling edge on P2.0. Status of Falling Edge Interrupt for P2.1. Status of Falling Edge Interrupt for P2.2. Status of Falling Edge Interrupt for P2.3. Status of Falling Edge Interrupt for P2.4. Status of Falling Edge Interrupt for P2.5. Status of Falling Edge Interrupt for P2.6.
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1 2 3 4 5 6
UM10360_1
P2.1FEI P2.2FEI P2.3FEI P2.4FEI P2.5FEI P2.6FEI
0 0 0 0 0 0
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
Table 120. GPIO Interrupt Status for port 2 Falling Edge Interrupt (IO2IntStatF - 0x4002 80A8) bit description Bit Symbol Value Description Reset value
7 8 9 10 11 12 13
P2.7FEI P2.8FEI P2.9FEI P2.10FEI P2.11FEI[1] P2.12FEI[1] P2.13FEI[1]
Status of Falling Edge Interrupt for P2.7. Status of Falling Edge Interrupt for P2.8. Status of Falling Edge Interrupt for P2.9. Status of Falling Edge Interrupt for P2.10. Status of Falling Edge Interrupt for P2.11. Status of Falling Edge Interrupt for P2.12. Status of Falling Edge Interrupt for P2.13. Reserved.
0 0 0 0 0 0 0 NA
31:14 [1]
Not available on 80-pin package.
5.6.10 GPIO Interrupt Clear register for port 0 (IO0IntClr - 0x4002 808C)
Writing a 1 into a bit in this write-only register clears any interrupts for the corresponding port 0 pin.
Table 121. GPIO Interrupt Clear register for port 0 (IO0IntClr - 0x4002 808C)) bit description Bit Symbol Value Description Reset value
0
P0.0CI 0 1
Clear GPIO port Interrupts for P0.0 Corresponding bits in IOxIntStatR and IOxIntStatF are unchanged. Corresponding bits in IOxIntStatR and IOxStatF are cleared. Clear GPIO port Interrupts for P0.1. Clear GPIO port Interrupts for P0.2. Clear GPIO port Interrupts for P0.3. Clear GPIO port Interrupts for P0.4. Clear GPIO port Interrupts for P0.5. Clear GPIO port Interrupts for P0.6. Clear GPIO port Interrupts for P0.7. Clear GPIO port Interrupts for P0.8. Clear GPIO port Interrupts for P0.9. Clear GPIO port Interrupts for P0.10. Clear GPIO port Interrupts for P0.11. Reserved. Clear GPIO port Interrupts for P0.15. Clear GPIO port Interrupts for P0.16. Clear GPIO port Interrupts for P0.17. Clear GPIO port Interrupts for P0.18. Clear GPIO port Interrupts for P0.19. Clear GPIO port Interrupts for P0.20. Clear GPIO port Interrupts for P0.21. Clear GPIO port Interrupts for P0.22.
Rev. 01 -- 4 January 2010
0
1 2 3 4 5 6 7 8 9 10 11 15 16 17 18 19 20 21 22
UM10360_1
P0.1CI P0.2CI P0.3CI P0.4CI[1] P0.5CI[1] P0.6CI P0.7CI P0.8CI P0.9CI P0.10CI P0.11CI P0.15CI P0.16CI P0.17CI P0.18CI P0.19CI[1] P0.20CI[1] P0.21CI[1] P0.22CI
0 0 0 0 0 0 0 0 0 0 0 NA 0 0 0 0 0 0 0 0
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Table 121. GPIO Interrupt Clear register for port 0 (IO0IntClr - 0x4002 808C)) bit description Bit Symbol Value Description Reset value
23 24 25 26 27 28 29 30 31
[1]
P0.23CI[1] P0.24CI[1] P0.25CI P0.26CI P0.27CI[1] P0.28CI[1] P0.29CI P0.30CI -
Clear GPIO port Interrupts for P0.23. Clear GPIO port Interrupts for P0.24. Clear GPIO port Interrupts for P0.25. Clear GPIO port Interrupts for P0.26. Clear GPIO port Interrupts for P0.27. Clear GPIO port Interrupts for P0.28. Clear GPIO port Interrupts for P0.29. Clear GPIO port Interrupts for P0.30. Reserved.
0 0 0 0 0 0 0 0 NA
Not available on 80-pin package.
5.6.11 GPIO Interrupt Clear register for port 0 (IO2IntClr - 0x4002 80AC)
Writing a 1 into a bit in this write-only register clears any interrupts for the corresponding port 2 pin.
Table 122. GPIO Interrupt Clear register for port 0 (IO2IntClr - 0x4002 80AC) bit description Bit Symbol Value Description Reset value
0
P2.0CI 0 1
Clear GPIO port Interrupts for P2.0 Corresponding bits in IOxIntStatR and IOxIntStatF are unchanged. Corresponding bits in IOxIntStatR and IOxStatF are cleared. Clear GPIO port Interrupts for P2.1. Clear GPIO port Interrupts for P2.2. Clear GPIO port Interrupts for P2.3. Clear GPIO port Interrupts for P2.4. Clear GPIO port Interrupts for P2.5. Clear GPIO port Interrupts for P2.6. Clear GPIO port Interrupts for P2.7. Clear GPIO port Interrupts for P2.8. Clear GPIO port Interrupts for P2.9. Clear GPIO port Interrupts for P2.10. Clear GPIO port Interrupts for P2.11. Clear GPIO port Interrupts for P2.12. Clear GPIO port Interrupts for P2.13. Reserved.
0
1 2 3 4 5 6 7 8 9 10 11 12 13
P2.1CI P2.2CI P2.3CI P2.4CI P2.5CI P2.6CI P2.7CI P2.8CI P2.9CI P2.10CI P2.11CI[1] P2.12CI[1] P2.13CI[1]
0 0 0 0 0 0 0 0 0 0 0 0 0 NA
31:14 [1]
Not available on 80-pin package.
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Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
6. GPIO usage notes
6.1 Example: An instantaneous output of 0s and 1s on a GPIO port
Solution 1: using 32-bit (word) accessible fast GPIO registers FIO0MASK = 0xFFFF00FF ; FIO0PIN = 0x0000A500; Solution 2: using 16-bit (half-word) accessible fast GPIO registers FIO0MASKL = 0x00FF; FIO0PINL = 0xA500; Solution 3: using 8-bit (byte) accessible fast GPIO registers FIO0PIN1 = 0xA5;
6.2 Writing to FIOSET/FIOCLR vs. FIOPIN
Writing to the FIOSET/FIOCLR registers allow a program to easily change a port's output pin(s) to both high and low levels at the same time. When FIOSET or FIOCLR are used, only pin/bit(s) written with 1 will be changed, while those written as 0 will remain unaffected. Writing to the FIOPIN register enables instantaneous output of a desired value on the parallel GPIO. Data written to the FIOPIN register will affect all pins configured as outputs on that port: zeroes in the value will produce low level pin outputs and ones in the value will produce high level pin outputs. A subset of a port's pins may be changed by using the FIOMASK register to define which pins are affected. FIOMASK is set up to contain zeroes in bits corresponding to pins that will be changed, and ones for all others. Solution 2 from Section 9-6.1 above illustrates output of 0xA5 on PORT0 pins 15 to 8 while preserving all other PORT0 output pins as they were before.
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Chapter 10: LPC17xx Ethernet
Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The Ethernet controller is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCENET. Remark: On reset, the Ethernet block is disabled (PCENET = 0). 2. Clock: see Table 4-38. 3. Pins: Enable Ethernet pins through the PINSEL registers and select their modes through the PINMODE registers, see Section 8-5. 4. Wake-up: Activity on the Ethernet port can wake up the microcontroller from Power-down mode, see Section 4-8.8. 5. Interrupts: Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 6. Initialization: see Section 10-17.2.
2. Introduction
The Ethernet block contains a full featured 10 Mbps or 100 Mbps Ethernet MAC (Media Access Controller) designed to provide optimized performance through the use of DMA hardware acceleration. Features include a generous suite of control registers, half or full duplex operation, flow control, control frames, hardware acceleration for transmit retry, receive packet filtering and wake-up on LAN activity. Automatic frame transmission and reception with Scatter-Gather DMA off-loads many operations from the CPU. The Ethernet block is an AHB master that drives the AHB bus matrix. Through the matrix, it has access to all on-chip RAM memories. A recommended use of RAM by the Ethernet is to use one of the RAM blocks exclusively for Ethernet traffic. That RAM would then be accessed only by the Ethernet and the CPU, and possibly the GPDMA, giving maximum bandwidth to the Ethernet function. The Ethernet block interfaces between an off-chip Ethernet PHY using the RMII (Reduced Media Independent Interface) protocol and the on-chip MIIM (Media Independent Interface Management) serial bus, also referred to as MDIO (Management Data Input/Output).
Table 123. Ethernet acronyms, abbreviations, and definitions Acronym or Abbreviation Definition
AHB CRC DMA Double-word FCS Fragment
Advanced High-performance bus Cyclic Redundancy Check Direct Memory Access 64-bit entity Frame Check Sequence (CRC) A (part of an) Ethernet frame; one or multiple fragments can add up to a single Ethernet frame.
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Chapter 10: LPC17xx Ethernet
Table 123. Ethernet acronyms, abbreviations, and definitions Acronym or Abbreviation Definition
Frame Half-word LAN MAC MII MIIM Octet Packet PHY RMII Rx TCP/IP Tx VLAN WoL Word
An Ethernet frame consists of destination address, source address, length type field, payload and frame check sequence. 16-bit entity Local Area Network Media Access Control sublayer Media Independent Interface MII management An 8-bit data entity, used in lieu of "byte" by IEEE 802.3 A frame that is transported across Ethernet; a packet consists of a preamble, a start of frame delimiter and an Ethernet frame. Ethernet Physical Layer Reduced MII Receive Transmission Control Protocol / Internet Protocol. The most common high-level protocol used with Ethernet. Transmit Virtual LAN Wake-up on LAN 32-bit entity
3. Features
* Ethernet standards support:
- Supports 10 or 100 Mbps PHY devices including 10 Base-T, 100 Base-TX, 100 Base-FX, and 100 Base-T4. - Fully compliant with IEEE standard 802.3. - Fully compliant with 802.3x Full Duplex Flow Control and Half Duplex back pressure. - Flexible transmit and receive frame options. - VLAN frame support.
* Memory management:
- Independent transmit and receive buffers memory mapped to shared SRAM. - DMA managers with scatter/gather DMA and arrays of frame descriptors. - Memory traffic optimized by buffering and prefetching.
* Enhanced Ethernet features:
- Receive filtering. - Multicast and broadcast frame support for both transmit and receive. - Optional automatic FCS insertion (CRC) for transmit. - Selectable automatic transmit frame padding.
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Chapter 10: LPC17xx Ethernet
- Over-length frame support for both transmit and receive allows any length frames. - Promiscuous receive mode. - Automatic collision backoff and frame retransmission. - Includes power management by clock switching. - Wake-on-LAN power management support allows system wake-up: using the receive filters or a magic frame detection filter.
* Physical interface:
- Attachment of external PHY chip through a standard Reduced MII (RMII) interface. - PHY register access is available via the Media Independent Interface Management (MIIM) interface.
4. Architecture and operation
Figure 10-16 shows the internal architecture of the Ethernet block.
BU S IN TER F ACE
BUS IN T ERF AC E
RMII
DMA interface (AHB master)
RECEIVE DMA
RECEIVE BUFFER MIIM RECEIVE FILTER
ETHERNET BLOCK
Fig 16. Ethernet block diagram
The block diagram for the Ethernet block consists of:
* The host registers module containing the registers in the software view and handling
AHB accesses to the Ethernet block. The host registers connect to the transmit and receive data path as well as the MAC.
* The DMA to AHB interface. This provides an AHB master connection that allows the
Ethernet block to access on-chip SRAM for reading of descriptors, writing of status, and reading and writing data buffers.
* The Ethernet MAC, which interfaces to the off-chip PHY via an RMII interface. * The transmit data path, including:
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ET HE RN ET PHY
TRANSMIT DMA
TRANSMIT RETRY
ETH ER N ET MAC
R MII A DAP TER
AH B BU S
register interface (AHB slave)
HOST REGISTERS
TRANSMIT FLOW CONTROL
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- The transmit DMA manager which reads descriptors and data from memory and writes status to memory. - The transmit retry module handling Ethernet retry and abort situations. - The transmit flow control module which can insert Ethernet pause frames.
* The receive data path, including:
- The receive DMA manager which reads descriptors from memory and writes data and status to memory. - The Ethernet MAC which detects frame types by parsing part of the frame header. - The receive filter which can filter out certain Ethernet frames by applying different filtering schemes. - The receive buffer implementing a delay for receive frames to allow the filter to filter out certain frames before storing them to memory.
5. DMA engine functions
The Ethernet block is designed to provide optimized performance via DMA hardware acceleration. Independent scatter/gather DMA engines connected to the AHB bus off-load many data transfers from the CPU. Descriptors, which are stored in memory, contain information about fragments of incoming or outgoing Ethernet frames. A fragment may be an entire frame or a much smaller amount of data. Each descriptor contains a pointer to a memory buffer that holds data associated with a fragment, the size of the fragment buffer, and details of how the fragment will be transmitted or received. Descriptors are stored in arrays in memory, which are located by pointer registers in the Ethernet block. Other registers determine the size of the arrays, point to the next descriptor in each array that will be used by the DMA engine, and point to the next descriptor in each array that will be used by the Ethernet device driver.
6. Overview of DMA operation
The DMA engine makes use of a Receive descriptor array and a Transmit descriptor array in memory. All or part of an Ethernet frame may be contained in a memory buffer associated with a descriptor. When transmitting, the transmit DMA engine uses as many descriptors as needed (one or more) to obtain (gather) all of the parts of a frame, and sends them out in sequence. When receiving, the receive DMA engine also uses as many descriptors as needed (one or more) to find places to store (scatter) all of the data in the received frame. The base address registers for the descriptor array, registers indicating the number of descriptor array entries, and descriptor array input/output pointers are contained in the Ethernet block. The descriptor entries and all transmit and receive packet data are stored in memory which is not a part of the Ethernet block. The descriptor entries tell where related frame data is stored in memory, certain aspects of how the data is handled, and the result status of each Ethernet transaction.
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Hardware in the DMA engine controls how data incoming from the Ethernet MAC is saved to memory, causes fragment related status to be saved, and advances the hardware receive pointer for incoming data. Driver software must handle the disposition of received data, changing of descriptor data addresses (to avoid unnecessary data movement), and advancing the software receive pointer. The two pointers create a circular queue in the descriptor array and allow both the DMA hardware and the driver software to know which descriptors (if any) are available for their use, including whether the descriptor array is empty or full. Similarly, driver software must set up pointers to data that will be transmitted by the Ethernet MAC, giving instructions for each fragment of data, and advancing the software transmit pointer for outgoing data. Hardware in the DMA engine reads this information and sends the data to the Ethernet MAC interface when possible, updating the status and advancing the hardware transmit pointer.
7. Ethernet Packet
Figure 10-17 illustrates the different fields in an Ethernet packet.
ethernet packet PREAMBLE 7 bytes start-of-frame delimiter 1 byte ETHERNET FRAME
DESTINATION ADDRESS
SOURCE ADDRESS
OPTIONAL VLAN
LEN TYPE
PAYLOAD
FCS
DesA oct6
DesA oct5
DesA oct4
DesA oct3
DesA oct2
DesA oct1
SrcA oct6
SrcA oct5
SrcA oct4
SrcA oct3
SrcA oct2
SrcA oct1
LSB oct(0)
oct(1)
oct(2)
oct(3)
oct(4)
oct(5)
oct(6)
MSB oct(7)
time
Fig 17. Ethernet packet fields
A packet consists of a preamble, a start-of-frame delimiter and an Ethernet frame.
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The Ethernet frame consists of the destination address, the source address, an optional VLAN field, the length/type field, the payload and the frame check sequence. Each address consists of 6 bytes where each byte consists of 8 bits. Bits are transferred starting with the least significant bit.
8. Overview
8.1 Partitioning
The Ethernet block and associated device driver software offer the functionality of the Media Access Control (MAC) sublayer of the data link layer in the OSI reference model (see IEEE std 802.3). The MAC sublayer offers the service of transmitting and receiving frames to the next higher protocol level, the MAC client layer, typically the Logical Link Control sublayer. The device driver software implements the interface to the MAC client layer. It sets up registers in the Ethernet block, maintains descriptor arrays pointing to frames in memory and receives results back from the Ethernet block through interrupts. When a frame is transmitted, the software partially sets up the Ethernet frames by providing pointers to the destination address field, source address field, the length/type field, the MAC client data field and optionally the CRC in the frame check sequence field. Preferably concatenation of frame fields should be done by using the scatter/gather functionality of the Ethernet core to avoid unnecessary copying of data. The hardware adds the preamble and start frame delimiter fields and can optionally add the CRC, if requested by software. When a packet is received the hardware strips the preamble and start frame delimiter and passes the rest of the packet - the Ethernet frame - to the device driver, including destination address, source address, length/type field, MAC client data and frame check sequence (FCS). Apart from the MAC, the Ethernet block contains receive and transmit DMA managers that control receive and transmit data streams between the MAC and the AHB interface. Frames are passed via descriptor arrays located in host memory, so that the hardware can process many frames without software/CPU support. Frames can consist of multiple fragments that are accessed with scatter/gather DMA. The DMA managers optimize memory bandwidth using prefetching and buffering. A receive filter block is used to identify received frames that are not addressed to this Ethernet station, so that they can be discarded. The Rx filters include a perfect address filter and a hash filter. Wake-on-LAN power management support makes it possible to wake the system up from a power-down state -a state in which some of the clocks are switched off -when wake-up frames are received over the LAN. Wake-up frames are recognized by the receive filtering modules or by a Magic Frame detection technology. System wake-up occurs by triggering an interrupt. An interrupt logic block raises and masks interrupts and keeps track of the cause of interrupts. The interrupt block sends an interrupt request signal to the host system. Interrupts can be enabled, cleared and set by software.
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Support for IEEE 802.3/clause 31 flow control is implemented in the flow control block. Receive flow control frames are automatically handled by the MAC. Transmit flow control frames can be initiated by software. In half duplex mode, the flow control module will generate back pressure by sending out continuous preamble only, interrupted by pauses to prevent the jabber limit from being exceeded. The Ethernet block has a standard Reduced Media Independent Interface (RMII) to connect to an external Ethernet PHY chip. Registers in the PHY chip are accessed via the AHB interface through the serial management connection of the MIIM bus, typically operating at 2.5 MHz.
8.2 Example PHY Devices
Some examples of compatible PHY devices are shown in Table 10-124.
Table 124. Example PHY Devices Manufacturer Part Number(s)
Broadcom ICS Intel LSI Logic Micrel National SMSC
BCM5221 ICS1893 LXT971A L80223, L80225, L80227 KS8721 DP83847, DP83846, DP83843 LAN83C185
9. Pin description
Table 10-125 shows the signals used for connecting the Reduced Media Independent Interface (RMII) to the external PHY.
Table 125. Ethernet RMII pin descriptions Pin Name Type Pin Description
ENET_TX_EN ENET_TXD[1:0] ENET_RXD[1:0] ENET_RX_ER ENET_CRS ENET_REF_CLK/ ENET_RX_CLK
Output Output Input Input Input Input
Transmit data enable Transmit data, 2 bits Receive data, 2 bits. Receive error. Carrier sense/data valid. Reference clock
Table 10-126 shows the signals used for Media Independent Interface Management (MIIM) of the external PHY.
Table 126. Ethernet MIIM pin descriptions Pin Name Type Pin Description
ENET_MDC ENET_MDIO
Output Input/Output
MIIM clock. MI data input and output
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10. Registers and software interface
The software interface of the Ethernet block consists of a register view and the format definitions for the transmit and receive descriptors. These two aspects are addressed in the next two subsections.
10.1 Register map
Table 10-127 lists the registers, register addresses and other basic information. The total AHB address space required is 4 kilobytes. After a hard reset or a soft reset via the RegReset bit of the Command register all bits in all registers are reset to 0 unless stated otherwise in the following register descriptions. Some registers will have unused bits which will return a 0 on a read via the AHB interface. Writing to unused register bits of an otherwise writable register will not have side effects. The register map consists of registers in the Ethernet MAC and registers around the core for controlling DMA transfers, flow control and filtering. Reading from reserved addresses or reserved bits leads to unpredictable data. Writing to reserved addresses or reserved bits has no effect. Reading of write-only registers will return a read error on the AHB interface. Writing of read-only registers will return a write error on the AHB interface.
Table 127. Ethernet register definitions Name MAC registers Description Access Reset Value Address
MAC1 MAC2 IPGT IPGR CLRT MAXF SUPP TEST MCFG MCMD MADR MWTD MRDD MIND SA0 SA1 SA2
Control registers
MAC configuration register 1. MAC configuration register 2. Back-to-Back Inter-Packet-Gap register. Non Back-to-Back Inter-Packet-Gap register. Collision window / Retry register. Maximum Frame register. PHY Support register. Test register. MII Mgmt Configuration register. MII Mgmt Command register. MII Mgmt Address register. MII Mgmt Write Data register. MII Mgmt Read Data register. MII Mgmt Indicators register. Station Address 0 register. Station Address 1 register. Station Address 2 register. Command register.
R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W WO RO RO R/W R/W R/W R/W
0x8000 0 0 0 0x370F 0x0600 0 0 0 0 0 0 0 0 0 0 0 0
0x5000 0000 0x5000 0004 0x5000 0008 0x5000 000C 0x5000 0010 0x5000 0014 0x5000 0018 0x5000 001C 0x5000 0020 0x5000 0024 0x5000 0028 0x5000 002C 0x5000 0030 0x5000 0034 0x5000 0040 0x5000 0044 0x5000 0048 0x5000 0100
Command
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Table 127. Ethernet register definitions Name Description Access Reset Value Address
Status RxDescriptor RxStatus RxDescriptorNumber RxProduceIndex RxConsumeIndex TxDescriptor TxStatus TxDescriptorNumber TxProduceIndex TxConsumeIndex TSV0 TSV1 RSV FlowControlCounter FlowControlStatus
Rx filter registers
Status register. Receive descriptor base address register. Receive status base address register. Receive number of descriptors register. Receive produce index register. Receive consume index register. Transmit descriptor base address register. Transmit status base address register. Transmit number of descriptors register. Transmit produce index register. Transmit consume index register. Transmit status vector 0 register. Transmit status vector 1 register. Receive status vector register. Flow control counter register. Flow control status register. Receive filter control register. Receive filter WoL status register. Receive filter WoL clear register. Hash filter table LSBs register. Hash filter table MSBs register. Interrupt status register. Interrupt enable register. Interrupt clear register. Interrupt set register. Power-down register.
RO R/W R/W R/W RO R/W R/W R/W R/W R/W RO RO RO RO R/W RO
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0x5000 0104 0x5000 0108 0x5000 010C 0x5000 0110 0x5000 0114 0x5000 0118 0x5000 011C 0x5000 0120 0x5000 0124 0x5000 0128 0x5000 012C 0x5000 0158 0x5000 015C 0x5000 0160 0x5000 0170 0x5000 0174 0x5000 0200 0x5000 0204 0x5000 0208 0x5000 0210 0x5000 0214 0x5000 0FE0 0x5000 0FE4 0x5000 0FE8 0x5000 0FEC 0x5000 0FF4
RxFliterCtrl RxFilterWoLStatus RxFilterWoLClear HashFilterL HashFilterH IntStatus IntEnable IntClear IntSet PowerDown
Module control registers
RO R/W WO WO R/W
0 0 0 0 0
The third column in the table lists the accessibility of the register: read-only, write-only, read/write. All AHB register write transactions except for accesses to the interrupt registers are posted i.e. the AHB transaction will complete before write data is actually committed to the register. Accesses to the interrupt registers will only be completed by accepting the write data when the data has been committed to the register.
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11. Ethernet MAC register definitions
This section defines the bits in the individual registers of the Ethernet block register map.
11.1 MAC Configuration Register 1 (MAC1 - 0x5000 0000)
The MAC configuration register 1 (MAC1) has an address of 0x5000 0000. Its bit definition is shown in Table 10-128.
Table 128. MAC Configuration register 1 (MAC1 - address 0x5000 0000) bit description Bit Symbol Function Reset value
0 1 2 3 4 7:5 8 9 10 11
RECEIVE ENABLE PASS ALL RECEIVE FRAMES
Set this to allow receive frames to be received. Internally the MAC synchronizes this control bit to the incoming receive stream. When enabled (set to '1'), the MAC will pass all frames regardless of type (normal vs. Control). When disabled, the MAC does not pass valid Control frames.
0 0 0 0
RX FLOW CONTROL When enabled (set to '1'), the MAC acts upon received PAUSE Flow Control frames. When disabled, received PAUSE Flow Control frames are ignored. TX FLOW CONTROL LOOPBACK RESET TX RESET MCS / TX RESET RX RESET MCS / RX When enabled (set to '1'), PAUSE Flow Control frames are allowed to be transmitted. When disabled, Flow Control frames are blocked.
Setting this bit will cause the MAC Transmit interface to be looped back to the MAC 0 Receive interface. Clearing this bit results in normal operation. Unused Setting this bit will put the Transmit Function logic in reset. Setting this bit resets the MAC Control Sublayer / Transmit logic. The MCS logic implements flow control. Setting this bit will put the Ethernet receive logic in reset. Setting this bit resets the MAC Control Sublayer / Receive logic. The MCS logic implements flow control. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0x0 0 0 0 0x0 0x0 0 1 0x0
13:12 14 15
SIMULATION RESET Setting this bit will cause a reset to the random number generator within the Transmit Function. SOFT RESET Setting this bit will put all modules within the MAC in reset except the Host Interface. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
31:16 -
11.2 MAC Configuration Register 2 (MAC2 - 0x5000 0004)
The MAC configuration register 2 (MAC2) has an address of 0x5000 0004. Its bit definition is shown in Table 10-129.
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Table 129. MAC Configuration register 2 (MAC2 - address 0x5000 0004) bit description Bit Symbol Function Reset value
0 1
FULL-DUPLEX FRAME LENGTH CHECKING HUGE FRAME ENABLE DELAYED CRC
When enabled (set to '1'), the MAC operates in Full-Duplex mode. When disabled, the MAC operates in Half-Duplex mode.
0
When enabled (set to '1'), both transmit and receive frame lengths are compared to 0 the Length/Type field. If the Length/Type field represents a length then the check is performed. Mismatches are reported in the StatusInfo word for each received frame. When enabled (set to '1'), frames of any length are transmitted and received. This bit determines the number of bytes, if any, of proprietary header information that exist on the front of IEEE 802.3 frames. When 1, four bytes of header (ignored by the CRC function) are added. When 0, there is no proprietary header. Set this bit to append a CRC to every frame whether padding was required or not. Must be set if PAD/CRC ENABLE is set. Clear this bit if frames presented to the MAC contain a CRC. 0 0
2 3
4
CRC ENABLE
0
5
PAD / CRC ENABLE
Set this bit to have the MAC pad all short frames. Clear this bit if frames presented 0 to the MAC have a valid length. This bit is used in conjunction with AUTO PAD ENABLE and VLAN PAD ENABLE. See Table 10-131 - Pad Operation for details on the pad function. Set this bit to cause the MAC to pad all short frames to 64 bytes and append a valid 0 CRC. Consult Table 10-131 - Pad Operation for more information on the various padding features. Note: This bit is ignored if PAD / CRC ENABLE is cleared. Set this bit to cause the MAC to automatically detect the type of frame, either tagged 0 or un-tagged, by comparing the two octets following the source address with 0x8100 (VLAN Protocol ID) and pad accordingly. Table 10-131 - Pad Operation provides a description of the pad function based on the configuration of this register. Note: This bit is ignored if PAD / CRC ENABLE is cleared. When enabled (set to '1'), the MAC will verify the content of the preamble to ensure 0 it contains 0x55 and is error-free. A packet with an incorrect preamble is discarded. When disabled, no preamble checking is performed. When enabled (set to '1'), the MAC only allows receive packets which contain preamble fields less than 12 bytes in length. When disabled, the MAC allows any length preamble as per the Standard. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. When enabled (set to '1'), the MAC will immediately retransmit following a collision rather than using the Binary Exponential Backoff algorithm as specified in the Standard. 0
6
VLAN PAD ENABLE
7
AUTO DETECT PAD ENABLE
8
PURE PREAMBLE ENFORCEMENT LONG PREAMBLE ENFORCEMENT NO BACKOFF
9
11:10 12
0x0 0
13
BACK PRESSURE / NO BACKOFF EXCESS DEFER
When enabled (set to '1'), after the MAC incidentally causes a collision during back 0 pressure, it will immediately retransmit without backoff, reducing the chance of further collisions and ensuring transmit packets get sent. When enabled (set to '1') the MAC will defer to carrier indefinitely as per the Standard. When disabled, the MAC will abort when the excessive deferral limit is reached. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0
14
31:15
-
0x0
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Table 130. Pad operation Type Auto detect VLAN pad pad enable enable MAC2 [7] MAC2 [6] Pad/CRC enable MAC2 [5] Action
Any Any Any Any
x 0 x 1
x 0 1 0
0 1 1 1
No pad or CRC check Pad to 60 bytes, append CRC Pad to 64 bytes, append CRC If untagged, pad to 60 bytes and append CRC. If VLAN tagged: pad to 64 bytes and append CRC.
11.3 Back-to-Back Inter-Packet-Gap Register (IPGT - 0x5000 0008)
The Back-to-Back Inter-Packet-Gap register (IPGT) has an address of 0x5000 0008. Its bit definition is shown in Table 10-131.
Table 131. Back-to-back Inter-packet-gap register (IPGT - address 0x5000 0008) bit description Bit Symbol Function Reset value
6:0
BACK-TO-BACK INTER-PACKET-GAP
This is a programmable field representing the nibble time offset of the minimum 0x0 possible period between the end of any transmitted packet to the beginning of the next. In Full-Duplex mode, the register value should be the desired period in nibble times minus 3. In Half-Duplex mode, the register value should be the desired period in nibble times minus 6. In Full-Duplex the recommended setting is 0x15 (21d), which represents the minimum IPG of 960 ns (in 100 Mbps mode) or 9.6 s (in 10 Mbps mode). In Half-Duplex the recommended setting is 0x12 (18d), which also represents the minimum IPG of 960 ns (in 100 Mbps mode) or 9.6 s (in 10 Mbps mode). Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0x0
31:7
-
11.4 Non Back-to-Back Inter-Packet-Gap Register (IPGR - 0x5000 000C)
The Non Back-to-Back Inter-Packet-Gap register (IPGR) has an address of 0x5000 000C. Its bit definition is shown in Table 10-132.
Table 132. Non Back-to-back Inter-packet-gap register (IPGR - address 0x5000 000C) bit description Bit Symbol Function Reset value
6:0
NON-BACK-TO-BACK INTER-PACKET-GAP PART2
This is a programmable field representing the Non-Back-to-Back Inter-Packet-Gap. The recommended value is 0x12 (18d), which represents the minimum IPG of 960 ns (in 100 Mbps mode) or 9.6 s (in 10 Mbps mode).
0x0
7 14:8
NON-BACK-TO-BACK INTER-PACKET-GAP PART1
Reserved. User software should not write ones to reserved bits. The value 0x0 read from a reserved bit is not defined. This is a programmable field representing the optional carrierSense 0x0 window referenced in IEEE 802.3/4.2.3.2.1 'Carrier Deference'. If carrier is detected during the timing of IPGR1, the MAC defers to carrier. If, however, carrier becomes active after IPGR1, the MAC continues timing IPGR2 and transmits, knowingly causing a collision, thus ensuring fair access to medium. Its range of values is 0x0 to IPGR2. The recommended value is 0xC (12d) Reserved. User software should not write ones to reserved bits. The value 0x0 read from a reserved bit is not defined.
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11.5 Collision Window / Retry Register (CLRT - 0x5000 0010)
The Collision window / Retry register (CLRT) has an address of 0x5000 0010. Its bit definition is shown in Table 10-133.
Table 133. Collision Window / Retry register (CLRT - address 0x5000 0010) bit description Bit Symbol Function Reset value
3:0
RETRANSMISSION MAXIMUM COLLISION WINDOW -
This is a programmable field specifying the number of retransmission attempts following a collision before aborting the packet due to excessive collisions. The Standard specifies the attemptLimit to be 0xF (15d). See IEEE 802.3/4.2.3.2.5.
0xF
7:4 13:8
Reserved. User software should not write ones to reserved bits. The value read from 0x0 a reserved bit is not defined. This is a programmable field representing the slot time or collision window during which collisions occur in properly configured networks. The default value of 0x37 (55d) represents a 56 byte window following the preamble and SFD. 0x37
31:14
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
11.6 Maximum Frame Register (MAXF - 0x5000 0014)
The Maximum Frame register (MAXF) has an address of 0x5000 0014. Its bit definition is shown in Table 10-134.
Table 134. Maximum Frame register (MAXF - address 0x5000 0014) bit description Bit Symbol Function Reset value
15:0
MAXIMUM FRAME This field resets to the value 0x0600, which represents a maximum receive frame of 0x0600 LENGTH 1536 octets. An untagged maximum size Ethernet frame is 1518 octets. A tagged frame adds four octets for a total of 1522 octets. If a shorter maximum length restriction is desired, program this 16-bit field. Unused 0x0
31:16
11.7 PHY Support Register (SUPP - 0x5000 0018)
The PHY Support register (SUPP) has an address of 0x5000 0018. The SUPP register provides additional control over the RMII interface. The bit definition of this register is shown in Table 10-135.
Table 135. PHY Support register (SUPP - address 0x5000 0018) bit description Bit Symbol Function Reset value
7:0 8 31:9
SPEED -
Unused
0x0
This bit configures the Reduced MII logic for the current operating speed. When set, 0 100 Mbps mode is selected. When cleared, 10 Mbps mode is selected. Unused 0x0
Unused bits in the PHY support register should be left as zeroes.
11.8 Test Register (TEST - 0x5000 001C)
The Test register (TEST) has an address of 0x5000 001C. The bit definition of this register is shown in Table 10-136. These bits are used for testing purposes only.
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Table 136. Test register (TEST - address 0x5000 ) bit description Bit Symbol Function Reset value
0 1 2
SHORTCUT PAUSE QUANTA TEST PAUSE TEST BACKPRESSURE -
This bit reduces the effective PAUSE quanta from 64 byte-times to 1 byte-time.
0
This bit causes the MAC Control sublayer to inhibit transmissions, just as if a 0 PAUSE Receive Control frame with a nonzero pause time parameter was received. Setting this bit will cause the MAC to assert backpressure on the link. Backpressure 0 causes preamble to be transmitted, raising carrier sense. A transmit packet from the system will be sent during backpressure. Unused 0x0
31:3
11.9 MII Mgmt Configuration Register (MCFG - 0x5000 0020)
The MII Mgmt Configuration register (MCFG) has an address of 0x5000 0020. The bit definition of this register is shown in Table 10-137.
Table 137. MII Mgmt Configuration register (MCFG - address 0x5000 0020) bit description Bit Symbol Function Reset value
0
SCAN INCREMENT
Set this bit to cause the MII Management hardware to perform read cycles across a 0 range of PHYs. When set, the MII Management hardware will perform read cycles from address 1 through the value set in PHY ADDRESS[4:0]. Clear this bit to allow continuous reads of the same PHY. Set this bit to cause the MII Management hardware to perform read/write cycles without the 32-bit preamble field. Clear this bit to cause normal cycles to be performed. Some PHYs support suppressed preamble. 0
1
SUPPRESS PREAMBLE CLOCK SELECT
5:2
This field is used by the clock divide logic in creating the MII Management Clock 0 (MDC) which IEEE 802.3u defines to be no faster than 2.5 MHz. Some PHYs support clock rates up to 12.5 MHz, however. The AHB bus clock (HCLK) is divided by the specified amount. Refer to Table 10-138 below for the definition of values for this field. Unused This bit resets the MII Management hardware. Unused 0x0 0 0x0
14:6 15 31:16
RESET MII MGMT -
Table 138. Clock select encoding Clock Select Bit 5 Bit 4 Bit 3 Bit 2 Maximum AHB clock supported
Host Clock divided by 4 Host Clock divided by 6 Host Clock divided by 8 Host Clock divided by 10 Host Clock divided by 14 Host Clock divided by 20 Host Clock divided by 28 Host Clock divided by 36 Host Clock divided by 40 Host Clock divided by 44
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0 0 0 0 0 0 0 1 1 1
0 0 0 1 1 1 1 0 0 0
0 1 1 0 0 1 1 0 0 1
x 0 1 0 1 0 1 0 1 0
10 15 20 25 35 50 70 80[1] 90[1] 100[1]
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Table 138. Clock select encoding Clock Select Bit 5 Bit 4 Bit 3 Bit 2 Maximum AHB clock supported
Host Clock divided by 48 Host Clock divided by 52 Host Clock divided by 56 Host Clock divided by 60 Host Clock divided by 64
[1]
1 1 1 1 1
0 1 1 1 1
1 0 0 1 1
1 0 1 0 1
120[1] 130[1] 140[1] 150[1] 160[1]
The maximum AHB clock rate allowed is limited to the maximum CPU clock rate for the device.
11.10 MII Mgmt Command Register (MCMD - 0x5000 0024)
The MII Mgmt Command register (MCMD) has an address of 0x5000 0024. The bit definition of this register is shown in Table 10-139.
Table 139. MII Mgmt Command register (MCMD - address 0x5000 0024) bit description Bit Symbol Function Reset value
0 1 31:2
READ SCAN -
This bit causes the MII Management hardware to perform a single Read cycle. The Read data is 0 returned in Register MRDD (MII Mgmt Read Data). This bit causes the MII Management hardware to perform Read cycles continuously. This is useful for monitoring Link Fail for example. Unused 0 0x0
11.11 MII Mgmt Address Register (MADR - 0x5000 0028)
The MII Mgmt Address register (MADR) has an address of 0x5000 0028. The bit definition of this register is shown in Table 10-140.
Table 140. MII Mgmt Address register (MADR - address 0x5000 0028) bit description Bit Symbol Function Reset value
4:0 7:5 12:8 31:13
REGISTER ADDRESS PHY ADDRESS -
This field represents the 5-bit Register Address field of Mgmt cycles. Up to 32 registers can be accessed. Unused This field represents the 5-bit PHY Address field of Mgmt cycles. Up to 31 PHYs can be addressed (0 is reserved). Unused
0x0 0x0 0x0 0x0
11.12 MII Mgmt Write Data Register (MWTD - 0x5000 002C)
The MII Mgmt Write Data register (MWTD) is a write-only register with an address of 0x5000 002C. The bit definition of this register is shown in Table 10-141.
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Table 141. MII Mgmt Write Data register (MWTD - address 0x5000 002C) bit description Bit Symbol Function Reset value
15:0
WRITE DATA -
When written, an MII Mgmt write cycle is performed using the 16-bit data and the pre-configured PHY and Register addresses from the MII Mgmt Address register (MADR). Unused
0x0
31:16
0x0
11.13 MII Mgmt Read Data Register (MRDD - 0x5000 0030)
The MII Mgmt Read Data register (MRDD) is a read-only register with an address of 0x5000 0030. The bit definition of this register is shown in Table 10-142.
Table 142. MII Mgmt Read Data register (MRDD - address 0x5000 0030) bit description Bit Symbol Function Reset value
15:0 31:16
READ DATA -
Following an MII Mgmt Read Cycle, the 16-bit data can be read from this location. Unused
0x0 0x0
11.14 MII Mgmt Indicators Register (MIND - 0x5000 0034)
The MII Mgmt Indicators register (MIND) is a read-only register with an address of 0x5000 0034. The bit definition of this register is shown in Table 10-143.
Table 143. MII Mgmt Indicators register (MIND - address 0x5000 0034) bit description Bit Symbol Function Reset value
0 1 2 3 31:4
BUSY
When '1' is returned - indicates MII Mgmt is currently performing an 0 MII Mgmt Read or Write cycle. 0 0 0 0x0
SCANNING When '1' is returned - indicates a scan operation (continuous MII Mgmt Read cycles) is in progress. NOT VALID When '1' is returned - indicates MII Mgmt Read cycle has not completed and the Read Data is not yet valid.
MII Link Fail When '1' is returned - indicates that an MII Mgmt link fail has occurred. Unused
Here are two examples to access PHY via the MII Management Controller. For PHY Write if scan is not used: 1. Write 0 to MCMD 2. Write PHY address and register address to MADR 3. Write data to MWTD 4. Wait for busy bit to be cleared in MIND For PHY Read if scan is not used: 1. Write 1 to MCMD 2. Write PHY address and register address to MADR
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3. Wait for busy bit to be cleared in MIND 4. Write 0 to MCMD 5. Read data from MRDD
11.15 Station Address 0 Register (SA0 - 0x5000 0040)
The Station Address 0 register (SA0) has an address of 0x5000 0040. The bit definition of this register is shown in Table 10-144.
Table 144. Station Address register (SA0 - address 0x5000 0040) bit description Bit Symbol Function Reset value
7:0 15:8 31:16
STATION ADDRESS, This field holds the second octet of the station address. 2nd octet STATION ADDRESS, This field holds the first octet of the station address. 1st octet Unused
0x0 0x0 0x0
The station address is used for perfect address filtering and for sending pause control frames. For the ordering of the octets in the packet please refer to Figure 10-17.
11.16 Station Address 1 Register (SA1 - 0x5000 0044)
The Station Address 1 register (SA1) has an address of 0x5000 0044. The bit definition of this register is shown in Table 10-145.
Table 145. Station Address register (SA1 - address 0x5000 0044) bit description Bit Symbol Function Reset value
7:0 15:8 31:16
STATION ADDRESS, This field holds the fourth octet of the station address. 4th octet STATION ADDRESS, This field holds the third octet of the station address. 3rd octet Unused
0x0 0x0 0x0
The station address is used for perfect address filtering and for sending pause control frames. For the ordering of the octets in the packet please refer to Figure 10-17.
11.17 Station Address 2 Register (SA2 - 0x5000 0048)
The Station Address 2 register (SA2) has an address of 0x5000 0048. The bit definition of this register is shown in Table 10-146.
Table 146. Station Address register (SA2 - address 0x5000 0048) bit description Bit Symbol Function Reset value
7:0 15:8 31:16
STATION ADDRESS, This field holds the sixth octet of the station address. 6th octet STATION ADDRESS, This field holds the fifth octet of the station address. 5th octet Unused
0x0 0x0 0x0
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The station address is used for perfect address filtering and for sending pause control frames. For the ordering of the octets in the packet please refer to Figure 10-17.
12. Control register definitions
12.1 Command Register (Command - 0x5000 0100)
The Command register (Command) register has an address of 0x5000 0100. Its bit definition is shown in Table 10-147.
Table 147. Command register (Command - address 0x5000 0100) bit description Bit Symbol Function Reset value
0 1 2 3 4 5 6
RxEnable TxEnable RegReset TxReset RxReset PassRuntFrame
Enable receive. Enable transmit. Unused When a '1' is written, all datapaths and the host registers are reset. The MAC needs to be reset separately. When a '1' is written, the transmit datapath is reset. When a '1' is written, the receive datapath is reset. When set to '1', passes runt frames smaller than 64 bytes to memory unless they have a CRC error. If '0' runt frames are filtered out. When set to '1', disables receive filtering i.e. all frames received are written to memory. Enable IEEE 802.3 / clause 31 flow control sending pause frames in full duplex and continuous preamble in half duplex.
0 0 0x0 0 0 0 0
7 8 9 10 31:11
PassRxFilter TxFlowControl RMII FullDuplex -
0 0
When set to "1", RMII mode is selected. This bit must be set to 0 one during Ethernet initialization. See Section 10-17.2. When set to "1", indicates full duplex operation. Unused 0 0x0
All bits can be written and read. The Tx/RxReset bits are write-only, reading will return a 0.
12.2 Status Register (Status - 0x5000 0104)
The Status register (Status) is a read-only register with an address of 0x5000 0104. Its bit definition is shown in Table 10-148.
Table 148. Status register (Status - address 0x5000 0104) bit description Bit Symbol Function Reset value
0 1 31:2
RxStatus If 1, the receive channel is active. If 0, the receive channel is inactive. Unused
0 0x0
TxStatus If 1, the transmit channel is active. If 0, the transmit channel is inactive. 0
The values represent the status of the two channels/data paths. When the status is 1, the channel is active, meaning:
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* It is enabled and the Rx/TxEnable bit is set in the Command register or it just got
disabled while still transmitting or receiving a frame.
* Also, for the transmit channel, the transmit queue is not empty
i.e. ProduceIndex != ConsumeIndex.
* Also, for the receive channel, the receive queue is not full
i.e. ProduceIndex != ConsumeIndex - 1. The status transitions from active to inactive if the channel is disabled by a software reset of the Rx/TxEnable bit in the Command register and the channel has committed the status and data of the current frame to memory. The status also transitions to inactive if the transmit queue is empty or if the receive queue is full and status and data have been committed to memory.
12.3 Receive Descriptor Base Address Register (RxDescriptor 0x5000 0108)
The Receive Descriptor base address register (RxDescriptor) has an address of 0x5000 0108. Its bit definition is shown in Table 10-149.
Table 149. Receive Descriptor Base Address register (RxDescriptor - address 0x5000 0108) bit description Bit Symbol Function Reset value
1:0 31:2
RxDescriptor
Fixed to '00' MSBs of receive descriptor base address.
0x0
The receive descriptor base address is a byte address aligned to a word boundary i.e. LSB 1:0 are fixed to "00". The register contains the lowest address in the array of descriptors.
12.4 Receive Status Base Address Register (RxStatus - 0x5000 010C)
The receive descriptor base address is a byte address aligned to a word boundary i.e. LSB 1:0 are fixed to "00". The register contains the lowest address in the array of descriptors.
Table 150. receive Status Base Address register (RxStatus - address 0x5000 010C) bit description Bit Symbol Function Reset value
2:0 31:3
RxStatus
Fixed to '000' MSBs of receive status base address.
0x0
The receive status base address is a byte address aligned to a double word boundary i.e. LSB 2:0 are fixed to "000".
12.5 Receive Number of Descriptors Register (RxDescriptor - 0x5000 0110)
The Receive Number of Descriptors register (RxDescriptorNumber) has an address of 0x5000 0110. Its bit definition is shown in Table 10-151.
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Table 151. Receive Number of Descriptors register (RxDescriptor - address 0x5000 0110) bit description Bit Symbol Function Reset value
15:0
RxDescriptorNumber
Number of descriptors in the descriptor array for which RxDescriptor is the base address. The number of descriptors is minus one encoded. Unused
0x0
31:16
-
0x0
The receive number of descriptors register defines the number of descriptors in the descriptor array for which RxDescriptor is the base address. The number of descriptors should match the number of statuses. The register uses minus one encoding i.e. if the array has 8 elements, the value in the register should be 7.
12.6 Receive Produce Index Register (RxProduceIndex - 0x5000 0114)
The Receive Produce Index register (RxProduceIndex) is a read-only register with an address of 0x5000 0114. Its bit definition is shown in Table 10-152.
Table 152. Receive Produce Index register (RxProduceIndex - address 0x5000 0114) bit description Bit Symbol Function Reset value
15:0 31:16
RxProduceIndex Index of the descriptor that is going to be filled next by the receive datapath. Unused
0x0 0x0
The receive produce index register defines the descriptor that is going to be filled next by the hardware receive process. After a frame has been received, hardware increments the index. The value is wrapped to 0 once the value of RxDescriptorNumber has been reached. If the RxProduceIndex equals RxConsumeIndex - 1, the array is full and any further frames being received will cause a buffer overrun error.
12.7 Receive Consume Index Register (RxConsumeIndex - 0x5000 0118)
The Receive consume index register (RxConsumeIndex) has an address of 0x5000 0118. Its bit definition is shown in Table 10-153.
Table 153. Receive Consume Index register (RxConsumeIndex - address 0x5000 0118) bit description Bit Symbol Function Reset value
15:0 31:16
RxConsumeIndex Index of the descriptor that is going to be processed next by the receive Unused 0x0
The receive consume register defines the descriptor that is going to be processed next by the software receive driver. The receive array is empty as long as RxProduceIndex equals RxConsumeIndex. As soon as the array is not empty, software can process the frame pointed to by RxConsumeIndex. After a frame has been processed by software, software should increment the RxConsumeIndex. The value must be wrapped to 0 once the value
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of RxDescriptorNumber has been reached. If the RxProduceIndex equals RxConsumeIndex - 1, the array is full and any further frames being received will cause a buffer overrun error.
12.8 Transmit Descriptor Base Address Register (TxDescriptor 0x5000 011C)
The Transmit Descriptor base address register (TxDescriptor) has an address of 0x5000 011C. Its bit definition is shown in Table 10-154.
Table 154. Transmit Descriptor Base Address register (TxDescriptor - address 0x5000 011C) bit description Bit Symbol Function Reset value
1:0 31:2
TxDescriptor
Fixed to '00' MSBs of transmit descriptor base address.
0x0
The transmit descriptor base address is a byte address aligned to a word boundary i.e. LSB 1:0 are fixed to "00". The register contains the lowest address in the array of descriptors.
12.9 Transmit Status Base Address Register (TxStatus - 0x5000 0120)
The Transmit Status base address register (TxStatus) has an address of 0x5000 0120. Its bit definition is shown in Table 10-155.
Table 155. Transmit Status Base Address register (TxStatus - address 0x5000 0120) bit description Bit Symbol Function Reset value
1:0 31:2
TxStatus
Fixed to '00' MSBs of transmit status base address.
0x0
The transmit status base address is a byte address aligned to a word boundary i.e. LSB 1:0 are fixed to "00". The register contains the lowest address in the array of statuses.
12.10 Transmit Number of Descriptors Register (TxDescriptorNumber 0x5000 0124)
The Transmit Number of Descriptors register (TxDescriptorNumber) has an address of 0x5000 0124. Its bit definition is shown in Table 10-156.
Table 156. Transmit Number of Descriptors register (TxDescriptorNumber - address 0x5000 0124) bit description Bit Symbol Function Reset value
15:0
TxDescriptorNumber
Number of descriptors in the descriptor array for which TxDescriptor is the base address. The register is minus one encoded. Unused 0x0
31:16
-
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The transmit number of descriptors register defines the number of descriptors in the descriptor array for which TxDescriptor is the base address. The number of descriptors should match the number of statuses. The register uses minus one encoding i.e. if the array has 8 elements, the value in the register should be 7.
12.11 Transmit Produce Index Register (TxProduceIndex - 0x5000 0128)
The Transmit Produce Index register (TxProduceIndex) has an address of 0x5000 0128. Its bit definition is shown in Table 10-157.
Table 157. Transmit Produce Index register (TxProduceIndex - address 0x5000 0128) bit description Bit Symbol Function Reset value
15:0 31:16
TxProduceIndex Index of the descriptor that is going to be filled next by the transmit software driver. Unused
0x0 0x0
The transmit produce index register defines the descriptor that is going to be filled next by the software transmit driver. The transmit descriptor array is empty as long as TxProduceIndex equals TxConsumeIndex. If the transmit hardware is enabled, it will start transmitting frames as soon as the descriptor array is not empty. After a frame has been processed by software, it should increment the TxProduceIndex. The value must be wrapped to 0 once the value of TxDescriptorNumber has been reached. If the TxProduceIndex equals TxConsumeIndex - 1 the descriptor array is full and software should stop producing new descriptors until hardware has transmitted some frames and updated the TxConsumeIndex.
12.12 Transmit Consume Index Register (TxConsumeIndex - 0x5000 012C)
The Transmit Consume Index register (TxConsumeIndex) is a read-only register with an address of 0x5000 012C. Its bit definition is shown in Table 10-158.
Table 158. Transmit Consume Index register (TxConsumeIndex - address 0x5000 012C) bit description Bit Symbol Function Reset value
15:0 31:16
TxConsumeIndex Index of the descriptor that is going to be transmitted next by the transmit datapath. Unused
0x0 0x0
The transmit consume index register defines the descriptor that is going to be transmitted next by the hardware transmit process. After a frame has been transmitted hardware increments the index, wrapping the value to 0 once the value of TxDescriptorNumber has been reached. If the TxConsumeIndex equals TxProduceIndex the descriptor array is empty and the transmit channel will stop transmitting until software produces new descriptors.
12.13 Transmit Status Vector 0 Register (TSV0 - 0x5000 0158)
The Transmit Status Vector 0 register (TSV0) is a read-only register with an address of 0x5000 0158. The transmit status vector registers store the most recent transmit status returned by the MAC. Since the status vector consists of more than 4 bytes, status is
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distributed over two registers TSV0 and TSV1. These registers are provided for debug purposes, because the communication between driver software and the Ethernet block takes place primarily through the frame descriptors. The status register contents are valid as long as the internal status of the MAC is valid and should typically only be read when the transmit and receive processes are halted. Table 10-159 lists the bit definitions of the TSV0 register.
Table 159. Transmit Status Vector 0 register (TSV0 - address 0x5000 0158) bit description Bit Symbol Function Reset value
0 1 2 3 4 5 6 7 8 9 10 11 27:12 28 29 30 31
[1]
CRC error Length check error
The attached CRC in the packet did not match the internally generated CRC. Indicates the frame length field does not match the actual number of data items and is not a type field.
0 0 0 0 0 0
Length out of range[1] Indicates that frame type/length field was larger than 1500 bytes. Done Multicast Broadcast Packet Defer Excessive Defer Excessive Collision Late Collision Giant Underrun Total bytes Control frame Pause Backpressure VLAN Transmission of packet was completed. Packet's destination was a multicast address. Packet's destination was a broadcast address.
Packet was deferred for at least one attempt, but less than 0 an excessive defer. Packet was deferred in excess of 6071 nibble times in 100 Mbps or 24287 bit times in 10 Mbps mode. 0
Packet was aborted due to exceeding of maximum allowed 0 number of collisions. Collision occurred beyond collision window, 512 bit times. Byte count in frame was greater than can be represented in the transmit byte count field in TSV1. Host side caused buffer underrun. The total number of bytes transferred including collided attempts. The frame was a control frame. The frame was a control frame with a valid PAUSE opcode. Carrier-sense method backpressure was previously applied. Frame's length/type field contained 0x8100 which is the VLAN protocol identifier. 0 0 0 0x0 0 0 0 0
The EMAC doesn't distinguish the frame type and frame length, so, e.g. when the IP(0x8000) or ARP(0x0806) packets are received, it compares the frame type with the max length and gives the "Length out of range" error. In fact, this bit is not an error indication, but simply a statement by the chip regarding the status of the received frame.
12.14 Transmit Status Vector 1 Register (TSV1 - 0x5000 015C)
The Transmit Status Vector 1 register (TSV1) is a read-only register with an address of 0x5000 015C. The transmit status vector registers store the most recent transmit status returned by the MAC. Since the status vector consists of more than 4 bytes, status is distributed over two registers TSV0 and TSV1. These registers are provided for debug
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purposes, because the communication between driver software and the Ethernet block takes place primarily through the frame descriptors. The status register contents are valid as long as the internal status of the MAC is valid and should typically only be read when the transmit and receive processes are halted.Table 10-160 lists the bit definitions of the TSV1 register.
Table 160. Transmit Status Vector 1 register (TSV1 - address 0x5000 015C) bit description Bit Symbol Function Reset value
15:0 19:16
Transmit byte count Transmit collision count -
The total number of bytes in the frame, not counting the collided bytes.
0x0
Number of collisions the current packet incurred during 0x0 transmission attempts. The maximum number of collisions (16) cannot be represented. Unused 0x0
31:20
12.15 Receive Status Vector Register (RSV - 0x5000 0160)
The Receive status vector register (RSV) is a read-only register with an address of 0x5000 0160. The receive status vector register stores the most recent receive status returned by the MAC. This register is provided for debug purposes, because the communication between driver software and the Ethernet block takes place primarily through the frame descriptors. The status register contents are valid as long as the internal status of the MAC is valid and should typically only be read when the transmit and receive processes are halted. Table 10-161 lists the bit definitions of the RSV register.
Table 161. Receive Status Vector register (RSV - address 0x5000 0160) bit description Bit Symbol Function Reset value
15:0 16 17 18 19 20 21 22 23 24 25
Received byte count Packet previously ignored RXDV event previously seen Carrier event previously seen Receive code violation CRC error Length check error
Indicates length of received frame. Indicates that a packet was dropped. Indicates that the last receive event seen was not long enough to be a valid packet.
0x0 0 0
Indicates that at some time since the last receive statistics, 0 a carrier event was detected. Indicates that received PHY data does not represent a valid receive code. The attached CRC in the packet did not match the internally generated CRC. Indicates the frame length field does not match the actual number of data items and is not a type field. 0 0 0 0 0 0 0
Length out of range[1] Indicates that frame type/length field was larger than 1518 bytes. Receive OK Multicast Broadcast The packet had valid CRC and no symbol errors. The packet destination was a multicast address. The packet destination was a broadcast address.
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Table 161. Receive Status Vector register (RSV - address 0x5000 0160) bit description Bit Symbol Function Reset value
26
Dribble Nibble
Indicates that after the end of packet another 1-7 bits were 0 received. A single nibble, called dribble nibble, is formed but not sent out. The frame was a control frame. The frame was a control frame with a valid PAUSE opcode. 0 0
27 28 29 30 31
[1]
Control frame PAUSE
Unsupported Opcode The current frame was recognized as a Control Frame but 0 contains an unknown opcode. VLAN Frame's length/type field contained 0x8100 which is the VLAN protocol identifier. Unused 0 0x0
The EMAC doesn't distinguish the frame type and frame length, so, e.g. when the IP(0x8000) or ARP(0x0806) packets are received, it compares the frame type with the max length and gives the "Length out of range" error. In fact, this bit is not an error indication, but simply a statement by the chip regarding the status of the received frame.
12.16 Flow Control Counter Register (FlowControlCounter - 0x5000 0170)
The Flow Control Counter register (FlowControlCounter) has an address of 0x5000 0170. Table 10-162 lists the bit definitions of the register.
Table 162. Flow Control Counter register (FlowControlCounter - address 0x5000 0170) bit description Bit Symbol Function Reset value
15:0 31:16
MirrorCounter PauseTimer
In full duplex mode the MirrorCounter specifies the number 0x0 of cycles before re-issuing the Pause control frame. In full-duplex mode the PauseTimer specifies the value that is inserted into the pause timer field of a pause flow control frame. In half duplex mode the PauseTimer specifies the number of backpressure cycles. 0x0
12.17 Flow Control Status Register (FlowControlStatus - 0x5000 0174)
The Flow Control Status register (FlowControlStatus) is a read-only register with an address of 0x5000 8174. Table 10-163 lists the bit definitions of the register.
Table 163. Flow Control Status register (FlowControlStatus - address 0x5000 8174) bit description Bit Symbol Function Reset value
15:0
MirrorCounterCurrent In full duplex mode this register represents the current 0x0 value of the datapath's mirror counter which counts up to the value specified by the MirrorCounter field in the FlowControlCounter register. In half duplex mode the register counts until it reaches the value of the PauseTimer bits in the FlowControlCounter register. Unused 0x0
31:16
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13. Receive filter register definitions
13.1 Receive Filter Control Register (RxFilterCtrl - 0x5000 0200)
The Receive Filter Control register (RxFilterCtrl) has an address of 0x5000 0200. Table 10-164 lists the definition of the individual bits in the register.
Table 164. Receive Filter Control register (RxFilterCtrl - address 0x5000 0200) bit description Bit Symbol Function Reset value
0 1 2 3 4 5
AcceptUnicastEn AcceptBroadcastEn AcceptMulticastEn AcceptUnicastHashEn AcceptMulticastHashEn AcceptPerfectEn
When set to '1', all unicast frames are accepted. When set to '1', all broadcast frames are accepted. When set to '1', all multicast frames are accepted.
0 0 0
When set to '1', unicast frames that pass the imperfect 0 hash filter are accepted. When set to '1', multicast frames that pass the imperfect hash filter are accepted. When set to '1', the frames with a destination address identical to the station address are accepted. 0 0
11:6
-
Reserved, user software should not write ones to NA reserved bits. The value read from a reserved bit is not defined. When set to '1', the result of the magic packet filter will 0 generate a WoL interrupt when there is a match. When set to '1', the result of the perfect address matching filter and the imperfect hash filter will generate a WoL interrupt when there is a match. Unused 0
12 13
MagicPacketEnWoL RxFilterEnWoL
31:14 -
0x0
13.2 Receive Filter WoL Status Register (RxFilterWoLStatus - 0x5000 0204)
The Receive Filter Wake-up on LAN Status register (RxFilterWoLStatus) is a read-only register with an address of 0x5000 0204. Table 10-165 lists the definition of the individual bits in the register.
Table 165. Receive Filter WoL Status register (RxFilterWoLStatus - address 0x5000 0204) bit description Bit Symbol Function Reset value
0 1 2 3 4 5
AcceptUnicastWoL AcceptBroadcastWoL AcceptMulticastWoL AcceptUnicastHashWoL
When the value is '1', a unicast frames caused WoL. When the value is '1', a broadcast frame caused WoL. When the value is '1', a multicast frame caused WoL. When the value is '1', a unicast frame that passes the imperfect hash filter caused WoL.
0 0 0 0 0
AcceptMulticastHashWoL When the value is '1', a multicast frame that passes the imperfect hash filter caused WoL. AcceptPerfectWoL
When the value is '1', the perfect address matching filter 0 caused WoL.
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Table 165. Receive Filter WoL Status register (RxFilterWoLStatus - address 0x5000 0204) bit description Bit Symbol Function Reset value
6 7 8
RxFilterWoL MagicPacketWoL
Unused When the value is '1', the receive filter caused WoL. When the value is '1', the magic packet filter caused WoL. Unused
0x0 0 0 0x0
31:9 -
The bits in this register record the cause for a WoL. Bits in RxFilterWoLStatus can be cleared by writing the RxFilterWoLClear register.
13.3 Receive Filter WoL Clear Register (RxFilterWoLClear - 0x5000 0208)
The Receive Filter Wake-up on LAN Clear register (RxFilterWoLClear) is a write-only register with an address of 0x5000 0208. Table 10-166 lists the definition of the individual bits in the register.
Table 166. Receive Filter WoL Clear register (RxFilterWoLClear - address 0x5000 0208) bit description Bit Symbol Function Reset value
0 1 2 3 4 5 6 7 8
AcceptUnicastWoLClr AcceptBroadcastWoLClr AcceptMulticastWoLClr AcceptUnicastHashWoLClr AcceptMulticastHashWoLClr AcceptPerfectWoLClr RxFilterWoLClr MagicPacketWoLClr
When a '1' is written to one of these bits (0 to 5), the corresponding status bit in the RxFilterWoLStatus register is cleared.
0 0 0 0 0 0
Unused
0x0
When a '1' is written to one of these bits (7 and/or 8), 0 the corresponding status bit in the RxFilterWoLStatus 0 register is cleared. Unused 0x0
31:9 -
The bits in this register are write-only; writing resets the corresponding bits in the RxFilterWoLStatus register.
13.4 Hash Filter Table LSBs Register (HashFilterL - 0x5000 0210)
The Hash Filter table LSBs register (HashFilterL) has an address of 0x5000 0210. Table 10-167 lists the bit definitions of the register. Details of Hash filter table use can be found in Section 10-17.10 "Receive filtering" on page 196.
Table 167. Hash Filter Table LSBs register (HashFilterL - address 0x5000 0210) bit description Bit Symbol Function Reset value
31:0
HashFilterL
Bits 31:0 of the imperfect filter hash table for receive filtering.
0x0
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13.5 Hash Filter Table MSBs Register (HashFilterH - 0x5000 0214)
The Hash Filter table MSBs register (HashFilterH) has an address of 0x5000 0214. Table 10-168 lists the bit definitions of the register. Details of Hash filter table use can be found in Section 10-17.10 "Receive filtering" on page 196.
Table 168. Hash Filter MSBs register (HashFilterH - address 0x5000 0214) bit description Bit Symbol Function Reset value
31:0
HashFilterH
Bits 63:32 of the imperfect filter hash table for receive filtering.
0x0
14. Module control register definitions
14.1 Interrupt Status Register (IntStatus - 0x5000 0FE0)
The Interrupt Status register (IntStatus) is a read-only register with an address of 0x5000 0FE0. The interrupt status register bit definition is shown in Table 10-169. Note that all bits are flip-flops with an asynchronous set in order to be able to generate interrupts if there are wake-up events while clocks are disabled.
Table 169. Interrupt Status register (IntStatus - address 0x5000 0FE0) bit description Bit Symbol Function Reset value
0
RxOverrunInt
Interrupt set on a fatal overrun error in the receive queue. The 0 fatal interrupt should be resolved by a Rx soft-reset. The bit is not set when there is a nonfatal overrun error. Interrupt trigger on receive errors: AlignmentError, RangeError, 0 LengthError, SymbolError, CRCError or NoDescriptor or Overrun. Interrupt triggered when all receive descriptors have been processed i.e. on the transition to the situation where ProduceIndex == ConsumeIndex. 0
1 2
RxErrorInt RxFinishedInt
3 4
RxDoneInt
Interrupt triggered when a receive descriptor has been processed 0 while the Interrupt bit in the Control field of the descriptor was set.
TxUnderrunInt Interrupt set on a fatal underrun error in the transmit queue. The 0 fatal interrupt should be resolved by a Tx soft-reset. The bit is not set when there is a nonfatal underrun error. TxErrorInt Interrupt trigger on transmit errors: LateCollision, ExcessiveCollision and ExcessiveDefer, NoDescriptor or Underrun. Interrupt triggered when all transmit descriptors have been processed i.e. on the transition to the situation where ProduceIndex == ConsumeIndex. Interrupt triggered when a descriptor has been transmitted while the Interrupt bit in the Control field of the descriptor was set. Unused Interrupt triggered by software writing a 1 to the SoftintSet bit in the IntSet register. Interrupt triggered by a Wake-up event detected by the receive filter. Unused 0
5
6
TxFinishedInt
0
7 11:8 12 13 31:14
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0 0x0 0 0 0x0
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The interrupt status register is read-only. Setting can be done via the IntSet register. Reset can be accomplished via the IntClear register.
14.2 Interrupt Enable Register (IntEnable - 0x5000 0FE4)
The Interrupt Enable register (IntEnable) has an address of 0x5000 0FE4. The interrupt enable register bit definition is shown in Table 10-170.
Table 170. Interrupt Enable register (intEnable - address 0x5000 0FE4) bit description Bit Symbol Function Reset value
0 1 2
RxOverrunIntEn RxErrorIntEn RxFinishedIntEn
Enable for interrupt trigger on receive buffer overrun or descriptor underrun situations. Enable for interrupt trigger on receive errors.
0 0
Enable for interrupt triggered when all receive descriptors have 0 been processed i.e. on the transition to the situation where ProduceIndex == ConsumeIndex. Enable for interrupt triggered when a receive descriptor has 0 been processed while the Interrupt bit in the Control field of the descriptor was set. 0 0 0
3
RxDoneIntEn
4 5 6
TxUnderrunIntEn Enable for interrupt trigger on transmit buffer or descriptor underrun situations. TxErrorIntEn TxFinishedIntEn Enable for interrupt trigger on transmit errors. Enable for interrupt triggered when all transmit descriptors have been processed i.e. on the transition to the situation where ProduceIndex == ConsumeIndex. Enable for interrupt triggered when a descriptor has been transmitted while the Interrupt bit in the Control field of the descriptor was set. Unused Enable for interrupt triggered by the SoftInt bit in the IntStatus register, caused by software writing a 1 to the SoftIntSet bit in the IntSet register. Enable for interrupt triggered by a Wake-up event detected by the receive filter. Unused
7
TxDoneIntEn
0
11:8 12
SoftIntEn
0x0 0
13 31:14
WakeupIntEn -
0 0x0
14.3 Interrupt Clear Register (IntClear - 0x5000 0FE8)
The Interrupt Clear register (IntClear) is a write-only register with an address of 0x5000 0FE8. The interrupt clear register bit definition is shown in Table 10-171.
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Table 171. Interrupt Clear register (IntClear - address 0x5000 0FE8) bit description Bit Symbol Function Reset value
0 1 2 3 4 5 6 7 11:8 12 13 31:14
RxOverrunIntClr RxErrorIntClr RxFinishedIntClr RxDoneIntClr TxUnderrunIntClr TxErrorIntClr TxFinishedIntClr TxDoneIntClr SoftIntClr WakeupIntClr -
Writing a '1' to one of these bits clears (0 to 7) the corresponding status bit in interrupt status register IntStatus.
0 0 0 0 0 0 0 0
Unused Writing a '1' to one of these bits (12 and/or 13) clears the corresponding status bit in interrupt status register IntStatus. Unused
0x0 0 0 0x0
The interrupt clear register is write-only. Writing a 1 to a bit of the IntClear register clears the corresponding bit in the status register. Writing a 0 will not affect the interrupt status.
14.4 Interrupt Set Register (IntSet - 0x5000 0FEC)
The Interrupt Set register (IntSet) is a write-only register with an address of 0x5000 0FEC. The interrupt set register bit definition is shown in Table 10-172.
Table 172. Interrupt Set register (IntSet - address 0x5000 0FEC) bit description Bit Symbol Function Reset value
0 1 2 3 4 5 6 7 11:8 12 13 31:14
RxOverrunIntSet RxErrorIntSet RxFinishedIntSet RxDoneIntSet TxUnderrunIntSet TxErrorIntSet TxFinishedIntSet TxDoneIntSet SoftIntSet WakeupIntSet -
Writing a '1' to one of these bits (0 to 7) sets the corresponding status bit in interrupt status register IntStatus.
0 0 0 0 0 0 0 0
Unused Writing a '1' to one of these bits (12 and/or 13) sets the corresponding status bit in interrupt status register IntStatus. Unused
0x0 0 0 0x0
The interrupt set register is write-only. Writing a 1 to a bit of the IntSet register sets the corresponding bit in the status register. Writing a 0 will not affect the interrupt status.
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14.5 Power-Down Register (PowerDown - 0x5000 0FF4)
The Power-Down register (PowerDown) is used to block all AHB accesses except accesses to the Power-Down register. The register has an address of 0x5000 0FF4. The bit definition of the register is listed in Table 10-173.
Table 173. Power-Down register (PowerDown - address 0x5000 0FF4) bit description Bit Symbol Function Reset value
30:0 31
PowerDownMACAHB
Unused If true, all AHB accesses will return a read/write error, except accesses to the Power-Down register.
0x0 0
Setting the bit will return an error on all read and write accesses on the MACAHB interface except for accesses to the Power-Down register.
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15. Descriptor and status formats
This section defines the descriptor format for the transmit and receive scatter/gather DMA engines. Each Ethernet frame can consist of one or more fragments. Each fragment corresponds to a single descriptor. The DMA managers in the Ethernet block scatter (for receive) and gather (for transmit) multiple fragments for a single Ethernet frame.
15.1 Receive descriptors and statuses
Figure 10-18 depicts the layout of the receive descriptors in memory.
RxDescriptor
RxStatus
1
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
2
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
3
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
4
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
5
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
RxDescriptorNumber
PACKET CONTROL
DATA BUFFER
StatusInfo StatusHashCRC
Fig 18. Receive descriptor memory layout
Receive descriptors are stored in an array in memory. The base address of the array is stored in the RxDescriptor register, and should be aligned on a 4 byte address boundary. The number of descriptors in the array is stored in the RxDescriptorNumber register using a minus one encoding style e.g. if the array has 8 elements the register value should be 7. Parallel to the descriptors there is an array of statuses. For each element of the descriptor array there is an associated status field in the status array. The base address of the status array is stored in the RxStatus register, and must be aligned on an 8 byte address boundary. During operation (when the receive data path is enabled) the RxDescriptor, RxStatus and RxDescriptorNumber registers should not be modified. Two registers, RxConsumeIndex and RxProduceIndex, define the descriptor locations that will be used next by hardware and software. Both registers act as counters starting at 0 and wrapping when they reach the value of RxDescriptorNumber. The RxProduceIndex contains the index of the descriptor that is going to be filled with the next frame being
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received. The RxConsumeIndex is programmed by software and is the index of the next descriptor that the software receive driver is going to process. When RxProduceIndex == RxConsumeIndex, the receive buffer is empty. When RxProduceIndex == RxConsumeIndex -1 (taking wraparound into account), the receive buffer is full and newly received data would generate an overflow unless the software driver frees up one or more descriptors. Each receive descriptor takes two word locations (8 bytes) in memory. Likewise each status field takes two words (8 bytes) in memory. Each receive descriptor consists of a pointer to the data buffer for storing receive data (Packet) and a control word (Control). The Packet field has a zero address offset, the control field has a 4 byte address offset with respect to the descriptor address as defined in Table 10-174.
Table 174. Receive Descriptor Fields Symbol Address Bytes Description offset
Packet Control
0x0 0x4
4 4
Base address of the data buffer for storing receive data. Control information, see Table 10-175.
The data buffer pointer (Packet) is a 32-bit, byte aligned address value containing the base address of the data buffer. The definition of the control word bits is listed in Table 10-175.
Table 175. Receive Descriptor Control Word Bit Symbol Description
10:0
Size
Size in bytes of the data buffer. This is the size of the buffer reserved by the device driver for a frame or frame fragment i.e. the byte size of the buffer pointed to by the Packet field. The size is -1 encoded e.g. if the buffer is 8 bytes the size field should be equal to 7. Unused If true generate an RxDone interrupt when the data in this frame or frame fragment and the associated status information has been committed to memory.
30:11 31 Interrupt
Table 10-176 lists the fields in the receive status elements from the status array.
Table 176. Receive Status Fields Symbol Address Bytes Description offset
StatusInfo
0x0
4 4
Receive status return flags, see Table 10-178. The concatenation of the destination address hash CRC and the source address hash CRC.
StatusHashCRC 0x4
Each receive status consists of two words. The StatusHashCRC word contains a concatenation of the two 9-bit hash CRCs calculated from the destination and source addresses contained in the received frame. After detecting the destination and source addresses, StatusHashCRC is calculated once, then held for every fragment of the same frame. The concatenation of the two CRCs is shown in Table 10-177:
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Table 177. Receive Status HashCRC Word Bit Symbol Description
8:0 15:9
SAHashCRC Hash CRC calculated from the source address. Unused Unused
24:16 DAHashCRC Hash CRC calculated from the destination address. 31:25 -
The StatusInfo word contains flags returned by the MAC and flags generated by the receive data path reflecting the status of the reception. Table 10-178 lists the bit definitions in the StatusInfo word.
Table 178. Receive status information word Bit Symbol Description
10:0
RxSize
The size in bytes of the actual data transferred into one fragment buffer. In other words, this is the size of the frame or fragment as actually written by the DMA manager for one descriptor. This may be different from the Size bits of the Control field in the descriptor that indicate the size of the buffer allocated by the device driver. Size is -1 encoded e.g. if the buffer has 8 bytes the RxSize value will be 7. Unused Indicates this is a control frame for flow control, either a pause frame or a frame with an unsupported opcode. Indicates a VLAN frame. Indicates this frame has failed the Rx filter. These frames will not normally pass to memory. But due to the limitation of the size of the buffer, part of this frame may already be passed to memory. Once the frame is found to have failed the Rx filter, the remainder of the frame will be discarded without being passed to the memory. However, if the PassRxFilter bit in the Command register is set, the whole frame will be passed to memory. Set when a multicast frame is received. Set when a broadcast frame is received. The received frame had a CRC error. The PHY reports a bit error over the PHY interface during reception. The frame length field value in the frame specifies a valid length, but does not match the actual data length. The received packet exceeds the maximum packet size.
17:11 18 19 20 ControlFrame VLAN FailFilter
21 22 23 24 25 26 27
Multicast Broadcast CRCError SymbolError LengthError RangeError[1]
AlignmentError An alignment error is flagged when dribble bits are detected and also a CRC error is detected. This is in accordance with IEEE std. 802.3/clause 4.3.2. Overrun NoDescriptor LastFlag Error Receive overrun. The adapter can not accept the data stream. No new Rx descriptor is available and the frame is too long for the buffer size in the current receive descriptor. When set to 1, indicates this descriptor is for the last fragment of a frame. If the frame consists of a single fragment, this bit is also set to 1. An error occurred during reception of this frame. This is a logical OR of AlignmentError, RangeError, LengthError, SymbolError, CRCError, and Overrun.
28 29 30 31
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[1]
The EMAC doesn't distinguish the frame type and frame length, so, e.g. when the IP(0x8000) or ARP(0x0806) packets are received, it compares the frame type with the max length and gives the "Range" error. In fact, this bit is not an error indication, but simply a statement by the chip regarding the status of the received frame.
For multi-fragment frames, the value of the AlignmentError, RangeError, LengthError, SymbolError and CRCError bits in all but the last fragment in the frame will be 0; likewise the value of the FailFilter, Multicast, Broadcast, VLAN and ControlFrame bits is undefined. The status of the last fragment in the frame will copy the value for these bits from the MAC. All fragment statuses will have valid LastFrag, RxSize, Error, Overrun and NoDescriptor bits.
15.2 Transmit descriptors and statuses
Figure 10-19 depicts the layout of the transmit descriptors in memory.
TxDescriptor
TxStatus
1
PACKET CONTROL
DATA BUFFER StatusInfo
2
PACKET CONTROL
DATA BUFFER StatusInfo
3
PACKET CONTROL
DATA BUFFER StatusInfo
4
PACKET CONTROL
DATA BUFFER StatusInfo
5
PACKET CONTROL
DATA BUFFER StatusInfo
TxDescriptorNumber
PACKET CONTROL
DATA BUFFER StatusInfo
Fig 19. Transmit descriptor memory layout
Transmit descriptors are stored in an array in memory. The lowest address of the transmit descriptor array is stored in the TxDescriptor register, and must be aligned on a 4 byte address boundary. The number of descriptors in the array is stored in the TxDescriptorNumber register using a minus one encoding style i.e. if the array has 8 elements the register value should be 7. Parallel to the descriptors there is an array of statuses. For each element of the descriptor array there is an associated status field in the status array. The base address of the status array is stored in the TxStatus register, and must be aligned on a 4 byte address boundary. During operation (when the transmit data path is enabled) the TxDescriptor, TxStatus, and TxDescriptorNumber registers should not be modified.
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Two registers, TxConsumeIndex and TxProduceIndex, define the descriptor locations that will be used next by hardware and software. Both register act as counters starting at 0 and wrapping when they reach the value of TxDescriptorNumber. The TxProduceIndex contains the index of the next descriptor that is going to be filled by the software driver. The TxConsumeIndex contains the index of the next descriptor going to be transmitted by the hardware. When TxProduceIndex == TxConsumeIndex, the transmit buffer is empty. When TxProduceIndex == TxConsumeIndex -1 (taking wraparound into account), the transmit buffer is full and the software driver cannot add new descriptors until the hardware has transmitted one or more frames to free up descriptors. Each transmit descriptor takes two word locations (8 bytes) in memory. Likewise each status field takes one word (4 bytes) in memory. Each transmit descriptor consists of a pointer to the data buffer containing transmit data (Packet) and a control word (Control). The Packet field has a zero address offset, whereas the control field has a 4 byte address offset, see Table 10-179.
Table 179. Transmit descriptor fields Symbol Address offset Bytes Description
Packet Control
0x0 0x4
4 4
Base address of the data buffer containing transmit data. Control information, see Table 10-180.
The data buffer pointer (Packet) is a 32-bit, byte aligned address value containing the base address of the data buffer. The definition of the control word bits is listed in Table 10-180.
Table 180. Transmit descriptor control word Bit Symbol Description
10:0
Size
Size in bytes of the data buffer. This is the size of the frame or fragment as it needs to be fetched by the DMA manager. In most cases it will be equal to the byte size of the data buffer pointed to by the Packet field of the descriptor. Size is -1 encoded e.g. a buffer of 8 bytes is encoded as the Size value 7. Unused Per frame override. If true, bits 30:27 will override the defaults from the MAC internal registers. If false, bits 30:27 will be ignored and the default values from the MAC will be used. If true, enables huge frame, allowing unlimited frame sizes. When false, prevents transmission of more than the maximum frame length (MAXF[15:0]). If true, pad short frames to 64 bytes. If true, append a hardware CRC to the frame. If true, indicates that this is the descriptor for the last fragment in the transmit frame. If false, the fragment from the next descriptor should be appended. If true, a TxDone interrupt will be generated when the data in this frame or frame fragment has been sent and the associated status information has been committed to memory.
25:11 26 Override
27 28 29 30 31
Huge Pad CRC Last Interrupt
Table 10-181 shows the one field transmit status.
Table 181. Transmit status fields Symbol Address offset Bytes Description
StatusInfo
0x0
4
Transmit status return flags, see Table 10-182.
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The transmit status consists of one word which is the StatusInfo word. It contains flags returned by the MAC and flags generated by the transmit data path reflecting the status of the transmission. Table 10-182 lists the bit definitions in the StatusInfo word.
Table 182. Transmit status information word Bit Symbol Description
20:0
-
Unused The number of collisions this packet incurred, up to the Retransmission Maximum. This packet incurred deferral, because the medium was occupied. This is not an error unless excessive deferral occurs. This packet incurred deferral beyond the maximum deferral limit and was aborted.
24:21 CollisionCount 25 26 27 28 29 30 31 Defer ExcessiveDefer
ExcessiveCollision Indicates this packet exceeded the maximum collision limit and was aborted. LateCollision Underrun NoDescriptor Error An Out of window Collision was seen, causing packet abort. A Tx underrun occurred due to the adapter not producing transmit data. The transmit stream was interrupted because a descriptor was not available. An error occurred during transmission. This is a logical OR of Underrun, LateCollision, ExcessiveCollision, and ExcessiveDefer.
For multi-fragment frames, the value of the LateCollision, ExcessiveCollision, ExcessiveDefer, Defer and CollissionCount bits in all but the last fragment in the frame will be 0. The status of the last fragment in the frame will copy the value for these bits from the MAC. All fragment statuses will have valid Error, NoDescriptor and Underrun bits.
16. Ethernet block functional description
This section defines the functions of the DMA capable 10/100 Ethernet MAC. After introducing the DMA concepts of the Ethernet block, and a description of the basic transmit and receive functions, this section elaborates on advanced features such as flow control, receive filtering, etc.
16.1 Overview
The Ethernet block can transmit and receive Ethernet packets from an off-chip Ethernet PHY connected through the RMII interface. Typically during system start-up, the Ethernet block will be initialized. Software initialization of the Ethernet block should include initialization of the descriptor and status arrays as well as the receiver fragment buffers. Remark: when initializing the Ethernet block, it is important to first configure the PHY and insure that reference clocks (ENET_REF_CLK signal in RMII mode, or both ENET_RX_CLK and ENET_TX_CLK signals in MII mode) are present at the external pins and connected to the EMAC module (selecting the appropriate pins using the PINSEL registers) prior to continuing with Ethernet configuration. Otherwise the CPU can become locked and no further functionality will be possible. This will cause JTAG lose communication with the target, if debug mode is being used.
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To transmit a packet the software driver has to set up the appropriate Control registers and a descriptor to point to the packet data buffer before transferring the packet to hardware by incrementing the TxProduceIndex register. After transmission, hardware will increment TxConsumeIndex and optionally generate an interrupt. The hardware will receive packets from the PHY and apply filtering as configured by the software driver. While receiving a packet the hardware will read a descriptor from memory to find the location of the associated receiver data buffer. Receive data is written in the data buffer and receive status is returned in the receive descriptor status word. Optionally an interrupt can be generated to notify software that a packet has been received. Note that the DMA manager will prefetch and buffer up to three descriptors.
16.2 AHB interface
The registers of the Ethernet block connect to an AHB slave interface to allow access to the registers from the CPU. The AHB interface has a 32-bit data path, which supports only word accesses and has an address aperture of 4 kB. Table 10-127 lists the registers of the Ethernet block. All AHB write accesses to registers are posted except for accesses to the IntSet, IntClear and IntEnable registers. AHB write operations are executed in order. If the PowerDown bit of the PowerDown register is set, all AHB read and write accesses will return a read or write error except for accesses to the PowerDown register. Bus Errors The Ethernet block generates errors for several conditions:
* The AHB interface will return a read error when there is an AHB read access to a
write-only register; likewise a write error is returned when there is an AHB write access to the read-only register. An AHB read or write error will be returned on AHB read or write accesses to reserved registers. These errors are propagated back to the CPU. Registers defined as read-only and write-only are identified in Table 10-127.
* If the PowerDown bit is set all accesses to AHB registers will result in an error
response except for accesses to the PowerDown register.
17. Interrupts
The Ethernet block has a single interrupt request output to the CPU (via the NVIC). The interrupt service routine must read the IntStatus register to determine the origin of the interrupt. All interrupt statuses can be set by software writing to the IntSet register; statuses can be cleared by software writing to the IntClear register. The transmit and receive data paths can only set interrupt statuses, they cannot clear statuses. The SoftInt interrupt cannot be set by hardware and can be used by software for test purposes.
17.1 Direct Memory Access (DMA)
Descriptor arrays
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The Ethernet block includes two DMA managers. The DMA managers make it possible to transfer frames directly to and from memory with little support from the processor and without the need to trigger an interrupt for each frame. The DMA managers work with arrays of frame descriptors and statuses that are stored in memory. The descriptors and statuses act as an interface between the Ethernet hardware and the device driver software. There is one descriptor array for receive frames and one descriptor array for transmit frames. Using buffering for frame descriptors, the memory traffic and memory bandwidth utilization of descriptors can be kept small. Each frame descriptor contains two 32-bit fields: the first field is a pointer to a data buffer containing a frame or a fragment, whereas the second field is a control word related to that frame or fragment. The software driver must write the base addresses of the descriptor and status arrays in the TxDescriptor/RxDescriptor and TxStatus/RxStatus registers. The number of descriptors/statuses in each array must be written in the TxDescriptorNumber/RxDescriptorNumber registers. The number of descriptors in an array corresponds to the number of statuses in the associated status array. Transmit descriptor arrays, receive descriptor arrays and transmit status arrays must be aligned on a 4 byte (32bit)address boundary, while the receive status array must be aligned on a 8 byte (64bit) address boundary. Ownership of descriptors Both device driver software and Ethernet hardware can read and write the descriptor arrays at the same time in order to produce and consume descriptors. A descriptor is "owned" either by the device driver or by the Ethernet hardware. Only the owner of a descriptor reads or writes its value. Typically, the sequence of use and ownership of descriptors and statuses is as follows: a descriptor is owned and set up by the device driver; ownership of the descriptor/status is passed by the device driver to the Ethernet block, which reads the descriptor and writes information to the status field; the Ethernet block passes ownership of the descriptor back to the device driver, which uses the status information and then recycles the descriptor to be used for another frame. Software must pre-allocate the memory used to hold the descriptor arrays. Software can hand over ownership of descriptors and statuses to the hardware by incrementing (and wrapping if on the array boundary) the TxProduceIndex/RxConsumeIndex registers. Hardware hands over descriptors and status to software by updating the TxConsumeIndex/ RxProduceIndex registers. After handing over a descriptor to the receive and transmit DMA hardware, device driver software should not modify the descriptor or reclaim the descriptor by decrementing the TxProduceIndex/ RxConsumeIndex registers because descriptors may have been prefetched by the hardware. In this case the device driver software will have to wait until the frame has been transmitted or the device driver has to soft-reset the transmit and/or receive data paths which will also reset the descriptor arrays. Sequential order with wrap-around When descriptors are read from and statuses are written to the arrays, this is done in sequential order with wrap-around. Sequential order means that when the Ethernet block has finished reading/writing a descriptor/status, the next descriptor/status it reads/writes is
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the one at the next higher, adjacent memory address. Wrap around means that when the Ethernet block has finished reading/writing the last descriptor/status of the array (with the highest memory address), the next descriptor/status it reads/writes is the first descriptor/status of the array at the base address of the array. Full and Empty state of descriptor arrays The descriptor arrays can be empty, partially full or full. A descriptor array is empty when all descriptors are owned by the producer. A descriptor array is partially full if both producer and consumer own part of the descriptors and both are busy processing those descriptors. A descriptor array is full when all descriptors (except one) are owned by the consumer, so that the producer has no more room to process frames. Ownership of descriptors is indicated with the use of a consume index and a produce index. The produce index is the first element of the array owned by the producer. It is also the index of the array element that is next going to be used by the producer of frames (it may already be busy using it and subsequent elements). The consume index is the first element of the array that is owned by the consumer. It is also the number of the array element next to be consumed by the consumer of frames (it and subsequent elements may already be in the process of being consumed). If the consume index and the produce index are equal, the descriptor array is empty and all array elements are owned by the producer. If the consume index equals the produce index plus one, then the array is full and all array elements (except the one at the produce index) are owned by the consumer. With a full descriptor array, still one array element is kept empty, to be able to easily distinguish the full or empty state by looking at the value of the produce index and consume index. An array must have at least 2 elements to be able to indicate a full descriptor array with a produce index of value 0 and a consume index of value 1. The wrap around of the arrays is taken into account when determining if a descriptor array is full, so a produce index that indicates the last element in the array and a consume index that indicates the first element in the array, also means the descriptor array is full. When the produce index and the consume index are unequal and the consume index is not the produce index plus one (with wrap around taken into account), then the descriptor array is partially full and both the consumer and producer own enough descriptors to be able to operate actively on the descriptor array. Interrupt bit The descriptors have an Interrupt bit, which is programmed by software. When the Ethernet block is processing a descriptor and finds this bit set, it will allow triggering an interrupt (after committing status to memory) by passing the RxDoneInt or TxDoneInt bits in the IntStatus register to the interrupt output pin. If the Interrupt bit is not set in the descriptor, then the RxDoneInt or TxDoneInt are not set and no interrupt is triggered (note that the corresponding bits in IntEnable must also be set to trigger interrupts). This offers flexible ways of managing the descriptor arrays. For instance, the device driver could add 10 frames to the Tx descriptor array, and set the Interrupt bit in descriptor number 5 in the descriptor array. This would invoke the interrupt service routine before the transmit descriptor array is completely exhausted. The device driver could add another batch of frames to the descriptor array, without interrupting continuous transmission of frames. Frame fragments For maximum flexibility in frame storage, frames can be split up into multiple frame fragments with fragments located in different places in memory. In this case one descriptor is used for each frame fragment. So, a descriptor can point to a single frame or
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to a fragment of a frame. By using fragments, scatter/gather DMA can be done: transmit frames are gathered from multiple fragments in memory and receive frames can be scattered to multiple fragments in memory. By stringing together fragments it is possible to create large frames from small memory areas. Another use of fragments is to be able to locate a frame header and frame payload in different places and to concatenate them without copy operations in the device driver. For transmissions, the Last bit in the descriptor Control field indicates if the fragment is the last in a frame; for receive frames, the LastFrag bit in the StatusInfo field of the status words indicates if the fragment is the last in the frame. If the Last(Frag) bit is 0 the next descriptor belongs to the same Ethernet frame, If the Last(Frag) bit is 1 the next descriptor is a new Ethernet frame.
17.2 Initialization
After reset, the Ethernet software driver needs to initialize the Ethernet block. During initialization the software needs to:
* Remove the soft reset condition from the MAC * Configure the PHY via the MIIM interface of the MAC.
Remark: it is important to configure the PHY and insure that reference clocks (ENET_REF_CLK signal in RMII mode, or both ENET_RX_CLK and ENET_TX_CLK signals in MII mode) are present at the external pins and connected to the EMAC module (selecting the appropriate pins using the PINSEL registers) prior to continuing with Ethernet configuration. Otherwise the CPU can become locked and no further functionality will be possible. This will cause JTAG lose communication with the target, if debug mode is being used.
* * * *
Select RMII mode Configure the transmit and receive DMA engines, including the descriptor arrays Configure the host registers (MAC1,MAC2 etc.) in the MAC Enable the receive and transmit data paths
Depending on the PHY, the software needs to initialize registers in the PHY via the MII Management interface. The software can read and write PHY registers by programming the MCFG, MCMD, MADR registers of the MAC. Write data should be written to the MWTD register; read data and status information can be read from the MRDD and MIND registers. The Ethernet block supports RMII PHYs. During initialization software must select RMII mode by programming the Command register. Before switching to RMII mode the default soft reset (MAC1 register bit 15) has to be de-asserted. The phy_ref_clk must be running and internally connected during this operation. Transmit and receive DMA engines should be initialized by the device driver by allocating the descriptor and status arrays in memory. Transmit and receive functions have their own dedicated descriptor and status arrays. The base addresses of these arrays need to be programmed in the TxDescriptor/TxStatus and RxDescriptor/RxStatus registers. The number of descriptors in an array matches the number of statuses in an array.
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Please note that the transmit descriptors, receive descriptors and receive statuses are 8 bytes each while the transmit statuses are 4 bytes each. All descriptor arrays and transmit statuses need to be aligned on 4 byte boundaries; receive status arrays need to be aligned on 8 byte boundaries. The number of descriptors in the descriptor arrays needs to be written to the TxDescriptorNumber/RxDescriptorNumber registers using a -1 encoding i.e. the value in the registers is the number of descriptors minus one e.g. if the descriptor array has 4 descriptors the value of the number of descriptors register should be 3. After setting up the descriptor arrays, frame buffers need to be allocated for the receive descriptors before enabling the receive data path. The Packet field of the receive descriptors needs to be filled with the base address of the frame buffer of that descriptor. Amongst others the Control field in the receive descriptor needs to contain the size of the data buffer using -1 encoding. The receive data path has a configurable filtering function for discarding/ignoring specific Ethernet frames. The filtering function should also be configured during initialization. After an assertion of the hardware reset, the soft reset bit in the MAC will be asserted. The soft reset condition must be removed before the Ethernet block can be enabled. Enabling of the receive function is located in two places. The receive DMA manager needs to be enabled and the receive data path of the MAC needs to be enabled. To prevent overflow in the receive DMA engine the receive DMA engine should be enabled by setting the RxEnable bit in the Command register before enabling the receive data path in the MAC by setting the RECEIVE ENABLE bit in the MAC1 register. The transmit DMA engine can be enabled at any time by setting the TxEnable bit in the Command register. Before enabling the data paths, several options can be programmed in the MAC, such as automatic flow control, transmit to receive loop-back for verification, full/half duplex modes, etc. Base addresses of descriptor arrays and descriptor array sizes cannot be modified without a (soft) reset of the receive and transmit data paths.
17.3 Transmit process
Overview This section outlines the transmission process. Device driver sets up descriptors and data If the descriptor array is full the device driver should wait for the descriptor arrays to become not full before writing to a descriptor in the descriptor array. If the descriptor array is not full, the device driver should use the descriptor numbered TxProduceIndex of the array pointed to by TxDescriptor. The Packet pointer in the descriptor is set to point to a data frame or frame fragment to be transmitted. The Size field in the Command field of the descriptor should be set to the number of bytes in the fragment buffer, -1 encoded. Additional control information can be indicated in the Control field in the descriptor (bits Interrupt, Last, CRC, Pad).
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After writing the descriptor the descriptor needs to be handed over to the hardware by incrementing (and possibly wrapping) the TxProduceIndex register. If the transmit data path is disabled, the device driver should not forget to enable the transmit data path by setting the TxEnable bit in the Command register. When there is a multi-fragment transmission for fragments other than the last, the Last bit in the descriptor must be set to 0; for the last fragment the Last bit must be set to 1. To trigger an interrupt when the frame has been transmitted and transmission status has been committed to memory, set the Interrupt bit in the descriptor Control field to 1. To have the hardware add a CRC in the frame sequence control field of this Ethernet frame, set the CRC bit in the descriptor. This should be done if the CRC has not already been added by software. To enable automatic padding of small frames to the minimum required frame size, set the Pad bit in the Control field of the descriptor to 1. In typical applications bits CRC and Pad are both set to 1. The device driver can set up interrupts using the IntEnable register to wait for a signal of completion from the hardware or can periodically inspect (poll) the progress of transmission. It can also add new frames at the end of the descriptor array, while hardware consumes descriptors at the start of the array. The device driver can stop the transmit process by resetting the TxEnable bit in the Command register to 0. The transmission will not stop immediately; frames already being transmitted will be transmitted completely and the status will be committed to memory before deactivating the data path. The status of the transmit data path can be monitored by the device driver reading the TxStatus bit in the Status register. As soon as the transmit data path is enabled and the corresponding TxConsumeIndex and TxProduceIndex are not equal i.e. the hardware still needs to process frames from the descriptor array, the TxStatus bit in the Status register will return to 1 (active). Tx DMA manager reads the Tx descriptor array When the TxEnable bit is set, the Tx DMA manager reads the descriptors from memory at the address determined by TxDescriptor and TxConsumeIndex. The number of descriptors requested is determined by the total number of descriptors owned by the hardware: TxProduceIndex - TxConsumeIndex. Block transferring descriptors minimizes memory loading. Read data returned from memory is buffered and consumed as needed. Tx DMA manager transmits data After reading the descriptor the transmit DMA engine reads the associated frame data from memory and transmits the frame. After transfer completion, the Tx DMA manager writes status information back to the StatusInfo and StatusHashCRC words of the status field. The value of the TxConsumeIndex is only updated after status information has been committed to memory, which is checked by an internal tag protocol in the memory interface. The Tx DMA manager continues to transmit frames until the descriptor array is empty. If the transmit descriptor array is empty the TxStatus bit in the Status register will return to 0 (inactive). If the descriptor array is empty the Ethernet hardware will set the TxFinishedInt bit of the IntStatus register. The transmit data path will still be enabled. The Tx DMA manager inspects the Last bit of the descriptor Control field when loading the descriptor. If the Last bit is 0, this indicates that the frame consists of multiple fragments. The Tx DMA manager gathers all the fragments from the host memory, visiting a string of
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frame descriptors, and sends them out as one Ethernet frame on the Ethernet connection. When the Tx DMA manager finds a descriptor with the Last bit in the Control field set to 1, this indicates the last fragment of the frame and thus the end of the frame is found. Update ConsumeIndex Each time the Tx DMA manager commits a status word to memory it completes the transmission of a descriptor and it increments the TxConsumeIndex (taking wrap around into account) to hand the descriptor back to the device driver software. Software can re-use the descriptor for new transmissions after hardware has handed it back. The device driver software can keep track of the progress of the DMA manager by reading the TxConsumeIndex register to see how far along the transmit process is. When the Tx descriptor array is emptied completely, the TxConsumeIndex register retains its last value. Write transmission status After the frame has been transmitted over the RMII bus, the StatusInfo word of the frame descriptor is updated by the DMA manager. If the descriptor is for the last fragment of a frame (or for the whole frame if there are no fragments), then depending on the success or failure of the frame transmission, error flags (Error, LateCollision, ExcessiveCollision, Underrun, ExcessiveDefer, Defer) are set in the status. The CollisionCount field is set to the number of collisions the frame incurred, up to the Retransmission Maximum programmed in the Collision window/retry register of the MAC. Statuses for all but the last fragment in the frame will be written as soon as the data in the frame has been accepted by the Tx DMA manager. Even if the descriptor is for a frame fragment other than the last fragment, the error flags are returned via the AHB interface. If the Ethernet block detects a transmission error during transmission of a (multi-fragment) frame, all remaining fragments of the frame are still read via the AHB interface. After an error, the remaining transmit data is discarded by the Ethernet block. If there are errors during transmission of a multi-fragment frame the error statuses will be repeated until the last fragment of the frame. Statuses for all but the last fragment in the frame will be written as soon as the data in the frame has been accepted by the Tx DMA manager. These may include error information if the error is detected early enough. The status for the last fragment in the frame will only be written after the transmission has completed on the Ethernet connection. Thus, the status for the last fragment will always reflect any error that occurred anywhere in the frame. The status of the last frame transmission can also be inspected by reading the TSV0 and TSV1 registers. These registers do not report statuses on a fragment basis and do not store information of previously sent frames. They are provided primarily for debug purposes, because the communication between driver software and the Ethernet block takes place through the frame descriptors. The status registers are valid as long as the internal status of the MAC is valid and should typically only be read when the transmit and receive processes are halted. Transmission error handling If an error occurs during the transmit process, the Tx DMA manager will report the error via the transmission StatusInfo word written in the Status array and the IntStatus interrupt status register.
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The transmission can generate several types of errors: LateCollision, ExcessiveCollision, ExcessiveDefer, Underrun, and NoDescriptor. All have corresponding bits in the transmission StatusInfo word. In addition to the separate bits in the StatusInfo word, LateCollision, ExcessiveCollision, and ExcessiveDefer are ORed together into the Error bit of the Status. Errors are also propagated to the IntStatus register; the TxError bit in the IntStatus register is set in the case of a LateCollision, ExcessiveCollision, ExcessiveDefer, or NoDescriptor error; Underrun errors are reported in the TxUnderrun bit of the IntStatus register. Underrun errors can have three causes:
* The next fragment in a multi-fragment transmission is not available. This is a nonfatal
error. A NoDescriptor status will be returned on the previous fragment and the TxError bit in IntStatus will be set.
* The transmission fragment data is not available when the Ethernet block has already
started sending the frame. This is a nonfatal error. An Underrun status will be returned on transfer and the TxError bit in IntStatus will be set.
* The flow of transmission statuses stalls and a new status has to be written while a
previous status still waits to be transferred across the memory interface. This is a fatal error which can only be resolved by a soft reset of the hardware. The first and second situations are nonfatal and the device driver has to re-send the frame or have upper software layers re-send the frame. In the third case the hardware is in an undefined state and needs to be soft reset by setting the TxReset bit in the Command register. After reporting a LateCollision, ExcessiveCollision, ExcessiveDefer or Underrun error, the transmission of the erroneous frame will be aborted, remaining transmission data and frame fragments will be discarded and transmission will continue with the next frame in the descriptor array. Device drivers should catch the transmission errors and take action. Transmit triggers interrupts The transmit data path can generate four different interrupt types:
* If the Interrupt bit in the descriptor Control field is set, the Tx DMA will set the
TxDoneInt bit in the IntStatus register after sending the fragment and committing the associated transmission status to memory. Even if a descriptor (fragment) is not the last in a multi-fragment frame the Interrupt bit in the descriptor can be used to generate an interrupt.
* If the descriptor array is empty while the Ethernet hardware is enabled the hardware
will set the TxFinishedInt bit of the IntStatus register.
* If the AHB interface does not consume the transmission statuses at a sufficiently high
bandwidth the transmission may underrun in which case the TxUnderrun bit will be set in the IntStatus register. This is a fatal error which requires a soft reset of the transmission queue.
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* In the case of a transmission error (LateCollision, ExcessiveCollision, or
ExcessiveDefer) or a multi-fragment frame where the device driver did provide the initial fragments but did not provide the rest of the fragments (NoDescriptor) or in the case of a nonfatal overrun, the hardware will set the TxErrorInt bit of the IntStatus register. All of the above interrupts can be enabled and disabled by setting or resetting the corresponding bits in the IntEnable register. Enabling or disabling does not affect the IntStatus register contents, only the propagation of the interrupt status to the CPU (via the NVIC). The interrupts, either of individual frames or of the whole list, are a good means of communication between the DMA manager and the device driver, triggering the device driver to inspect the status words of descriptors that have been processed. Transmit example Figure 10-20 illustrates the transmit process in an example transmitting uses a frame header of 8 bytes and a frame payload of 12 bytes.
TxDescriptor 0x200810EC
0x2008131B
0x20081314
TxStatus 0x200811F8
status 0
0x200810EC
PACKET 0 HEADER (8 bytes) descriptor 0
0x2008141C 0x20081411 0x20081419
Packet 0x20081314
0x200811F8 StatusInfo
0x200810F0
status 1
PACKET 0 PAYLOAD (12 bytes) descriptor 1 Packet 0x20081411 status 2 0x200810F4 StatusInfo 0x20081200
descriptor array
0 0 CONTROL 7 Control
status 3
0x200810F8
StatusInfo
0x20081204
descriptor 2
0x20081100 1 1 CONTROL 3 Control
0x2008132B
0x20081324
0x200810FC
Packet 0x20081419
TxProduceIndex TxConsumeIndex TxDescriptorNumber =3
PACKET 1 HEADER (8 bytes) 0x20081104 descriptor 3 Packet 0x20081324
0x20081108
0 0 CONTROL 7 Control descriptor array
fragment buffers
status array
Fig 20. Transmit example memory and registers
After reset the values of the DMA registers will be zero. During initialization the device driver will allocate the descriptor and status array in memory. In this example, an array of four descriptors is allocated; the array is 4x2x4 bytes and aligned on a 4 byte address
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boundary. Since the number of descriptors matches the number of statuses the status array consists of four elements; the array is 4x1x4 bytes and aligned on a 4 byte address boundary. The device driver writes the base address of the descriptor array (0x2008 10EC) to the TxDescriptor register and the base address of the status array (0x2008 11F8) to the TxStatus register. The device driver writes the number of descriptors and statuses minus 1(3) to the TxDescriptorNumber register. The descriptors and statuses in the arrays need not be initialized, yet. At this point, the transmit data path may be enabled by setting the TxEnable bit in the Command register. If the transmit data path is enabled while there are no further frames to send the TxFinishedInt interrupt flag will be set. To reduce the processor interrupt load only the desired interrupts can be enabled by setting the relevant bits in the IntEnable register. Now suppose application software wants to transmit a frame of 12 bytes using a TCP/IP protocol (in real applications frames will be larger than 12 bytes). The TCP/IP stack will add a header to the frame. The frame header need not be immediately in front of the payload data in memory. The device driver can program the Tx DMA to collect header and payload data. To do so, the device driver will program the first descriptor to point at the frame header; the Last flag in the descriptor will be set to false/0 to indicate a multi-fragment transmission. The device driver will program the next descriptor to point at the actual payload data. The maximum size of a payload buffer is 2 kB so a single descriptor suffices to describe the payload buffer. For the sake of the example though the payload is distributed across two descriptors. After the first descriptor in the array describing the header, the second descriptor in the array describes the initial 8 bytes of the payload; the third descriptor in the array describes the remaining 4 bytes of the frame. In the third descriptor the Last bit in the Control word is set to true/1 to indicate it is the last descriptor in the frame. In this example the Interrupt bit in the descriptor Control field is set in the last fragment of the frame in order to trigger an interrupt after the transmission completed. The Size field in the descriptor's Control word is set to the number of bytes in the fragment buffer, -1 encoded. Note that in real device drivers, the payload will typically only be split across multiple descriptors if it is more than 2 kB. Also note that transmission payload data is forwarded to the hardware without the device driver copying it (zero copy device driver). After setting up the descriptors for the transaction the device driver increments the TxProduceIndex register by 3 since three descriptors have been programmed. If the transmit data path was not enabled during initialization the device driver needs to enable the data path now. If the transmit data path is enabled the Ethernet block will start transmitting the frame as soon as it detects the TxProduceIndex is not equal to TxConsumeIndex - both were zero after reset. The Tx DMA will start reading the descriptors from memory. The memory system will return the descriptors and the Ethernet block will accept them one by one while reading the transmit data fragments. As soon as transmission read data is returned from memory, the Ethernet block will try to start transmission on the Ethernet connection via the RMII interface.
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After transmitting each fragment of the frame the Tx DMA will write the status of the fragment's transmission. Statuses for all but the last fragment in the frame will be written as soon as the data in the frame has been accepted by the Tx DMA manager. The status for the last fragment in the frame will only be written after the transmission has completed on the Ethernet connection. Since the Interrupt bit in the descriptor of the last fragment is set, after committing the status of the last fragment to memory the Ethernet block will trigger a TxDoneInt interrupt, which triggers the device driver to inspect the status information. In this example the device driver cannot add new descriptors as long as the Ethernet block has not incremented the TxConsumeIndex because the descriptor array is full (even though one descriptor is not programmed yet). Only after the hardware commits the status for the first fragment to memory and the TxConsumeIndex is set to 1 by the DMA manager can the device driver program the next (the fourth) descriptor. The fourth descriptor can already be programmed before completely transmitting the first frame. In this example the hardware adds the CRC to the frame. If the device driver software adds the CRC, the CRC trailer can be considered another frame fragment which can be added by doing another gather DMA. Each data byte is transmitted across the RMII interface as four 2-bit values. The Ethernet block adds the preamble, frame delimiter leader, and the CRC trailer if hardware CRC is enabled. Once transmission on the RMII interface commences the transmission cannot be interrupted without generating an underrun error, which is why descriptors and data read commands are issued as soon as possible and pipelined. Using an RMII PHY, the data communication between the Ethernet block and the PHY is communicated at 50 MHz. In 10 Mbps mode data will only be transmitted once every 10 clock cycles.
17.4 Receive process
This section outlines the receive process including the activities in the device driver software. Device driver sets up descriptors After initializing the receive descriptor and status arrays to receive frames from the Ethernet connection, the receive data path should be enabled in the MAC1 register and the Control register. During initialization, each Packet pointer in the descriptors is set to point to a data fragment buffer. The size of the buffer is stored in the Size bits of the Control field of the descriptor. Additionally, the Control field in the descriptor has an Interrupt bit. The Interrupt bit allows generation of an interrupt after a fragment buffer has been filled and its status has been committed to memory. After the initialization and enabling of the receive data path, all descriptors are owned by the receive hardware and should not be modified by the software unless hardware hands over the descriptor by incrementing the RxProduceIndex, indicating that a frame has been received. The device driver is allowed to modify the descriptors after a (soft) reset of the receive data path.
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Rx DMA manager reads Rx descriptor arrays When the RxEnable bit in the Command register is set, the Rx DMA manager reads the descriptors from memory at the address determined by RxDescriptor and RxProduceIndex. The Ethernet block will start reading descriptors even before actual receive data arrives on the RMII interface (descriptor prefetching). The block size of the descriptors to be read is determined by the total number of descriptors owned by the hardware: RxConsumeIndex - RxProduceIndex - 1. Block transferring of descriptors minimizes memory load. Read data returned from memory is buffered and consumed as needed. RX DMA manager receives data After reading the descriptor, the receive DMA engine waits for the MAC to return receive data from the RMII interface that passes the receive filter. Receive frames that do not match the filtering criteria are not passed to memory. Once a frame passes the receive filter, the data is written in the fragment buffer associated with the descriptor. The Rx DMA does not write beyond the size of the buffer. When a frame is received that is larger than a descriptor's fragment buffer, the frame will be written to multiple fragment buffers of consecutive descriptors. In the case of a multi-fragment reception, all but the last fragment in the frame will return a status where the LastFrag bit is set to 0. Only on the last fragment of a frame the LastFrag bit in the status will be set to 1. If a fragment buffer is the last of a frame, the buffer may not be filled completely. The first receive data of the next frame will be written to the fragment buffer of the next descriptor. After receiving a fragment, the Rx DMA manager writes status information back to the StatusInfo and StatusHashCRC words of the status. The Ethernet block writes the size in bytes of a descriptor's fragment buffer in the RxSize field of the Status word. The value of the RxProduceIndex is only updated after the fragment data and the fragment status information has been committed to memory, which is checked by an internal tag protocol in the memory interface. The Rx DMA manager continues to receive frames until the descriptor array is full. If the descriptor array is full, the Ethernet hardware will set the RxFinishedInt bit of the IntStatus register. The receive data path will still be enabled. If the receive descriptor array is full any new receive data will generate an overflow error and interrupt. Update ProduceIndex Each time the Rx DMA manager commits a data fragment and the associated status word to memory, it completes the reception of a descriptor and increments the RxProduceIndex (taking wrap around into account) in order to hand the descriptor back to the device driver software. Software can re-use the descriptor for new receptions by handing it back to hardware when the receive data has been processed. The device driver software can keep track of the progress of the DMA manager by reading the RxProduceIndex register to see how far along the receive process is. When the Rx descriptor array is emptied completely, the RxProduceIndex retains its last value. Write reception status After the frame has been received from the RMII bus, the StatusInfo and StatusHashCRC words of the frame descriptor are updated by the DMA manager.
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If the descriptor is for the last fragment of a frame (or for the whole frame if there are no fragments), then depending on the success or failure of the frame reception, error flags (Error, NoDescriptor, Overrun, AlignmentError, RangeError, LengthError, SymbolError, or CRCError) are set in StatusInfo. The RxSize field is set to the number of bytes actually written to the fragment buffer, -1 encoded. For fragments not being the last in the frame the RxSize will match the size of the buffer. The hash CRCs of the destination and source addresses of a packet are calculated once for all the fragments belonging to the same packet and then stored in every StatusHashCRC word of the statuses associated with the corresponding fragments. If the reception reports an error, any remaining data in the receive frame is discarded and the LastFrag bit will be set in the receive status field, so the error flags in all but the last fragment of a frame will always be 0. The status of the last received frame can also be inspected by reading the RSV register. The register does not report statuses on a fragment basis and does not store information of previously received frames. RSV is provided primarily for debug purposes, because the communication between driver software and the Ethernet block takes place through the frame descriptors. Reception error handling When an error occurs during the receive process, the Rx DMA manager will report the error via the receive StatusInfo written in the Status array and the IntStatus interrupt status register. The receive process can generate several types of errors: AlignmentError, RangeError, LengthError, SymbolError, CRCError, Overrun, and NoDescriptor. All have corresponding bits in the receive StatusInfo. In addition to the separate bits in the StatusInfo, AlignmentError, RangeError, LengthError, SymbolError, and CRCError are ORed together into the Error bit of the StatusInfo. Errors are also propagated to the IntStatus register; the RxError bit in the IntStatus register is set if there is an AlignmentError, RangeError, LengthError, SymbolError, CRCError, or NoDescriptor error; nonfatal overrun errors are reported in the RxError bit of the IntStatus register; fatal Overrun errors are report in the RxOverrun bit of the IntStatus register. On fatal overrun errors, the Rx data path needs to be soft reset by setting the RxReset bit in the Command register. Overrun errors can have three causes:
* In the case of a multi-fragment reception, the next descriptor may be missing. In this
case the NoDescriptor field is set in the status word of the previous descriptor and the RxError in the IntStatus register is set. This error is nonfatal.
* The data flow on the receiver data interface stalls, corrupting the packet. In this case
the overrun bit in the status word is set and the RxError bit in the IntStatus register is set. This error is nonfatal.
* The flow of reception statuses stalls and a new status has to be written while a
previous status still waits to be transferred across the memory interface. This error will corrupt the hardware state and requires the hardware to be soft reset. The error is detected and sets the Overrun bit in the IntStatus register. The first overrun situation will result in an incomplete frame with a NoDescriptor status and the RxError bit in IntStatus set. Software should discard the partially received frame. In the second overrun situation the frame data will be corrupt which results in the Overrun status bit being set in the Status word while the IntError interrupt bit is set. In the third case
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receive errors cannot be reported in the receiver Status arrays which corrupts the hardware state; the errors will still be reported in the IntStatus register's Overrun bit. The RxReset bit in the Command register should be used to soft reset the hardware. Device drivers should catch the above receive errors and take action. Receive triggers interrupts The receive data path can generate four different interrupt types:
* If the Interrupt bit in the descriptor Control field is set, the Rx DMA will set the
RxDoneInt bit in the IntStatus register after receiving a fragment and committing the associated data and status to memory. Even if a descriptor (fragment) is not the last in a multi-fragment frame, the Interrupt bit in the descriptor can be used to generate an interrupt.
* If the descriptor array is full while the Ethernet hardware is enabled, the hardware will
set the RxFinishedInt bit of the IntStatus register.
* If the AHB interface does not consume receive statuses at a sufficiently high
bandwidth, the receive status process may overrun, in which case the RxOverrun bit will be set in the IntStatus register.
* If there is a receive error (AlignmentError, RangeError, LengthError, SymbolError, or
CRCError), or a multi-fragment frame where the device driver did provide descriptors for the initial fragments but did not provide the descriptors for the rest of the fragments, or if a nonfatal data Overrun occurred, the hardware will set the RxErrorInt bit of the IntStatus register. All of the above interrupts can be enabled and disabled by setting or resetting the corresponding bits in the IntEnable register. Enabling or disabling does not affect the IntStatus register contents, only the propagation of the interrupt status to the CPU (via the NVIC). The interrupts, either of individual frames or of the whole list, are a good means of communication between the DMA manager and the device driver, triggering the device driver to inspect the status words of descriptors that have been processed. Device driver processes receive data As a response to status (e.g. RxDoneInt) interrupts or polling of the RxProduceIndex, the device driver can read the descriptors that have been handed over to it by the hardware (RxProduceIndex - RxConsumeIndex). The device driver should inspect the status words in the status array to check for multi-fragment receptions and receive errors. The device driver can forward receive data and status to upper software layers. After processing of data and status, the descriptors, statuses and data buffers may be recycled and handed back to hardware by incrementing the RxConsumeIndex. Receive example Figure 10-21 illustrates the receive process in an example receiving a frame of 19 bytes.
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0x20081409
RxDescriptor 0x200810EC
0x20081410
RxStatus 0x200811F8
Status 0
0x200810EC
FRAGMENT 0 BUFFER bytes) (8 Descriptor 0
0x20081411 0x20081418
StatusInfo
7
0x200811F8
PACKET 0x20081409
StatusHashCRC StatusInfo 7
0x20081200
0x200810F0 1 CONTROL 7
Status 1
StatusHashCRC StatusInfo 2
0x20081208
FRAGMENT 1 BUFFER bytes) (8 Descriptor 1 0x200810F4
0x2008141B 0x20081419
PACKET 0x20081411
Status 2
StatusHashCRC StatusInfo 7
0x20081210
descriptor array
Status 3
0x200810F8 1 CONTROL 7
FRAGMENT 2 BUFFER bytes) (3 Descriptor 2
0x20081325 0x2008132C
StatusHashCRC
0x200810FC
PACKET 0x20081419
0x20081100 1 CONTROL 7
FRAGMENT 3 BUFFER bytes) (8 0x20081104 Descriptor 3 PACKET 0x20081325 RxProduceIndex RxConsumeIndex RxDescriptorNumber= 3 fragment buffers status array
0x20081108
1 CONTROL 7 descriptor array
Fig 21. Receive Example Memory and Registers
After reset, the values of the DMA registers will be zero. During initialization, the device driver will allocate the descriptor and status array in memory. In this example, an array of four descriptors is allocated; the array is 4x2x4 bytes and aligned on a 4 byte address boundary. Since the number of descriptors matches the number of statuses, the status array consists of four elements; the array is 4x2x4 bytes and aligned on a 8 byte address boundary. The device driver writes the base address of the descriptor array (0x2008 10EC) in the RxDescriptor register, and the base address of the status array (0x2008 11F8) in the RxStatus register. The device driver writes the number of descriptors and statuses minus 1 (3) in the RxDescriptorNumber register. The descriptors and statuses in the arrays need not be initialized yet. After allocating the descriptors, a fragment buffer needs to be allocated for each of the descriptors. Each fragment buffer can be between 1 byte and 2 k bytes. The base address of the fragment buffer is stored in the Packet field of the descriptors. The number of bytes in the fragment buffer is stored in the Size field of the descriptor Control word. The Interrupt field in the Control word of the descriptor can be set to generate an interrupt as soon as the descriptor has been filled by the receive process. In this example the fragment buffers are 8 bytes, so the value of the Size field in the Control word of the descriptor is set to 7. Note that in this example, the fragment buffers are actually a
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continuous memory space; even when a frame is distributed over multiple fragments it will typically be in a linear, continuous memory space; when the descriptors wrap at the end of the descriptor array the frame will not be in a continuous memory space. The device driver should enable the receive process by writing a 1 to the RxEnable bit of the Command register, after which the MAC needs to be enabled by writing a 1 to the `RECEIVE ENABLE' bit of the MAC1 configuration register. The Ethernet block will now start receiving Ethernet frames. To reduce the processor interrupt load, some interrupts can be disabled by setting the relevant bits in the IntEnable register. After the Rx DMA manager is enabled, it will start issuing descriptor read commands. In this example the number of descriptors is 4. Initially the RxProduceIndex and RxConsumeIndex are 0. Since the descriptor array is considered full if RxProduceIndex == RxConsumeIndex - 1, the Rx DMA manager can only read (RxConsumeIndex RxProduceIndex - 1 =) 3 descriptors; note the wrapping. After enabling the receive function in the MAC, data reception will begin starting at the next frame i.e. if the receive function is enabled while the RMII interface is halfway through receiving a frame, the frame will be discarded and reception will start at the next frame. The Ethernet block will strip the preamble and start of frame delimiter from the frame. If the frame passes the receive filtering, the Rx DMA manager will start writing the frame to the first fragment buffer. Suppose the frame is 19 bytes long. Due to the buffer sizes specified in this example, the frame will be distributed over three fragment buffers. After writing the initial 8 bytes in the first fragment buffer, the status for the first fragment buffer will be written and the Rx DMA will continue filling the second fragment buffer. Since this is a multi-fragment receive, the status of the first fragment will have a 0 for the LastFrag bit in the StatusInfo word; the RxSize field will be set to 7 (8, -1 encoded). After writing the 8 bytes in the second fragment the Rx DMA will continue writing the third fragment. The status of the second fragment will be like the status of the first fragment: LastFrag = 0, RxSize = 7. After writing the three bytes in the third fragment buffer, the end of the frame has been reached and the status of the third fragment is written. The third fragment's status will have the LastFrag bit set to 1 and the RxSize equal to 2 (3, -1 encoded). The next frame received from the RMII interface will be written to the fourth fragment buffer i.e. five bytes of the third buffer will be unused. The Rx DMA manager uses an internal tag protocol in the memory interface to check that the receive data and status have been committed to memory. After the status of the fragments are committed to memory, an RxDoneInt interrupt will be triggered, which activates the device driver to inspect the status information. In this example, all descriptors have the Interrupt bit set in the Control word i.e. all descriptors will generate an interrupt after committing data and status to memory. In this example the receive function cannot read new descriptors as long as the device driver does not increment the RxConsumeIndex, because the descriptor array is full (even though one descriptor is not programmed yet). Only after the device driver has forwarded the receive data to application software, and after the device driver has updated the RxConsumeIndex by incrementing it, will the Ethernet block can continue reading descriptors and receive data. The device driver will probably increment the RxConsumeIndex by 3, since the driver will forward the complete frame consisting of three fragments to the application, and hence free up three descriptors at the same time.
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Each four pairs of bits transferred on the RMII interface are transferred as a byte on the data write interface after being delayed by 128 or 136 cycles for filtering by the receive filter and buffer modules. The Ethernet block removes preamble, frame start delimiter, and CRC from the data and checks the CRC. To limit the buffer NoDescriptor error probability, three descriptors are buffered. The value of the RxProduceIndex is only updated after status information has been committed to memory, which is checked by an internal tag protocol in the memory interface. The software device driver will process the receive data, after which the device driver will update the RxConsumeIndex.
17.5 Transmission retry
If a collision on the Ethernet occurs, it usually takes place during the collision window spanning the first 64 bytes of a frame. If collision is detected, the Ethernet block will retry the transmission. For this purpose, the first 64 bytes of a frame are buffered, so that this data can be used during the retry. A transmission retry within the first 64 bytes in a frame is fully transparent to the application and device driver software. When a collision occurs outside of the 64 byte collision window, a LateCollision error is triggered, and the transmission is aborted. After a LateCollision error, the remaining data in the transmit frame will be discarded. The Ethernet block will set the Error and LateCollision bits in the frame's status fields. The TxError bit in the IntStatus register will be set. If the corresponding bit in the IntEnable register is set, the TxError bit in the IntStatus register will be propagated to the CPU (via the NVIC). The device driver software should catch the interrupt and take appropriate actions. The `RETRANSMISSION MAXIMUM' field of the CLRT register can be used to configure the maximum number of retries before aborting the transmission.
17.6 Status hash CRC calculations
For each received frame, the Ethernet block is able to detect the destination address and source address and from them calculate the corresponding hash CRCs. To perform the computation, the Ethernet block features two internal blocks: one is a controller synchronized with the beginning and the end of each frame, the second block is the CRC calculator. When a new frame is detected, internal signaling notifies the controller.The controller starts counting the incoming bytes of the frame, which correspond to the destination address bytes. When the sixth (and last) byte is counted, the controller notifies the calculator to store the corresponding 32-bit CRC into a first inner register. Then the controller repeats counting the next incoming bytes, in order to get synchronized with the source address. When the last byte of the source address is encountered, the controller again notifies the CRC calculator, which freezes until the next new frame. When the calculator receives this second notification, it stores the present 32-bit CRC into a second inner register. Then the CRCs remain frozen in their own registers until new notifications arise. The destination address and source address hash CRCs being written in the StatusHashCRC word are the nine most significant bits of the 32-bit CRCs as calculated by the CRC calculator.
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17.7 Duplex modes
The Ethernet block can operate in full duplex and half duplex mode. Half or full duplex mode needs to be configured by the device driver software during initialization. For a full duplex connection the FullDuplex bit of the Command register needs to be set to 1 and the FULL-DUPLEX bit of the MAC2 configuration register needs to be set to 1; for half duplex the same bits need to be set to 0.
17.8 IEE 802.3/Clause 31 flow control
Overview For full duplex connections, the Ethernet block supports IEEE 802.3/clause 31 flow control using pause frames. This type of flow control may be used in full-duplex point-to-point connections. Flow control allows a receiver to stall a transmitter e.g. when the receive buffers are (almost) full. For this purpose, the receiving side sends a pause frame to the transmitting side. Pause frames use units of 512 bit times corresponding to 128 rx_clk/tx_clk cycles. Receive flow control In full-duplex mode, the Ethernet block will suspend its transmissions when the it receives a pause frame. Rx flow control is initiated by the receiving side of the transmission. It is enabled by setting the `RX FLOW CONTROL' bit in the MAC1 configuration register. If the RX FLOW CONTROL' bit is zero, then the Ethernet block ignores received pause control frames. When a pause frame is received on the Rx side of the Ethernet block, transmission on the Tx side will be interrupted after the currently transmitting frame has completed, for an amount of time as indicated in the received pause frame. The transmit data path will stop transmitting data for the number of 512 bit slot times encoded in the pause-timer field of the received pause control frame. By default the received pause control frames are not forwarded to the device driver. To forward the receive flow control frames to the device driver, set the `PASS ALL RECEIVE FRAMES' bit in the MAC1 configuration register. Transmit flow control If case device drivers need to stall the receive data e.g. because software buffers are full, the Ethernet block can transmit pause control frames. Transmit flow control needs to be initiated by the device driver software; there is no IEEE 802.3/31 flow control initiated by hardware, such as the DMA managers. With software flow control, the device driver can detect a situation in which the process of receiving frames needs to be interrupted by sending out Tx pause frames. Note that due to Ethernet delays, a few frames can still be received before the flow control takes effect and the receive stream stops. Transmit flow control is activated by writing 1 to the TxFlowControl bit of the Command register. When the Ethernet block operates in full duplex mode, this will result in transmission of IEEE 802.3/31 pause frames. The flow control continues until a 0 is written to TxFlowControl bit of the Command register.
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If the MAC is operating in full-duplex mode, then setting the TxFlowControl bit of the Command register will start a pause frame transmission. The value inserted into the pause-timer value field of transmitted pause frames is programmed via the PauseTimer[15:0] bits in the FlowControlCounter register. When the TxFlowControl bit is de-asserted, another pause frame having a pause-timer value of 0x0000 is automatically sent to abort flow control and resume transmission. When flow control be in force for an extended time, a sequence of pause frames must be transmitted. This is supported with a mirror counter mechanism. To enable mirror counting, a nonzero value is written to the MirrorCounter[15:0] bits in the FlowControlCounter register. When the TxFlowControl bit is asserted, a pause frame is transmitted. After sending the pause frame, an internal mirror counter is initialized to zero. The internal mirror counter starts incrementing one every 512 bit-slot times. When the internal mirror counter reaches the MirrorCounter value, another pause frame is transmitted with pause-timer value equal to the PauseTimer field from the FlowControlCounter register, the internal mirror counter is reset to zero and restarts counting. The register MirrorCounter[15:0] is usually set to a smaller value than register PauseTimer[15:0] to ensure an early expiration of the mirror counter, allowing time to send a new pause frame before the transmission on the other side can resume. By continuing to send pause frames before the transmitting side finishes counting the pause timer, the pause can be extended as long as TxFlowControl is asserted. This continues until TxFlowControl is de-asserted when a final pause frame having a pause-timer value of 0x0000 is automatically sent to abort flow control and resume transmission. To disable the mirror counter mechanism, write the value 0 to MirrorCounter field in the FlowControlCounter register. When using the mirror counter mechanism, account for time-of-flight delays, frame transmission time, queuing delays, crystal frequency tolerances, and response time delays by programming the MirrorCounter conservatively, typically about 80% of the PauseTimer value. If the software device driver sets the MirrorCounter field of the FlowControlCounter register to zero, the Ethernet block will only send one pause control frame. After sending the pause frame an internal pause counter is initialized at zero; the internal pause counter is incremented by one every 512 bit-slot times. Once the internal pause counter reaches the value of the PauseTimer register, the TxFlowControl bit in the Command register will be reset. The software device driver can poll the TxFlowControl bit to detect when the pause completes. The value of the internal counter in the flow control module can be read out via the FlowControlStatus register. If the MirrorCounter is nonzero, the FlowControlStatus register will return the value of the internal mirror counter; if the MirrorCounter is zero the FlowControlStatus register will return the value of the internal pause counter value. The device driver is allowed to dynamically modify the MirrorCounter register value and switch between zero MirrorCounter and nonzero MirrorCounter modes. Transmit flow control is enabled via the `TX FLOW CONTROL' bit in the MAC1 configuration register. If the `TX FLOW CONTROL' bit is zero, then the MAC will not transmit pause control frames, software must not initiate pause frame transmissions, and the TxFlowControl bit in the Command register should be zero. Transmit flow control example Figure 10-22 illustrates the transmit flow control.
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device driver PauseTimer register MirrorCounter TxFlowCtl writes RMII transmit MirrorCounter (1/515 bit slots) RMII receive normal receive normal transmission
pause control frame transmission
clear TxFlowCtl
normal transimisson
pause control frame transmission
pause control frame transmission
pause in effect
normal receive
0
50
100
150
200
250
300
350
400
450
500
Fig 22. Transmit Flow Control
In this example, a frame is received while transmitting another frame (full duplex.) The device driver detects that some buffer might overrun and enables the transmit flow control by programming the PauseTimer and MirrorCounter fields of the FlowControlCounter register, after which it enables the transmit flow control by setting the TxFlowControl bit in the Command register. As a response to the enabling of the flow control a pause control frame will be sent after the currently transmitting frame has been transmitted. When the pause frame transmission completes the internal mirror counter will start counting bit slots; as soon as the counter reaches the value in the MirrorCounter field another pause frame is transmitted. While counting the transmit data path will continue normal transmissions. As soon as software disables transmit flow control a zero pause control frame is transmitted to resume the receive process.
17.9 Half-Duplex mode backpressure
When in half-duplex mode, backpressure can be generated to stall receive packets by sending continuous preamble that basically jams any other transmissions on the Ethernet medium. When the Ethernet block operates in half duplex mode, asserting the TxFlowControl bit in the Command register will result in applying continuous preamble on the Ethernet wire, effectively blocking traffic from any other Ethernet station on the same segment. In half duplex mode, when the TxFlowControl bit goes high, continuous preamble is sent until TxFlowControl is de-asserted. If the medium is idle, the Ethernet block begins transmitting preamble, which raises carrier sense causing all other stations to defer. In the event the transmitting of preamble causes a collision, the backpressure `rides through' the collision. The colliding station backs off and then defers to the backpressure. If during backpressure, the user wishes to send a frame, the backpressure is interrupted, the frame sent and then the backpressure resumed. If TxFlowControl is asserted for longer than 3.3 ms in 10 Mbps mode or 0.33 ms in 100 Mbps mode, backpressure will cease sending preamble for several byte times to avoid the jabber limit.
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17.10 Receive filtering
Features of receive filtering The Ethernet MAC has several receive packet filtering functions that can be configured from the software driver:
* Perfect address filter: allows packets with a perfectly matching station address to be
identified and passed to the software driver.
* Hash table filter: allows imperfect filtering of packets based on the station address. * Unicast/multicast/broadcast filtering: allows passing of all unicast, multicast, and/or
broadcast packets.
* Magic packet filter: detection of magic packets to generate a Wake-on-LAN interrupt.
The filtering functions can be logically combined to create complex filtering functions. Furthermore, the Ethernet block can pass or reject runt packets smaller than 64 bytes; a promiscuous mode allows all packets to be passed to software. Overview The Ethernet block has the capability to filter out receive frames by analyzing the Ethernet destination address in the frame. This capability greatly reduces the load on the host system, because Ethernet frames that are addressed to other stations would otherwise need to be inspected and rejected by the device driver software, using up bandwidth, memory space, and host CPU time. Address filtering can be implemented using the perfect address filter or the (imperfect) hash filter. The latter produces a 6-bit hash code which can be used as an index into a 64 entry programmable hash table. Figure 10-23 depicts a functional view of the receive filter. At the top of the diagram the Ethernet receive frame enters the filters. Each filter is controlled by signals from control registers; each filter produces a `Ready' output and a `Match' output. If `Ready' is 0 then the Match value is `don't care'; if a filter finishes filtering then it will assert its Ready output; if the filter finds a matching frame it will assert the Match output along with the Ready output. The results of the filters are combined by logic functions into a single RxAbort output. If the RxAbort output is asserted, the frame does not need to be received. In order to reduce memory traffic, the receive data path has a buffer of 68 bytes. The Ethernet MAC will only start writing a frame to memory after 68 byte delays. If the RxAbort signal is asserted during the initial 68 bytes of the frame, the frame can be discarded and removed from the buffer and not stored to memory at all, not using up receive descriptors, etc. If the RxAbort signal is asserted after the initial 68 bytes in a frame (probably due to reception of a Magic Packet), part of the frame is already written to memory and the Ethernet MAC will stop writing further data in the frame to memory; the FailFilter bit in the status word of the frame will be set to indicate that the software device driver can discard the frame immediately.
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packet
AcceptUnicastEn AcceptMulticastEn AcceptMulticastHashEn IMPERFECT HASH FILTER AcceptUnicastHashEn HashFilter H FMatc h PAReady HFReady PAMatch StationAddress AcceptPerfectEn
PERFECT ADDRESS FILTER
CRC OK?
FMatch
RxFilterWoL
RxFilterEnWoL FReady RxAbort
Fig 23. Receive filter block diagram
Unicast, broadcast and multicast Generic filtering based on the type of frame (unicast, multicast or broadcast) can be programmed using the AcceptUnicastEn, AcceptMulticastEn, or AcceptBroadcastEn bits of the RxFilterCtrl register. Setting the AcceptUnicast, AcceptMulticast, and AcceptBroadcast bits causes all frames of types unicast, multicast and broadcast, respectively, to be accepted, ignoring the Ethernet destination address in the frame. To program promiscuous mode, i.e. to accept all frames, set all 3 bits to 1. Perfect address match When a frame with a unicast destination address is received, a perfect filter compares the destination address with the 6 byte station address programmed in the station address registers SA0, SA1, SA2. If the AcceptPerfectEn bit in the RxFilterCtrl register is set to 1, and the address matches, the frame is accepted. Imperfect hash filtering An imperfect filter is available, based on a hash mechanism. This filter applies a hash function to the destination address and uses the hash to access a table that indicates if the frame should be accepted. The advantage of this type of filter is that a small table can cover any possible address. The disadvantage is that the filtering is imperfect, i.e. sometimes frames are accepted that should have been discarded.
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* Hash function:
- The standard Ethernet cyclic redundancy check (CRC) function is calculated from the 6 byte destination address in the Ethernet frame (this CRC is calculated anyway as part of calculating the CRC of the whole frame), then bits [28:23] out of the 32-bit CRC result are taken to form the hash. The 6-bit hash is used to access the hash table: it is used as an index in the 64-bit HashFilter register that has been programmed with accept values. If the selected accept value is 1, the frame is accepted. - The device driver can initialize the hash filter table by writing to the registers HashFilterL and HashfilterH. HashFilterL contains bits 0 through 31 of the table and HashFilterH contains bit 32 through 63 of the table. So, hash value 0 corresponds to bit 0 of the HashfilterL register and hash value 63 corresponds to bit 31 of the HashFilterH register.
* Multicast and unicast
- The imperfect hash filter can be applied to multicast addresses, by setting the AcceptMulticastHashEn bit in the RxFilter register to 1. - The same imperfect hash filter that is available for multicast addresses can also be used for unicast addresses. This is useful to be able to respond to a multitude of unicast addresses without enabling all unicast addresses. The hash filter can be applied to unicast addresses by setting the AcceptUnicastHashEn bit in the RxFilter register to 1. Enabling and disabling filtering The filters as defined in the sections above can be bypassed by setting the PassRxFilter bit in the Command register. When the PassRxFilter bit is set, all receive frames will be passed to memory. In this case the device driver software has to implement all filtering functionality in software. Setting the PassRxFilter bit does not affect the runt frame filtering as defined in the next section. Runt frames A frame with less than 64 bytes (or 68 bytes for VLAN frames) is shorter than the minimum Ethernet frame size and therefore considered erroneous; they might be collision fragments. The receive data path automatically filters and discards these runt frames without writing them to memory and using a receive descriptor. When a runt frame has a correct CRC there is a possibility that it is intended to be useful. The device driver can receive the runt frames with correct CRC by setting the PassRuntFrame bit of the Command register to 1.
17.11 Power management
The Ethernet block supports power management by means of clock switching. All clocks in the Ethernet core can be switched off. If Wake-up on LAN is needed, the rx_clk should not be switched off.
17.12 Wake-up on LAN
Overview
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The Ethernet block supports power management with remote wake-up over LAN. The host system can be powered down, even including part of the Ethernet block itself, while the Ethernet block continues to listen to packets on the LAN. Appropriately formed packets can be received and recognized by the Ethernet block and used to trigger the host system to wake up from its power-down state. Wake-up of the system takes effect through an interrupt. When a wake-up event is detected, the WakeupInt bit in the IntStatus register is set. The interrupt status will trigger an interrupt if the corresponding WakeupIntEn bit in the IntEnable register is set. This interrupt should be used by system power management logic to wake up the system. While in a power-down state the packet that generates a Wake-up on LAN event is lost. There are two ways in which Ethernet packets can trigger wake-up events: generic Wake-up on LAN and Magic Packet. Magic Packet filtering uses an additional filter for Magic Packet detection. In both cases a Wake-up on LAN event is only triggered if the triggering packet has a valid CRC. Figure 10-23 shows the generation of the wake-up signal. The RxFilterWoLStatus register can be read by the software to inspect the reason for a Wake-up event. Before going to power-down the power management software should clear the register by writing the RxFilterWolClear register. NOTE: when entering in power-down mode, a receive frame might be not entirely stored into the Rx buffer. In this situation, after turning exiting power-down mode, the next receive frame is corrupted due to the data of the previous frame being added in front of the last received frame. Software drivers have to reset the receive data path just after exiting power-down mode. The following subsections describe the two Wake-up on LAN mechanisms. Filtering for WoL The receive filter functionality can be used to generate Wake-up on LAN events. If the RxFilterEnWoL bit of the RxFilterCtrl register is set, the receive filter will set the WakeupInt bit of the IntStatus register if a frame is received that passes the filter. The interrupt will only be generated if the CRC of the frame is correct. Magic Packet WoL The Ethernet block supports wake-up using Magic Packet technology (see `Magic Packet technology', Advanced Micro Devices). A Magic Packet is a specially formed packet solely intended for wake-up purposes. This packet can be received, analyzed and recognized by the Ethernet block and used to trigger a wake-up event. A Magic Packet is a packet that contains in its data portion the station address repeated 16 times with no breaks or interruptions, preceded by 6 Magic Packet synchronization bytes with the value 0xFF. Other data may be surrounding the Magic Packet pattern in the data portion of the packet. The whole packet must be a well-formed Ethernet frame. The magic packet detection unit analyzes the Ethernet packets, extracts the packet address and checks the payload for the Magic Packet pattern. The address from the packet is used for matching the pattern (not the address in the SA0/1/2 registers.) A magic
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packet only sets the wake-up interrupt status bit if the packet passes the receive filter as illustrated in Figure 10-23: the result of the receive filter is ANDed with the magic packet filter result to produce the result. Magic Packet filtering is enabled by setting the MagicPacketEnWoL bit of the RxFilterCtrl register. Note that when doing Magic Packet WoL, the RxFilterEnWoL bit in the RxFilterCtrl register should be 0. Setting the RxFilterEnWoL bit to 1 would accept all packets for a matching address, not just the Magic Packets i.e. WoL using Magic Packets is more strict. When a magic packet is detected, apart from the WakeupInt bit in the IntStatus register, the MagicPacketWoL bit is set in the RxFilterWoLStatus register. Software can reset the bit writing a 1 to the corresponding bit of the RxFilterWoLClear register. Example: An example of a Magic Packet with station address 0x11 0x22 0x33 0x44 0x55 0x66 is the following (MISC indicates miscellaneous additional data bytes in the packet): FF FF FF FF FF FF 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44 11 22 33 44 55 66 11 22 33 44
55 55 55 55 55 55 55 55
66 66 66 66 66 66 66 66
17.13 Enabling and disabling receive and transmit
Enabling and disabling reception After reset, the receive function of the Ethernet block is disabled. The receive function can be enabled by the device driver setting the RxEnable bit in the Command register and the "RECEIVE ENABLE' bit in the MAC1 configuration register (in that order). The status of the receive data path can be monitored by the device driver by reading the RxStatus bit of the Status register. Figure 10-24 illustrates the state machine for the generation of the RxStatus bit.
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ACTIVE RxStatus = 1 xxxxxxxxxxxxxxxxxx
RxEnable = 1
RxEnable = 0 and not busy receiving OR RxProduceIndex = RxConsumeIndex - 1
INACTIVE RxStatus = 0
reset
Fig 24. Receive Active/Inactive state machine
After a reset, the state machine is in the INACTIVE state. As soon as the RxEnable bit is set in the Command register, the state machine transitions to the ACTIVE state. As soon as the RxEnable bit is cleared, the state machine returns to the INACTIVE state. If the receive data path is busy receiving a packet while the receive data path gets disabled, the packet will be received completely, stored to memory along with its status before returning to the INACTIVE state. Also if the Receive descriptor array is full, the state machine will return to the INACTIVE state. For the state machine in Figure 10-24, a soft reset is like a hardware reset assertion, i.e. after a soft reset the receive data path is inactive until the data path is re-enabled. Enabling and disabling transmission After reset, the transmit function of the Ethernet block is disabled. The Tx transmit data path can be enabled by the device driver setting the TxEnable bit in the Command register to 1. The status of the transmit data paths can be monitored by the device driver reading the TxStatus bit of the Status register. Figure 10-25 illustrates the state machine for the generation of the TxStatus bit.
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ACTIVE TxStatus = 1 xxxxxxxxxxxxxxxxxxxxxx
TxEnable = 1 AND TxProduceIndex <> TxConsumeIndex
TxEnable = 0 and not busy transmitting OR TxProduceIndex = TxConsumeIndex
INACTIVE TxStatus = 0
reset
Fig 25. Transmit Active/Inactive state machine
After reset, the state machine is in the INACTIVE state. As soon as the TxEnable bit is set in the Command register and the Produce and Consume indices are not equal, the state machine transitions to the ACTIVE state. As soon as the TxEnable bit is cleared and the transmit data path has completed all pending transmissions, including committing the transmission status to memory, the state machine returns to the INACTIVE state. The state machine will also return to the INACTIVE state if the Produce and Consume indices are equal again i.e. all frames have been transmitted. For the state machine in Figure 10-25, a soft reset is like a hardware reset assertion, i.e. after a soft reset the transmit data path is inactive until the data path is re-enabled.
17.14 Transmission padding and CRC
In the case of a frame of less than 60 bytes (or 64 bytes for VLAN frames), the Ethernet block can pad the frame to 64 or 68 bytes including a 4 bytes CRC Frame Check Sequence (FCS). Padding is affected by the value of the `AUTO DETECT PAD ENABLE' (ADPEN), `VLAN PAD ENABLE' (VLPEN) and `PAD/CRC ENABLE' (PADEN) bits of the MAC2 configuration register, as well as the Override and Pad bits from the transmit descriptor Control word. CRC generation is affected by the `CRC ENABLE' (CRCE) and `DELAYED CRC' (DCRC) bits of the MAC2 configuration register, and the Override and CRC bits from the transmit descriptor Control word. The effective pad enable (EPADEN) is equal to the `PAD/CRC ENABLE' bit from the MAC2 register if the Override bit in the descriptor is 0. If the Override bit is 1, then EPADEN will be taken from the descriptor Pad bit. Likewise the effective CRC enable (ECRCE) equals CRCE if the Override bit is 0, otherwise it equal the CRC bit from the descriptor. If padding is required and enabled, a CRC will always be appended to the padded frames. A CRC will only be appended to the non-padded frames if ECRCE is set. If EPADEN is 0, the frame will not be padded and no CRC will be added unless ECRCE is set.
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If EPADEN is 1, then small frames will be padded and a CRC will always be added to the padded frames. In this case if ADPEN and VLPEN are both 0, then the frames will be padded to 60 bytes and a CRC will be added creating 64 bytes frames; if VLPEN is 1, the frames will be padded to 64 bytes and a CRC will be added creating 68 bytes frames; if ADPEN is 1, while VLPEN is 0 VLAN frames will be padded to 64 bytes, non VLAN frames will be padded to 60 bytes, and a CRC will be added to padded frames, creating 64 or 68 bytes padded frames. If CRC generation is enabled, CRC generation can be delayed by four bytes by setting the DELAYED CRC bit in the MAC2 register, in order to skip proprietary header information.
17.15 Huge frames and frame length checking
The `HUGE FRAME ENABLE' bit in the MAC2 configuration register can be set to 1 to enable transmission and reception of frames of any length. Huge frame transmission can be enabled on a per frame basis by setting the Override and Huge bits in the transmit descriptor Control word. When enabling huge frames, the Ethernet block will not check frame lengths and report frame length errors (RangeError and LengthError). If huge frames are enabled, the received byte count in the RSV register may be invalid because the frame may exceed the maximum size; the RxSize fields from the receive status arrays will be valid. Frame lengths are checked by comparing the length/type field of the frame to the actual number of bytes in the frame. A LengthError is reported by setting the corresponding bit in the receive StatusInfo word. The MAXF register allows the device driver to specify the maximum number of bytes in a frame. The Ethernet block will compare the actual receive frame to the MAXF value and report a RangeError in the receive StatusInfo word if the frame is larger.
17.16 Statistics counters
Generally, Ethernet applications maintain many counters that track Ethernet traffic statistics. There are a number of standards specifying such counters, such as IEEE std 802.3 / clause 30. Other standards are RFC 2665 and RFC 2233. The approach taken here is that by default all counters are implemented in software. With the help of the StatusInfo field in frame statuses, many of the important statistics events listed in the standards can be counted by software.
17.17 MAC status vectors
Transmit and receive status information as detected by the MAC are available in registers TSV0, TSV1 and RSV so that software can poll them. These registers are normally of limited use because the communication between driver software and the Ethernet block takes place primarily through frame descriptors. Statistical events can be counted by software in the device driver. However, for debug purposes the transmit and receive status vectors are made visible. They are valid as long as the internal status of the MAC is valid and should typically only be read when the transmit and receive processes are halted.
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17.18 Reset
The Ethernet block has a hard reset input which is connected to the chip reset, as well as several soft resets which can be activated by setting the appropriate bit(s) in registers. All registers in the Ethernet block have a value of 0 after a hard reset, unless otherwise specified. Hard reset After a hard reset, all registers will be set to their default value. Soft reset Parts of the Ethernet block can be soft reset by setting bits in the Command register and the MAC1 configuration register.The MAC1 register has six different reset bits:
* SOFT RESET: Setting this bit will put all modules in the MAC in reset, except for the
MAC registers (at addresses 0x000 to 0x0FC). The value of the soft reset after a hardware reset assertion is 1, i.e. the soft reset needs to be cleared after a hardware reset.
* SIMULATION RESET: Resets the random number generator in the Transmit
Function. The value after a hardware reset assertion is 0.
* RESET MCS/Rx: Setting this bit will reset the MAC Control Sublayer (pause frame
logic) and the receive function in the MAC. The value after a hardware reset assertion is 0.
* RESET Rx: Setting this bit will reset the receive function in the MAC. The value after a
hardware reset assertion is 0.
* RESET MCS/Tx: Setting this bit will reset the MAC Control Sublayer (pause frame
logic) and the transmit function in the MAC. The value after a hardware reset assertion is 0.
* RESET Tx: Setting this bit will reset the transmit function of the MAC. The value after
a hardware reset assertion is 0. The above reset bits must be cleared by software. The Command register has three different reset bits:
* TxReset: Writing a `1' to the TxReset bit will reset the transmit data path, excluding the
MAC portions, including all (read-only) registers in the transmit data path, as well as the TxProduceIndex register in the host registers module. A soft reset of the transmit data path will abort all AHB transactions of the transmit data path. The reset bit will be cleared autonomously by the Ethernet block. A soft reset of the Tx data path will clear the TxStatus bit in the Status register.
* RxReset: Writing a `1' to the RxReset bit will reset the receive data path, excluding the
MAC portions, including all (read-only) registers in the receive data path, as well as the RxConsumeIndex register in the host registers module. A soft reset of the receive data path will abort all AHB transactions of the receive data path. The reset bit will be cleared autonomously by the Ethernet block. A soft reset of the Rx data path will clear the RxStatus bit in the Status register.
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* RegReset: Resets all of the data paths and registers in the host registers module,
excluding the registers in the MAC. A soft reset of the registers will also abort all AHB transactions of the transmit and receive data path. The reset bit will be cleared autonomously by the Ethernet block. To do a full soft reset of the Ethernet block, device driver software must:
* * * *
Set the `SOFT RESET' bit in the MAC1 register to 1. Set the RegReset bit in the Command register, this bit clears automatically. Re-initialize the MAC registers (0x000 to 0x0FC). Reset the `SOFT RESET' bit in the MAC1 register to 0.
To reset just the transmit data path, the device driver software has to:
* Set the `RESET MCS/Tx' bit in the MAC1 register to 1. * Disable the Tx DMA managers by setting the TxEnable bits in the Command register
to 0.
* Set the TxReset bit in the Command register, this bit clears automatically. * Reset the `RESET MCS/Tx' bit in the MAC1 register to 0.
To reset just the receive data path, the device driver software has to:
* Disable the receive function by resetting the `RECEIVE ENABLE' bit in the MAC1
configuration register and resetting of the RxEnable bit of the Command register.
* Set the `RESET MCS/Rx' bit in the MAC1 register to 1. * Set the RxReset bit in the Command register, this bit clears automatically. * Reset the `RESET MCS/Rx' bit in the MAC1 register to 0. 17.19 Ethernet errors
The Ethernet block generates errors for the following conditions:
* A reception can cause an error: AlignmentError, RangeError, LengthError,
SymbolError, CRCError, NoDescriptor, or Overrun. These are reported back in the receive StatusInfo and in the interrupt status register (IntStatus).
* A transmission can cause an error: LateCollision, ExcessiveCollision,
ExcessiveDefer, NoDescriptor, or Underrun. These are reported back in the transmission StatusInfo and in the interrupt status register (IntStatus).
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18. AHB bandwidth
The Ethernet block is connected to an AHB bus which must carry all of the data and control information associated with all Ethernet traffic in addition to the CPU accesses required to operate the Ethernet block and deal with message contents.
18.1 DMA access
Assumptions By making some assumptions, the bandwidth needed for each type of AHB transfer can be calculated and added in order to find the overall bandwidth requirement. The flexibility of the descriptors used in the Ethernet block allows the possibility of defining memory buffers in a range of sizes. In order to analyze bus bandwidth requirements, some assumptions must be made about these buffers. The "worst case" is not addressed since that would involve all descriptors pointing to single byte buffers, with most of the memory occupied in holding descriptors and very little data. It can easily be shown that the AHB cannot handle the huge amount of bus traffic that would be caused by such a degenerate (and illogical) case. For this analysis, an Ethernet packet is assumed to consist of a 64 byte frame. Continuous traffic is assumed on both the transmit and receive channels. This analysis does not reflect the flow of Ethernet traffic over time, which would include inter-packet gaps in both the transmit and receive channels that reduce the bandwidth requirements over a larger time frame. Types of DMA access and their bandwidth requirements The interface to an external Ethernet PHY is via RMII. RMII operates at 50 MHz, transferring a byte in 4 clock cycles. The data transfer rate is 12.5 Mbps. The Ethernet block initiates DMA accesses for the following cases:
* Tx descriptor read:
- Transmit descriptors occupy 2 words (8 bytes) of memory and are read once for each use of a descriptor. - Two word read happens once every 64 bytes (16 words) of transmitted data. - This gives 1/8th of the data rate, which = 1.5625 Mbps.
* Rx descriptor read:
- Receive descriptors occupy 2 words (8 bytes) of memory and are read once for each use of a descriptor. - Two word read happens once every 64 bytes (16 words) of received data. - This gives 1/8th of the data rate, which = 1.5625 Mbps.
* Tx status write:
- Transmit status occupies 1 word (4 bytes) of memory and is written once for each use of a descriptor. - One word write happens once every 64 bytes (16 words) of transmitted data. - This gives 1/16th of the data rate, which = 0.7813 Mbps.
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* Rx status write:
- Receive status occupies 2 words (8 bytes) of memory and is written once for each use of a descriptor. - Two word write happens once every 64 bytes (16 words) of received data. - This gives 1/8 of the data rate, which = 1.5625 Mbps.
* Tx data read:
- Data transmitted in an Ethernet frame, the size is variable. - Basic Ethernet rate = 12.5 Mbps.
* Rx data write:
- Data to be received in an Ethernet frame, the size is variable. - Basic Ethernet rate = 12.5 Mbps. This gives a total rate of 30.5 Mbps for the traffic generated by the Ethernet DMA function.
18.2 Types of CPU access * Accesses that mirror each of the DMA access types:
- All or part of status values must be read, and all or part of descriptors need to be written after each use, transmitted data must be stored in the memory by the CPU, and eventually received data must be retrieved from the memory by the CPU. - This gives roughly the same or slightly lower rate as the combined DMA functions, which = 30.5 Mbps.
* Access to registers in the Ethernet block:
- The CPU must read the RxProduceIndex, TxConsumeIndex, and IntStatus registers, and both read and write the RxConsumeIndex and TxProduceIndex registers. - 7 word read/writes once every 64 bytes (16 words) of transmitted and received data. - This gives 7/16 of the data rate, which = 5.4688 Mbps. This gives a total rate of 36 Mbps for the traffic generated by the Ethernet DMA function.
18.3 Overall bandwidth
Overall traffic on the AHB is the sum of DMA access rates and CPU access rates, which comes to approximately 66.5 MB/s. The peak bandwidth requirement can be somewhat higher due to the use of small memory buffers, in order to hold often used addresses (e.g. the station address) for example. Driver software can determine how to build frames in an efficient manner that does not overutilize the AHB. The bandwidth available on the AHB bus depends on the system clock frequency. As an example, assume that the system clock is set at 60 MHz. All or nearly all of bus accesses related to the Ethernet will be word transfers. The raw AHB bandwidth can be approximated as 4 bytes per two system clocks, which equals 2 times the system clock rate. With a 60 MHz system clock, the bandwidth is 120 MB/s, giving about 55% utilization
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for Ethernet traffic during simultaneous transmit and receive operations. This shows that it is not necessary to use the maximum CPU frequency for the Ethernet to work with plenty of bandwidth headroom.
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19. CRC calculation
The calculation is used for several purposes:
* Generation the FCS at the end of the Ethernet frame. * Generation of the hash table index for the hash table filtering. * Generation of the destination and source address hash CRCs.
The C pseudocode function below calculates the CRC on a frame taking the frame (without FCS) and the number of bytes in the frame as arguments. The function returns the CRC as a 32-bit integer. int crc_calc(char frame_no_fcs[], int frame_len) { int i; // iterator int j; // another iterator char byte; // current byte int crc; // CRC result int q0, q1, q2, q3; // temporary variables crc = 0xFFFFFFFF; for (i = 0; i < frame_len; i++) { byte = *frame_no_fcs++; for (j = 0; j < 2; j++) { if (((crc >> 28) ^ (byte >> 3)) & 0x00000001) q3 = 0x04C11DB7; } else { q3 = 0x00000000; } if (((crc >> 29) ^ (byte >> 2)) & 0x00000001) q2 = 0x09823B6E; } else { q2 = 0x00000000; } if (((crc >> 30) ^ (byte >> 1)) & 0x00000001) q1 = 0x130476DC; } else { q1 = 0x00000000; } if (((crc >> 31) ^ (byte >> 0)) & 0x00000001) q0 = 0x2608EDB8; } else { q0 = 0x00000000; } crc = (crc << 4) ^ q3 ^ q2 ^ q1 ^ q0; byte >>= 4; } } return crc; }
{
{
{
{
For FCS calculation, this function is passed a pointer to the first byte of the frame and the length of the frame without the FCS.
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For hash filtering, this function is passed a pointer to the destination address part of the frame and the CRC is only calculated on the 6 address bytes. The hash filter uses bits [28:23] for indexing the 64-bits { HashFilterH, HashFilterL } vector. If the corresponding bit is set the packet is passed, otherwise it is rejected by the hash filter. For obtaining the destination and source address hash CRCs, this function calculates first both the 32-bit CRCs, then the nine most significant bits from each 32-bit CRC are extracted, concatenated, and written in every StatusHashCRC word of every fragment status.
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1. How to read this chapter
This chapter describes the USB controller which is present on all LPC17xx devices except the LPC1767. On some LPC17xx family devices, the USB controller can also be configured for Host or OTG operation.
2. Basic configuration
The USB controller is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCUSB. Remark: On reset, the USB block is disabled (PCUSB = 0). 2. Clock: The USB block can be used with a dedicated USB PLL (PLL1) to obtain the USB clock or with the Main PLL (PLL0). See Section 4-6.1. 3. Pins: Select USB pins and their modes in PINSEL0 to PINSEL5 and PINMODE0 to PINMODE5 (Section 8-5). 4. Wake-up: Activity on the USB bus port can wake up the microcontroller from Power-down mode, see Section 4-8.8. 5. Interrupts: Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 6. Initialization: see Section 11-13.
3. Introduction
The Universal Serial Bus (USB) is a four-wire bus that supports communication between a host and one or more (up to 127) peripherals. The host controller allocates the USB bandwidth to attached devices through a token-based protocol. The bus supports hot plugging and dynamic configuration of the devices. All transactions are initiated by the host controller. The host schedules transactions in 1 ms frames. Each frame contains a Start-Of-Frame (SOF) marker and transactions that transfer data to or from device endpoints. Each device can have a maximum of 16 logical or 32 physical endpoints. There are four types of transfers defined for the endpoints. Control transfers are used to configure the device. Interrupt transfers are used for periodic data transfer. Bulk transfers are used when the rate of transfer is not critical. Isochronous transfers have guaranteed delivery time but no error correction. For more information on the Universal Serial Bus, see the USB Implementers Forum website. The USB device controller on the LPC17xx enables full-speed (12 Mb/s) data exchange with a USB host controller.
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Table 183. USB related acronyms, abbreviations, and definitions used in this chapter Acronym/abbreviation Description
AHB ATLE ATX DD DDP DMA EOP EP EP_RAM FS LED LS MPS NAK PLL RAM SOF SIE SRAM UDCA USB
Advanced High-performance bus Auto Transfer Length Extraction Analog Transceiver DMA Descriptor DMA Description Pointer Direct Memory Access End-Of-Packet Endpoint Endpoint RAM Full Speed Light Emitting Diode Low Speed Maximum Packet Size Negative Acknowledge Phase Locked Loop Random Access Memory Start-Of-Frame Serial Interface Engine Synchronous RAM USB Device Communication Area Universal Serial Bus
4. Features
* * * * * * * * *
Fully compliant with the USB 2.0 specification (full speed). Supports 32 physical (16 logical) endpoints. Supports Control, Bulk, Interrupt and Isochronous endpoints. Scalable realization of endpoints at run time. Endpoint maximum packet size selection (up to USB maximum specification) by software at run time. Supports SoftConnect and GoodLink features. Supports DMA transfers on all non-control endpoints. Allows dynamic switching between CPU controlled and DMA modes. Double buffer implementation for Bulk and Isochronous endpoints.
5. Fixed endpoint configuration
Table 11-184 shows the supported endpoint configurations. Endpoints are realized and configured at run time using the Endpoint realization registers, documented in Section 11-10.4 "Endpoint realization registers".
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Table 184. Fixed endpoint configuration Logical endpoint Physical endpoint Endpoint type Direction Packet size (bytes) Double buffer
0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Control Control Interrupt Interrupt Bulk Bulk Isochronous Isochronous Interrupt Interrupt Bulk Bulk Isochronous Isochronous Interrupt Interrupt Bulk Bulk Isochronous Isochronous Interrupt Interrupt Bulk Bulk Isochronous Isochronous Interrupt Interrupt Bulk Bulk Bulk Bulk
Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In Out In
8, 16, 32, 64 8, 16, 32, 64 1 to 64 1 to 64 8, 16, 32, 64 8, 16, 32, 64 1 to 1023 1 to 1023 1 to 64 1 to 64 8, 16, 32, 64 8, 16, 32, 64 1 to 1023 1 to 1023 1 to 64 1 to 64 8, 16, 32, 64 8, 16, 32, 64 1 to 1023 1 to 1023 1 to 64 1 to 64 8, 16, 32, 64 8, 16, 32, 64 1 to 1023 1 to 1023 1 to 64 1 to 64 8, 16, 32, 64 8, 16, 32, 64 8, 16, 32, 64 8, 16, 32, 64
No No No No Yes Yes Yes Yes No No Yes Yes Yes Yes No No Yes Yes Yes Yes No No Yes Yes Yes Yes No No Yes Yes Yes Yes
6. Functional description
The architecture of the USB device controller is shown below in Figure 11-26.
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BUS MASTER INTERFACE DMA interface (AHB master) AHB BUS
VBUS DMA ENGINE USB_CONNECT
REGISTER INTERFACE
EP_RAM ACCESS CONTROL
SERIAL INTERFACE ENGINE
USB ATX
USB_D+
USB_D-
USB_UP_LED register interface (AHB slave) EP_RAM (4K)
USB DEVICE BLOCK
Fig 26. USB device controller block diagram
6.1 Analog transceiver
The USB Device Controller has a built-in analog transceiver (ATX). The USB ATX sends/receives the bi-directional D+ and D- signals of the USB bus.
6.2 Serial Interface Engine (SIE)
The SIE implements the full USB protocol layer. It is completely hardwired for speed and needs no firmware intervention. It handles transfer of data between the endpoint buffers in EP_RAM and the USB bus. The functions of this block include: synchronization pattern recognition, parallel/serial conversion, bit stuffing/de-stuffing, CRC checking/generation, PID verification/generation, address recognition, and handshake evaluation/generation.
6.3 Endpoint RAM (EP_RAM)
Each endpoint buffer is implemented as an SRAM based FIFO. The SRAM dedicated for this purpose is called the EP_RAM. Each realized endpoint has a reserved space in the EP_RAM. The total EP_RAM space required depends on the number of realized endpoints, the maximum packet size of the endpoint, and whether the endpoint supports double buffering.
6.4 EP_RAM access control
The EP_RAM Access Control logic handles transfer of data from/to the EP_RAM and the three sources that can access it: the CPU (via the Register Interface), the SIE, and the DMA Engine.
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6.5 DMA engine and bus master interface
When enabled for an endpoint, the DMA Engine transfers data between RAM on the AHB bus and the endpoint's buffer in EP_RAM. A single DMA channel is shared between all endpoints. When transferring data, the DMA Engine functions as a master on the AHB bus through the bus master interface.
6.6 Register interface
The Register Interface allows the CPU to control the operation of the USB Device Controller. It also provides a way to write transmit data to the controller and read receive data from the controller.
6.7 SoftConnect
The connection to the USB is accomplished by bringing D+ (for a full-speed device) HIGH through a 1.5 kOhm pull-up resistor. The SoftConnect feature can be used to allow software to finish its initialization sequence before deciding to establish connection to the USB. Re-initialization of the USB bus connection can also be performed without having to unplug the cable. To use the SoftConnect feature, the CONNECT signal should control an external switch that connects the 1.5 kOhm resistor between D+ and +3.3V. Software can then control the CONNECT signal by writing to the CON bit using the SIE Set Device Status command.
6.8 GoodLink
Good USB connection indication is provided through GoodLink technology. When the device is successfully enumerated and configured, the LED indicator will be permanently ON. During suspend, the LED will be OFF. This feature provides a user-friendly indicator on the status of the USB device. It is a useful field diagnostics tool to isolate faulty equipment. To use the GoodLink feature the UP_LED signal should control an LED. The UP_LED signal is controlled using the SIE Configure Device command.
7. Operational overview
Transactions on the USB bus transfer data between device endpoints and the host. The direction of a transaction is defined with respect to the host. OUT transactions transfer data from the host to the device. IN transactions transfer data from the device to the host. All transactions are initiated by the host controller. For an OUT transaction, the USB ATX receives the bi-directional D+ and D- signals of the USB bus. The Serial Interface Engine (SIE) receives the serial data from the ATX and converts it into a parallel data stream. The parallel data is written to the corresponding endpoint buffer in the EP_RAM. For IN transactions, the SIE reads the parallel data from the endpoint buffer in EP_RAM, converts it into serial data, and transmits it onto the USB bus using the USB ATX.
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Once data has been received or sent, the endpoint buffer can be read or written. How this is accomplished depends on the endpoint's type and operating mode. The two operating modes for each endpoint are Slave (CPU-controlled) mode, and DMA mode. In Slave mode, the CPU transfers data between RAM and the endpoint buffer using the Register Interface. See Section 11-14 "Slave mode operation" for a detailed description of this mode. In DMA mode, the DMA transfers data between RAM and the endpoint buffer. See Section 11-15 "DMA operation" for a detailed description of this mode.
8. Pin description
Table 185. USB external interface Name Direction Description
VBUS
I
VBUS status input. When this function is not enabled via its corresponding PINSEL register, it is driven HIGH internally. SoftConnect control signal. GoodLink LED control signal. Positive differential data. Negative differential data.
USB_CONNECT USB_UP_LED USB_D+ USB_D-
O O I/O I/O
9. Clocking and power management
This section describes the clocking and power management features of the USB Device Controller.
9.1 Power requirements
The USB protocol insists on power management by the device. This becomes very critical if the device draws power from the bus (bus-powered device). The following constraints should be met by a bus-powered device: 1. A device in the non-configured state should draw a maximum of 100 mA from the bus. 2. A configured device can draw only up to what is specified in the Max Power field of the configuration descriptor. The maximum value is 500 mA. 3. A suspended device can draw a maximum of 2.5 mA.
9.2 Clocks
The USB device controller clocks are shown in Table 11-186
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Table 186. USB device controller clock sources Clock source Description
AHB master clock AHB slave clock usbclk
Clock for the AHB master bus interface and DMA Clock for the AHB slave interface 48 MHz clock from the dedicated USB PLL (PLL1) or the Main PLL (PLL0), used to recover the 12 MHz clock from the USB bus
9.3 Power management support
To help conserve power, the USB device controller automatically disables the AHB master clock and usbclk when not in use. When the USB Device Controller goes into the suspend state (bus is idle for 3 ms), the usbclk input to the device controller is automatically disabled, helping to conserve power. However, if software wishes to access the device controller registers, usbclk must be active. To allow access to the device controller registers while in the suspend state, the USBClkCtrl and USBClkSt registers are provided. When software wishes to access the device controller registers, it should first ensure usbclk is enabled by setting DEV_CLK_EN in the USBClkCtrl register, and then poll the corresponding DEV_CLK_ON bit in USBClkSt until set. Once set, usbclk will remain enabled until DEV_CLK_EN is cleared by software. When a DMA transfer occurs, the device controller automatically turns on the AHB master clock. Once asserted, it remains active for a minimum of 2 ms (2 frames), to help ensure that DMA throughput is not affected by turning off the AHB master clock. 2 ms after the last DMA access, the AHB master clock is automatically disabled to help conserve power. If desired, software also has the capability of forcing this clock to remain enabled using the USBClkCtrl register. Note that the AHB slave clock is always enabled as long as the PCUSB bit of PCONP is set. When the device controller is not in use, all of the device controller clocks may be disabled by clearing PCUSB. The USB_NEED_CLK signal is used to facilitate going into and waking up from chip Power-down mode. USB_NEED_CLK is asserted if any of the bits of the USBClkSt register are asserted. After entering the suspend state with DEV_CLK_EN and AHB_CLK_EN cleared, the DEV_CLK_ON and AHB_CLK_ON will be cleared when the corresponding clock turns off. When both bits are zero, USB_NEED_CLK will be low, indicating that the chip can be put into Power-down mode by writing to the PCON register. The status of USB_NEED_CLK can be read from the USBIntSt register. Any bus activity in the suspend state will cause the USB_NEED_CLK signal to be asserted. When the chip is in Power-down mode and the USB interrupt is enabled, the assertion of USB_NEED_CLK causes the chip to wake up from Power-down mode.
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9.4 Remote wake-up
The USB device controller supports software initiated remote wake-up. Remote wake-up involves resume signaling on the USB bus initiated from the device. This is done by clearing the SUS bit in the SIE Set Device Status register. Before writing into the register, all the clocks to the device controller have to be enabled using the USBClkCtrl register.
10. Register description
Table 11-187 shows the USB Device Controller registers directly accessible by the CPU. The Serial Interface Engine (SIE) has other registers that are indirectly accessible via the SIE command registers. See Section 11-12 "Serial interface engine command description" for more info.
Table 187. USB device register map Name Clock control registers Description Access Reset value[1] Address
USBClkCtrl USBClkSt USBIntSt USBDevIntSt USBDevIntEn USBDevIntClr USBDevIntSet USBDevIntPri USBEpIntSt USBEpIntEn USBEpIntClr USBEpIntSet USBEpIntPri USBReEp USBEpInd USBMaxPSize
USB transfer registers
USB Clock Control USB Clock Status USB Interrupt Status USB Device Interrupt Status USB Device Interrupt Enable USB Device Interrupt Clear USB Device Interrupt Set USB Device Interrupt Priority USB Endpoint Interrupt Status USB Endpoint Interrupt Enable USB Endpoint Interrupt Clear USB Endpoint Interrupt Set USB Endpoint Priority USB Realize Endpoint USB Endpoint Index USB MaxPacketSize USB Receive Data USB Receive Packet Length USB Transmit Data USB Transmit Packet Length USB Control USB Command Code USB Command Data
R/W RO R/W RO R/W WO WO WO RO R/W WO WO WO[2] R/W WO[2] R/W RO RO WO[2] WO[2] R/W WO[2] RO
0 0 0x8000 0000 0x10 0 0 0 0 0 0 0 0 0 0x3 0 0x8 0 0 0 0 0 0 0
0x5000 CFF4 0x5000 CFF8 0x400F C1C0 0x5000 C200 0x5000 C204 0x5000 C208 0x5000 C20C 0x5000 C22C 0x5000 C230 0x5000 C234 0x5000 C238 0x5000 C23C 0x5000 C240 0x5000 C244 0x5000 C248 0x5000 C24C 0x5000 C218 0x5000 C220 0x5000 C21C 0x5000 C224 0x5000 C228 0x5000 C210 0x5000 C214
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Device interrupt registers
Endpoint interrupt registers
Endpoint realization registers
USBRxData USBRxPLen USBTxData USBTxPLen USBCtrl USBCmdCode USBCmdData
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Table 187. USB device register map Name DMA registers Description Access Reset value[1] Address
USBDMARSt USBDMARClr USBDMARSet USBUDCAH USBEpDMASt USBEpDMAEn USBEpDMADis USBDMAIntSt USBDMAIntEn USBEoTIntSt USBEoTIntClr USBEoTIntSet USBNDDRIntSt USBNDDRIntClr USBNDDRIntSet USBSysErrIntSt USBSysErrIntClr USBSysErrIntSet
[1] [2]
USB DMA Request Status USB DMA Request Clear USB DMA Request Set USB UDCA Head USB Endpoint DMA Status USB Endpoint DMA Enable USB Endpoint DMA Disable USB DMA Interrupt Status USB DMA Interrupt Enable USB End of Transfer Interrupt Status USB End of Transfer Interrupt Clear USB End of Transfer Interrupt Set USB New DD Request Interrupt Status USB New DD Request Interrupt Clear USB New DD Request Interrupt Set USB System Error Interrupt Status USB System Error Interrupt Clear USB System Error Interrupt Set
RO WO[2] WO[2] R/W RO WO[2] WO[2] RO R/W RO WO[2] WO[2] RO WO[2] WO[2] RO WO[2] WO[2]
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0x5000 C250 0x5000 C254 0x5000 C258 0x5000 C280 0x5000 C284 0x5000 C288 0x5000 C28C 0x5000 C290 0x5000 C294 0x5000 C2A0 0x5000 C2A4 0x5000 C2A8 0x5000 C2AC 0x5000 C2B0 0x5000 C2B4 0x5000 C2B8 0x5000 C2BC 0x5000 C2C0
Reset value reflects the data stored in used bits only. It does not include reserved bits content. Reading WO register will return an invalid value.
10.1 Clock control registers
10.1.1 USB Clock Control register (USBClkCtrl - 0x5000 CFF4)
This register controls the clocking of the USB Device Controller. Whenever software wants to access the device controller registers, both DEV_CLK_EN and AHB_CLK_EN must be set. The PORTSEL_CLK_EN bit need only be set when accessing the OTGStCtrl register (see Section 13-8.6) when the USB is used in OTG configuration. The software does not have to repeat this exercise for every register access, provided that the corresponding USBClkCtrl bits are already set. Note that this register is functional only when the PCUSB bit of PCONP is set; when PCUSB is cleared, all clocks to the device controller are disabled irrespective of the contents of this register. USBClkCtrl is a read/write register.
Table 188. USBClkCtrl register (USBClkCtrl - address 0x5000 CFF4) bit description Bit Symbol Description Reset value
0 1 2
DEV_CLK_EN -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Device clock enable. Enables the usbclk input to the device controller Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0 NA
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Table 188. USBClkCtrl register (USBClkCtrl - address 0x5000 CFF4) bit description Bit Symbol Description Reset value
3 4 31:5
PORTSEL_CLK_EN AHB_CLK_EN -
Port select register clock enable. AHB clock enable Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0 NA
10.1.2 USB Clock Status register (USBClkSt - 0x5000 CFF8)
This register holds the clock availability status. The bits of this register are ORed together to form the USB_NEED_CLK signal. When enabling a clock via USBClkCtrl, software should poll the corresponding bit in USBClkSt. If it is set, then software can go ahead with the register access. Software does not have to repeat this exercise for every access, provided that the USBClkCtrl bits are not disturbed. USBClkSt is a read-only register.
Table 189. USB Clock Status register (USBClkSt - address 0x5000 CFF8) bit description Bit Symbol Description Reset value
0 1 2 3 4 31:5
DEV_CLK_ON PORTSEL_CLK_ON AHB_CLK_ON -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Device clock on. The usbclk input to the device controller is active. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Port select register clock on. AHB clock on. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0 NA NA 0 NA
10.2 Device interrupt registers
10.2.1 USB Interrupt Status register (USBIntSt - 0x5000 C1C0)
The USB Device Controller has three interrupt lines. This register allows software to determine their status with a single read operation. All three interrupt lines are ORed together to a single channel of the vectored interrupt controller. This register also contains the USB_NEED_CLK status and EN_USB_INTS control bits. USBIntSt is a read/write register.
Table 190. USB Interrupt Status register (USBIntSt - address 0x5000 C1C0) bit description Bit Symbol Description Reset value
0 1 2 7:3
USB_INT_REQ_LP USB_INT_REQ_HP USB_INT_REQ_DMA -
Low priority interrupt line status. This bit is read-only. High priority interrupt line status. This bit is read-only. DMA interrupt line status. This bit is read-only. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 0 NA
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Table 190. USB Interrupt Status register (USBIntSt - address 0x5000 C1C0) bit description Bit Symbol Description Reset value
8
USB_NEED_CLK
USB need clock indicator. This bit is set to 1 when USB activity or a change 1 of state on the USB data pins is detected, and it indicates that a PLL supplied clock of 48 MHz is needed. Once USB_NEED_CLK becomes one, it resets to zero 5 ms after the last packet has been received/sent, or 2 ms after the Suspend Change (SUS_CH) interrupt has occurred. A change of this bit from 0 to 1 can wake up the microcontroller if activity on the USB bus is selected to wake up the part from the Power-down mode (see Section 4-8.8 "Wake-up from Reduced Power Modes" for details). Also see Section 4-5.9 "PLL0 and Power-down mode" and Section 4-8.9 "Power Control for Peripherals register (PCONP - 0x400F C0C4)" for considerations about the PLL and invoking the Power-down mode. This bit is read-only. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Enable all USB interrupts. When this bit is cleared, the Vectored Interrupt Controller does not see the ORed output of the USB interrupt lines. NA 1
30:9 31
EN_USB_INTS
10.2.2 USB Device Interrupt Status register (USBDevIntSt - 0x5000 C200)
The USBDevIntSt register holds the status of each interrupt. A 0 indicates no interrupt and 1 indicates the presence of the interrupt. USBDevIntSt is a read-only register.
Table 191. USB Device Interrupt Status register (USBDevIntSt - address 0x5000 C200) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
ERR_INT
1
EP_RLZED
0
TxENDPKT
Rx ENDPKT
CDFULL
CCEMPTY
DEV_STAT
EP_SLOW
EP_FAST
FRAME
Table 192. USB Device Interrupt Status register (USBDevIntSt - address 0x5000 C200) bit description Bit Symbol Description Reset value
0 1 2 3
FRAME EP_FAST EP_SLOW DEV_STAT
The frame interrupt occurs every 1 ms. This is used in isochronous packet transfers.
0
Fast endpoint interrupt. If an Endpoint Interrupt Priority register (USBEpIntPri) bit is set, 0 the corresponding endpoint interrupt will be routed to this bit. Slow endpoints interrupt. If an Endpoint Interrupt Priority Register (USBEpIntPri) bit is not set, the corresponding endpoint interrupt will be routed to this bit. 0
Set when USB Bus reset, USB suspend change or Connect change event occurs. 0 Refer to Section 11-12.6 "Set Device Status (Command: 0xFE, Data: write 1 byte)" on page 245. The command code register (USBCmdCode) is empty (New command can be written). 1 Command data register (USBCmdData) is full (Data can be read now). The current packet in the endpoint buffer is transferred to the CPU. 0 0
4 5 6 7
CCEMPTY CDFULL RxENDPKT TxENDPKT
The number of data bytes transferred to the endpoint buffer equals the number of bytes 0 programmed in the TxPacket length register (USBTxPLen).
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Table 192. USB Device Interrupt Status register (USBDevIntSt - address 0x5000 C200) bit description Bit Symbol Description Reset value
8 9
EP_RLZED ERR_INT
Endpoints realized. Set when Realize Endpoint register (USBReEp) or MaxPacketSize 0 register (USBMaxPSize) is updated and the corresponding operation is completed. Error Interrupt. Any bus error interrupt from the USB device. Refer to Section 11-12.9 "Read Error Status (Command: 0xFB, Data: read 1 byte)" on page 247 0
31:10 -
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
10.2.3 USB Device Interrupt Enable register (USBDevIntEn - 0x5000 C204)
Writing a one to a bit in this register enables the corresponding bit in USBDevIntSt to generate an interrupt on one of the interrupt lines when set. By default, the interrupt is routed to the USB_INT_REQ_LP interrupt line. Optionally, either the EP_FAST or FRAME interrupt may be routed to the USB_INT_REQ_HP interrupt line by changing the value of USBDevIntPri. USBDevIntEn is a read/write register.
Table 193. USB Device Interrupt Enable register (USBDevIntEn - address 0x5000 C204) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
ERR_INT
1
EP_RLZED
0
TxENDPKT
Rx ENDPKT
CDFULL
CCEMPTY
DEV_STAT
EP_SLOW
EP_FAST
FRAME
Table 194. USB Device Interrupt Enable register (USBDevIntEn - address 0x5000 C204) bit description Bit Symbol Value Description Reset value
31:0
See 0 USBDevIntEn 1 bit allocation table above
No interrupt is generated. An interrupt will be generated when the corresponding bit in the Device Interrupt Status (USBDevIntSt) register (Table 11-191) is set. By default, the interrupt is routed to the USB_INT_REQ_LP interrupt line. Optionally, either the EP_FAST or FRAME interrupt may be routed to the USB_INT_REQ_HP interrupt line by changing the value of USBDevIntPri.
0
10.2.4 USB Device Interrupt Clear register (USBDevIntClr - 0x5000 C208)
Writing one to a bit in this register clears the corresponding bit in USBDevIntSt. Writing a zero has no effect. Remark: Before clearing the EP_SLOW or EP_FAST interrupt bits, the corresponding endpoint interrupts in USBEpIntSt should be cleared. USBDevIntClr is a write-only register.
Table 195. USB Device Interrupt Clear register (USBDevIntClr - address 0x5000 C208) bit allocation Reset value: 0x0000 0000 Bit Symbol
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Bit Symbol Bit Symbol Bit Symbol
23
15
14
13
12
11
10
9
8
7
6
5
4
3
2
ERR_INT
1
EP_RLZED
0
TxENDPKT
Rx ENDPKT
CDFULL
CCEMPTY
DEV_STAT
EP_SLOW
EP_FAST
FRAME
Table 196. USB Device Interrupt Clear register (USBDevIntClr - address 0x5000 C208) bit description Bit Symbol Value Description Reset value
31:0
See 0 USBDevIntClr 1 bit allocation table above
No effect. The corresponding bit in USBDevIntSt (Section 11-10.2.2) is cleared.
0
10.2.5 USB Device Interrupt Set register (USBDevIntSet - 0x5000 C20C)
Writing one to a bit in this register sets the corresponding bit in the USBDevIntSt. Writing a zero has no effect USBDevIntSet is a write-only register.
Table 197. USB Device Interrupt Set register (USBDevIntSet - address 0x5000 C20C) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
ERR_INT
1
EP_RLZED
0
TxENDPKT
Rx ENDPKT
CDFULL
CCEMPTY
DEV_STAT
EP_SLOW
EP_FAST
FRAME
Table 198. USB Device Interrupt Set register (USBDevIntSet - address 0x5000 C20C) bit description Bit Symbol Value Description Reset value
31:0
See 0 USBDevIntSet 1 bit allocation table above
No effect. The corresponding bit in USBDevIntSt (Section 11-10.2.2) is set.
0
10.2.6 USB Device Interrupt Priority register (USBDevIntPri - 0x5000 C22C)
Writing one to a bit in this register causes the corresponding interrupt to be routed to the USB_INT_REQ_HP interrupt line. Writing zero causes the interrupt to be routed to the USB_INT_REQ_LP interrupt line. Either the EP_FAST or FRAME interrupt can be routed to USB_INT_REQ_HP, but not both. If the software attempts to set both bits to one, no interrupt will be routed to USB_INT_REQ_HP. USBDevIntPri is a write-only register.
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Table 199. USB Device Interrupt Priority register (USBDevIntPri - address 0x5000 C22C) bit description Bit Symbol Value Description Reset value
0 1 31:2
FRAME EP_FAST -
0 1 0 1
FRAME interrupt is routed to USB_INT_REQ_LP. FRAME interrupt is routed to USB_INT_REQ_HP. EP_FAST interrupt is routed to USB_INT_REQ_LP. EP_FAST interrupt is routed to USB_INT_REQ_HP. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 NA
10.3 Endpoint interrupt registers
The registers in this group facilitate handling of endpoint interrupts. Endpoint interrupts are used in Slave mode operation.
10.3.1 USB Endpoint Interrupt Status register (USBEpIntSt - 0x5000 C230)
Each physical non-isochronous endpoint is represented by a bit in this register to indicate that it has generated an interrupt. All non-isochronous OUT endpoints generate an interrupt when they receive a packet without an error. All non-isochronous IN endpoints generate an interrupt when a packet is successfully transmitted, or when a NAK handshake is sent on the bus and the interrupt on NAK feature is enabled (see Section 11-12.3 "Set Mode (Command: 0xF3, Data: write 1 byte)" on page 244). A bit set to one in this register causes either the EP_FAST or EP_SLOW bit of USBDevIntSt to be set depending on the value of the corresponding bit of USBEpDevIntPri. USBEpIntSt is a read-only register. Note that for Isochronous endpoints, handling of packet data is done when the FRAME interrupt occurs.
Table 200. USB Endpoint Interrupt Status register (USBEpIntSt - address 0x5000 C230) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
EP15TX
23
EP15RX
22
EP14TX
21
EP14RX
20
EP13TX
19
EP13RX
18
EP12TX
17
EP12RX
16
EP11TX
15
EP11RX
14
EP10TX
13
EP10RX
12
EP9TX
11
EP9RX
10
EP8TX
9
EP8RX
8
EP7TX
7
EP7RX
6
EP6TX
5
EP6RX
4
EP5TX
3
EP5RX
2
EP4TX
1
EP4RX
0
EP3TX
EP3RX
EP2TX
EP2RX
EP1TX
EP1RX
EP0TX
EP0RX
Table 201. USB Endpoint Interrupt Status register (USBEpIntSt - address 0x5000 C230) bit description Bit Symbol Description Reset value
0 1 2 3 4 5
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EP0RX EP0TX EP1RX EP1TX EP2RX EP2TX
Endpoint 0, Data Received Interrupt bit. Endpoint 0, Data Transmitted Interrupt bit or sent a NAK. Endpoint 1, Data Received Interrupt bit. Endpoint 1, Data Transmitted Interrupt bit or sent a NAK. Endpoint 2, Data Received Interrupt bit. Endpoint 2, Data Transmitted Interrupt bit or sent a NAK.
0 0 0 0 0 0
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Table 201. USB Endpoint Interrupt Status register (USBEpIntSt - address 0x5000 C230) bit description Bit Symbol Description Reset value
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
EP3RX EP3TX EP4RX EP4TX EP5RX EP5TX EP6RX EP6TX EP7RX EP7TX EP8RX EP8TX EP9RX EP9TX EP10RX EP10TX EP11RX EP11TX EP12RX EP12TX EP13RX EP13TX EP14RX EP14TX EP15RX EP15TX
Endpoint 3, Isochronous endpoint. Endpoint 3, Isochronous endpoint. Endpoint 4, Data Received Interrupt bit. Endpoint 4, Data Transmitted Interrupt bit or sent a NAK. Endpoint 5, Data Received Interrupt bit. Endpoint 5, Data Transmitted Interrupt bit or sent a NAK. Endpoint 6, Isochronous endpoint. Endpoint 6, Isochronous endpoint. Endpoint 7, Data Received Interrupt bit. Endpoint 7, Data Transmitted Interrupt bit or sent a NAK. Endpoint 8, Data Received Interrupt bit. Endpoint 8, Data Transmitted Interrupt bit or sent a NAK. Endpoint 9, Isochronous endpoint. Endpoint 9, Isochronous endpoint. Endpoint 10, Data Received Interrupt bit. Endpoint 10, Data Transmitted Interrupt bit or sent a NAK. Endpoint 11, Data Received Interrupt bit. Endpoint 11, Data Transmitted Interrupt bit or sent a NAK. Endpoint 12, Isochronous endpoint. Endpoint 12, Isochronous endpoint. Endpoint 13, Data Received Interrupt bit. Endpoint 13, Data Transmitted Interrupt bit or sent a NAK. Endpoint 14, Data Received Interrupt bit. Endpoint 14, Data Transmitted Interrupt bit or sent a NAK. Endpoint 15, Data Received Interrupt bit. Endpoint 15, Data Transmitted Interrupt bit or sent a NAK.
NA NA 0 0 0 0 NA NA 0 0 0 0 NA NA 0 0 0 0 NA NA 0 0 0 0 0 0
10.3.2 USB Endpoint Interrupt Enable register (USBEpIntEn - 0x5000 C234)
Setting a bit to 1 in this register causes the corresponding bit in USBEpIntSt to be set when an interrupt occurs for the associated endpoint. Setting a bit to 0 causes the corresponding bit in USBDMARSt to be set when an interrupt occurs for the associated endpoint. USBEpIntEn is a read/write register.
Table 202. USB Endpoint Interrupt Enable register (USBEpIntEn - address 0x5000 C234) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
EP15TX
23
EP15RX
22
EP14TX
21
EP14RX
20
EP13TX
19
EP13RX
18
EP12TX
17
EP12RX
16
EP11TX
15
EP11RX
14
EP10TX
13
EP10RX
12
EP9TX
11
EP9RX
10
EP8TX
9
EP8RX
8
EP7TX
EP7RX
EP6TX
EP6RX
EP5TX
EP5RX
EP4TX
EP4RX
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6 5 4 3 2 1 0
Bit Symbol
7
EP3TX
EP3RX
EP2TX
EP2RX
EP1TX
EP1RX
EP0TX
EP0RX
Table 203. USB Endpoint Interrupt Enable register (USBEpIntEn - address 0x5000 C234) bit description Bit Symbol Value Description Reset value
31:0
See USBEpIntEn bit 0 allocation table above 1
The corresponding bit in USBDMARSt is set when an interrupt occurs 0 for this endpoint.
The corresponding bit in USBEpIntSt is set when an interrupt occurs for this endpoint. Implies Slave mode for this endpoint.
10.3.3 USB Endpoint Interrupt Clear register (USBEpIntClr - 0x5000 C238)
Writing a one to this a bit in this register causes the SIE Select Endpoint/Clear Interrupt command to be executed (Table 11-247) for the corresponding physical endpoint. Writing zero has no effect. Before executing the Select Endpoint/Clear Interrupt command, the CDFULL bit in USBDevIntSt is cleared by hardware. On completion of the command, the CDFULL bit is set, USBCmdData contains the status of the endpoint, and the corresponding bit in USBEpIntSt is cleared. Notes:
* When clearing interrupts using USBEpIntClr, software should wait for CDFULL to be
set to ensure the corresponding interrupt has been cleared before proceeding.
* While setting multiple bits in USBEpIntClr simultaneously is possible, it is not
recommended; only the status of the endpoint corresponding to the least significant interrupt bit cleared will be available at the end of the operation.
* Alternatively, the SIE Select Endpoint/Clear Interrupt command can be directly
invoked using the SIE command registers, but using USBEpIntClr is recommended because of its ease of use. Each physical endpoint has its own reserved bit in this register. The bit field definition is the same as that of USBEpIntSt shown in Table 11-200. USBEpIntClr is a write-only register.
Table 204. USB Endpoint Interrupt Clear register (USBEpIntClr - address 0x5000 C238) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
EP15TX
23
EP15RX
22
EP14TX
21
EP14RX
20
EP13TX
19
EP13RX
18
EP12TX
17
EP12RX
16
EP11TX
15
EP11RX
14
EP10TX
13
EP10RX
12
EP9TX
11
EP9RX
10
EP8TX
9
EP8RX
8
EP7TX
7
EP7RX
6
EP6TX
5
EP6RX
4
EP5TX
3
EP5RX
2
EP4TX
1
EP4RX
0
EP3TX
EP3RX
EP2TX
EP2RX
EP1TX
EP1RX
EP0TX
EP0RX
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Chapter 11: LPC17xx USB device controller
Table 205. USB Endpoint Interrupt Clear register (USBEpIntClr - address 0x5000 C238) bit description Bit Symbol Value Description Reset value
31:0
See USBEpIntClr bit allocation table above
0 1
No effect. Clears the corresponding bit in USBEpIntSt, by executing the SIE Select Endpoint/Clear Interrupt command for this endpoint.
0
10.3.4 USB Endpoint Interrupt Set register (USBEpIntSet - 0x5000 C23C)
Writing a one to a bit in this register sets the corresponding bit in USBEpIntSt. Writing zero has no effect. Each endpoint has its own bit in this register. USBEpIntSet is a write-only register.
Table 206. USB Endpoint Interrupt Set register (USBEpIntSet - address 0x5000 C23C) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
EP15TX
23
EP15RX
22
EP14TX
21
EP14RX
20
EP13TX
19
EP13RX
18
EP12TX
17
EP12RX
16
EP11TX
15
EP11RX
14
EP10TX
13
EP10RX
12
EP9TX
11
EP9RX
10
EP8TX
9
EP8RX
8
EP7TX
7
EP7RX
6
EP6TX
5
EP6RX
4
EP5TX
3
EP5RX
2
EP4TX
1
EP4RX
0
EP3TX
EP3RX
EP2TX
EP2RX
EP1TX
EP1RX
EP0TX
EP0RX
Table 207. USB Endpoint Interrupt Set register (USBEpIntSet - address 0x5000 C23C) bit description Bit Symbol Value Description Reset value
31:0
See USBEpIntSet bit allocation table above
0 1
No effect. Sets the corresponding bit in USBEpIntSt.
0
10.3.5 USB Endpoint Interrupt Priority register (USBEpIntPri - 0x5000 C240)
This register determines whether an endpoint interrupt is routed to the EP_FAST or EP_SLOW bits of USBDevIntSt. If a bit in this register is set to one, the interrupt is routed to EP_FAST, if zero it is routed to EP_SLOW. Routing of multiple endpoints to EP_FAST or EP_SLOW is possible. Note that the USBDevIntPri register determines whether the EP_FAST interrupt is routed to the USB_INT_REQ_HP or USB_INT_REQ_LP interrupt line. USBEpIntPri is a write-only register.
Table 208. USB Endpoint Interrupt Priority register (USBEpIntPri - address 0x5000 C240) bit allocation Reset value: 0x0000 0000 Bit Symbol Bit Symbol Bit Symbol Bit Symbol
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30
29
28
27
26
25
24
EP15TX
23
EP15RX
22
EP14TX
21
E14RX
20
EP13TX
19
EP13RX
18
EP12TX
17
EP12RX
16
EP11TX
15
EP11RX
14
EP10TX
13
EP10RX
12
EP9TX
11
EP9RX
10
EP8TX
9
EP8RX
8
EP7TX
7
EP7RX
6
EP6TX
5
EP6RX
4
EP5TX
3
EP5RX
2
EP4TX
1
EP4RX
0
EP3TX
EP3RX
EP2TX
EP2RX
EP1TX
EP1RX
EP0TX
EP0RX
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Table 209. USB Endpoint Interrupt Priority register (USBEpIntPri - address 0x5000 C240) bit description Bit Symbol Value Description Reset value
31:0
See USBEpIntPri bit allocation table above
0 1
The corresponding interrupt is routed to the EP_SLOW bit of USBDevIntSt The corresponding interrupt is routed to the EP_FAST bit of USBDevIntSt
0
10.4 Endpoint realization registers
The registers in this group allow realization and configuration of endpoints at run time.
10.4.1 EP RAM requirements
The USB device controller uses a RAM based FIFO for each endpoint buffer. The RAM dedicated for this purpose is called the Endpoint RAM (EP_RAM). Each endpoint has space reserved in the EP_RAM. The EP_RAM space required for an endpoint depends on its MaxPacketSize and whether it is double buffered. 32 words of EP_RAM are used by the device for storing the endpoint buffer pointers. The EP_RAM is word aligned but the MaxPacketSize is defined in bytes hence the RAM depth has to be adjusted to the next word boundary. Also, each buffer has one word header showing the size of the packet length received. The EP_ RAM space (in words) required for the physical endpoint can be expressed as
MaxPacketSize + 3 EPRAMspace = ------------------------------------------------- + 1 x dbstatus 4
where dbstatus = 1 for a single buffered endpoint and 2 for double a buffered endpoint. Since all the realized endpoints occupy EP_RAM space, the total EP_RAM requirement is
N
TotalEPRAMspace = 32 +
n=0
EPRAMspace ( n )
where N is the number of realized endpoints. Total EP_RAM space should not exceed 4096 bytes (4 kB, 1 kwords).
10.4.2 USB Realize Endpoint register (USBReEp - 0x5000 C244)
Writing one to a bit in this register causes the corresponding endpoint to be realized. Writing zeros causes it to be unrealized. This register returns to its reset state when a bus reset occurs. USBReEp is a read/write register.
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Table 210. USB Realize Endpoint register (USBReEp - address 0x5000 C244) bit allocation Reset value: 0x0000 0003 Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
EP31
23
EP30
22
EP29
21
EP28
20
EP27
19
EP26
18
EP25
17
EP24
16
EP23
15
EP22
14
EP21
13
EP20
12
EP19
11
EP18
10
EP17
9
EP16
8
EP15
7
EP14
6
EP13
5
EP12
4
EP11
3
EP10
2
EP9
1
EP8
0
EP7
EP6
EP5
EP4
EP3
EP2
EP1
EP0
Table 211. USB Realize Endpoint register (USBReEp - address 0x5000 C244) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0 EP1 EPxx
0 1 0 1 0 1
Control endpoint EP0 is not realized. Control endpoint EP0 is realized. Control endpoint EP1 is not realized. Control endpoint EP1 is realized. Endpoint EPxx is not realized. Endpoint EPxx is realized.
1 1 0
On reset, only the control endpoints are realized. Other endpoints, if required, are realized by programming the corresponding bits in USBReEp. To calculate the required EP_RAM space for the realized endpoints, see Section 11-10.4.1. Realization of endpoints is a multi-cycle operation. Pseudo code for endpoint realization is shown below. Clear EP_RLZED bit in USBDevIntSt; for every endpoint to be realized, { /* OR with the existing value of the Realize Endpoint register */ USBReEp |= (UInt32) ((0x1 << endpt)); /* Load Endpoint index Reg with physical endpoint no.*/ USBEpIn = (UInt32) endpointnumber; /* load the max packet size Register */ USBEpMaxPSize = MPS; /* check whether the EP_RLZED bit in the Device Interrupt Status register is set */ while (!(USBDevIntSt & EP_RLZED)) { /* wait until endpoint realization is complete */ } /* Clear the EP_RLZED bit */ Clear EP_RLZED bit in USBDevIntSt; }
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The device will not respond to any transactions to unrealized endpoints. The SIE Configure Device command will only cause realized and enabled endpoints to respond to transactions. For details see Table 11-242.
10.4.3 USB Endpoint Index register (USBEpIn - 0x5000 C248)
Each endpoint has a register carrying the MaxPacketSize value for that endpoint. This is in fact a register array. Hence before writing, this register is addressed through the USBEpIn register. The USBEpIn register will hold the physical endpoint number. Writing to USBMaxPSize will set the array element pointed to by USBEpIn. USBEpIn is a write-only register.
Table 212. USB Endpoint Index register (USBEpIn - address 0x5000 C248) bit description Bit Symbol Description Reset value
4:0 31:5
PHY_EP -
Physical endpoint number (0-31) Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
10.4.4 USB MaxPacketSize register (USBMaxPSize - 0x5000 C24C)
On reset, the control endpoint is assigned the maximum packet size of 8 bytes. Other endpoints are assigned 0. Modifying USBMaxPSize will cause the endpoint buffer addresses within the EP_RAM to be recalculated. This is a multi-cycle process. At the end, the EP_RLZED bit will be set in USBDevIntSt (Table 11-191). USBMaxPSize array indexing is shown in Figure 11-27. USBMaxPSize is a read/write register.
Table 213. USB MaxPacketSize register (USBMaxPSize - address 0x5000 C24C) bit description Bit Symbol Description Reset value
9:0
MPS
The maximum packet size value.
0x008[1]
31:10 -
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
[1] Reset value for EP0 and EP1. All other endpoints have a reset value of 0x0.
MPS_EP0 ENDPOINT INDEX
MPS_EP31
The Endpoint Index is set via the USBEpIn register. MPS_EP0 to MPS_EP31 are accessed via the USBMaxPSize register.
Fig 27. USB MaxPacketSize register array indexing
10.5 USB transfer registers
The registers in this group are used for transferring data between endpoint buffers and RAM in Slave mode operation. See Section 11-14 "Slave mode operation".
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10.5.1 USB Receive Data register (USBRxData - 0x5000 C218)
For an OUT transaction, the CPU reads the endpoint buffer data from this register. Before reading this register, the RD_EN bit and LOG_ENDPOINT field of the USBCtrl register should be set appropriately. On reading this register, data from the selected endpoint buffer is fetched. The data is in little endian format: the first byte received from the USB bus will be available in the least significant byte of USBRxData. USBRxData is a read-only register.
Table 214. USB Receive Data register (USBRxData - address 0x5000 C218) bit description Bit Symbol Description Reset value
31:0
RX_DATA
Data received.
0x0000 0000
10.5.2 USB Receive Packet Length register (USBRxPLen - 0x5000 C220)
This register contains the number of bytes remaining in the endpoint buffer for the current packet being read via the USBRxData register, and a bit indicating whether the packet is valid or not. Before reading this register, the RD_EN bit and LOG_ENDPOINT field of the USBCtrl register should be set appropriately. This register is updated on each read of the USBRxData register. USBRxPLen is a read-only register.
Table 215. USB Receive Packet Length register (USBRxPlen - address 0x5000 C220) bit description Bit Symbol Value Description Reset value
9:0
PKT_LNGTH
-
The remaining number of bytes to be read from the currently selected 0 endpoint's buffer. When this field decrements to 0, the RxENDPKT bit will be set in USBDevIntSt. Data valid. This bit is useful for isochronous endpoints. Non-isochronous endpoints do not raise an interrupt when an erroneous data packet is received. But invalid data packet can be produced with a bus reset. For isochronous endpoints, data transfer will happen even if an erroneous packet is received. In this case DV bit will not be set for the packet. 0
10
DV
0 1 11 PKT_RDY 31:12 -
Data is invalid. Data is valid. The PKT_LNGTH field is valid and the packet is ready for reading. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 NA
10.5.3 USB Transmit Data register (USBTxData - 0x5000 C21C)
For an IN transaction, the CPU writes the endpoint data into this register. Before writing to this register, the WR_EN bit and LOG_ENDPOINT field of the USBCtrl register should be set appropriately, and the packet length should be written to the USBTxPlen register. On writing this register, the data is written to the selected endpoint buffer. The data is in little endian format: the first byte sent on the USB bus will be the least significant byte of USBTxData. USBTxData is a write-only register.
Table 216. USB Transmit Data register (USBTxData - address 0x5000 C21C) bit description Bit Symbol Description Reset value
31:0
TX_DATA
Transmit Data.
0x0000 0000
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10.5.4 USB Transmit Packet Length register (USBTxPLen - 0x5000 C224)
This register contains the number of bytes transferred from the CPU to the selected endpoint buffer. Before writing data to USBTxData, software should first write the packet length ( MaxPacketSize) to this register. After each write to USBTxData, hardware decrements USBTxPLen by 4. The WR_EN bit and LOG_ENDPOINT field of the USBCtrl register should be set to select the desired endpoint buffer before starting this process. For data buffers larger than the endpoint's MaxPacketSize, software should submit data in packets of MaxPacketSize, and send the remaining extra bytes in the last packet. For example, if the MaxPacketSize is 64 bytes and the data buffer to be transferred is of length 130 bytes, then the software sends two 64-byte packets and the remaining 2 bytes in the last packet. So, a total of 3 packets are sent on USB. USBTxPLen is a write-only register.
Table 217. USB Transmit Packet Length register (USBTxPLen - address 0x5000 C224) bit description Bit Symbol Value Description Reset value
9:0
PKT_LNGTH
-
The remaining number of bytes to be written to the selected endpoint buffer. This field is decremented by 4 by hardware after each write to USBTxData. When this field decrements to 0, the TxENDPKT bit will be set in USBDevIntSt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x000
31:10 -
-
NA
10.5.5 USB Control register (USBCtrl - 0x5000 C228)
This register controls the data transfer operation of the USB device. It selects the endpoint buffer that is accessed by the USBRxData and USBTxData registers, and enables reading and writing them. USBCtrl is a read/write register.
Table 218. USB Control register (USBCtrl - address 0x5000 C228) bit description Bit Symbol Value Description Reset value
0
RD_EN
Read mode control. Enables reading data from the OUT endpoint buffer 0 for the endpoint specified in the LOG_ENDPOINT field using the USBRxData register. This bit is cleared by hardware when the last word of the current packet is read from USBRxData. 0 1 Read mode is disabled. Read mode is enabled. Write mode control. Enables writing data to the IN endpoint buffer for the 0 endpoint specified in the LOG_ENDPOINT field using the USBTxData register. This bit is cleared by hardware when the number of bytes in USBTxLen have been sent. 0 1 Write mode is disabled. Write mode is enabled. Logical Endpoint number. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0x0 NA
1
WR_EN
5:2 31:6
LOG_ENDPOINT -
-
10.6 SIE command code registers
The SIE command code registers are used for communicating with the Serial Interface Engine. See Section 11-12 "Serial interface engine command description" for more information.
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10.6.1 USB Command Code register (USBCmdCode - 0x5000 C210)
This register is used for sending the command and write data to the SIE. The commands written here are propagated to the SIE and executed there. After executing the command, the register is empty, and the CCEMPTY bit of USBDevIntSt register is set. See Section 11-12 for details. USBCmdCode is a write-only register.
Table 219. USB Command Code register (USBCmdCode - address 0x5000 C210) bit description Bit Symbol Value Description Reset value
7:0 15:8
CMD_PHASE
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. The command phase: Read Write Command This is a multi-purpose field. When CMD_PHASE is Command or Read, this field contains the code for the command (CMD_CODE). When CMD_PHASE is Write, this field contains the command write data (CMD_WDATA).
NA 0x00
0x01 0x02 0x05 23:16 CMD_CODE/ CMD_WDATA
0x00
31:24 -
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
10.6.2 USB Command Data register (USBCmdData - 0x5000 C214)
This register contains the data retrieved after executing a SIE command. When the data is ready to be read, the CD_FULL bit of the USBDevIntSt register is set. See Table 11-191 for details. USBCmdData is a read-only register.
Table 220. USB Command Data register (USBCmdData - address 0x5000 C214) bit description Bit Symbol Description Reset value
7:0 31:8
CMD_RDATA -
Command Read Data.
0x00
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
10.7 DMA registers
The registers in this group are used for the DMA mode of operation (see Section 11-15 "DMA operation")
10.7.1 USB DMA Request Status register (USBDMARSt - 0x5000 C250)
A bit in this register associated with a non-isochronous endpoint is set by hardware when an endpoint interrupt occurs (see the description of USBEpIntSt) and the corresponding bit in USBEpIntEn is 0. A bit associated with an isochronous endpoint is set when the corresponding bit in USBEpIntEn is 0 and a FRAME interrupt occurs. A set bit serves as a flag for the DMA engine to start the data transfer if the DMA is enabled for the corresponding endpoint in the USBEpDMASt register. The DMA cannot be enabled for control endpoints (EP0 and EP1). USBDMARSt is a read-only register.
Table 221. USB DMA Request Status register (USBDMARSt - address 0x5000 C250) bit allocation Reset value: 0x0000 0000 Bit Symbol
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31
30
29
28
27
26
25
24
EP31
EP30
EP29
EP28
EP27
EP26
EP25
EP24
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22 21 20 19 18 17 16
Bit Symbol Bit Symbol Bit Symbol
23
EP23
15
EP22
14
EP21
13
EP20
12
EP19
11
EP18
10
EP17
9
EP16
8
EP15
7
EP14
6
EP13
5
EP12
4
EP11
3
EP10
2
EP9
1
EP8
0
EP7
EP6
EP5
EP4
EP3
EP2
EP1
EP0
Table 222. USB DMA Request Status register (USBDMARSt - address 0x5000 C250) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0 EP1 EPxx
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and EP0 bit must be 0). Control endpoint IN (DMA cannot be enabled for this endpoint and EP1 bit must be 0). Endpoint xx (2 xx 31) DMA request. DMA not requested by endpoint xx. DMA requested by endpoint xx.
0 0 0
0 1
[1]
DMA can not be enabled for this endpoint and the corresponding bit in the USBDMARSt must be 0.
10.7.2 USB DMA Request Clear register (USBDMARClr - 0x5000 C254)
Writing one to a bit in this register will clear the corresponding bit in the USBDMARSt register. Writing zero has no effect. This register is intended for initialization prior to enabling the DMA for an endpoint. When the DMA is enabled for an endpoint, hardware clears the corresponding bit in USBDMARSt on completion of a packet transfer. Therefore, software should not clear the bit using this register while the endpoint is enabled for DMA operation. USBDMARClr is a write-only register. The USBDMARClr bit allocation is identical to the USBDMARSt register (Table 11-221).
Table 223. USB DMA Request Clear register (USBDMARClr - address 0x5000 C254) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0 EP1 EPxx
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and the EP0 bit must be 0).
0
Control endpoint IN (DMA cannot be enabled for this endpoint and the EP1 bit 0 must be 0). Clear the endpoint xx (2 xx 31) DMA request. 0 No effect. Clear the corresponding bit in USBDMARSt.
0 1
10.7.3 USB DMA Request Set register (USBDMARSet - 0x5000 C258)
Writing one to a bit in this register sets the corresponding bit in the USBDMARSt register. Writing zero has no effect.
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This register allows software to raise a DMA request. This can be useful when switching from Slave to DMA mode of operation for an endpoint: if a packet to be processed in DMA mode arrives before the corresponding bit of USBEpIntEn is cleared, the DMA request is not raised by hardware. Software can then use this register to manually start the DMA transfer. Software can also use this register to initiate a DMA transfer to proactively fill an IN endpoint buffer before an IN token packet is received from the host. USBDMARSet is a write-only register. The USBDMARSet bit allocation is identical to the USBDMARSt register (Table 11-221).
Table 224. USB DMA Request Set register (USBDMARSet - address 0x5000 C258) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0 EP1 EPxx
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and the EP0 bit must be 0).
0
Control endpoint IN (DMA cannot be enabled for this endpoint and the EP1 bit must 0 be 0). Set the endpoint xx (2 xx 31) DMA request. 0 No effect. Set the corresponding bit in USBDMARSt.
0 1
10.7.4 USB UDCA Head register (USBUDCAH - 0x5000 C280)
The UDCA (USB Device Communication Area) Head register maintains the address where the UDCA is located in the RAM. Refer to Section 11-15.2 "USB device communication area" and Section 11-15.4 "The DMA descriptor" for more details on the UDCA and DMA descriptors. USBUDCAH is a read/write register.
Table 225. USB UDCA Head register (USBUDCAH - address 0x5000 C280) bit description Bit Symbol Description Reset value
6:0 31:7
UDCA_ADDR
Reserved. Software should not write ones to reserved bits. The UDCA is aligned to 0x00 128-byte boundaries. Start address of the UDCA. 0
10.7.5 USB EP DMA Status register (USBEpDMASt - 0x5000 C284)
Bits in this register indicate whether DMA operation is enabled for the corresponding endpoint. A DMA transfer for an endpoint can start only if the corresponding bit is set in this register. USBEpDMASt is a read-only register.
Table 226. USB EP DMA Status register (USBEpDMASt - address 0x5000 C284) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0_DMA_ENABLE EP1_DMA_ENABLE EPxx_DMA_ENABLE
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and 0 the EP0_DMA_ENABLE bit must be 0). Control endpoint IN (DMA cannot be enabled for this endpoint and the EP1_DMA_ENABLE bit must be 0). endpoint xx (2 xx 31) DMA enabled bit. The DMA for endpoint EPxx is disabled. The DMA for endpoint EPxx is enabled. 0 0
0 1
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10.7.6 USB EP DMA Enable register (USBEpDMAEn - 0x5000 C288)
Writing one to a bit to this register will enable the DMA operation for the corresponding endpoint. Writing zero has no effect.The DMA cannot be enabled for control endpoints EP0 and EP1. USBEpDMAEn is a write-only register.
Table 227. USB EP DMA Enable register (USBEpDMAEn - address 0x5000 C288) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0_DMA_ENABLE EP1_DMA_ENABLE EPxx_DMA_ENABLE
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and the EP0_DMA_ENABLE bit value must be 0).
0
Control endpoint IN (DMA cannot be enabled for this endpoint and the 0 EP1_DMA_ENABLE bit must be 0). Endpoint xx(2 xx 31) DMA enable control bit. 0 No effect. Enable the DMA operation for endpoint EPxx.
0 1
10.7.7 USB EP DMA Disable register (USBEpDMADis - 0x5000 C28C)
Writing a one to a bit in this register clears the corresponding bit in USBEpDMASt. Writing zero has no effect on the corresponding bit of USBEpDMASt. Any write to this register clears the internal DMA_PROCEED flag. Refer to Section 11-15.5.4 "Optimizing descriptor fetch" for more information on the DMA_PROCEED flag. If a DMA transfer is in progress for an endpoint when its corresponding bit is cleared, the transfer is completed before the DMA is disabled. When an error condition is detected during a DMA transfer, the corresponding bit is cleared by hardware. USBEpDMADis is a write-only register.
Table 228. USB EP DMA Disable register (USBEpDMADis - address 0x5000 C28C) bit description Bit Symbol Value Description Reset value
0 1 31:2
EP0_DMA_DISABLE EP1_DMA_DISABLE EPxx_DMA_DISABLE
0 0
Control endpoint OUT (DMA cannot be enabled for this endpoint and the EP0_DMA_DISABLE bit value must be 0).
0
Control endpoint IN (DMA cannot be enabled for this endpoint and the 0 EP1_DMA_DISABLE bit value must be 0). Endpoint xx (2 xx 31) DMA disable control bit. 0 No effect. Disable the DMA operation for endpoint EPxx.
0 1
10.7.8 USB DMA Interrupt Status register (USBDMAIntSt - 0x5000 C290)
Each bit of this register reflects whether any of the 32 bits in the corresponding interrupt status register are set. USBDMAIntSt is a read-only register.
Table 229. USB DMA Interrupt Status register (USBDMAIntSt - address 0x5000 C290) bit description Bit Symbol Value Description Reset value
0
EOT 0 1
End of Transfer Interrupt bit. All bits in the USBEoTIntSt register are 0. At least one bit in the USBEoTIntSt is set. New DD Request Interrupt bit. 0 1 All bits in the USBNDDRIntSt register are 0. At least one bit in the USBNDDRIntSt is set.
0
1
NDDR
0
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Table 229. USB DMA Interrupt Status register (USBDMAIntSt - address 0x5000 C290) bit description Bit Symbol Value Description Reset value
2
ERR 0 1
System Error Interrupt bit. All bits in the USBSysErrIntSt register are 0. At least one bit in the USBSysErrIntSt is set. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
31:3
-
-
NA
10.7.9 USB DMA Interrupt Enable register (USBDMAIntEn - 0x5000 C294)
Writing a one to a bit in this register enables the corresponding bit in USBDMAIntSt to generate an interrupt on the USB_INT_REQ_DMA interrupt line when set. USBDMAIntEn is a read/write register.
Table 230. USB DMA Interrupt Enable register (USBDMAIntEn - address 0x5000 C294) bit description Bit Symbol Value Description Reset value
0
EOT 0 1
End of Transfer Interrupt enable bit. The End of Transfer Interrupt is disabled. The End of Transfer Interrupt is enabled. New DD Request Interrupt enable bit. 0 1 The New DD Request Interrupt is disabled. The New DD Request Interrupt is enabled. System Error Interrupt enable bit. 0 1 The System Error Interrupt is disabled. The System Error Interrupt is enabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
NDDR
0
2
ERR
0
31:3
-
-
NA
10.7.10 USB End of Transfer Interrupt Status register (USBEoTIntSt - 0x5000 C2A0)
When the DMA transfer completes for the current DMA descriptor, either normally (descriptor is retired) or because of an error, the bit corresponding to the endpoint is set in this register. The cause of the interrupt is recorded in the DD_status field of the descriptor. USBEoTIntSt is a read-only register.
Table 231. USB End of Transfer Interrupt Status register (USBEoTIntSt - address 0x5000 C2A0s) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Endpoint xx (2 xx 31) End of Transfer Interrupt request. There is no End of Transfer interrupt request for endpoint xx. There is an End of Transfer Interrupt request for endpoint xx.
0
10.7.11 USB End of Transfer Interrupt Clear register (USBEoTIntClr - 0x5000 C2A4)
Writing one to a bit in this register clears the corresponding bit in the USBEoTIntSt register. Writing zero has no effect. USBEoTIntClr is a write-only register.
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Table 232. USB End of Transfer Interrupt Clear register (USBEoTIntClr - address 0x5000 C2A4) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Clear endpoint xx (2 xx 31) End of Transfer Interrupt request. No effect. Clear the EPxx End of Transfer Interrupt request in the USBEoTIntSt register.
0
10.7.12 USB End of Transfer Interrupt Set register (USBEoTIntSet - 0x5000 C2A8)
Writing one to a bit in this register sets the corresponding bit in the USBEoTIntSt register. Writing zero has no effect. USBEoTIntSet is a write-only register.
Table 233. USB End of Transfer Interrupt Set register (USBEoTIntSet - address 0x5000 C2A8) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Set endpoint xx (2 xx 31) End of Transfer Interrupt request. No effect. Set the EPxx End of Transfer Interrupt request in the USBEoTIntSt register.
0
10.7.13 USB New DD Request Interrupt Status register (USBNDDRIntSt - 0x5000 C2AC)
A bit in this register is set when a transfer is requested from the USB device and no valid DD is detected for the corresponding endpoint. USBNDDRIntSt is a read-only register.
Table 234. USB New DD Request Interrupt Status register (USBNDDRIntSt - address 0x5000 C2AC) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Endpoint xx (2 xx 31) new DD interrupt request. There is no new DD interrupt request for endpoint xx. There is a new DD interrupt request for endpoint xx.
0
10.7.14 USB New DD Request Interrupt Clear register (USBNDDRIntClr - 0x5000 C2B0)
Writing one to a bit in this register clears the corresponding bit in the USBNDDRIntSt register. Writing zero has no effect. USBNDDRIntClr is a write-only register.
Table 235. USB New DD Request Interrupt Clear register (USBNDDRIntClr - address 0x5000 C2B0) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Clear endpoint xx (2 xx 31) new DD interrupt request. No effect. Clear the EPxx new DD interrupt request in the USBNDDRIntSt register.
0
10.7.15 USB New DD Request Interrupt Set register (USBNDDRIntSet - 0x5000 C2B4)
Writing one to a bit in this register sets the corresponding bit in the USBNDDRIntSt register. Writing zero has no effect. USBNDDRIntSet is a write-only register
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Table 236. USB New DD Request Interrupt Set register (USBNDDRIntSet - address 0x5000 C2B4) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Set endpoint xx (2 xx 31) new DD interrupt request. No effect. Set the EPxx new DD interrupt request in the USBNDDRIntSt register.
0
10.7.16 USB System Error Interrupt Status register (USBSysErrIntSt - 0x5000 C2B8)
If a system error (AHB bus error) occurs when transferring the data or when fetching or updating the DD the corresponding bit is set in this register. USBSysErrIntSt is a read-only register.
Table 237. USB System Error Interrupt Status register (USBSysErrIntSt - address 0x5000 C2B8) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Endpoint xx (2 xx 31) System Error Interrupt request. There is no System Error Interrupt request for endpoint xx. There is a System Error Interrupt request for endpoint xx.
0
10.7.17 USB System Error Interrupt Clear register (USBSysErrIntClr - 0x5000 C2BC)
Writing one to a bit in this register clears the corresponding bit in the USBSysErrIntSt register. Writing zero has no effect. USBSysErrIntClr is a write-only register.
Table 238. USB System Error Interrupt Clear register (USBSysErrIntClr - address 0x5000 C2BC) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Clear endpoint xx (2 xx 31) System Error Interrupt request. No effect. Clear the EPxx System Error Interrupt request in the USBSysErrIntSt register.
0
10.7.18 USB System Error Interrupt Set register (USBSysErrIntSet - 0x5000 C2C0)
Writing one to a bit in this register sets the corresponding bit in the USBSysErrIntSt register. Writing zero has no effect. USBSysErrIntSet is a write-only register.
Table 239. USB System Error Interrupt Set register (USBSysErrIntSet - address 0x5000 C2C0) bit description Bit Symbol Value Description Reset value
31:0
EPxx 0 1
Set endpoint xx (2 xx 31) System Error Interrupt request. No effect. Set the EPxx System Error Interrupt request in the USBSysErrIntSt register.
0
11. Interrupt handling
This section describes how an interrupt event on any of the endpoints is routed to the Nested Vectored Interrupt Controller (NVIC). For a diagram showing interrupt event handling, see Figure 11-28. All non-isochronous OUT endpoints (control, bulk, and interrupt endpoints) generate an interrupt when they receive a packet without an error. All non-isochronous IN endpoints generate an interrupt when a packet has been successfully transmitted or when a NAK signal is sent and interrupts on NAK are enabled by the SIE Set Mode command, see Section 11-12.3. For isochronous endpoints, a frame interrupt is generated every 1 ms.
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The interrupt handling is different for Slave and DMA mode. Slave mode If an interrupt event occurs on an endpoint and the endpoint interrupt is enabled in the USBEpIntEn register, the corresponding status bit in the USBEpIntSt is set. For non-isochronous endpoints, all endpoint interrupt events are divided into two types by the corresponding USBEpIntPri[n] registers: fast endpoint interrupt events and slow endpoint interrupt events. All fast endpoint interrupt events are ORed and routed to bit EP_FAST in the USBDevIntSt register. All slow endpoint interrupt events are ORed and routed to the EP_SLOW bit in USBDevIntSt. For isochronous endpoints, the FRAME bit in USBDevIntSt is set every 1 ms. The USBDevIntSt register holds the status of all endpoint interrupt events as well as the status of various other interrupts (see Section 11-10.2.2). By default, all interrupts (if enabled in USBDevIntEn) are routed to the USB_INT_REQ_LP bit in the USBIntSt register to request low priority interrupt handling. However, the USBDevIntPri register can route either the FRAME or the EP_FAST bit to the USB_INT_REQ_HP bit in the USBIntSt register. Only one of the EP_FAST and FRAME interrupt events can be routed to the USB_INT_REQ_HP bit. If routing both bits to USB_INT_REQ_HP is attempted, both interrupt events are routed to USB_INT_REQ_LP. Slow endpoint interrupt events are always routed directly to the USB_INT_REQ_LP bit for low priority interrupt handling by software. The final interrupt signal to the NVIC is gated by the EN_USB_INTS bit in the USBIntSt register. The USB interrupts are routed to the NVIC only if EN_USB_INTS is set. DMA mode If an interrupt event occurs on a non-control endpoint and the endpoint interrupt is not enabled in the USBEpIntEn register, the corresponding status bit in the USBDMARSt is set by hardware. This serves as a flag for the DMA engine to transfer data if DMA transfer is enabled for the corresponding endpoint in the USBEpDMASt register. Three types of interrupts can occur for each endpoint for data transfers in DMA mode: End of transfer interrupt, new DD request interrupt, and system error interrupt. These interrupt events set a bit for each endpoint in the respective registers USBEoTIntSt, USBNDDRIntSt, and USBSysErrIntSt. The End of transfer interrupts from all endpoints are then Ored and routed to the EOT bit in USBDMAIntSt. Likewise, all New DD request interrupts and system error interrupt events are routed to the NDDR and ERR bits respectively in the USBDMAStInt register. The EOT, NDDR, and ERR bits (if enabled in USBDMAIntEn) are ORed to set the USB_INT_REQ_DMA bit in the USBIntSt register. If the EN_USB_INTS bit is set in USBIntSt, the interrupt is routed to the NVIC.
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interrupt event on EPn
Slave mode from other Endpoints . . . . n . . . . USBDevIntSt
FRAME EP_FAST EP_SLOW USBDevIntPri[0]
USBEpIntSt
USBEpIntEn[n]
. . . . . USBEpIntPri[n] . . .
. . . .
USBDevIntPri[1] ERR_INT
. . . .
USBDMARSt
USBIntSt
USB_INT_REQ_HP USB_INT_REQ_LP USB_INT_REQ_DMA
to NVIC
n
to DMA engine
EN_USB_INTS
USBEoTIntST 0 . . . . 31 USBNDDRIntSt 0 . . . . 31 USBSysErrIntSt 0 . . . . 31
DMA Mode
USBDMAIntSt EOT NDDR ERR
For simplicity, USBDevIntEn and USBDMAIntEn are not shown.
Fig 28. Interrupt event handling
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12. Serial interface engine command description
The functions and registers of the Serial Interface Engine (SIE) are accessed using commands, which consist of a command code followed by optional data bytes (read or write action). The USBCmdCode (Table 11-219) and USBCmdData (Table 11-220) registers are used for these accesses. A complete access consists of two phases: 1. Command phase: the USBCmdCode register is written with the CMD_PHASE field set to the value 0x05 (Command), and the CMD_CODE field set to the desired command code. On completion of the command, the CCEMPTY bit of USBDevIntSt is set. 2. Data phase (optional): for writes, the USBCmdCode register is written with the CMD_PHASE field set to the value 0x01 (Write), and the CMD_WDATA field set with the desired write data. On completion of the write, the CCEMPTY bit of USBDevIntSt is set. For reads, USBCmdCode register is written with the CMD_PHASE field set to the value 0x02 (Read), and the CMD_CODE field set with command code the read corresponds to. On completion of the read, the CDFULL bit of USBDevInSt will be set, indicating the data is available for reading in the USBCmdData register. In the case of multi-byte registers, the least significant byte is accessed first. An overview of the available commands is given in Table 11-240. Here is an example of the Read Current Frame Number command (reading 2 bytes): USBDevIntClr = 0x30; // USBCmdCode = 0x00F50500; // while (!(USBDevIntSt & 0x10)); // USBDevIntClr = 0x10; // USBCmdCode = 0x00F50200; // while (!(USBDevIntSt & 0x20)); // USBDevIntClr = 0x20; // CurFrameNum = USBCmdData; // USBCmdCode = 0x00F50200; // while (!(USBDevIntSt & 0x20)); // Temp = USBCmdData; // USBDevIntClr = 0x20; // CurFrameNum = CurFrameNum | (Temp Clear both CCEMPTY & CDFULL CMD_CODE=0xF5, CMD_PHASE=0x05(Command) Wait for CCEMPTY. Clear CCEMPTY interrupt bit. CMD_CODE=0xF5, CMD_PHASE=0x02(Read) Wait for CDFULL. Clear CDFULL. Read Frame number LSB byte. CMD_CODE=0xF5, CMD_PHASE=0x02(Read) Wait for CDFULL. Read Frame number MSB byte Clear CDFULL interrupt bit. << 8);
Here is an example of the Set Address command (writing 1 byte): // // // // // // while (!(USBDevIntSt & 0x10)); // USBDevIntClr = 0x10; // USBDevIntClr = 0x10; USBCmdCode = 0x00D00500; while (!(USBDevIntSt & 0x10)); USBDevIntClr = 0x10; USBCmdCode = 0x008A0100; Clear CCEMPTY. CMD_CODE=0xD0, CMD_PHASE=0x05(Command) Wait for CCEMPTY. Clear CCEMPTY. CMD_WDATA=0x8A(DEV_EN=1, DEV_ADDR=0xA), CMD_PHASE=0x01(Write) Wait for CCEMPTY. Clear CCEMPTY.
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Table 240. SIE command code table Command name Device commands Recipient Code (Hex) Data phase
Set Address Configure Device Set Mode Read Current Frame Number Read Test Register Set Device Status Get Device Status Get Error Code Read Error Status
Endpoint Commands
Device Device Device Device Device Device Device Device Device Endpoint 0 Endpoint 1 Endpoint xx
D0 D8 F3 F5 FD FE FE FF FB 00 01 xx 40 41 xx + 40 40 41 xx + 40 F2 FA
Write 1 byte Write 1 byte Write 1 byte Read 1 or 2 bytes Read 2 bytes Write 1 byte Read 1 byte Read 1 byte Read 1 byte Read 1 byte (optional) Read 1 byte (optional) Read 1 byte (optional) Read 1 byte Read 1 byte Read 1 byte Write 1 byte Write 1 byte Write 1 byte Read 1 byte (optional) None
Select Endpoint
Select Endpoint/Clear Interrupt
Endpoint 0 Endpoint 1 Endpoint xx
Set Endpoint Status
Endpoint 0 Endpoint 1 Endpoint xx
Clear Buffer Validate Buffer
Selected Endpoint Selected Endpoint
12.1 Set Address (Command: 0xD0, Data: write 1 byte)
The Set Address command is used to set the USB assigned address and enable the (embedded) function. The address set in the device will take effect after the status stage of the control transaction. After a bus reset, DEV_ADDR is set to 0x00, and DEV_EN is set to 1. The device will respond to packets for function address 0x00, endpoint 0 (default endpoint).
Table 241. Set Address command bit description Bit Symbol Description Reset value
6:0 7
DEV_ADDR DEV_EN
Device address set by the software. After a bus reset this field is set to 0x00. Device Enable. After a bus reset this bit is set to 1. 0: Device will not respond to any packets. 1: Device will respond to packets for function address DEV_ADDR.
0x00 0
12.2 Configure Device (Command: 0xD8, Data: write 1 byte)
A value of 1 written to the register indicates that the device is configured and all the enabled non-control endpoints will respond. Control endpoints are always enabled and respond even if the device is not configured, in the default state.
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Table 242. Configure Device command bit description Bit Symbol Description Reset value
0
CONF_DEVICE
Device is configured. All enabled non-control endpoints will respond. This bit is cleared by hardware when a bus reset occurs. When set, the UP_LED signal is driven LOW if the device is not in the suspended state (SUS=0). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
7:1
-
12.3 Set Mode (Command: 0xF3, Data: write 1 byte)
Table 243. Set Mode command bit description Bit Symbol Value Description Reset value
0
AP_CLK 0 1
Always PLL Clock. USB_NEED_CLK is functional; the 48 MHz clock can be stopped when the device enters suspend state. USB_NEED_CLK is fixed to 1; the 48 MHz clock cannot be stopped when the device enters suspend state. Interrupt on NAK for Control IN endpoint. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed IN transactions generate interrupts. Interrupt on NAK for Control OUT endpoint. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed OUT transactions generate interrupts. Interrupt on NAK for Interrupt IN endpoint. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed IN transactions generate interrupts. Interrupt on NAK for Interrupt OUT endpoints. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed OUT transactions generate interrupts. Interrupt on NAK for Bulk IN endpoints. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed IN transactions generate interrupts. Interrupt on NAK for Bulk OUT endpoints. 0 1 Only successful transactions generate an interrupt. Both successful and NAKed OUT transactions generate interrupts.
0
1
INAK_CI
0
2
INAK_CO
0
3
INAK_II
0
4
INAK_IO[1]
0
5
INAK_BI
0
6
INAK_BO[2]
0
7
-
-
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined.
[1] [2] This bit should be reset to 0 if the DMA is enabled for any of the Interrupt OUT endpoints. This bit should be reset to 0 if the DMA is enabled for any of the Bulk OUT endpoints.
12.4 Read Current Frame Number (Command: 0xF5, Data: read 1 or 2 bytes)
Returns the frame number of the last successfully received SOF. The frame number is eleven bits wide. The frame number returns least significant byte first. In case the user is only interested in the lower 8 bits of the frame number, only the first byte needs to be read.
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* In case no SOF was received by the device at the beginning of a frame, the frame
number returned is that of the last successfully received SOF.
* In case the SOF frame number contained a CRC error, the frame number returned will
be the corrupted frame number as received by the device.
12.5 Read Test Register (Command: 0xFD, Data: read 2 bytes)
The test register is 16 bits wide. It returns the value of 0xA50F if the USB clocks (usbclk and AHB slave clock) are running.
12.6 Set Device Status (Command: 0xFE, Data: write 1 byte)
The Set Device Status command sets bits in the Device Status Register.
Table 244. Set Device Status command bit description Bit Symbol Value Description Reset value
0
CON
The Connect bit indicates the current connect status of the device. It controls the 0 CONNECT output pin, used for SoftConnect. Reading the connect bit returns the current connect status. This bit is cleared by hardware when the VBUS status input is LOW for more than 3 ms. The 3 ms delay filters out temporary dips in the VBUS voltage. 0 1 Writing a 0 will make the CONNECT pin go HIGH. Writing a 1 will make the CONNECT pin go LOW. Connect Change. 0 1 This bit is cleared when read. This bit is set when the device's pull-up resistor is disconnected because VBUS disappeared. The DEV_STAT interrupt is generated when this bit is 1. Suspend: The Suspend bit represents the current suspend state. 0 When the device is suspended (SUS = 1) and the CPU writes a 0 into it, the device will generate a remote wake-up. This will only happen when the device is connected (CON = 1). When the device is not connected or not suspended, writing a 0 has no effect. Writing a 1 to this bit has no effect. 0 1 This bit is reset to 0 on any activity. This bit is set to 1 when the device hasn't seen any activity on its upstream port for more than 3 ms. Suspend (SUS) bit change indicator. The SUS bit can toggle because: 0 0
1
CON_CH
2
SUS
3
SUS_CH
* * *
0 1
The device goes into the suspended state. The device is disconnected. The device receives resume signalling on its upstream port.
This bit is cleared when read. SUS bit not changed. SUS bit changed. At the same time a DEV_STAT interrupt is generated.
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Table 244. Set Device Status command bit description Bit Symbol Value Description Reset value
4
RST
Bus Reset bit. On a bus reset, the device will automatically go to the default state. In the default state:
0
* * * * * * * *
0 1 7:5 -
Device is unconfigured. Will respond to address 0. Control endpoint will be in the Stalled state. All endpoints are unrealized except control endpoints EP0 and EP1. Data toggling is reset for all endpoints. All buffers are cleared. There is no change to the endpoint interrupt status. DEV_STAT interrupt is generated.
Note: Bus resets are ignored when the device is not connected (CON=0). This bit is cleared when read. This bit is set when the device receives a bus reset. A DEV_STAT interrupt is generated. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
12.7 Get Device Status (Command: 0xFE, Data: read 1 byte)
The Get Device Status command returns the Device Status Register. Reading the device status returns 1 byte of data. The bit field definition is same as the Set Device Status Register as shown in Table 11-244. Remark: To ensure correct operation, the DEV_STAT bit of USBDevIntSt must be cleared before executing the Get Device Status command.
12.8 Get Error Code (Command: 0xFF, Data: read 1 byte)
Different error conditions can arise inside the SIE. The Get Error Code command returns the last error code that occurred. The 4 least significant bits form the error code.
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Table 245. Get Error Code command bit description Bit Symbol Value Description Reset value
3:0
EC 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
Error Code. No Error. PID Encoding Error. Unknown PID. Unexpected Packet - any packet sequence violation from the specification. Error in Token CRC. Error in Data CRC. Time Out Error. Babble. Error in End of Packet. Sent/Received NAK. Sent Stall. Buffer Overrun Error. Sent Empty Packet (ISO Endpoints only). Bitstuff Error. Error in Sync. Wrong Toggle Bit in Data PID, ignored data. The Error Active bit will be reset once this register is read. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x0
4 7:5
EA -
-
NA
12.9 Read Error Status (Command: 0xFB, Data: read 1 byte)
This command reads the 8-bit Error register from the USB device. This register records which error events have recently occurred in the SIE. If any of these bits are set, the ERR_INT bit of USBDevIntSt is set. The error bits are cleared after reading this register.
Table 246. Read Error Status command bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7
PID_ERR UEPKT DCRC TIMEOUT EOP B_OVRN BTSTF TGL_ERR
PID encoding error or Unknown PID or Token CRC. Unexpected Packet - any packet sequence violation from the specification. Data CRC error. Time out error. End of packet error. Buffer Overrun. Bit stuff error. Wrong toggle bit in data PID, ignored data.
0 0 0 0 0 0 0 0
12.10 Select Endpoint (Command: 0x00 - 0x1F, Data: read 1 byte (optional))
The Select Endpoint command initializes an internal pointer to the start of the selected buffer in EP_RAM. Optionally, this command can be followed by a data read, which returns some additional information on the packet(s) in the endpoint buffer(s). The command code of the Select Endpoint command is equal to the physical endpoint number. In the case of a single buffered endpoint the B_2_FULL bit is not valid.
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Table 247. Select Endpoint command bit description Bit Symbol Value Description Reset value
0
FE
Full/Empty. This bit indicates the full or empty status of the endpoint buffer(s). For IN endpoints, the FE bit gives the ANDed result of the B_1_FULL and B_2_FULL bits. For OUT endpoints, the FE bit gives ORed result of the B_1_FULL and B_2_FULL bits. For single buffered endpoints, this bit simply reflects the status of B_1_FULL. 0 1 For an IN endpoint, at least one write endpoint buffer is empty. For an OUT endpoint, at least one endpoint read buffer is full. Stalled endpoint indicator. 0 1 The selected endpoint is not stalled. The selected endpoint is stalled. SETUP bit: the value of this bit is updated after each successfully received packet (i.e. an ACKed package on that particular physical endpoint). 0 1 The STP bit is cleared by doing a Select Endpoint/Clear Interrupt on this endpoint. The last received packet for the selected endpoint was a SETUP packet. Packet over-written bit. 0 1 The PO bit is cleared by the `Select Endpoint/Clear Interrupt' command. The previously received packet was over-written by a SETUP packet.
0
1
ST
0
2
STP
0
3
PO
0
4
EPN
EP NAKed bit indicates sending of a NAK. If the host sends an OUT packet to a 0 filled OUT buffer, the device returns NAK. If the host sends an IN token packet to an empty IN buffer, the device returns NAK. 0 1 The EPN bit is reset after the device has sent an ACK after an OUT packet or when the device has seen an ACK after sending an IN packet. The EPN bit is set when a NAK is sent and the interrupt on NAK feature is enabled. The buffer 1 status. 0 1 Buffer 1 is empty. Buffer 1 is full. The buffer 2 status. 0 1 Buffer 2 is empty. Buffer 2 is full. Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. 0 0
5
B_1_FULL
6
B_2_FULL
7
-
-
12.11 Select Endpoint/Clear Interrupt (Command: 0x40 - 0x5F, Data: read 1 byte)
Commands 0x40 to 0x5F are identical to their Select Endpoint equivalents, with the following differences:
* They clear the bit corresponding to the endpoint in the USBEpIntSt register. * In case of a control OUT endpoint, they clear the STP and PO bits in the
corresponding Select Endpoint Register.
* Reading one byte is obligatory.
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Remark: This command may be invoked by using the USBCmdCode and USBCmdData registers, or by setting the corresponding bit in USBEpIntClr. For ease of use, using the USBEpIntClr register is recommended.
12.12 Set Endpoint Status (Command: 0x40 - 0x55, Data: write 1 byte (optional))
The Set Endpoint Status command sets status bits 7:5 and 0 of the endpoint. The Command Code of Set Endpoint Status is equal to the sum of 0x40 and the physical endpoint number in hex. Not all bits can be set for all types of endpoints.
Table 248. Set Endpoint Status command bit description Bit Symbol Value Description Reset value
0
ST
Stalled endpoint bit. A Stalled control endpoint is automatically unstalled when it 0 receives a SETUP token, regardless of the content of the packet. If the endpoint should stay in its stalled state, the CPU can stall it again by setting this bit. When a stalled endpoint is unstalled - either by the Set Endpoint Status command or by receiving a SETUP token - it is also re-initialized. This flushes the buffer: in case of an OUT buffer it waits for a DATA 0 PID; in case of an IN buffer it writes a DATA 0 PID. There is no change of the interrupt status of the endpoint. When already unstalled, writing a zero to this bit initializes the endpoint. When an endpoint is stalled by the Set Endpoint Status command, it is also re-initialized. 0 1 The endpoint is unstalled. The endpoint is stalled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Disabled endpoint bit. 0 1 The endpoint is enabled. The endpoint is disabled. Rate Feedback Mode. 0 1 Interrupt endpoint is in the Toggle mode. Interrupt endpoint is in the Rate Feedback mode. This means that transfer takes place without data toggle bit. Conditional Stall bit. 0 1 Unstalls both control endpoints. Stall both control endpoints, unless the STP bit is set in the Select Endpoint register. It is defined only for control OUT endpoints. 0 0 NA 0
4:1 5
DA
-
6
RF_MO
7
CND_ST
12.13 Clear Buffer (Command: 0xF2, Data: read 1 byte (optional))
When an OUT packet sent by the host has been received successfully, an internal hardware FIFO status Buffer_Full flag is set. All subsequent packets will be refused by returning a NAK. When the device software has read the data, it should free the buffer by issuing the Clear Buffer command. This clears the internal Buffer_Full flag. When the buffer is cleared, new packets will be accepted. When bit 0 of the optional data byte is 1, the previously received packet was over-written by a SETUP packet. The Packet over-written bit is used only in control transfers. According to the USB specification, a SETUP packet should be accepted irrespective of the buffer status. The software should always check the status of the PO bit after reading
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the SETUP data. If it is set then it should discard the previously read data, clear the PO bit by issuing a Select Endpoint/Clear Interrupt command, read the new SETUP data and again check the status of the PO bit. See Section 11-14 "Slave mode operation" for a description of when this command is used.
Table 249. Clear Buffer command bit description Bit Symbol Value Description Reset value
0
PO 0 1
Packet over-written bit. This bit is only applicable to the control endpoint EP0. The previously received packet is intact. The previously received packet was over-written by a later SETUP packet.
0
7:1
-
-
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
12.14 Validate Buffer (Command: 0xFA, Data: none)
When the CPU has written data into an IN buffer, software should issue a Validate Buffer command. This tells hardware that the buffer is ready for sending on the USB bus. Hardware will send the contents of the buffer when the next IN token packet is received. Internally, there is a hardware FIFO status flag called Buffer_Full. This flag is set by the Validate Buffer command and cleared when the data has been sent on the USB bus and the buffer is empty. A control IN buffer cannot be validated when its corresponding OUT buffer has the Packet Over-written (PO) bit (see the Clear Buffer Register) set or contains a pending SETUP packet. For the control endpoint the validated buffer will be invalidated when a SETUP packet is received. See Section 11-14 "Slave mode operation" for a description of when this command is used.
13. USB device controller initialization
The LPC17xx USB device controller initialization includes the following steps: 1. Enable the device controller by setting the PCUSB bit of PCONP. 2. Configure and enable the PLL and Clock Dividers to provide 48 MHz for usbclk and the desired frequency for cclk. For correct operation of synchronization logic in the device controller, the minimum cclk frequency is 18 MHz. For the procedure for determining the PLL setting and configuration, see Section 4-5.11 "Procedure for determining PLL0 settings". 3. Enable the device controller clocks by setting DEV_CLK_EN and AHB_CLK_EN bits in the USBClkCtrl register. Poll the respective clock bits in the USBClkSt register until they are set. 4. Enable the USB pin functions by writing to the corresponding PINSEL register. 5. Disable the pull-ups and pull-downs on the VBUS pin using the corresponding PINMODE register by putting the pin in the "pin has neither pull-up nor pull-down resistor enabled" mode. See Section 8-4 "Pin mode select register values".
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6. Set USBEpIn and USBMaxPSize registers for EP0 and EP1, and wait until the EP_RLZED bit in USBDevIntSt is set so that EP0 and EP1 are realized. 7. Enable endpoint interrupts (Slave mode): - Clear all endpoint interrupts using USBEpIntClr. - Clear any device interrupts using USBDevIntClr. - Enable Slave mode for the desired endpoints by setting the corresponding bits in USBEpIntEn. - Set the priority of each enabled interrupt using USBEpIntPri. - Configure the desired interrupt mode using the SIE Set Mode command. - Enable device interrupts using USBDevIntEn (normally DEV_STAT, EP_SLOW, and possibly EP_FAST). 8. Configure the DMA (DMA mode): - Disable DMA operation for all endpoints using USBEpDMADis. - Clear any pending DMA requests using USBDMARClr. - Clear all DMA interrupts using USBEoTIntClr, USBNDDRIntClr, and USBSysErrIntClr. - Prepare the UDCA in system memory. - Write the desired address for the UDCA to USBUDCAH (for example 0x7FD0 0000). - Enable the desired endpoints for DMA operation using USBEpDMAEn. - Set EOT, DDR, and ERR bits in USBDMAIntEn. 9. Install USB interrupt handler in the NVIC by writing its address to the appropriate vector table location and enabling the USB interrupt in the NVIC. 10. Set default USB address to 0x0 and DEV_EN to 1 using the SIE Set Address command. A bus reset will also cause this to happen. 11. Set CON bit to 1 to make CONNECT active using the SIE Set Device Status command. The configuration of the endpoints varies depending on the software application. By default, all the endpoints are disabled except control endpoints EP0 and EP1. Additional endpoints are enabled and configured by software after a SET_CONFIGURATION or SET_INTERFACE device request is received from the host.
14. Slave mode operation
In Slave mode, the CPU transfers data between RAM and the endpoint buffer using the Register Interface.
14.1 Interrupt generation
In slave mode, data packet transfer between RAM and an endpoint buffer can be initiated in response to an endpoint interrupt. Endpoint interrupts are enabled using the USBEpIntEn register, and are observable in the USBEpIntSt register.
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All non-isochronous OUT endpoints generate an endpoint interrupt when they receive a packet without an error. All non-isochronous IN endpoints generate an interrupt when a packet is successfully transmitted, or when a NAK handshake is sent on the bus and the interrupt on NAK feature is enabled. For Isochronous endpoints, transfer of data is done when the FRAME interrupt (in USBDevIntSt) occurs.
14.2 Data transfer for OUT endpoints
When the software wants to read the data from an endpoint buffer it should set the RD_EN bit and program LOG_ENDPOINT with the desired endpoint number in the USBCtrl register. The control logic will fetch the packet length to the USBRxPLen register, and set the PKT_RDY bit (Table 11-215). Software can now start reading the data from the USBRxData register (Table 11-214). When the end of packet is reached, the RD_EN bit is cleared, and the RxENDPKT bit is set in the USBDevSt register. Software now issues a Clear Buffer (refer to Table 11-249) command. The endpoint is now ready to accept the next packet. For OUT isochronous endpoints, the next packet will be received irrespective of whether the buffer has been cleared. Any data not read from the buffer before the end of the frame is lost. See Section 11-16 "Double buffered endpoint operation" for more details. If the software clears RD_EN before the entire packet is read, reading is terminated, and the data remains in the endpoint's buffer. When RD_EN is set again for this endpoint, the data will be read from the beginning.
14.3 Data transfer for IN endpoints
When writing data to an endpoint buffer, WR_EN (Section 11-10.5.5 "USB Control register (USBCtrl - 0x5000 C228)") is set and software writes to the number of bytes it is going to send in the packet to the USBTxPLen register (Section 11-10.5.4). It can then write data continuously in the USBTxData register. When the number of bytes programmed in USBTxPLen have been written to USBTxData, the WR_EN bit is cleared, and the TxENDPKT bit is set in the USBDevIntSt register. Software issues a Validate Buffer (Section 11-12.14 "Validate Buffer (Command: 0xFA, Data: none)") command. The endpoint is now ready to send the packet. For IN isochronous endpoints, the data in the buffer will be sent only if the buffer is validated before the next FRAME interrupt occurs; otherwise, an empty packet will be sent in the next frame. If the software clears WR_EN before the entire packet is written, writing will start again from the beginning the next time WR_EN is set for this endpoint. Both RD_EN and WR_EN can be high at the same time for the same logical endpoint. Interleaved read and write operation is possible.
15. DMA operation
In DMA mode, the DMA transfers data between RAM and the endpoint buffer. The following sections discuss DMA mode operation. Background information is given in sections Section 11-15.2 "USB device communication area" and Section 11-15.3 "Triggering the DMA engine". The fields of the DMA Descriptor are described in Section
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11-15.4 "The DMA descriptor". The last three sections describe DMA operation: Section 11-15.5 "Non-isochronous endpoint operation", Section 11-15.6 "Isochronous endpoint operation", and Section 11-15.7 "Auto Length Transfer Extraction (ATLE) mode operation".
15.1 Transfer terminology
Within this section three types of transfers are mentioned: 1. USB transfers - transfer of data over the USB bus. The USB 2.0 specification refers to these simply as transfers. Within this section they are referred to as USB transfers to distinguish them from DMA transfers. A USB transfer is composed of transactions. Each transaction is composed of packets. 2. DMA transfers - the transfer of data between an endpoint buffer and system memory (RAM). 3. Packet transfers - in this section, a packet transfer refers to the transfer of a packet of data between an endpoint buffer and system memory (RAM). A DMA transfer is composed of one or more packet transfers.
15.2 USB device communication area
The CPU and DMA controller communicate through a common area of memory, called the USB Device Communication Area, or UDCA. The UDCA is a 32-word array of DMA Descriptor Pointers (DDPs), each of which corresponds to a physical endpoint. Each DDP points to the start address of a DMA Descriptor, if one is defined for the endpoint. DDPs for unrealized endpoints and endpoints disabled for DMA operation are ignored and can be set to a NULL (0x0) value. The start address of the UDCA is stored in the USBUDCAH register. The UDCA can reside at any 128-byte boundary of RAM that is accessible to both the CPU and DMA controller. Figure 11-29 illustrates the UDCA and its relationship to the UDCA Head (USBUDCAH) register and DMA Descriptors.
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UDCA
0 1 2
NULL NULL NULL Next_DD_pointer Next_DD_pointer Next_DD_pointer
DDP-EP2 DD-EP2-a DD-EP2-b DD-EP2-c
NULL UDCA HEAD REGISTER Next_DD_pointer 16 DDP-EP16 DD-EP16-a DD-EP16-b Next_DD_pointer NULL
31 DDP-EP31
Fig 29. UDCA Head register and DMA Descriptors
15.3 Triggering the DMA engine
An endpoint raises a DMA request when Slave mode is disabled by setting the corresponding bit in the USBEpIntEn register to 0 (Section 11-10.3.2) and an endpoint interrupt occurs (see Section 11-10.7.1 "USB DMA Request Status register (USBDMARSt - 0x5000 C250)"). A DMA transfer for an endpoint starts when the endpoint is enabled for DMA operation in USBEpDMASt, the corresponding bit in USBDMARSt is set, and a valid DD is found for the endpoint. All endpoints share a single DMA channel to minimize hardware overhead. If more than one DMA request is active in USBDMARSt, the endpoint with the lowest physical endpoint number is processed first. In DMA mode, the bits corresponding to Interrupt on NAK for Bulk OUT and Interrupt OUT endpoints (INAK_BO and INAK_IO) should be set to 0 using the SIE Set Mode command (Section 11-12.3).
15.4 The DMA descriptor
DMA transfers are described by a data structure called the DMA Descriptor (DD). DDs are placed in RAM. These descriptors can be located anywhere in on-chip RAM at word-aligned addresses. DDs for non-isochronous endpoints are four words long. DDs for isochronous endpoints are five words long. The parameters associated with a DMA transfer are:
* The start address of the DMA buffer
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* * * * *
The length of the DMA buffer The start address of the next DMA descriptor Control information Count information (number of bytes transferred) Status information
Table 11-250 lists the DMA descriptor fields.
Table 250. DMA descriptor Word position Access (H/W) Access (S/W) Bit position Description
0 1
R R R R R R/W[1]
R/W R/W R/W R/W R/W R/W
31:0 1:0 2 3 4 15:5 31:16
Next_DD_pointer DMA_mode (00 -Normal; 01 - ATLE) Next_DD_valid (1 - valid; 0 - invalid) Reserved Isochronous_endpoint (1 - isochronous; 0 - non-isochronous) Max_packet_size DMA_buffer_length This value is specified in bytes for non-isochronous endpoints and in number of packets for isochronous endpoints.
2 3
R/W R/W W
R/W R/I R/I
31:0 0 4:1
DMA_buffer_start_addr DD_retired (To be initialized to 0) DD_status (To be initialized to 0000): 0000 - NotServiced 0001 - BeingServiced 0010 - NormalCompletion 0011 - DataUnderrun (short packet) 1000 - DataOverrun 1001 - SystemError
W W W R R/W 4 R/W
R/I R/I R/I W R/I R/W
[1]
5 6 7 13:8 15:14 31:16 31:0
Packet_valid (To be initialized to 0) LS_byte_extracted (ATLE mode) (To be initialized to 0) MS_byte_extracted (ATLE mode) (To be initialized to 0) Message_length_position (ATLE mode) Reserved Present_DMA_count (To be initialized to 0) Isochronous_packetsize_memory_address
Write-only in ATLE mode
Legend: R - Read; W - Write; I - Initialize
15.4.1 Next_DD_pointer
Pointer to the memory location from where the next DMA descriptor will be fetched.
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15.4.2 DMA_mode
Specifies the DMA mode of operation. Two modes have been defined: Normal and Automatic Transfer Length Extraction (ATLE) mode. In normal mode, software initializes the DMA_buffer_length for OUT endpoints. In ATLE mode, the DMA_buffer_length is extracted from the incoming data. See Section 11-15.7 "Auto Length Transfer Extraction (ATLE) mode operation" on page 261 for more details.
15.4.3 Next_DD_valid
This bit indicates whether the software has prepared the next DMA descriptor. If set, the DMA engine fetches the new descriptor when it is finished with the current one.
15.4.4 Isochronous_endpoint
When set, this bit indicates that the descriptor belongs to an isochronous endpoint. Hence 5 words have to be read when fetching it.
15.4.5 Max_packet_size
The maximum packet size of the endpoint. This parameter is used while transferring the data for IN endpoints from the memory. It is used for OUT endpoints to detect the short packet. This is applicable to non-isochronous endpoints only. This field should be set to the same MPS value that is assigned for the endpoint using the USBMaxPSize register.
15.4.6 DMA_buffer_length
This indicates the depth of the DMA buffer allocated for transferring the data. The DMA engine will stop using this descriptor when this limit is reached and will look for the next descriptor. In Normal mode operation, software sets this value for both IN and OUT endpoints. In ATLE mode operation, software sets this value for IN endpoints only. For OUT endpoints, hardware sets this value using the extracted length of the data stream. For isochronous endpoints, DMA_buffer_length is specified in number of packets, for non-isochronous endpoints in bytes.
15.4.7 DMA_buffer_start_addr
The address where the data is read from or written to. This field is updated each time the DMA engine finishes transferring a packet.
15.4.8 DD_retired
This bit is set by hardware when the DMA engine finishes the current descriptor. This happens when the end of the buffer is reached, a short packet is transferred (non-isochronous endpoints), or an error condition is detected.
15.4.9 DD_status
The status of the DMA transfer is encoded in this field. The following codes are defined:
* NotServiced - No packet has been transferred yet. * BeingServiced - At least one packet is transferred. * NormalCompletion - The DD is retired because the end of the buffer is reached and
there were no errors. The DD_retired bit is also set.
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* DataUnderrun - Before reaching the end of the DMA buffer, the USB transfer is
terminated because a short packet is received. The DD_retired bit is also set.
* DataOverrun - The end of the DMA buffer is reached in the middle of a packet
transfer. This is an error situation. The DD_retired bit is set. The present DMA count field is equal to the value of DMA_buffer_length. The packet must be re-transmitted from the endpoint buffer in another DMA transfer. The corresponding EPxx_DMA_ENABLE bit in USBEpDMASt is cleared.
* SystemError - The DMA transfer being serviced is terminated because of an error on
the AHB bus. The DD_retired bit is not set in this case. The corresponding EPxx_DMA_ENABLE in USBEpDMASt is cleared. Since a system error can happen while updating the DD, the DD fields in RAM may be unreliable.
15.4.10 Packet_valid
This bit is used for isochronous endpoints. It indicates whether the last packet transferred to the memory is received with errors or not. This bit is set if the packet is valid, i.e., it was received without errors. See Section 11-15.6 "Isochronous endpoint operation" on page 259 for isochronous endpoint operation. This bit is unnecessary for non-isochronous endpoints because a DMA request is generated only for packets without errors, and thus Packet_valid will always be set when the request is generated.
15.4.11 LS_byte_extracted
Used in ATLE mode. When set, this bit indicates that the Least Significant Byte (LSB) of the transfer length has been extracted. The extracted size is reflected in the DMA_buffer_length field, bits 23:16.
15.4.12 MS_byte_extracted
Used in ATLE mode. When set, this bit indicates that the Most Significant Byte (MSB) of the transfer size has been extracted. The size extracted is reflected in the DMA_buffer_length field, bits 31:24. Extraction stops when LS_Byte_extracted and MS_byte_extracted bits are set.
15.4.13 Present_DMA_count
The number of bytes transferred by the DMA engine. The DMA engine updates this field after completing each packet transfer. For isochronous endpoints, Present_DMA_count is the number of packets transferred; for non-isochronous endpoints, Present_DMA_count is the number of bytes.
15.4.14 Message_length_position
Used in ATLE mode. This field gives the offset of the message length position embedded in the incoming data packets. This is applicable only for OUT endpoints. Offset 0 indicates that the message length starts from the first byte of the first packet.
15.4.15 Isochronous_packetsize_memory_address
The memory buffer address where the packet size information along with the frame number has to be transferred or fetched. See Figure 11-30. This is applicable to isochronous endpoints only.
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15.5 Non-isochronous endpoint operation
15.5.1 Setting up DMA transfers
Software prepares the DMA Descriptors (DDs) for those physical endpoints to be enabled for DMA transfer. These DDs are present in on-chip RAM. The start address of the first DD is programmed into the DMA Description pointer (DDP) location for the corresponding endpoint in the UDCA. Software then sets the EPxx_DMA_ENABLE bit for this endpoint in the USBEpDMAEn register (Section 11-10.7.6).The DMA_mode bit field in the descriptor is set to `00' for normal mode operation. All other DD fields are initialized as specified in Table 11-250. DMA operation is not supported for physical endpoints 0 and 1 (default control endpoints).
15.5.2 Finding DMA Descriptor
When there is a trigger for a DMA transfer for an endpoint, the DMA engine will first determine whether a new descriptor has to the fetched or not. A new descriptor does not have to be fetched if the last packet transferred was for the same endpoint and the DD is not yet in the retired state. An internal flag called DMA_PROCEED is used to identify this condition (see Section 11-15.5.4 "Optimizing descriptor fetch" on page 258). If a new descriptor has to be read, the DMA engine will calculate the location of the DDP for this endpoint and will fetch the start address of the DD from this location. A DD start address at location zero is considered invalid. In this case the NDDR interrupt is raised. All other word-aligned addresses are considered valid. When the DD is fetched, the DD status word (word 3) is read first and the status of the DD_retired bit is checked. If not set, DDP points to a valid DD. If DD_retired is set, the DMA engine will read the control word (word 1) of the DD. If Next_DD_valid bit is set, the DMA engine will fetch the Next_DD_pointer field (word 0) of the DD and load it to the DDP. The new DDP is written to the UDCA area. The full DD (4 words) will then be fetched from the address in the DDP. The DD will give the details of the DMA transfer to be done. The DMA engine will load its hardware resources with the information fetched from the DD (start address, DMA count etc.). If Next_DD_valid is not set and DD_retired bit is set, the DMA engine raises the NDDR interrupt for this endpoint and clears the corresponding EPxx_DMA_ENABLE bit.
15.5.3 Transferring the data
For OUT endpoints, the current packet is read from the EP_RAM by the DMA Engine and transferred to on-chip RAM memory locations starting from DMA_buffer_start_addr. For IN endpoints, the data is fetched from on-chip RAM at DMA_buffer_start_addr and written to the EP_RAM. The DMA_buffer_start_addr and Present_DMA_count fields are updated after each packet is transferred.
15.5.4 Optimizing descriptor fetch
A DMA transfer normally involves multiple packet transfers. Hardware will not re-fetch a new DD from memory unless the endpoint changes. To indicate an ongoing multi-packet transfer, hardware sets an internal flag called DMA_PROCEED.
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The DMA_PROCEED flag is cleared after the required number of bytes specified in the DMA_buffer_length field is transferred. It is also cleared when the software writes into the USBEpDMADis register. The ability to clear the DMA_PROCEED flag allows software to to force the DD to be re-fetched for the next packet transfer. Writing all zeros into the USBEpDMADis register clears the DMA_PROCEED flag without disabling DMA operation for any endpoint.
15.5.5 Ending the packet transfer
On completing a packet transfer, the DMA engine writes back the DD with updated status information to the same memory location from where it was read. The DMA_buffer_start_addr, Present_DMA_count, and the DD_status fields in the DD are updated. A DD can have the following types of completion: Normal completion - If the current packet is fully transferred and the Present_DMA_count field equals the DMA_buffer_length, the DD has completed normally. The DD will be written back to memory with DD_retired set and DD_status set to NormalCompletion. The EOT interrupt is raised for this endpoint. USB transfer end completion - If the current packet is fully transferred and its size is less than the Max_packet_size field, and the end of the DMA buffer is still not reached, the USB transfer end completion occurs. The DD will be written back to the memory with DD_retired set and DD_Status set to the DataUnderrun completion code. The EOT interrupt is raised for this endpoint. Error completion - If the current packet is partially transferred i.e. the end of the DMA buffer is reached in the middle of the packet transfer, an error situation occurs. The DD is written back with DD_retired set and DD_status set to the DataOverrun status code. The EOT interrupt is raised for this endpoint and the corresponding bit in USBEpDMASt register is cleared. The packet will be re-sent from the endpoint buffer to memory when the corresponding EPxx_DMA_ENABLE bit is set again using the USBEpDMAEn register.
15.5.6 No_Packet DD
For an IN transfer, if the system does not have any data to send for a while, it can respond to an NDDR interrupt by programming a No_Packet DD. This is done by setting both the Max_packet_size and DMA_buffer_length fields in the DD to 0. On processing a No_Packet DD, the DMA engine clears the DMA request bit in USBDMARSt corresponding to the endpoint without transferring a packet. The DD is retired with a status code of NormalCompletion. This can be repeated as often as necessary. The device will respond to IN token packets on the USB bus with a NAK until a DD with a data packet is programmed and the DMA transfers the packet into the endpoint buffer.
15.6 Isochronous endpoint operation
For isochronous endpoints, the packet size can vary for each packet. There is one packet per isochronous endpoint for each frame.
15.6.1 Setting up DMA transfers
Software sets the isochronous endpoint bit to 1 in the DD, and programs the initial value of the Isochronous_packetsize_memory_address field. All other fields are initialized the same as for non-isochronous endpoints.
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For isochronous endpoints, the DMA_buffer_length and Present_DMA_count fields are in frames rather than bytes.
15.6.2 Finding the DMA Descriptor
Finding the descriptors is done in the same way as that for a non-isochronous endpoint. A DMA request will be placed for DMA-enabled isochronous endpoints on every FRAME interrupt. On processing the request, the DMA engine will fetch the descriptor and if Isochronous_endpoint is set, will fetch the Isochronous_packetsize_memory_address from the fifth word of the DD.
15.6.3 Transferring the Data
The data is transferred to or from the memory location DMA_buffer_start_addr. After the end of the packet transfer the Present_DMA_count value is incremented by 1. The isochronous packet size is stored in memory as shown in Figure 11-30. Each word in the packet size memory shown is divided into fields: Frame_number (bits 31 to 17), Packet_valid (bit 16), and Packet_length (bits 15 to 0). The space allocated for the packet size memory for a given DD should be DMA_buffer_length words in size - one word for each packet to transfer. OUT endpoints At the completion of each frame, the packet size is written to the address location in Isochronous_packet_size_memory_address, and Isochronous_packet_size_memory_address is incremented by 4. IN endpoints Only the Packet_length field of the isochronous packet size word is used. For each frame, an isochronous data packet of size specified by this field is transferred from the USB device to the host, and Isochronous_packet_size_memory_address is incremented by 4 at the end of the packet transfer. If Packet_length is zero, an empty packet will be sent by the USB device.
15.6.4 DMA descriptor completion
DDs for isochronous endpoints can only end with a status code of NormalCompletion since there is no short packet on Isochronous endpoints, and the USB transfer continues indefinitely until a SystemError occurs. There is no DataOverrun detection for isochronous endpoints.
15.6.5 Isochronous OUT Endpoint Operation Example
Assume that an isochronous endpoint is programmed for the transfer of 10 frames and that the transfer begins when the frame number is 21. After transferring four frames with packet sizes of 10,15, 8 and 20 bytes without errors, the descriptor and memory map appear as shown in Figure 11-30. The_total_number_of_bytes_transferred = 0x0A + 0x0F + 0x08 + 0x14 = 0x35. The Packet_valid bit (bit 16) of all the words in the packet length memory is set to 1.
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Next_DD_Pointer W0 NULL
DMA_buffer_length Max_packet_size Isochronous_endpoint Next_DD_Valid DMA_mode
W1
0x000A
0x0
1
DMA_buffer_start_addr
0
0
W2 0x80000000
Present_DMA_Count ATLE settings Packet_Valid DD_Status DD_Retired
W3 0x0 W4 NA NA 0x0 0
Isocronous_packetsize_memory_address 0x60000000
after 4 packets
W0 W1 W2 W3 W4 0x4
0x0
0x000A0010 FULL 0x80000035 -0x1 0 frame_ number Packet_Valid Packet_Length 0x60000010 31 21 22 23 24 16 1 1 1 1 15 10 15 8 20 data memory 0 EMPTY
packet size memory
Fig 30. Isochronous OUT endpoint operation example
15.7 Auto Length Transfer Extraction (ATLE) mode operation
Some host drivers such as NDIS (Network Driver Interface Specification) host drivers are capable of concatenating small USB transfers (delta transfers) to form a single large USB transfer. For OUT USB transfers, the device hardware has to break up this concatenated transfer back into the original delta transfers and transfer them to separate DMA buffers. This is achieved by setting the DMA mode to Auto Transfer Length Extraction (ATLE) mode in the DMA descriptor. ATLE mode is supported for Bulk endpoints only. OUT transfers in ATLE mode
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data to be sent by host driver
data in packets as seen on USB
data to be stored in RAM by DMA engine DMA_buffer_start_addr of DD1
160 bytes 64 bytes 160 bytes 64 bytes
32 bytes 32 bytes 100 bytes 100 bytes 64 bytes DMA_buffer_start_addr of DD2 4 bytes
Fig 31. Data transfer in ATLE mode
Figure 11-31 shows a typical OUT USB transfer in ATLE mode, where the host concatenates two USB transfers of 160 bytes and 100 bytes, respectively. Given a MaxPacketSize of 64, the device hardware interprets this USB transfer as four packets of 64 bytes and a short packet of 4 bytes. The third and fourth packets are concatenated. Note that in Normal mode, the USB transfer would be interpreted as packets of 64, 64, 32, and 64 and 36 bytes. It is now the responsibility of the DMA engine to separate these two USB transfers and put them in the memory locations in the DMA_buffer_start_addr field of DMA Descriptor 1 (DD1) and DMA Descriptor 2 (DD2). Hardware reads the two-byte-wide DMA_buffer_length at the offset (from the start of the USB transfer) specified by Message_length_position from the incoming data packets and writes it in the DMA_buffer_length field of the DD. To ensure that both bytes of the DMA_buffer_length are extracted in the event they are split between two packets, the flags LS_byte_extracted and MS_byte_extracted are set by hardware after the respective byte is extracted. After the extraction of the MS byte, the DMA transfer continues as in the normal mode. The flags LS_byte_extracted and MS_byte_extracted are set to 0 by software when preparing a new DD. Therefore, once a DD is retired, the transfer length is extracted again for the next DD. If DD1 is retired during the transfer of a concatenated packet (such as the third packet in Figure 11-31), and DD2 is not programmed (Next_DD_valid field of DD1 is 0), then DD1 is retired with DD_status set to the DataOverrun status code. This is treated as an error condition and the corresponding EPxx_DMA_ENABLE bit of USBEpDMASt is cleared by hardware.
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In ATLE mode, the last buffer length to be transferred always ends with a short or empty packet indicating the end of the USB transfer. If the concatenated transfer lengths are such that the USB transfer ends on a MaxPacketSize packet boundary, the (NDIS) host will send an empty packet to mark the end of the USB transfer. IN transfers in ATLE mode For IN USB transfers from the device to the host, DMA_buffer_length is set by the device software as in normal mode. In ATLE mode, the device concatenates data from multiple DDs to form a single USB transfer. If a DD is retired in the middle of a packet (packet size is less than MaxPacketSize), the next DD referenced by Next_DD_pointer is fetched, and the remaining bytes to form a packet of MaxPacketSize are transferred from the next DD's buffer. If the next DD is not programmed (i.e. Next_DD_valid field in DD is 0), and the DMA buffer length for the current DD has completed before the MaxPacketSize packet boundary, then the available bytes from current DD are sent as a short packet on USB, which marks the end of the USB transfer for the host. If the last buffer length completes on a MaxPacketSize packet boundary, the device software must program the next DD with DMA_buffer_length field 0, so that an empty packet is sent by the device to mark the end of the USB transfer for the host.
15.7.1 Setting up the DMA transfer
For OUT endpoints, the host hardware needs to set the field Message_length_position in the DD. This indicates the start location of the message length in the incoming data packets. Also the device software has to set the DMA_buffer_length field to 0 for OUT endpoints because this field is updated by the device hardware after the extraction of the buffer length. For IN endpoints, descriptors are set in the same way as in normal mode operation. Since a single packet can be split between two DDs, software should always keep two DDs ready, except for the last DMA transfer which ends with a short or empty packet.
15.7.2 Finding the DMA Descriptor
DMA descriptors are found in the same way as the normal mode operation.
15.7.3 Transferring the Data
OUT endpoints If the LS_byte_extracted or MS_byte_extracted bit in the status field is not set, the hardware will extract the transfer length from the data stream and program DMA_buffer_length. Once the extraction is complete both the LS_byte_extracted and MS_byte_extracted bits will be set. IN endpoints The DMA transfer proceeds as in normal mode and continues until the number of bytes transferred equals the DMA_buffer_length.
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15.7.4 Ending the packet transfer
The DMA engine proceeds with the transfer until the number of bytes specified in the field DMA_buffer_length is transferred to or from on-chip RAM. Then the EOT interrupt will be generated. If this happens in the middle of the packet, the linked DD will get loaded and the remaining part of the packet gets transferred to or from the address pointed by the new DD. OUT endpoints If the linked DD is not valid and the packet is partially transferred to memory, the DD ends with DataOverrun status code set, and the DMA will be disabled for this endpoint. Otherwise DD_status will be updated with the NormalCompletion status code. IN endpoints If the linked DD is not valid and the packet is partially transferred to USB, the DD ends with a status code of NormalCompletion in the DD_status field. This situation corresponds to the end of the USB transfer, and the packet will be sent as a short packet. Also, when the linked DD is valid and buffer length is 0, an empty packet will be sent to indicate the end of the USB transfer.
16. Double buffered endpoint operation
The Bulk and Isochronous endpoints of the USB Device Controller are double buffered to increase data throughput. When a double-buffered endpoint is realized, enough space for both endpoint buffers is automatically allocated in the EP_RAM. See Section 11-10.4.1. For the following discussion, the endpoint buffer currently accessible to the CPU or DMA engine for reading or writing is said to be the active buffer.
16.1 Bulk endpoints
For Bulk endpoints, the active endpoint buffer is switched by the SIE Clear Buffer or Validate Buffer commands. The following example illustrates how double buffering works for a Bulk OUT endpoint in Slave mode: Assume that both buffer 1 (B_1) and buffer 2 (B_2) are empty, and that the active buffer is B_1. 1. The host sends a data packet to the endpoint. The device hardware puts the packet into B_1, and generates an endpoint interrupt. 2. Software clears the endpoint interrupt and begins reading the packet data from B_1. While B_1 is still being read, the host sends a second packet, which device hardware places in B_2, and generates an endpoint interrupt. 3. Software is still reading from B_1 when the host attempts to send a third packet. Since both B_1 and B_2 are full, the device hardware responds with a NAK. 4. Software finishes reading the first packet from B_1 and sends a SIE Clear Buffer command to free B_1 to receive another packet. B_2 becomes the active buffer.
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Chapter 11: LPC17xx USB device controller
5. Software sends the SIE Select Endpoint command to read the Select Endpoint Register and test the FE bit. Software finds that the active buffer (B_2) has data (FE=1). Software clears the endpoint interrupt and begins reading the contents of B_2. 6. The host re-sends the third packet which device hardware places in B_1. An endpoint interrupt is generated. 7. Software finishes reading the second packet from B_2 and sends a SIE Clear Buffer command to free B_2 to receive another packet. B_1 becomes the active buffer. Software waits for the next endpoint interrupt to occur (it already has been generated back in step 6). 8. Software responds to the endpoint interrupt by clearing it and begins reading the third packet from B_1. 9. Software finishes reading the third packet from B_1 and sends a SIE Clear Buffer command to free B_1 to receive another packet. B_2 becomes the active buffer. 10. Software tests the FE bit and finds that the active buffer (B_2) is empty (FE=0). 11. Both B_1 and B_2 are empty. Software waits for the next endpoint interrupt to occur. The active buffer is now B_2. The next data packet sent by the host will be placed in B_2. The following example illustrates how double buffering works for a Bulk IN endpoint in Slave mode: Assume that both buffer 1 (B_1) and buffer 2 (B_2) are empty and that the active buffer is B_1. The interrupt on NAK feature is enabled. 1. The host requests a data packet by sending an IN token packet. The device responds with a NAK and generates an endpoint interrupt. 2. Software clears the endpoint interrupt. The device has three packets to send. Software fills B_1 with the first packet and sends a SIE Validate Buffer command. The active buffer is switched to B_2. 3. Software sends the SIE Select Endpoint command to read the Select Endpoint Register and test the FE bit. It finds that B_2 is empty (FE=0) and fills B_2 with the second packet. Software sends a SIE Validate Buffer command, and the active buffer is switched to B_1. 4. Software waits for the endpoint interrupt to occur. 5. The device successfully sends the packet in B_1 and clears the buffer. An endpoint interrupt occurs. 6. Software clears the endpoint interrupt. Software fills B_1 with the third packet and validates it using the SIE Validate Buffer command. The active buffer is switched to B_2. 7. The device successfully sends the second packet from B_2 and generates an endpoint interrupt. 8. Software has no more packets to send, so it simply clears the interrupt. 9. The device successfully sends the third packet from B_1 and generates an endpoint interrupt. 10. Software has no more packets to send, so it simply clears the interrupt.
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11. Both B_1 and B_2 are empty, and the active buffer is B_2. The next packet written by software will go into B_2. In DMA mode, switching of the active buffer is handled automatically in hardware. For Bulk IN endpoints, proactively filling an endpoint buffer to take advantage of the double buffering can be accomplished by manually starting a packet transfer using the USBDMARSet register.
16.2 Isochronous endpoints
For isochronous endpoints, the active data buffer is switched by hardware when the FRAME interrupt occurs. The SIE Clear Buffer and Validate Buffer commands do not cause the active buffer to be switched. Double buffering allows the software to make full use of the frame interval writing or reading a packet to or from the active buffer, while the packet in the other buffer is being sent or received on the bus. For an OUT isochronous endpoint, any data not read from the active buffer before the end of the frame is lost when it switches. For an IN isochronous endpoint, if the active buffer is not validated before the end of the frame, an empty packet is sent on the bus when the active buffer is switched, and its contents will be overwritten when it becomes active again.
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Chapter 12: LPC17xx USB Host controller
Rev. 01 -- 4 January 2010 User manual
1. How to read this chapter
The USB host controller is available on the LPC1768, LPC1766, LPC1765, LPC1758, LPC1756, and LPC1754. On these devices, the USB controller can be configured for device, Host, or OTG operation.
2. Basic configuration
The USB controller is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCUSB. Remark: On reset, the USB block is disabled (PCUSB = 0). 2. Clock: The USB block can be used with a dedicated USB PLL (PLL1) to obtain the USB clock or with the Main PLL (PLL0). See Section 4-6.1. 3. Pins: Select USB pins and their modes in PINSEL0 to PINSEL5 and PINMODE0 to PINMODE5 (Section 8-5). 4. Wake-up: Activity on the USB bus port can wake up the microcontroller from Power-down mode, see Section 4-8.8. 5. Interrupts: Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 6. Initialization: see Section 13-11.
3. Introduction
This section describes the host portion of the USB 2.0 OTG dual role core which integrates the host controller (OHCI compliant), device controller, and I2C interface. The I2C interface controls the external OTG ATX. The USB is a 4 wire bus that supports communication between a host and a number (127 max.) of peripherals. The host controller allocates the USB bandwidth to attached devices through a token based protocol. The bus supports hot plugging, un-plugging and dynamic configuration of the devices. All transactions are initiated by the host controller. The host controller enables data exchange with various USB devices attached to the bus. It consists of register interface, serial interface engine and DMA controller. The register interface complies to the OHCI specification.
Table 251. USB (OHCI) related acronyms and abbreviations used in this chapter Acronym/abbreviation Description
AHB ATX DMA FS
Advanced High-Performance Bus Analog Transceiver Direct Memory Access Full Speed
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Chapter 12: LPC17xx USB Host controller
Table 251. USB (OHCI) related acronyms and abbreviations used in this chapter Acronym/abbreviation Description
LS OHCI USB
Low Speed Open Host Controller Interface Universal Serial Bus
3.1 Features * OHCI compliant. * OpenHCI specifies the operation and interface of the USB Host Controller and SW
Driver - USBOperational: Process Lists and generate SOF Tokens. - USBReset: Forces reset signaling on the bus, SOF disabled. - USBSuspend: Monitor USB for wake-up activity. - USBResume: Forces resume signaling on the bus.
* The Host Controller has four USB states visible to the SW Driver. * HCCA register points to Interrupt and Isochronous Descriptors List. * ControlHeadED and BulkHeadED registers point to Control and Bulk Descriptors List. 3.2 Architecture
The architecture of the USB host controller is shown below in Figure 12-32.
register interface (AHB slave)
REGISTER INTERFACE
AHB bus
DMA interface (AHB master)
HOST CONTROLLER BUS MASTER INTERFACE
ATX CONTROL LOGIC/ PORT MUX
USB port USB ATX
USB HOST BLOCK
Fig 32. USB Host controller block diagram
4. Interfaces
The USB interface is controlled by the OTG controller. It has one USB port.
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Chapter 12: LPC17xx USB Host controller
4.1 Pin description
Table 252. USB Host port pins Pin name Direction Description Type
USB_D+ USB_D- USB_UP_LED USB_PPWR USB_PWRD USB_OVRCR
I/O I/O O O I I
Positive differential data Negative differential data GoodLink LED control signal Port power enable Port power status Over-current status
USB Connector USB Connector Control Host power switch Host power switch Host power switch
4.1.1 USB host usage note
The USB block can be configured as USB host. For details on how to connect the USB port, see the USB OTG chapter, Section 13-7. The USB device/host/OTG controller is disabled after RESET and must be enabled by writing a 1 to the PCUSB bit in the PCONP register, see Table 4-46.
4.2 Software interface
The software interface of the USB host block consists of a register view and the format definitions for the endpoint descriptors. For details on these two aspects see the OHCI specification. The register map is shown in the next subsection.
4.2.1 Register map
The following registers are located in the AHB clock `cclk' domain. They can be accessed directly by the processor. All registers are 32-bit wide and aligned in the word address boundaries.
Table 253. USB Host register address definitions Name Address R/W[1] Function Reset value
HcRevision HcControl HcCommandStatus
0x5000 C000 0x5000 C004 0x5000 C008
R R/W R/W
BCD representation of the version of the HCI specification that is implemented by the Host Controller. Defines the operating modes of the HC.
0x10 0x0
This register is used to receive the commands from the 0x0 Host Controller Driver (HCD). It also indicates the status of the HC. Indicates the status on various events that cause hardware interrupts by setting the appropriate bits. Controls the bits in the HcInterruptStatus register and indicates which events will generate a hardware interrupt. The bits in this register are used to disable corresponding bits in the HCInterruptStatus register and in turn disable that event leading to hardware interrupt. Contains the physical address of the host controller communication area. 0x0 0x0
HcInterruptStatus HcInterruptEnable
0x5000 C00C 0x5000 C010
R/W R/W
HcInterruptDisable
0x5000 C014
R/W
0x0
HcHCCA HcPeriodCurrentED
0x5000 C018 0x5000 C01C
R/W R
0x0
Contains the physical address of the current isochronous 0x0 or interrupt endpoint descriptor.
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Chapter 12: LPC17xx USB Host controller
Table 253. USB Host register address definitions ...continued Name Address R/W[1] Function Reset value
HcControlHeadED HcControlCurrentED HcBulkHeadED HcBulkCurrentED HcDoneHead HcFmInterval
0x5000 C020 0x5000 C024 0x5000 C028 0x5000 C02C 0x5000 C030 0x5000 C034
R/W R/W R/W R/W R R/W
Contains the physical address of the first endpoint descriptor of the control list. Contains the physical address of the current endpoint descriptor of the control list Contains the physical address of the first endpoint descriptor of the bulk list. Contains the physical address of the current endpoint descriptor of the bulk list. Contains the physical address of the last transfer descriptor added to the `Done' queue.
0x0 0x0 0x0 0x0 0x0
Defines the bit time interval in a frame and the full speed 0x2EDF maximum packet size which would not cause an overrun. A 14-bit counter showing the bit time remaining in the current frame. Contains a 16-bit counter and provides the timing reference among events happening in the HC and the HCD. 0x0 0x0
HcFmRemaining HcFmNumber
0x5000 C038 0x5000 C03C
R R
HcPeriodicStart
0x5000 C040
R/W
Contains a programmable 14-bit value which determines 0x0 the earliest time HC should start processing a periodic list. Contains 11-bit value which is used by the HC to determine whether to commit to transfer a maximum of 8-byte LS packet before EOF. First of the two registers which describes the characteristics of the root hub. Second of the two registers which describes the characteristics of the Root Hub. This register is divided into two parts. The lower D-word represents the hub status field and the upper word represents the hub status change field. 0x628h
HcLSThreshold
0x5000 C044
R/W
HcRhDescriptorA HcRhDescriptorB HcRhStatus
0x5000 C048 0x5000 C04C 0x5000 C050
R/W R/W R/W
0xFF000902 0x60000h 0x0
HcRhPortStatus[1] HcRhPortStatus[2] Module_ID/Ver_Rev_ID
0x5000 C054 0x5000 C058 0x5000 C0FC
R/W R/W R
Controls and reports the port events on a per-port basis. 0x0 Controls and reports the port events on a per port basis. 0x0 IP number, where yy (0x00) is unique version number and zz (0x00) is a unique revision number. 0x3505yyzz
[1]
The R/W column in Table 12-253 lists the accessibility of the register: a) Registers marked `R' for access will return their current value when read. b) Registers marked `R/W' allow both read and write.
4.2.2 USB Host Register Definitions
Refer to the OHCI specification document on the Compaq website for register definitions.
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Chapter 13: LPC17xx USB OTG controller
Rev. 01 -- 4 January 2010 User manual
1. How to read this chapter
The USB OTG controller is available in the LPC1768, LPC1766, LPC1765, LPC1758, LPC1756, and LPC1754. On these devices, the USB controller can be configured for device, Host, or OTG operation.
2. Basic configuration
The USB controller is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCUSB. Remark: On reset, the USB block is disabled (PCUSB = 0). 2. Clock: The USB clock can generated using the dedicated USB PLL (PLL1) or with the Main PLL (PLL0). See Section 4-6.1. 3. Pins: Select USB pins and their modes in PINSEL0 to PINSEL5 and PINMODE0 to PINMODE5 (Section 8-5). 4. Wake-up: Activity on the USB bus port can wake up the microcontroller from Power-down mode (see Section 13-10.2 and Section 4-8.8). 5. Interrupts: Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 6. Initialization: see Section 13-11.
3. Introduction
This chapter describes the OTG and I2C portions of the USB 2.0 OTG dual role device controller which integrates the (OHCI) host controller, device controller, and I2C. The I2C interface that is part of the USB block is intended to control an external OTG transceiver, and is not the same as the I2C peripherals described in Section 19-1. USB OTG (On-The-Go) is a supplement to the USB 2.0 specification that augments the capability of existing mobile devices and USB peripherals by adding host functionality for connection to USB peripherals. The specification and more information on USB OTG can be found on the USB Implementers Forum web site.
4. Features
* Fully compliant with On-The-Go supplement to the USB 2.0 Specification, Revision
1.0a.
* Hardware support for Host Negotiation Protocol (HNP). * Includes a programmable timer required for HNP and SRP. * Supports any OTG transceiver compliant with the OTG Transceiver Specification
(CEA-2011), Rev. 1.0.
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Chapter 13: LPC17xx USB OTG controller
5. Architecture
The architecture of the USB OTG controller is shown below in the block diagram. The host, device, OTG, and I2C controllers can be programmed through the register interface. The OTG controller enables dynamic switching between host and device roles through the HNP protocol. One port may be connected to an external OTG transceiver to support an OTG connection. The communication between the register interface and an external OTG transceiver is handled through an I2C interface and through the external OTG transceiver interrupt signal. For USB connections that use the device or host controller only (not OTG), the ports use an embedded USB Analog Transceiver (ATX).
OTG TRANSCEIVER
register interface (AHB slave)
I2C CONTROLLER REGISTER INTERFACE OTG CONTROLLER ATX CONTROL LOGIC/ PORT MUX USB ATX USB port
AHB bus
DMA interface (AHB master)
BUS MASTER INTERFACE
DEVICE CONTROLLER
HOST CONTROLLER
USB OTG BLOCK
EP_RAM
Fig 33. USB OTG controller block diagram
6. Modes of operation
The OTG controller is capable of operating in the following modes:
* Host mode (see Figure 13-34) * Device mode (see Figure 13-35) * OTG mode (see Figure 13-36)
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Chapter 13: LPC17xx USB OTG controller
7. Pin configuration
The OTG controller has one USB port.
Table 254. USB OTG port pins Pin name Direction Description Pin category
USB_D+ USB_D- USB_UP_LED USB_SCL USB_SDA
I/O I/O O I/O I/O
Positive differential data Negative differential data GoodLink LED control signal I2C serial clock I2C serial data
USB Connector USB Connector Control External OTG transceiver External OTG transceiver
The following figures show different ways to realize connections to an USB device. The example described here uses an ISP1302 (ST-Ericsson) for the external OTG transceiver and the USB Host power switch LM3526-L (National Semiconductors).
7.1 Connecting the USB port to an external OTG transceiver
For OTG functionality an external OTG transceiver must be connected to the LPC17xx: Use the internal USB transceiver for USB signalling and use the external OTG transceiver for OTG functionality only (see Figure 13-34). This option uses the internal transceiver in VP/VM mode.
VDD
RSTOUT
RESET_N ADR/PSW VDD OE_N/INT_N SPEED SUSPEND
VBUS ID DP DM
33 33
Mini-AB connector
ISP1302
VSSIO, VSSCORE
LPC17xx
USB_SCL USB_SDA EINTn USB_D+ USB_D- USB_UP_LED
SCL SDA INT_N
VDD
Fig 34. USB OTG port configuration
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Chapter 13: LPC17xx USB OTG controller
7.2 Connecting USB as a host
The USB port is connected as host using an embedded USB transceiver. There is no OTG functionality on the port.
VDD USB_UP_LED VSS USB_D+ USB_D-
33 33 15 k 15 k
D+ D- USB-A connector VDD
LPC176x
USB_PWRD USB_OVRCR USB_PPWR 5V
VBUS
ENA IN
FLAGA
LM3526-L
OUTA
graphicID
Fig 35. USB host port configuration
7.3 Connecting USB as device
The USB port is connected as device. There is no OTG functionality on the USB port.
VDD USB_UP_LED
VDD
LPC176x
USB_CONNECT
VSS USB_D+ USB_D- VBUS
33 33
D+ D- VBUS USB-B connector
graphicID
Fig 36. USB device port configuration
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Chapter 13: LPC17xx USB OTG controller
8. Register description
The OTG and I2C registers are summarized in the following table. The Device and Host registers are explained in Table 12-253 and Table 11-187 in the USB Device Controller and USB Host (OHCI) Controller chapters. All registers are 32 bits wide and aligned to word address boundaries.
Table 255. USB OTG and I2C register address definitions Name Interrupt register Description Access Reset value Address
USBIntSt
OTG registers
USB Interrupt Status OTG Interrupt Status OTG Interrupt Enable OTG Interrupt Set OTG Interrupt Clear OTG Status and Control OTG Timer I2C Receive I2C I2C I2C I2C Transmit Status Clock High Clock Low
R/W RO R/W WO WO R/W R/W RO WO RO R/W R/W WO R/W RO
0x8000 0100 0 0 NA NA 0 0xFFFF NA NA 0x0A00 0 0xB9 0xB9 0 0
0x400F C1C0 0x5000 C100 0x5000 C104 0x5000 C108 0x5000 C10C 0x5000 C110 0x5000 C114 0x5000 C300 0x5000 C300 0x5000 C304 0x5000 C308 0x5000 C30C 0x5000 C310 0x5000 CFF4 0x5000 CFF8
OTGIntSt OTGIntEn OTGIntSet OTGIntClr OTGStCtrl OTGTmr
I2C registers
I2C_RX I2C_TX I2C_STS I2C_CTL I2C_CLKHI I2C_CLKLO OTGClkCtrl OTGClkSt
I2C Control
Clock control registers
OTG clock controller OTG clock status
8.1 USB Interrupt Status Register (USBIntSt - 0x5000 C1C0)
The USB OTG controller has seven interrupt lines. This register allows software to determine their status with a single read operation. The interrupt lines are ORed together to a single channel of the vectored interrupt controller.
Table 256. USB Interrupt Status register - (USBIntSt - address 0x5000 C1C0) bit description Bit Symbol Description Reset Value
0 1 2 3 4 5
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USB_INT_REQ_LP USB_INT_REQ_HP USB_INT_REQ_DMA USB_HOST_INT USB_ATX_INT USB_OTG_INT
Low priority interrupt line status. This bit is read-only. High priority interrupt line status. This bit is read-only. DMA interrupt line status. This bit is read-only. USB host interrupt line status. This bit is read-only. External ATX interrupt line status. This bit is read-only. OTG interrupt line status. This bit is read-only.
0 0 0 0 0 0
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Chapter 13: LPC17xx USB OTG controller
Table 256. USB Interrupt Status register - (USBIntSt - address 0x5000 C1C0) bit description Bit Symbol Description Reset Value
6 7
USB_I2C_INT -
I2C module interrupt line status. This bit is read-only. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. USB need clock indicator. This bit is read-only. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
8 30:9
USB_NEED_CLK -
1 NA
31
EN_USB_INTS
Enable all USB interrupts. When this bit is cleared, the 1 NVIC does not see the ORed output of the USB interrupt lines.
8.2 OTG Interrupt Status Register (OTGIntSt - 0x5000 C100)
Bits in this register are set by hardware when the interrupt event occurs during the HNP handoff sequence. See Section 13-9 for more information on when these bits are set.
Table 257. OTG Interrupt Status register (OTGIntSt - address 0x5000 C100) bit description Bit Symbol Description Reset Value
0 1
TMR REMOVE_PU
Timer time-out. Remove pull-up. This bit is set by hardware to indicate that software needs to disable the D+ pull-up resistor.
0 0
2
HNP_FAILURE
HNP failed. This bit is set by hardware to indicate that the HNP switching has failed.
0
3
HNP_SUCCESS
HNP succeeded. This bit is set by hardware to indicate that the HNP switching has succeeded.
0
31:4
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
8.3 OTG Interrupt Enable Register (OTGIntEn - 0x5000 C104)
Writing a one to a bit in this register enables the corresponding bit in OTGIntSt to generate an interrupt on one of the interrupt lines. The interrupt is routed to the USB_OTG_INT interrupt line in the USBIntSt register. The bit allocation and reset value of OTGIntEn is the same as OTGIntSt.
8.4 OTG Interrupt Set Register (OTGIntSet - 0x5000 C20C)
Writing a one to a bit in this register will set the corresponding bit in the OTGIntSt register. Writing a zero has no effect. The bit allocation of OTGIntSet is the same as in OTGIntSt.
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Chapter 13: LPC17xx USB OTG controller
8.5 OTG Interrupt Clear Register (OTGIntClr - 0x5000 C10C)
Writing a one to a bit in this register will clear the corresponding bit in the OTGIntSt register. Writing a zero has no effect. The bit allocation of OTGIntClr is the same as in OTGIntSt.
8.6 OTG Status and Control Register (OTGStCtrl - 0x5000 C110)
The OTGStCtrl register allows enabling hardware tracking during the HNP hand over sequence, controlling the OTG timer, monitoring the timer count, and controlling the functions mapped to port U1 and U2. Time critical events during the switching sequence are controlled by the OTG timer. The timer can operate in two modes: 1. Monoshot mode: an interrupt is generated at the end of TIMEOUT_CNT (see Section 13-8.7 "OTG Timer Register (OTGTmr - 0x5000 C114)"), the TMR bit is set in OTGIntSt, and the timer will be disabled. 2. Free running mode: an interrupt is generated at the end of TIMEOUT_CNT (see Section 13-8.7 "OTG Timer Register (OTGTmr - 0x5000 C114)"), the TMR bit is set, and the timer value is reloaded into the counter. The timer is not disabled in this mode.
Table 258. OTG Status Control register (OTGStCtrl - address 0x5000 C110) bit description Bit Symbol Description Reset Value
1:0
PORT_FUNC
Controls port function. Bit 0 is set or cleared by hardware when B_HNP_TRACK or A_HNP_TRACK is set and HNP succeeds. See Section 13-9. Bit 1 is reserved. Timer scale selection. This field determines the duration of each timer count. 00: 10 s (100 KHz) 01: 100 s (10 KHz) 10: 1000 s (1 KHz) 11: Reserved 0x0
3:2
TMR_SCALE
4
TMR_MODE
Timer mode selection. 0: monoshot 1: free running
0
5 6
TMR_EN TMR_RST
Timer enable. When set, TMR_CNT increments. When cleared, TMR_CNT is reset to 0.
0
Timer reset. Writing one to this bit resets TMR_CNT to 0. 0 This provides a single bit control for the software to restart the timer when the timer is enabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Enable HNP tracking for B-device (peripheral), see Section 13-9. Hardware clears this bit when HNP_SUCCESS or HNP_FAILURE is set. Enable HNP tracking for A-device (host), see Section 13-9. Hardware clears this bit when HNP_SUCCESS or HNP_FAILURE is set.
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7
-
NA
8
B_HNP_TRACK
0
9
A_HNP_TRACK
0
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Chapter 13: LPC17xx USB OTG controller
Table 258. OTG Status Control register (OTGStCtrl - address 0x5000 C110) bit description Bit Symbol Description Reset Value
10
PU_REMOVED
0 When the B-device changes its role from peripheral to host, software sets this bit when it removes the D+ pull-up, see Section 13-9. Hardware clears this bit when HNP_SUCCESS or HNP_FAILURE is set. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Current timer count value. NA
15:11 -
31:16 TMR_CNT
0x0
8.7 OTG Timer Register (OTGTmr - 0x5000 C114)
Table 259. OTG Timer register (OTGTmr - address 0x5000 C114) bit description Bit Symbol Description Reset Value
15:0
TIMEOUT_CNT The TMR interrupt is set when TMR_CNT reaches this value. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0xFFFF NA
31:16 -
8.8 OTG Clock Control Register (OTGClkCtrl - 0x5000 CFF4)
This register controls the clocking of the OTG controller. Whenever software wants to access the registers, the corresponding clock control bit needs to be set. The software does not have to repeat this exercise for every register access, provided that the corresponding OTGClkCtrl bits are already set.
Table 260. OTG clock control register (OTG_clock_control - address 0x5000 CFF4) bit description Bit Symbol Value Description Reset Value
0
HOST_CLK_EN 0 1
Host clock enable Disable the Host clock. Enable the Host clock. Device clock enable 0 1 Disable the Device clock. Enable the Device clock. I2C clock enable 0 1 Disable the I2C clock. Enable the I2C clock. OTG clock enable 0 1 Disable the OTG clock. Enable the OTG clock.
0
1
DEV_CLK_EN
0
2
I2C_CLK_EN
0
3
OTG_CLK_EN
0
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Table 260. OTG clock control register (OTG_clock_control - address 0x5000 CFF4) bit description Bit Symbol Value Description Reset Value
4
AHB_CLK_EN 0 1
AHB master clock enable Disable the AHB clock. Enable the AHB clock.
0
31:5
-
NA
Reserved, user software should not write ones NA to reserved bits. The value read from a reserved bit is not defined.
8.9 OTG Clock Status Register (OTGClkSt - 0x5000 CFF8)
This register holds the clock availability status. When enabling a clock via OTGClkCtrl, software should poll the corresponding bit in this register. If it is set, then software can go ahead with the register access. Software does not have to repeat this exercise for every access, provided that the OTGClkCtrl bits are not disturbed.
Table 261. OTG clock status register (OTGClkSt - address 0x5000 CFF8) bit description Bit Symbol Value Description Reset Value
0
HOST_CLK_ON 0 1
Host clock status. Host clock is not available. Host clock is available. Device clock status. 0 1 Device clock is not available. Device clock is available. I2C clock status. 0 1 I2C clock is not available. I2C clock is available. OTG clock status. 0 1 OTG clock is not available. OTG clock is available. AHB master clock status. 0 1 AHB clock is not available. AHB clock is available.
0
1
DEV_CLK_ON
0
2
I2C_CLK_ON
0
3
OTG_CLK_ON
0
4
AHB_CLK_ON
0
31:5
-
NA
Reserved, user software should not write ones NA to reserved bits. The value read from a reserved bit is not defined.
8.10 I2C Receive Register (I2C_RX - 0x5000 C300)
This register is the top byte of the receive FIFO. The receive FIFO is 4 bytes deep. The Rx FIFO is flushed by a hard reset or by a soft reset (I2C_CTL bit 7). Reading an empty FIFO gives unpredictable data results.
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Table 262. I2C Receive register (I2C_RX - address 0x5000 C300) bit description Bit Symbol Description Reset Value
7:0
RX Data
Receive data.
-
8.11 I2C Transmit Register (I2C_TX - 0x5000 C300)
This register is the top byte of the transmit FIFO. The transmit FIFO is 4 bytes deep. The Tx FIFO is flushed by a hard reset, soft reset (I2C_CTL bit 7) or if an arbitration failure occurs (I2C_STS bit 3). Data writes to a full FIFO are ignored. I2C_TX must be written for both write and read operations to transfer each byte. Bits [7:0] are ignored for master-receive operations. The master-receiver must write a dummy byte to the TX FIFO for each byte it expects to receive in the RX FIFO. When the STOP bit is set or the START bit is set to cause a RESTART condition on a byte written to the TX FIFO (master-receiver), then the byte read from the slave is not acknowledged. That is, the last byte of a master-receive operation is not acknowledged.
Table 263. I2C Transmit register (I2C_TX - address 0x5000 C300) bit description Bit Symbol Description Reset Value
7:0 8 9
TX Data START STOP
Transmit data. When 1, issue a START condition before transmitting this byte. When 1, issue a STOP condition after transmitting this byte. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
-
31:10 -
8.12 I2C Status Register (I2C_STS - 0x5000 C304)
The I2C_STS register provides status information on the TX and RX blocks as well as the current state of the external buses. Individual bits are enabled as interrupts by the I2C_CTL register and routed to the I2C_USB_INT bit in USBIntSt.
Table 264. I2C status register (I2C_STS - address 0x5000 C304) bit description Bit Symbol Value Description Reset Value
0
TDI
Transaction Done Interrupt. This flag is set if a transaction completes successfully. It is cleared by writing a one to bit 0 of the status register. It is unaffected by slave transactions. 0 1 Transaction has not completed. Transaction completed.
0
1
AFI
Arbitration Failure Interrupt. When transmitting, if the SDA is low 0 when SDAOUT is high, then this I2C has lost the arbitration to another device on the bus. The Arbitration Failure bit is set when this happens. It is cleared by writing a one to bit 1 of the status register. 0 1 No arbitration failure on last transmission. Arbitration failure occurred on last transmission.
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Table 264. I2C status register (I2C_STS - address 0x5000 C304) bit description Bit Symbol Value Description Reset Value
2
NAI
No Acknowledge Interrupt. After every byte of data is sent, the 0 transmitter expects an acknowledge from the receiver. This bit is set if the acknowledge is not received. It is cleared when a byte is written to the master TX FIFO. 0 1 Last transmission received an acknowledge. Last transmission did not receive an acknowledge. Master Data Request Interrupt. Once a transmission is started, 0 the transmitter must have data to transmit as long as it isn't followed by a stop condition or it will hold SCL low until more data is available. The Master Data Request bit is set when the master transmitter is data-starved. If the master TX FIFO is empty and the last byte did not have a STOP condition flag, then SCL is held low until the CPU writes another byte to transmit. This bit is cleared when a byte is written to the master TX FIFO. 0 1 Master transmitter does not need data. Master transmitter needs data. Slave Data Request Interrupt. Once a transmission is started, 0 the transmitter must have data to transmit as long as it isn't followed by a STOP condition or it will hold SCL low until more data is available. The Slave Data Request bit is set when the slave transmitter is data-starved. If the slave TX FIFO is empty and the last byte transmitted was acknowledged, then SCL is held low until the CPU writes another byte to transmit. This bit is cleared when a byte is written to the slave Tx FIFO. 0 1 Slave transmitter does not need data. Slave transmitter needs data. Indicates whether the bus is busy. This bit is set when a START 0 condition has been seen. It is cleared when a STOP condition is seen.. The current value of the SCL signal. The current value of the SDA signal. -
3
DRMI
4
DRSI
5
Active
6 7 8
SCL SDA RFF
Receive FIFO Full (RFF). This bit is set when the RX FIFO is full 0 and cannot accept any more data. It is cleared when the RX FIFO is not full. If a byte arrives when the Receive FIFO is full, the SCL is held low until the CPU reads the RX FIFO and makes room for it. 0 1 RX FIFO is not full RX FIFO is full Receive FIFO Empty. RFE is set when the RX FIFO is empty and is cleared when the RX FIFO contains valid data. 0 1 RX FIFO contains data. RX FIFO is empty Transmit FIFO Full. TFF is set when the TX FIFO is full and is cleared when the TX FIFO is not full. 0 1 TX FIFO is not full. TX FIFO is full 0 1
9
RFE
10
TFF
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Table 264. I2C status register (I2C_STS - address 0x5000 C304) bit description Bit Symbol Value Description Reset Value
11
TFE 0 1
Transmit FIFO Empty. TFE is set when the TX FIFO is empty and is cleared when the TX FIFO contains valid data. TX FIFO contains valid data. TX FIFO is empty Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
1
31:12 -
NA
NA
8.13 I2C Control Register (I2C_CTL - 0x5000 C308)
The I2C_CTL register is used to enable interrupts and reset the I2C state machine. Enabled interrupts cause the USB_I2C_INT interrupt output line to be asserted when set.
Table 265. I2C Control register (I2C_CTL - address 0x5000 C308) bit description Bit Symbol Value Description Reset Value
0
TDIE 0 1
Transmit Done Interrupt Enable. This enables the TDI interrupt signalling that this I2C issued a STOP condition. Disable the TDI interrupt. Enable the TDI interrupt. Transmitter Arbitration Failure Interrupt Enable. This enables the AFI interrupt which is asserted during transmission when trying to set SDA high, but the bus is driven low by another device. 0 1 Disable the AFI. Enable the AFI. Transmitter No Acknowledge Interrupt Enable. This enables the NAI interrupt signalling that transmitted byte was not acknowledged. 0 1 Disable the NAI. Enable the NAI.
0
1
AFIE
0
2
NAIE
0
3
DRMIE
Master Transmitter Data Request Interrupt Enable. This enables the DRMI interrupt which 0 signals that the master transmitter has run out of data, has not issued a STOP, and is holding the SCL line low. 0 1 Disable the DRMI interrupt. Enable the DRMI interrupt. Slave Transmitter Data Request Interrupt Enable. This enables the DRSI interrupt which 0 signals that the slave transmitter has run out of data and the last byte was acknowledged, so the SCL line is being held low. 0 1 Disable the DRSI interrupt. Enable the DRSI interrupt. Receive FIFO Full Interrupt Enable. This enables the Receive FIFO Full interrupt to indicate that the receive FIFO cannot accept any more data. 0 1 Disable the RFFI. Enable the RFFI. 0
4
DRSIE
5
REFIE
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Table 265. I2C Control register (I2C_CTL - address 0x5000 C308) bit description Bit Symbol Value Description Reset Value
6
RFDAIE 0 1
Receive Data Available Interrupt Enable. This enables the DAI interrupt to indicate that data is available in the receive FIFO (i.e. not empty). Disable the DAI. Enable the DAI.
0
7
TFFIE
Transmit FIFO Not Full Interrupt Enable. This enables the Transmit FIFO Not Full interrupt 0 to indicate that the more data can be written to the transmit FIFO. Note that this is not full. It is intended help the CPU to write to the I2C block only when there is room in the FIFO and do this without polling the status register. 0 1 Disable the TFFI. Enable the TFFI. Soft reset. This is only needed in unusual circumstances. If a device issues a start condition without issuing a stop condition. A system timer may be used to reset the I2C if the bus remains busy longer than the time-out period. On a soft reset, the Tx and Rx FIFOs are flushed, I2C_STS register is cleared, and all internal state machines are reset to appear idle. The I2C_CLKHI, I2C_CLKLO and I2C_CTL (except Soft Reset Bit) are NOT modified by a soft reset. 0 1 See the text. Reset the I2C to idle state. Self clearing. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA 0
8
SRST
31:9 -
NA
8.14 I2C Clock High Register (I2C_CLKHI - 0x5000 C30C)
The CLK register holds a terminal count for counting 48 MHz clock cycles to create the high period of the slower I2C serial clock, SCL.
Table 266. I2C_CLKHI register (I2C_CLKHI - address 0x5000 C30C) bit description Bit Symbol Description Reset Value
7:0
CDHI
Clock divisor high. This value is the number of 48 MHz clocks the serial clock (SCL) will be high.
0xB9
8.15 I2C Clock Low Register (I2C_CLKLO - 0x5000 C310)
The CLK register holds a terminal count for counting 48 MHz clock cycles to create the low period of the slower I2C serial clock, SCL.
Table 267. I2C_CLKLO register (I2C_CLKLO - address 0x5000 C310) bit description Bit Symbol Description Reset Value
7:0
CDLO
Clock divisor low. This value is the number of 48 MHz clocks the serial clock (SCL) will be low.
0xB9
8.16 Interrupt handling
The interrupts set in the OTGIntSt register are set and cleared during HNP switching. All OTG related interrupts, if enabled, are routed to the USB_OTG_INT bit in the USBIntSt register.
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I2C related interrupts are set in the I2C_STS register and routed, if enabled by I2C_CTL, to the USB_I2C_INT bit. For more details on the interrupts created by device controller, see the USB device chapter. For interrupts created by the host controllers, see the OHCI specification. The EN_USB_INTS bit in the USBIntSt register enables the routing of any of the USB related interrupts to the NVIC controller (see Figure 13-37). Remark: During the HNP switching between host and device with the OTG stack active, an action may raise several levels of interrupts. It is advised to let the OTG stack initiate any actions based on interrupts and ignore device and host level interrupts. This means that during HNP switching, the OTG stack provides the communication to the host and device controllers.
USBIntSt
USB DEVICE INTERRUPTS USB_INT_REQ_HP USB_INT_REQ_LP USB_INT_REQ_DMA USB_HOST_INT USB HOST INTERRUPTS OTGIntSt TMR REMOVE_PU HNP_SUCCESS HNP_FAILURE USB_NEED_CLOCK USB_OTG_INT USB_I2C_INT
to NVIC
USB I2C INTERRUPTS
EN_USB_INTS
Fig 37. USB OTG interrupt handling
9. HNP support
This section describes the hardware support for the Host Negotiation Protocol (HNP) provided by the OTG controller. When two dual-role OTG devices are connected to each other, the plug inserted into the mini-AB receptacle determines the default role of each device. The device with the mini-A plug inserted becomes the default Host (A-device), and the device with the mini-B plug inserted becomes the default Peripheral (B-device). Once connected, the default Host (A-device) and the default Peripheral (B-device) can switch Host and Peripheral roles using HNP. The context of the OTG controller operation is shown in Figure 13-38. Each controller (Host, Device, or OTG) communicates with its software stack through a set of status and control registers and interrupts. In addition, the OTG software stack communicates with the external OTG transceiver through the I2C interface and the external transceiver interrupt signal.
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The OTG software stack is responsible for implementing the HNP state machines as described in the On-The-Go Supplement to the USB 2.0 Specification. The OTG controller hardware provides support for some of the state transitions in the HNP state machines as described in the following subsections. The USB state machines, the HNP switching, and the communications between the USB controllers are described in more detail in the following documentation:
* * * *
USB OHCI specification USB OTG supplement, version 1.2 USB 2.0 specification ISP1302 data sheet and user manual
OHCI STACK
HOST CONTROLLER
OTG STACK
OTG CONTROLLER
USB BUS MUX
DEVICE STACK
DEVICE CONTROLLER
I2C CONTROLLER
ISP1302
Fig 38. USB OTG controller with software stack
9.1 B-device: peripheral to host switching
In this case, the default role of the OTG controller is peripheral (B-device), and it switches roles from Peripheral to Host. The On-The-Go Supplement defines the behavior of a dual-role B-device during HNP using a state machine diagram. The OTG software stack is responsible for implementing all of the states in the Dual-Role B-Device State Diagram. The OTG controller hardware provides support for the state transitions between the states b_peripheral, b_wait_acon, and b_host in the Dual-Role B-Device state diagram. Setting B_HNP_TRACK in the OTGStCtrl register enables hardware support for the B-device switching from peripheral to host. The hardware actions after setting this bit are shown in Figure 13-39.
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idle B_HNP_TRACK = 0
no
B_HNP_TRACK = 1 ? set HNP_FAILURE, clear B_HNP_TRACK, clear PU_REMOVED
no
bus suspended ?
disconnect device controller from U1 set REMOVE_PU
no
PU_REMOVED set?
yes
PU_REMOVED set? reconnect port U1 to the device controller yes
bus reset/resume detected? no
reconnect port U1 to the device controller
wait 25 s for bus to settle
yes connect from A-device detected? bus reset/resume detected?
yes
no
no
set HNP_SUCCESS set PORT_FUNC[0] drive J on internal host controller port and SE0 on U1
yes SE0 sent by host? no
connect U1 to host controller clear B_HNP_TRACK clear PU_REMOVED
Fig 39. Hardware support for B-device switching from peripheral state to host state
Figure 13-40 shows the actions that the OTG software stack should take in response to the hardware actions setting REMOVE_PU, HNP_SUCCESS, AND HNP_FAILURE. The relationship of the software actions to the Dual-Role B-Device states is also shown. B-device states are in bold font with a circle around them.
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b_peripheral when host sends SET_FEATURE with b_hnp_enable, set B_HNP_TRACK
no REMOVE_PU set?
yes remove D+ pull-up, set PU_REMOVED
go to b_wait_acon
go to b_peripheral
HNP_FAILURE set?
yes add D+ pull-up
no no HNP_SUCCESS set?
yes go to b_host
Fig 40. State transitions implemented in software during B-device switching from peripheral to host
Note that only the subset of B-device HNP states and state transitions supported by hardware are shown. Software is responsible for implementing all of the HNP states. Figure 13-40 may appear to imply that the interrupt bits such as REMOVE_PU should be polled, but this is not necessary if the corresponding interrupt is enabled. Following are code examples that show how the actions in Figure 13-40 are accomplished. The examples assume that ISP1302 is being used as the external OTG transceiver. Remove D+ pull-up /* Remove D+ OTG_I2C_TX = OTG_I2C_TX = OTG_I2C_TX =
UM10360_1
pull-up through ISP1302 */ 0x15A; // Send ISP1302 address, R/W=0 0x007; // Send OTG Control (Clear) register address 0x201; // Clear DP_PULLUP bit, send STOP condition
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/* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI; Add D+ pull-up /* Add D+ pull-up through ISP1302 */ OTG_I2C_TX = 0x15A; // Send ISP1302 address, R/W=0 OTG_I2C_TX = 0x006; // Send OTG Control (Set) register address OTG_I2C_TX = 0x201; // Set DP_PULLUP bit, send STOP condition /* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI;
9.2 A-device: host to peripheral HNP switching
In this case, the role of the OTG controller is host (A-device), and the A-device switches roles from host to peripheral. The On-The-Go Supplement defines the behavior of a dual-role A-device during HNP using a state machine diagram. The OTG software stack is responsible for implementing all of the states in the Dual-Role A-Device State Diagram. The OTG controller hardware provides support for the state transitions between a_host, a_suspend, a_wait_vfall, and a_peripheral in the Dual-Role A-Device state diagram. Setting A_HNP_TRACK in the OTGStCtrl register enables hardware support for switching the A-device from the host state to the device state. The hardware actions after setting this bit are shown in Figure 13-41.
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idle A_HNP_TRACK = 0
no
A_HNP_TRACK = 1 ?
set HNP_FAILURE, clear A_HNP_TRACK
disconnect host controller from U1
no bus suspended ? yes resume detected ? yes
no
connnect host controller back to U1
yes bus reset detected? no resume detected? no
yes
no
OTG timer expired? (TMR =1 ) yes
clear A_HNP_TRACK set HNP_SUCCESS connect device to U1 by clearing PORT_FUNC[0]
Fig 41. Hardware support for A-device switching from host state to peripheral state
Figure 13-42 shows the actions that the OTG software stack should take in response to the hardware actions setting TMR, HNP_SUCCESS, and HNP_FAILURE. The relationship of the software actions to the Dual-Role A-Device states is also shown. A-device states are shown in bold font with a circle around them.
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a_host when host sends SET_FEATURE with a_hnp_enable, set A_HNP_TRACK
set BDIS_ACON_EN in external OTG transceiver
load and enable OTG timer
suspend host on port 1
go to a_suspend
no no TMR set? HNP_SUCCESS set? HNP_FAILURE set? no
yes clear BDIS_ACON_EN bit in external OTG transceiver discharge VBUS
yes yes stop the OTG timer stop OTG timer
go to a_peripheral go to a_wait_vfall go to a_host clear BDIS_ACON_EN bit in external OTG transceiver
Fig 42. State transitions implemented in software during A-device switching from host to peripheral
Note that only the subset of A-device HNP states and state transitions supported by hardware are shown. Software is responsible for implementing all of the HNP states. Figure 13-42 may appear to imply that the interrupt bits such as TMR should be polled, but this is not necessary if the corresponding interrupt is enabled. Following are code examples that show how the actions in Figure 13-42 are accomplished. The examples assume that ISP1302 is being used as the external OTG transceiver.
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Set BDIS_ACON_EN in external OTG transceiver /* Set BDIS_ACON_EN OTG_I2C_TX = 0x15A; OTG_I2C_TX = 0x004; OTG_I2C_TX = 0x210; in // // // ISP1302 */ Send ISP1302 address, R/W=0 Send Mode Control 1 (Set) register address Set BDIS_ACON_EN bit, send STOP condition
/* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI; Clear BDIS_ACON_EN in external OTG transceiver /* Set BDIS_ACON_EN OTG_I2C_TX = 0x15A; OTG_I2C_TX = 0x005; OTG_I2C_TX = 0x210; in // // // ISP1302 */ Send ISP1302 address, R/W=0 Send Mode Control 1 (Clear) register address Clear BDIS_ACON_EN bit, send STOP condition
/* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI; Discharge VBUS /* Clear the OTG_I2C_TX = OTG_I2C_TX = OTG_I2C_TX = VBUS_DRV bit in ISP1302 */ 0x15A; // Send ISP1302 address, R/W=0 0x007; // Send OTG Control (Clear) register address 0x220; // Clear VBUS_DRV bit, send STOP condition
/* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI; /* Set the OTG_I2C_TX OTG_I2C_TX OTG_I2C_TX VBUS_DISCHRG bit in ISP1302 */ = 0x15A; // Send ISP1302 address, R/W=0 = 0x006; // Send OTG Control (Set) register address = 0x240; // Set VBUS_DISCHRG bit, send STOP condition
/* Wait for TDI to be set */ while (!(OTG_I2C_STS & TDI)); /* Clear TDI */ OTG_I2C_STS = TDI;
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Load and enable OTG timer /* The following assumes that the OTG timer has previously been */ /* configured for a time scale of 1 ms (TMR_SCALE = "10") /* and monoshot mode (TMR_MODE = 0) */ */
/* Load the timeout value to implement the a_aidl_bdis_tmr timer */ /* the minimum value is 200 ms */ OTG_TIMER = 200; /* Enable the timer */ OTG_STAT_CTRL |= TMR_EN; Stop OTG timer /* Disable the timer - causes TMR_CNT to be reset to 0 */ OTG_STAT_CTRL &= ~TMR_EN; /* Clear TMR interrupt */ OTG_INT_CLR = TMR; Suspend host on port 1 /* Write to PortSuspendStatus bit to suspend host port 1 - */ /* this example demonstrates the low-level action software needs to take. */ /* The host stack code where this is done will be somewhat more involved. */ HC_RH_PORT_STAT1 = PSS;
10. Clocking and power management
The OTG controller clocking is shown in Figure 13-43. A clock switch controls each clock with the exception of ahb_slave_clk. When the enable of the clock switch is asserted, its clock output is turned on and its CLK_ON output is asserted. The CLK_ON signals are observable in the OTGClkSt register. To conserve power, the clocks to the Device, Host, OTG, and I2C controllers can be disabled when not in use by clearing the respective CLK_EN bit in the OTGClkCtrl register. When the entire USB block is not in use, all of its clocks can be disabled by clearing the PCUSB bit in the PCONP register. When software wishes to access registers in one of the controllers, it should first ensure that the respective controller's 48 MHz clock is enabled by setting its CLK_EN bit in the OTGClkCtrl register and then poll the corresponding CLK_ON bit in OTGClkSt until set. Once set, the controller's clock will remain enabled until CLK_EN is cleared by software. Accessing the register of a controller when its 48 MHz clock is not enabled will result in a data abort exception.
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cclk PCUSB
ahb_slave_clk
REGISTER INTERFACE
ahb_master_clk CLOCK SWITCH EN
AHB_CLK_ON ahb_need_clk AHB_CLK_EN
USB CLOCK DIVIDER
usbclk (48 MHz)
CLOCK SWITCH EN
DEV_CLK_ON
DEVICE CONTROLLER
dev_dma_need_clk dev_need_clk
DEV_CLK_EN
CLOCK SWITCH EN
host_dma_need_clk HOST_CLK_ON HOST CONTROLLER host_need_clk
HOST_CLK_EN
CLOCK SWITCH EN
OTG_CLK_ON
OTG CONTROLLER OTG_CLK_EN
USB_NEED_CLK
CLOCK SWITCH EN
I2C_CLK_ON
I2C CONTROLLER I2C_CLK_EN
Fig 43. Clocking and power control
10.1 Device clock request signals
The Device controller has two clock request signals, dev_need_clk and dev_dma_need_clk. When asserted, these signals turn on the device's 48 MHz clock and ahb_master_clk respectively. The dev_need_clk signal is asserted while the device is not in the suspend state, or if the device is in the suspend state and activity is detected on the USB bus. The dev_need_clk signal is de-asserted if a disconnect is detected (CON bit is cleared in the SIE Get Device Status register - Section 11-10.6). This signal allows DEV_CLK_EN to be cleared during normal operation when software does not need to access the Device controller registers - the Device will continue to function normally and automatically shut off its clock when it is suspended or disconnected.
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The dev_dma_need_clk signal is asserted on any Device controller DMA access to memory. Once asserted, it remains active for 2 ms (2 frames), to help assure that DMA throughput is not affected by any latency associated with re-enabling ahb_master_clk. 2 ms after the last DMA access, dev_dma_need_clk is de-asserted to help conserve power. This signal allows AHB_CLK_EN to be cleared during normal operation.
10.1.1 Host clock request signals
The Host controller has two clock request signals, host_need_clk and host_dma_need_clk. When asserted, these signals turn on the host's 48 MHz clock and ahb_master_clk respectively. The host_need_clk signal is asserted while the Host controller functional state is not UsbSuspend, or if the functional state is UsbSuspend and resume signaling or a disconnect is detected on the USB bus. This signal allows HOST_CLK_EN to be cleared during normal operation when software does not need to access the Host controller registers - the Host will continue to function normally and automatically shut off its clock when it goes into the UsbSuspend state. The host_dma_need_clk signal is asserted on any Host controller DMA access to memory. Once asserted, it remains active for 2 ms (2 frames), to help assure that DMA throughput is not affected by any latency associated with re-enabling ahb_master_clk. 2 ms after the last DMA access, host_dma_need_clk is de-asserted to help conserve power. This signal allows AHB_CLK_EN to be cleared during normal operation.
10.2 Power-down mode support
The LPC17xx can be configured to wake up from Power-down mode on any USB bus activity. When the chip is in Power-down mode and the USB interrupt is enabled, the assertion of USB_NEED_CLK causes the chip to wake up from Power-down mode. Before Power-down mode can be entered when the USB activity interrupt is enabled, USB_NEED_CLK must be de-asserted. This is accomplished by clearing all of the CLK_EN bits in OTGClkCtrl and putting the Host controller into the UsbSuspend functional state. If it is necessary to wait for either of the dma_need_clk signals or the dev_need_clk to be de-asserted, the status of USB_NEED_CLK can be polled in the USBIntSt register to determine when they have all been de-asserted.
11. USB OTG controller initialization
The LPC17xx OTG device controller initialization includes the following steps: 1. Enable the device controller by setting the PCUSB bit of PCONP. 2. Configure and enable the USB PLL (PLL1) or Main PLL (PLL0) to provide 48 MHz for usbclk and the desired frequency for cclk. For correct operation of synchronization logic in the device controller, the minimum cclk frequency is 18 MHz. For the procedure for determining the PLL setting and configuration, see Section 4-5.11 "Procedure for determining PLL0 settings" or Section 4-6.9 "Procedure for determining PLL1 settings". 3. Enable the desired controller clocks by setting their respective CLK_EN bits in the USBClkCtrl register. Poll the corresponding CLK_ON bits in the USBClkSt register until they are set.
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4. Enable the desired USB pin functions by writing to the corresponding PINSEL registers. 5. Follow the appropriate steps in Section 11-13 "USB device controller initialization" to initialize the device controller. 6. Follow the guidelines given in the OpenHCI specification for initializing the host controller.
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Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The UART0/2/3 peripherals are configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bits PCUART0/2/3. Remark: On reset, UART0 is enabled (PCUART0 = 1), and UART2/3 are disabled (PCUART2/3 = 0). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_UART0; in the PCLKSEL1 register (Table 4-41), select PCLK_UART2/3. 3. Baud rate: In register U0/2/3LCR (Table 14-278), set bit DLAB =1. This enables access to registers DLL (Table 14-272) and DLM (Table 14-273) for setting the baud rate. Also, if needed, set the fractional baud rate in the fractional divider register (Table 14-284). 4. UART FIFO: Use bit FIFO enable (bit 0) in register U0/2/3FCR (Table 14-277) to enable FIFO. 5. Pins: Select UART pins through the PINSEL registers and pin modes through the PINMODE registers (Section 8-5). Remark: UART receive pins should not have pull-down resistors enabled. 6. Interrupts: To enable UART interrupts set bit DLAB =0 in register U0/2/3LCR (Table 14-278). This enables access to U0/2/3IER (Table 14-274). Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 7. DMA: UART0/2/3 transmit and receive functions can operate with the GPDMA controller (see Table 31-544).
2. Features
* * * * * * * * * * *
Data sizes of 5, 6, 7, and 8 bits. Parity generation and checking: odd, even mark, space or none. One or two stop bits. 16 byte Receive and Transmit FIFOs. Built-in baud rate generator, including a fractional rate divider for great versatility. Supports DMA for both transmit and receive. Auto-baud capability Break generation and detection. Multiprocessor addressing mode. IrDA mode to support infrared communication. Support for software flow control.
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3. Pin description
Table 268: UARTn Pin description Pin Type Description Serial Input. Serial receive data. Serial Output. Serial transmit data.
RXD0, RXD2, RXD3 TXD0, TXD2, TXD3
Input Output
4. Register description
Each UART contains registers as shown in Table 14-269. The Divisor Latch Access Bit (DLAB) is contained in UnLCR7 and enables access to the Divisor Latches.
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Table 269. UART0/2/3 Register Map Generic Name Description Access Reset UARTn Register value[1] Name & Address
RBR (DLAB =0)
Receiver Buffer Register. Contains the next received character to be read. Transmit Holding Register. The next character to be transmitted is written here. Divisor Latch LSB. Least significant byte of the baud rate divisor value. The full divisor is used to generate a baud rate from the fractional rate divider. Divisor Latch MSB. Most significant byte of the baud rate divisor value. The full divisor is used to generate a baud rate from the fractional rate divider. Interrupt Enable Register. Contains individual interrupt enable bits for the 7 potential UART interrupts. Interrupt ID Register. Identifies which interrupt(s) are pending.
RO
NA
U0RBR - 0x4000 C000 U2RBR - 0x4009 8000 U3RBR - 0x4009 C000 U0THR - 0x4000 C000 U2THR - 0x4009 8000 U3THR - 0x4009 C000 U0DLL - 0x4000 C000 U2DLL - 0x4009 8000 U3DLL - 0x4009 C000 U0DLM - 0x4000 C004 U2DLM - 0x4009 8004 U3DLM - 0x4009 C004 U0IER - 0x4000 C004 U2IER - 0x4009 8004 U3IER - 0x4009 C004 U0IIR - 0x4000 C008 U2IIR - 0x4009 8008 U3IIR - 0x4009 C008 U0FCR - 0x4000 C008 U2FCR - 0x4009 8008 U3FCR - 0x4009 C008 U0LCR - 0x4000 C00C U2LCR - 0x4009 800C U3LCR - 0x4009 C00C U0LSR - 0x4000 C014 U2LSR - 0x4009 8014 U3LSR - 0x4009 C014 U0SCR - 0x4000 C01C U2SCR - 0x4009 801C U3SCR - 0x4009 C01C U0ACR - 0x4000 C020 U2ACR - 0x4009 8020 U3ACR - 0x4009 C020 U0ICR - 0x4000 C024 U12CR - 0x4009 8024 U3ICR - 0x4009 C024 U0FDR - 0x4000 C028 U2FDR - 0x4009 8028 U3FDR - 0x4009 C028 U0TER - 0x4000 C030 U2TER - 0x4009 8030 U3TER - 0x4009 C030 U0FIFOLVL - 0x4000 C058 U2FIFOLVL - 0x4009 8058 U3FIFOLVL - 0x4009 C058
THR (DLAB =0)
WO
NA
DLL (DLAB =1)
R/W
0x01
DLM (DLAB =1)
R/W
0x00
IER (DLAB =0)
R/W
0x00
IIR
RO
0x01
FCR
FIFO Control Register. Controls UART FIFO usage and WO modes. Line Control Register. Contains controls for frame formatting and break generation. Line Status Register. Contains flags for transmit and receive status, including line errors. Scratch Pad Register. 8-bit temporary storage for software. Auto-baud Control Register. Contains controls for the auto-baud feature. IrDA Control Register. Enables and configures the R/W
0x00
LCR
0x00
LSR
RO
0x60
SCR
R/W
0x00
ACR
R/W
0x00
ICR
R/W
0x00
IrDA mode.
FDR Fractional Divider Register. Generates a clock input for the baud rate divider. Transmit Enable Register. Turns off UART transmitter for use with software flow control. R/W 0x10
TER
R/W
0x80
FIFOLVL
FIFO Level register. Provides the current fill levels of the RO transmit and receive FIFOs.
0x00
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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14.4.1 UARTn Receiver Buffer Register (U0RBR - 0x4000 C000, U2RBR 0x4009 8000, U3RBR - 0x4009 C000 when DLAB = 0)
The UnRBR is the top byte of the UARTn Rx FIFO. The top byte of the Rx FIFO contains the oldest character received and can be read via the bus interface. The LSB (bit 0) represents the "oldest" received data bit. If the character received is less than 8 bits, the unused MSBs are padded with zeroes. The Divisor Latch Access Bit (DLAB) in LCR must be zero in order to access the UnRBR. The UnRBR is always read-only. Since PE, FE and BI bits correspond to the byte sitting on the top of the RBR FIFO (i.e. the one that will be read in the next read from the RBR), the right approach for fetching the valid pair of received byte and its status bits is first to read the content of the U0LSR register, and then to read a byte from the UnRBR.
Table 270: UARTn Receiver Buffer Register (U0RBR - address 0x4000 C000, U2RBR - 0x4009 8000, U3RBR 04009 C000 when DLAB = 0) bit description Bit Symbol Description Reset Value
7:0
RBR
The UARTn Receiver Buffer Register contains the oldest received byte in the UARTn Rx FIFO. Reserved, the value read from a reserved bit is not defined.
Undefined NA
31:8 -
4.2 UARTn Transmit Holding Register (U0THR - 0x4000 C000, U2THR 0x4009 8000, U3THR - 0x4009 C000 when DLAB = 0)
The UnTHR is the top byte of the UARTn TX FIFO. The top byte is the newest character in the TX FIFO and can be written via the bus interface. The LSB represents the first bit to transmit. The Divisor Latch Access Bit (DLAB) in UnLCR must be zero in order to access the UnTHR. The UnTHR is always write-only.
Table 271: UARTn Transmit Holding Register (U0THR - address 0x4000 C000, U2THR - 0x4009 8000, U3THR 0x4009 C000 when DLAB = 0) bit description Bit Symbol Description Reset Value
7:0
THR
Writing to the UARTn Transmit Holding Register causes the data to be stored in the UARTn transmit FIFO. The byte will be sent when it reaches the bottom of the FIFO and the transmitter is available. Reserved, user software should not write ones to reserved bits.
NA
31:8 -
NA
4.3 UARTn Divisor Latch LSB register (U0DLL - 0x4000 C000, U2DLL 0x4009 8000, U3DLL - 0x4009 C000 when DLAB = 1) and UARTn Divisor Latch MSB register (U0DLM - 0x4000 C004, U2DLL 0x4009 8004, U3DLL - 0x4009 C004 when DLAB = 1)
The UARTn Divisor Latch is part of the UARTn Baud Rate Generator and holds the value used, along with the Fractional Divider, to divide the APB clock (PCLK) in order to produce the baud rate clock, which must be 16x the desired baud rate. The UnDLL and UnDLM registers together form a 16-bit divisor where UnDLL contains the lower 8 bits of the divisor and UnDLM contains the higher 8 bits of the divisor. A 0x0000 value is treated like a 0x0001 value as division by zero is not allowed. The Divisor Latch Access Bit (DLAB) in
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UnLCR must be one in order to access the UARTn Divisor Latches. Details on how to select the right value for U1DLL and U1DLM can be found later in this chapter, see Section 14-4.12.
Table 272: UARTn Divisor Latch LSB register (U0DLL - address 0x4000 C000, U2DLL - 0x4009 8000, U3DLL 0x4009 C000 when DLAB = 1) bit description Bit Symbol Description Reset Value
7:0
DLLSB
The UARTn Divisor Latch LSB Register, along with the UnDLM register, determines the baud rate of the UARTn. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x01 NA
31:8 -
Table 273: UARTn Divisor Latch MSB register (U0DLM - address 0x4000 C004, U2DLM - 0x4009 8004, U3DLM 0x4009 C004 when DLAB = 1) bit description Bit Symbol Description Reset Value
7:0
DLMSB
The UARTn Divisor Latch MSB Register, along with the U0DLL register, determines the baud rate of the UARTn. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
31:8 -
4.4 UARTn Interrupt Enable Register (U0IER - 0x4000 C004, U2IER 0x4009 8004, U3IER - 0x4009 C004 when DLAB = 0)
The UnIER is used to enable the three UARTn interrupt sources.
Table 274: UARTn Interrupt Enable Register (U0IER - address 0x4000 C004, U2IER - 0x4009 8004, U3IER 0x4009 C004 when DLAB = 0) bit description Bit Symbol Value Description Reset Value
0
RBR Interrupt Enable 0 1
Enables the Receive Data Available interrupt for UARTn. It also controls the Character Receive Time-out interrupt. Disable the RDA interrupts. Enable the RDA interrupts. Enables the THRE interrupt for UARTn. The status of this can be read from UnLSR[5]. 0 1 Disable the THRE interrupts. Enable the THRE interrupts. Enables the UARTn RX line status interrupts. The status of this interrupt can be read from UnLSR[4:1]. 0 1 Disable the RX line status interrupts. Enable the RX line status interrupts.
0
1
THRE Interrupt Enable
0
2
RX Line Status Interrupt Enable
0
7:3 8
ABEOIntEn 0 1
Reserved, user software should not write ones to reserved bits. The value NA read from a reserved bit is not defined. Enables the end of auto-baud interrupt. Disable end of auto-baud Interrupt. Enable end of auto-baud Interrupt. 0
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Table 274: UARTn Interrupt Enable Register (U0IER - address 0x4000 C004, U2IER - 0x4009 8004, U3IER 0x4009 C004 when DLAB = 0) bit description Bit Symbol Value Description Reset Value
9
ABTOIntEn 0 1
Enables the auto-baud time-out interrupt. Disable auto-baud time-out Interrupt. Enable auto-baud time-out Interrupt.
0
31:10 -
Reserved, user software should not write ones to reserved bits. The value NA read from a reserved bit is not defined.
4.5 UARTn Interrupt Identification Register (U0IIR - 0x4000 C008, U2IIR 0x4009 8008, U3IIR - 0x4009 C008)
The UnIIR provides a status code that denotes the priority and source of a pending interrupt. The interrupts are frozen during an UnIIR access. If an interrupt occurs during an UnIIR access, the interrupt is recorded for the next UnIIR access.
Table 275: UARTn Interrupt Identification Register (U0IIR - address 0x4000 C008, U2IIR - 0x4009 8008, U3IIR 0x4009 C008) bit description Bit Symbol Value Description Reset Value
0
IntStatus 0 1
Interrupt status. Note that U1IIR[0] is active low. The pending interrupt can be determined by evaluating UnIIR[3:1]. At least one interrupt is pending. No interrupt is pending. Interrupt identification. UnIER[3:1] identifies an interrupt corresponding to the UARTn Rx or TX FIFO. All other combinations of UnIER[3:1] not listed below are reserved (000,100,101,111). 011 010 110 001 1 - Receive Line Status (RLS). 2a - Receive Data Available (RDA). 2b - Character Time-out Indicator (CTI). 3 - THRE Interrupt
1
3:1
IntId
0
5:4 7:6 8 9
FIFO Enable ABEOInt ABTOInt
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. Copies of UnFCR[0]. End of auto-baud interrupt. True if auto-baud has finished successfully and interrupt is enabled. Auto-baud time-out interrupt. True if auto-baud has timed out and interrupt is enabled. 0 0 0
31:10 -
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined.
Bit UnIIR[9:8] are set by the auto-baud function and signal a time-out or end of auto-baud condition. The auto-baud interrupt conditions are cleared by setting the corresponding Clear bits in the Auto-baud Control Register. If the IntStatus bit is 1 no interrupt is pending and the IntId bits will be zero. If the IntStatus is 0, a non auto-baud interrupt is pending in which case the IntId bits identify the type of interrupt and handling as described in Table 14-276. Given the status of UnIIR[3:0], an interrupt handler routine can determine the cause of the interrupt and how to clear the active interrupt. The UnIIR must be read in order to clear the interrupt prior to exiting the Interrupt Service Routine.
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The UARTn RLS interrupt (UnIIR[3:1] = 011) is the highest priority interrupt and is set whenever any one of four error conditions occur on the UARTn Rx input: overrun error (OE), parity error (PE), framing error (FE) and break interrupt (BI). The UARTn Rx error condition that set the interrupt can be observed via U0LSR[4:1]. The interrupt is cleared upon an UnLSR read. The UARTn RDA interrupt (UnIIR[3:1] = 010) shares the second level priority with the CTI interrupt (UnIIR[3:1] = 110). The RDA is activated when the UARTn Rx FIFO reaches the trigger level defined in UnFCR[7:6] and is reset when the UARTn Rx FIFO depth falls below the trigger level. When the RDA interrupt goes active, the CPU can read a block of data defined by the trigger level. The CTI interrupt (UnIIR[3:1] = 110) is a second level interrupt and is set when the UARTn Rx FIFO contains at least one character and no UARTn Rx FIFO activity has occurred in 3.5 to 4.5 character times. Any UARTn Rx FIFO activity (read or write of UARTn RSR) will clear the interrupt. This interrupt is intended to flush the UARTn RBR after a message has been received that is not a multiple of the trigger level size. For example, if a peripheral wished to send a 105 character message and the trigger level was 10 characters, the CPU would receive 10 RDA interrupts resulting in the transfer of 100 characters and 1 to 5 CTI interrupts (depending on the service routine) resulting in the transfer of the remaining 5 characters.
Table 276: UARTn Interrupt Handling U0IIR[3:0] Priority Interrupt value[1] Type Interrupt Source Interrupt Reset
0001 0110 0100 1100
Highest Second Second
None RX Line Status / Error RX Data Available Character Time-out indication
None OE[2] or PE[2] or FE[2] or BI[2]
UnLSR Read[2] UnRBR Read[3] or UARTn FIFO drops below trigger level UnRBR Read[3]
Rx data available or trigger level reached in FIFO (UnFCR0=1) Minimum of one character in the Rx FIFO and no character input or removed during a time period depending on how many characters are in FIFO and what the trigger level is set at (3.5 to 4.5 character times). The exact time will be: [(word length) x 7 - 2] x 8 + [(trigger level - number of characters) x 8 + 1] RCLKs
0010
Third
THRE
THRE[2]
UnIIR Read (if source of interrupt) or THR write[4]
[1] [2] [3] [4]
Values "0000", "0011", "0101", "0111", "1000", "1001", "1010", "1011","1101","1110","1111" are reserved. For details see Section 14-4.8 "UARTn Line Status Register (U0LSR - 0x4000 C014, U2LSR 0x4009 8014, U3LSR - 0x4009 C014)" For details see Section 14-14.4.1 "UARTn Receiver Buffer Register (U0RBR - 0x4000 C000, U2RBR 0x4009 8000, U3RBR - 0x4009 C000 when DLAB = 0)" For details see Section 14-4.5 "UARTn Interrupt Identification Register (U0IIR - 0x4000 C008, U2IIR 0x4009 8008, U3IIR - 0x4009 C008)" and Section 14-4.2 "UARTn Transmit Holding Register (U0THR 0x4000 C000, U2THR - 0x4009 8000, U3THR - 0x4009 C000 when DLAB = 0)"
The UARTn THRE interrupt (UnIIR[3:1] = 001) is a third level interrupt and is activated when the UARTn THR FIFO is empty provided certain initialization conditions have been met. These initialization conditions are intended to give the UARTn THR FIFO a chance to
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fill up with data to eliminate many THRE interrupts from occurring at system start-up. The initialization conditions implement a one character delay minus the stop bit whenever THRE = 1 and there have not been at least two characters in the UnTHR at one time since the last THRE = 1 event. This delay is provided to give the CPU time to write data to UnTHR without a THRE interrupt to decode and service. A THRE interrupt is set immediately if the UARTn THR FIFO has held two or more characters at one time and currently, the UnTHR is empty. The THRE interrupt is reset when a UnTHR write occurs or a read of the UnIIR occurs and the THRE is the highest interrupt (UnIIR[3:1] = 001).
4.6 UARTn FIFO Control Register (U0FCR - 0x4000 C008, U2FCR 0x4009 8008, U3FCR - 0x4009 C008)
The write-only UnFCR controls the operation of the UARTn Rx and TX FIFOs.
Table 277: UARTn FIFO Control Register (U0FCR - address 0x4000 C008, U2FCR - 0x4009 8008, U3FCR 0x4007 C008) bit description Bit Symbol Value Description Reset Value
0
FIFO Enable 0 1
UARTn FIFOs are disabled. Must not be used in the application. Active high enable for both UARTn Rx and TX FIFOs and UnFCR[7:1] access. This bit must be set for proper UART operation. Any transition on this bit will automatically clear the related UART FIFOs. No impact on either of UARTn FIFOs. Writing a logic 1 to UnFCR[1] will clear all bytes in UARTn Rx FIFO, reset the pointer logic. This bit is self-clearing. No impact on either of UARTn FIFOs. Writing a logic 1 to UnFCR[2] will clear all bytes in UARTn TX FIFO, reset the pointer logic. This bit is self-clearing.
0
1
RX FIFO Reset TX FIFO Reset DMA Mode Select RX Trigger Level
0 1 0 1
0
2
0
3 5:4 7:6
When the FIFO enable bit (bit 0 of this register) is set, this bit selects the DMA 0 mode. See Section 14-4.6.1. Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. These two bits determine how many receiver UARTn FIFO characters must be 0 written before an interrupt or DMA request is activated. 00 01 10 11 Trigger level 0 (1 character or 0x01) Trigger level 1 (4 characters or 0x04) Trigger level 2 (8 characters or 0x08) Trigger level 3 (14 characters or 0x0E) Reserved, user software should not write ones to reserved bits. NA
31:8
-
4.6.1 DMA Operation
The user can optionally operate the UART transmit and/or receive using DMA. The DMA mode is determined by the DMA Mode Select bit in the FCR register. This bit only has an affect when the FIFOs are enabled via the FIFO Enable bit in the FCR register. UART receiver DMA In DMA mode, the receiver DMA request is asserted on the event of the receiver FIFO level becoming equal to or greater than trigger level, or if a character timeout occurs. See the description of the RX Trigger Level above. The receiver DMA request is cleared by the DMA controller.
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UART transmitter DMA In DMA mode, the transmitter DMA request is asserted on the event of the transmitter FIFO transitioning to not full. The transmitter DMA request is cleared by the DMA controller.
4.7 UARTn Line Control Register (U0LCR - 0x4000 C00C, U2LCR 0x4009 800C, U3LCR - 0x4009 C00C)
The UnLCR determines the format of the data character that is to be transmitted or received.
Table 278: UARTn Line Control Register (U0LCR - address 0x4000 C00C, U2LCR - 0x4009 800C, U3LCR 0x4009 C00C) bit description Bit Symbol Value Description Reset Value
1:0
Word Length Select 00 01 10 11
5-bit character length 6-bit character length 7-bit character length 8-bit character length 1 stop bit. 2 stop bits (1.5 if UnLCR[1:0]=00). Disable parity generation and checking. Enable parity generation and checking. Odd parity. Number of 1s in the transmitted character and the attached parity bit will be odd. Even Parity. Number of 1s in the transmitted character and the attached parity bit will be even. Forced "1" stick parity. Forced "0" stick parity. Disable break transmission. Enable break transmission. Output pin UARTn TXD is forced to logic 0 when UnLCR[6] is active high. Disable access to Divisor Latches. Enable access to Divisor Latches. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
2 3 5:4
Stop Bit Select Parity Enable Parity Select
0 1 0 1 00 01 10 11
0 0 0
6
Break Control
0 1
0
7 31:8
Divisor Latch Access Bit (DLAB) -
0 1
0 NA
4.8 UARTn Line Status Register (U0LSR - 0x4000 C014, U2LSR 0x4009 8014, U3LSR - 0x4009 C014)
The UnLSR is a read-only register that provides status information on the UARTn TX and RX blocks.
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Table 279: UARTn Line Status Register (U0LSR - address 0x4000 C014, U2LSR - 0x4009 8014, U3LSR - 0x4009 C014) bit description Bit Symbol Value Description Reset Value
0
Receiver Data Ready (RDR) 0 1
UnLSR0 is set when the UnRBR holds an unread character and is cleared when the UARTn RBR FIFO is empty. The UARTn receiver FIFO is empty. The UARTn receiver FIFO is not empty.
0
1
Overrun Error (OE)
The overrun error condition is set as soon as it occurs. An UnLSR read clears 0 UnLSR1. UnLSR1 is set when UARTn RSR has a new character assembled and the UARTn RBR FIFO is full. In this case, the UARTn RBR FIFO will not be overwritten and the character in the UARTn RSR will be lost. 0 1 Overrun error status is inactive. Overrun error status is active. When the parity bit of a received character is in the wrong state, a parity error occurs. An UnLSR read clears UnLSR[2]. Time of parity error detection is dependent on UnFCR[0].
Note: A parity error is associated with the character at the top of the UARTn RBR FIFO.
2
Parity Error (PE)
0
0 1 3 Framing Error (FE)
Parity error status is inactive. Parity error status is active. When the stop bit of a received character is a logic 0, a framing error occurs. An 0 UnLSR read clears UnLSR[3]. The time of the framing error detection is dependent on UnFCR0. Upon detection of a framing error, the Rx will attempt to resynchronize to the data and assume that the bad stop bit is actually an early start bit. However, it cannot be assumed that the next received byte will be correct even if there is no Framing Error.
Note: A framing error is associated with the character at the top of the UARTn RBR FIFO.
0 1 4 Break Interrupt (BI)
Framing error status is inactive. Framing error status is active. When RXDn is held in the spacing state (all zeroes) for one full character 0 transmission (start, data, parity, stop), a break interrupt occurs. Once the break condition has been detected, the receiver goes idle until RXDn goes to marking state (all ones). An UnLSR read clears this status bit. The time of break detection is dependent on UnFCR[0].
Note: The break interrupt is associated with the character at the top of the UARTn RBR FIFO.
0 1 5 Transmitter Holding Register Empty (THRE))
Break interrupt status is inactive. Break interrupt status is active. THRE is set immediately upon detection of an empty UARTn THR and is cleared 1 on a UnTHR write.
0 1
UnTHR contains valid data. UnTHR is empty. TEMT is set when both UnTHR and UnTSR are empty; TEMT is cleared when either the UnTSR or the UnTHR contain valid data. 1
6
Transmitter Empty (TEMT) 0 1
UnTHR and/or the UnTSR contains valid data. UnTHR and the UnTSR are empty.
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Table 279: UARTn Line Status Register (U0LSR - address 0x4000 C014, U2LSR - 0x4009 8014, U3LSR - 0x4009 C014) bit description Bit Symbol Value Description Reset Value
7
Error in RX FIFO (RXFE) 0 1
UnLSR[7] is set when a character with a Rx error such as framing error, parity error or break interrupt, is loaded into the UnRBR. This bit is cleared when the UnLSR register is read and there are no subsequent errors in the UARTn FIFO. UnRBR contains no UARTn RX errors or UnFCR[0]=0. UARTn RBR contains at least one UARTn RX error. Reserved, the value read from a reserved bit is not defined.
0
31:8
-
NA
4.9 UARTn Scratch Pad Register (U0SCR - 0x4000 C01C, U2SCR 0x4009 801C U3SCR - 0x4009 C01C)
The UnSCR has no effect on the UARTn operation. This register can be written and/or read at user's discretion. There is no provision in the interrupt interface that would indicate to the host that a read or write of the UnSCR has occurred.
Table 280: UARTn Scratch Pad Register (U0SCR - address 0x4000 C01C, U2SCR - 0x4009 801C, U3SCR 0x4009 C01C) bit description Bit Symbol Description Reset Value
7:0 31:8
Pad -
A readable, writable byte. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
4.10 UARTn Auto-baud Control Register (U0ACR - 0x4000 C020, U2ACR 0x4009 8020, U3ACR - 0x4009 C020)
The UARTn Auto-baud Control Register (UnACR) controls the process of measuring the incoming clock/data rate for the baud rate generation and can be read and written at user's discretion.
Table 281: UARTn Auto-baud Control Register (U0ACR - address 0x4000 C020, U2ACR - 0x4009 8020, U3ACR 0x4009 C020) bit description Bit Symbol Value Description Reset value
0
Start 0 1
This bit is automatically cleared after auto-baud completion. Auto-baud stop (auto-baud is not running). Auto-baud start (auto-baud is running). Auto-baud run bit. This bit is automatically cleared after auto-baud completion. Auto-baud mode select bit. 0 1 Mode 0. Mode 1. No restart. Restart in case of time-out (counter restarts at next UARTn Rx falling edge) Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
Mode
0
2 7:3
AutoRestart -
0 1
0 0 NA
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Table 281: UARTn Auto-baud Control Register (U0ACR - address 0x4000 C020, U2ACR - 0x4009 8020, U3ACR 0x4009 C020) bit description Bit Symbol Value Description Reset value
8 9
ABEOIntClr ABTOIntClr
End of auto-baud interrupt clear bit (write-only accessible). Writing a 1 will clear the corresponding interrupt in the UnIIR. Writing a 0 has no impact. Auto-baud time-out interrupt clear bit (write-only accessible). Writing a 1 will clear the corresponding interrupt in the UnIIR. Writing a 0 has no impact. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 NA
31:10 -
14.4.10.1
Auto-baud The UARTn auto-baud function can be used to measure the incoming baud-rate based on the "AT" protocol (Hayes command). If enabled the auto-baud feature will measure the bit time of the receive data stream and set the divisor latch registers UnDLM and UnDLL accordingly. Remark: the fractional rate divider is not connected during auto-baud operations, and therefore should not be used when the auto-baud feature is needed. Auto-baud is started by setting the UnACR Start bit. Auto-baud can be stopped by clearing the UnACR Start bit. The Start bit will clear once auto-baud has finished and reading the bit will return the status of auto-baud (pending/finished). Two auto-baud measuring modes are available which can be selected by the UnACR Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the UARTn Rx pin (the falling edge of the start bit and the falling edge of the least significant bit). In mode 1 the baud-rate is measured between the falling edge and the subsequent rising edge of the UARTn Rx pin (the length of the start bit). The UnACR AutoRestart bit can be used to automatically restart baud-rate measurement if a time-out occurs (the rate measurement counter overflows). If this bit is set the rate measurement will restart at the next falling edge of the UARTn Rx pin. The auto-baud function can generate two interrupts.
* The UnIIR ABTOInt interrupt will get set if the interrupt is enabled (UnIER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
* The UnIIR ABEOInt interrupt will get set if the interrupt is enabled (UnIER ABEOIntEn
is set and the auto-baud has completed successfully). The auto-baud interrupts have to be cleared by setting the corresponding UnACR ABTOIntClr and ABEOIntEn bits. Typically the fractional baud-rate generator is disabled (DIVADDVAL = 0) during auto-baud. However, if the fractional baud-rate generator is enabled (DIVADDVAL > 0), it is going to impact the measuring of UARTn Rx pin baud-rate, but the value of the UnFDR register is not going to be modified after rate measurement. Also, when auto-baud is used, any write to UnDLM and UnDLL registers should be done before UnACR register write. The minimum and the maximum baud rates supported by UARTn are function of pclk, number of data bits, stop bits and parity bits.
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2 x P CLK PCLK ratemin = ------------------------ UARTn baudrate ----------------------------------------------------------------------------------------------------------- = ratemax 16 x 2 15 16 x ( 2 + databits + paritybits + stopbits )
14.4.10.2
Auto-baud modes When the software is expecting an "AT" command, it configures the UARTn with the expected character format and sets the UnACR Start bit. The initial values in the divisor latches UnDLM and UnDLM don`t care. Because of the "A" or "a" ASCII coding ("A" = 0x41, "a" = 0x61), the UARTn Rx pin sensed start bit and the LSB of the expected character are delimited by two falling edges. When the UnACR Start bit is set, the auto-baud protocol will execute the following phases: 1. On UnACR Start bit setting, the baud rate measurement counter is reset and the UARTn UnRSR is reset. The UnRSR baud rate is switch to the highest rate. 2. A falling edge on UARTn Rx pin triggers the beginning of the start bit. The rate measuring counter will start counting pclk cycles optionally pre-scaled by the fractional baud-rate generator. 3. During the receipt of the start bit, 16 pulses are generated on the RSR baud input with the frequency of the (fractional baud-rate pre-scaled) UARTn input clock, guaranteeing the start bit is stored in the UnRSR. 4. During the receipt of the start bit (and the character LSB for mode = 0) the rate counter will continue incrementing with the pre-scaled UARTn input clock (pclk). 5. If Mode = 0 then the rate counter will stop on next falling edge of the UARTn Rx pin. If Mode = 1 then the rate counter will stop on the next rising edge of the UARTn Rx pin. 6. The rate counter is loaded into UnDLM/UnDLL and the baud-rate will be switched to normal operation. After setting the UnDLM/UnDLL the end of auto-baud interrupt UnIIR ABEOInt will be set, if enabled. The UnRSR will now continue receiving the remaining bits of the "A/a" character.
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'A' (0x41) or 'a' (0x61) start UARTn RX start bit LSB of 'A' or 'a' bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop
U0ACR start rate counter 16xbaud_rate
16 cycles
16 cycles
a. Mode 0 (start bit and LSB are used for auto-baud)
'A' (0x41) or 'a' (0x61) start UARTn RX start bit LSB of 'A' or 'a' bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop
U1ACR start rate counter 16xbaud_rate
16 cycles
b. Mode 1 (only start bit is used for auto-baud)
Fig 44. Auto-baud a) mode 0 and b) mode 1 waveform
4.11 UARTn IrDA Control Register (U0ICR - 0x4000 C024, U2ICR - 0x4009 8024, U3ICR - 0x4009 C024)
The IrDA Control Register enables and configures the IrDA mode on each UART. The value of UnICR should not be changed while transmitting or receiving data, or data loss or corruption may occur.
Table 282: UARTn IrDA Control Register (U0ICR - 0x4000 C024, U2ICR - 0x4009 8024, U3ICR - 0x4009 C024) bit description Bit Symbol Value Description Reset value
0 1
IrDAEn IrDAInv
0 1
IrDA mode on UARTn is disabled, UARTn acts as a standard UART. IrDA mode on UARTn is enabled. When 1, the serial input is inverted. This has no effect on the serial output. When 0, the serial input is not inverted.
0 0
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Table 282: UARTn IrDA Control Register (U0ICR - 0x4000 C024, U2ICR - 0x4009 8024, U3ICR - 0x4009 C024) bit description Bit Symbol Value Description Reset value
2 5:3 31:6
FixPulseEn PulseDiv NA
When 1, enabled IrDA fixed pulse width mode. Configures the pulse when FixPulseEn = 1. See text below for details.
0 0
Reserved, user software should not write ones to reserved bits. The value read 0 from a reserved bit is not defined.
The PulseDiv bits in UnICR are used to select the pulse width when the fixed pulse width mode is used in IrDA mode (IrDAEn = 1 and FixPulseEn = 1). The value of these bits should be set so that the resulting pulse width is at least 1.63 s. Table 14-283 shows the possible pulse widths.
Table 283: IrDA Pulse Width FixPulseEn PulseDiv IrDA Transmitter Pulse width (s)
0 1 1 1 1 1 1 1 1
x 0 1 2 3 4 5 6 7
3 / (16 x baud rate) 2 x TPCLK 4 x TPCLK 8 x TPCLK 16 x TPCLK 32 x TPCLK 64 x TPCLK 128 x TPCLK 256 x TPCLK
4.12 UARTn Fractional Divider Register (U0FDR - 0x4000 C028, U2FDR 0x4009 8028, U3FDR - 0x4009 C028)
The UART0/2/3 Fractional Divider Register (U0/2/3FDR) controls the clock pre-scaler for the baud rate generation and can be read and written at the user's discretion. This pre-scaler takes the APB clock and generates an output clock according to the specified fractional requirements. Important: If the fractional divider is active (DIVADDVAL > 0) and DLM = 0, the value of the DLL register must be greater than 2.
Table 284: UARTn Fractional Divider Register (U0FDR - address 0x4000 C028, U2FDR - 0x4009 8028, U3FDR 0x4009 C028) bit description Bit Function Value Description Reset value
3:0 7:4
DIVADDVAL MULVAL
0 1
Baud-rate generation pre-scaler divisor value. If this field is 0, fractional baud-rate generator will not impact the UARTn baudrate. Baud-rate pre-scaler multiplier value. This field must be greater or equal 1 for UARTn to operate properly, regardless of whether the fractional baud-rate generator is used or not.
0 1
31:8
-
NA
Reserved, user software should not write ones to reserved bits. The value read 0 from a reserved bit is not defined.
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This register controls the clock pre-scaler for the baud rate generation. The reset value of the register keeps the fractional capabilities of UART0/2/3 disabled making sure that UART0/2/3 is fully software and hardware compatible with UARTs not equipped with this feature. UART0/2/3 baud rate can be calculated as (n = 0/2/3): (2)
PCLK UARTn baudrate = ---------------------------------------------------------------------------------------------------------------------------------DivAddVal 16 x ( 256 x UnDLM + UnDLL ) x 1 + ---------------------------- MulVal Where PCLK is the peripheral clock, U0/2/3DLM and U0/2/3DLL are the standard UART0/2/3 baud rate divider registers, and DIVADDVAL and MULVAL are UART0/2/3 fractional baud rate generator specific parameters. The value of MULVAL and DIVADDVAL should comply to the following conditions: 1. 1 MULVAL 15 2. 0 DIVADDVAL 14 3. DIVADDVAL < MULVAL The value of the U0/2/3FDR should not be modified while transmitting/receiving data or data may be lost or corrupted. If the U0/2/3FDR register value does not comply to these two requests, then the fractional divider output is undefined. If DIVADDVAL is zero then the fractional divider is disabled, and the clock will not be divided.
4.12.1 Baud rate calculation
UARTn can operate with or without using the Fractional Divider. In real-life applications it is likely that the desired baud rate can be achieved using several different Fractional Divider settings. The following algorithm illustrates one way of finding a set of DLM, DLL, MULVAL, and DIVADDVAL values. Such set of parameters yields a baud rate with a relative error of less than 1.1% from the desired one.
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Calculating UART baudrate (BR)
PCLK, BR
DL est = PCLK/(16 x BR)
DL est is an integer?
True
False FR est = 1.5
DIVADDVAL = 0 MULVAL = 1
Pick another FR est from the range [1.1, 1.9]
DL est = Int(PCLK/(16 x BR x FR est))
FR est = PCLK/(16 x BR x DL est)
False 1.1 < FR est < 1.9?
True
DIVADDVAL = table(FR est ) MULVAL = table(FR est )
DLM = DL est [15:8] DLL = DLest [7:0]
End
Fig 45. Algorithm for setting UART dividers
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Table 285. Fractional Divider setting look-up table FR DivAddVal/ MulVal FR DivAddVal/ MulVal FR DivAddVal/ MulVal FR DivAddVal/ MulVal
1.000 1.067 1.071 1.077 1.083 1.091 1.100 1.111 1.125 1.133 1.143 1.154 1.167 1.182 1.200 1.214 1.222 1.231
0/1 1/15 1/14 1/13 1/12 1/11 1/10 1/9 1/8 2/15 1/7 2/13 1/6 2/11 1/5 3/14 2/9 3/13
1.250 1.267 1.273 1.286 1.300 1.308 1.333 1.357 1.364 1.375 1.385 1.400 1.417 1.429 1.444 1.455 1.462 1.467
1/4 4/15 3/11 2/7 3/10 4/13 1/3 5/14 4/11 3/8 5/13 2/5 5/12 3/7 4/9 5/11 6/13 7/15
1.500 1.533 1.538 1.545 1.556 1.571 1.583 1.600 1.615 1.625 1.636 1.643 1.667 1.692 1.700 1.714 1.727 1.733
1/2 8/15 7/13 6/11 5/9 4/7 7/12 3/5 8/13 5/8 7/11 9/14 2/3 9/13 7/10 5/7 8/11 11/15
1.750 1.769 1.778 1.786 1.800 1.818 1.833 1.846 1.857 1.867 1.875 1.889 1.900 1.909 1.917 1.923 1.929 1.933
3/4 10/13 7/9 11/14 4/5 9/11 5/6 11/13 6/7 13/15 7/8 8/9 9/10 10/11 11/12 12/13 13/14 14/15
4.12.1.1
Example 1: PCLK = 14.7456 MHz, BR = 9600 According to the provided algorithm DLest = PCLK/(16 x BR) = 14.7456 MHz / (16 x 9600) = 96. Since this DLest is an integer number, DIVADDVAL = 0, MULVAL = 1, DLM = 0, and DLL = 96.
4.12.1.2
Example 2: PCLK = 12 MHz, BR = 115200 According to the provided algorithm DLest = PCLK/(16 x BR) = 12 MHz / (16 x 115200) = 6.51. This DLest is not an integer number and the next step is to estimate the FR parameter. Using an initial estimate of FRest = 1.5 a new DLest = 4 is calculated and FRest is recalculated as FRest = 1.628. Since FRest = 1.628 is within the specified range of 1.1 and 1.9, DIVADDVAL and MULVAL values can be obtained from the attached look-up table. The closest value for FRest = 1.628 in the look-up Table 14-285 is FR = 1.625. It is equivalent to DIVADDVAL = 5 and MULVAL = 8. Based on these findings, the suggested UART setup would be: DLM = 0, DLL = 4, DIVADDVAL = 5, and MULVAL = 8. According to Equation 14-2 the UART rate is 115384. This rate has a relative error of 0.16% from the originally specified 115200.
4.13 UARTn Transmit Enable Register (U0TER - 0x4000 C030, U2TER 0x4009 8030, U3TER - 0x4009 C030)
The UnTER register enables implementation of software flow control. When TXEn=1, UARTn transmitter will keep sending data as long as they are available. As soon as TXEn becomes 0, UARTn transmission will stop.
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Table 14-286 describes how to use TXEn bit in order to achieve software flow control.
Table 286: UARTn Transmit Enable Register (U0TER - address 0x4000 C030, U2TER - 0x4009 8030, U3TER 0x4009 C030) bit description Bit Symbol Description Reset Value
6:0 7
TXEN
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
When this bit is 1, as it is after a Reset, data written to the THR is output on the TXD pin as 1 soon as any preceding data has been sent. If this bit is cleared to 0 while a character is being sent, the transmission of that character is completed, but no further characters are sent until this bit is set again. In other words, a 0 in this bit blocks the transfer of characters from the THR or TX FIFO into the transmit shift register. Software implementing software-handshaking can clear this bit when it receives an XOFF character (DC3). Software can set this bit again when it receives an XON (DC1) character.
4.14 UARTn FIFO Level register (U0FIFOLVL - 0x4000 C058, U2FIFOLVL 0x4009 8058, U3FIFOLVL - 0x4009 C058)
UnFIFOLVL register is a read-only register that allows software to read the current FIFO level status. Both the transmit and receive FIFO levels are present in this register.
Table 287. UARTn FIFO Level register (U0FIFOLVL - 0x4000 C058, U2FIFOLVL - 0x4009 8058, U3FIFOLVL - 0x4009 C058) bit description Bit Symbol Description Reset value
3:0 7:4 11:8
RXFIFILVL TXFIFOLVL
Reflects the current level of the UART receiver FIFO. 0 = empty, 0xF = FIFO full. Reserved. The value read from a reserved bit is not defined. Reflects the current level of the UART transmitter FIFO. 0 = empty, 0xF = FIFO full. Reserved. The value read from a reserved bit is not defined.
0x00 NA 0x00 NA
31:12 -
5. Architecture
The architecture of the UARTs 0, 2 and 3 are shown below in the block diagram. The APB interface provides a communications link between the CPU or host and the UART. The UARTn receiver block, UnRX, monitors the serial input line, RXDn, for valid input. The UARTn RX Shift Register (UnRSR) accepts valid characters via RXDn. After a valid character is assembled in the UnRSR, it is passed to the UARTn RX Buffer Register FIFO to await access by the CPU or host via the generic host interface. The UARTn transmitter block, UnTX, accepts data written by the CPU or host and buffers the data in the UARTn TX Holding Register FIFO (UnTHR). The UARTn TX Shift Register (UnTSR) reads the data stored in the UnTHR and assembles the data to transmit via the serial output pin, TXDn. The UARTn Baud Rate Generator block, UnBRG, generates the timing enables used by the UARTn TX block. The UnBRG clock input source is the APB clock (PCLK). The main clock is divided down per the divisor specified in the UnDLL and UnDLM registers. This divided down clock is a 16x oversample clock, NBAUDOUT.
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The interrupt interface contains registers UnIER and UnIIR. The interrupt interface receives several one clock wide enables from the UnTX and UnRX blocks. Status information from the UnTX and UnRX is stored in the UnLSR. Control information for the UnTX and UnRX is stored in the UnLCR.
Transmitter Transmitter Holding Register Transmitter FIFO Transmitter DMA Interface TX_DMA_REQ TX_DMA_CLR Baud Rate Generator Fractional Main Rate Divider Divider (DLM, DLL) FIFO Control & Status Interrupt UARTn interrupt Control & Status Line Control & Status RS485, IrDA, & Auto-baud Receiver Receiver Buffer Register Receiver FIFO Receiver DMA Interface RX_DMA_REQ RX_DMA_CLR Receiver Shift Register Un_RXD Un_OE Transmitter Shift Register Un_TXD
PCLK
Fig 46. UART0, 2 and 3 block diagram
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1. Basic configuration
The UART1 peripheral is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bits PCUART1. Remark: On reset, UART1 is enabled (PCUART1 = 1). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_UART1. 3. Baud rate: In register U1LCR (Table 15-298), set bit DLAB =1. This enables access to registers DLL (Table 15-292) and DLM (Table 15-293) for setting the baud rate. Also, if needed, set the fractional baud rate in the fractional divider register (Table 15-305). 4. UART FIFO: Use bit FIFO enable (bit 0) in register U0FCR (Table 15-297) to enable FIFO. 5. Pins: Select UART pins through PINSEL registers and pin modes through the PINMODE registers (Section 8-5). Remark: UART receive pins should not have pull-down resistors enabled. 6. Interrupts: To enable UART interrupts set bit DLAB =0 in register U1LCR (Table 15-298). This enables access to U1IER (Table 15-294). Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 7. DMA: UART1 transmit and receive functions can operated with the GPDMA controller (see Table 31-544).
2. Features
* * * * * * * * * * *
Full modem control handshaking available Data sizes of 5, 6, 7, and 8 bits. Parity generation and checking: odd, even mark, space or none. One or two stop bits. 16 byte Receive and Transmit FIFOs. Built-in baud rate generator, including a fractional rate divider for great versatility. Supports DMA for both transmit and receive. Auto-baud capability Break generation and detection. Multiprocessor addressing mode. RS-485 support.
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3. Pin description
Table 288: UART1 Pin Description Pin Type Description Serial Input. Serial receive data. Clear To Send. Active low signal indicates if the external modem is ready to accept transmitted data via TXD1 from the UART1. In normal operation of the modem interface (U1MCR[4] = 0), the complement value of this signal is stored in U1MSR[4]. State change information is stored in U1MSR[0] and is a source for a priority level 4 interrupt, if enabled (U1IER[3] = 1).
RXD1 Input CTS1 Input
TXD1 Output Serial Output. Serial transmit data.
Clear to send. CTS1 is an asynchronous, active low modem status signal. Its condition can be checked by reading bit 4 (CTS) of the modem status register. Bit 0 (DCTS) of the Modem Status Register (MSR) indicates that CTS1 has changed states since the last read from the MSR. If the modem status interrupt is enabled when CTS1 changes levels and the auto-cts mode is not enabled, an interrupt is generated. CTS1 is also used in the auto-cts mode to control the transmitter. DCD1 Input
Data Carrier Detect. Active low signal indicates if the external modem has established a communication link with the UART1 and data may be exchanged. In normal operation of the modem interface (U1MCR[4]=0), the complement value of this signal is stored in U1MSR[7]. State change information is stored in U1MSR3 and is a source for a priority level 4 interrupt, if enabled (U1IER[3] = 1). Data Set Ready. Active low signal indicates if the external modem is ready to establish a communications link with the UART1. In normal operation of the modem interface (U1MCR[4] = 0), the complement value of this signal is stored in U1MSR[5]. State change information is stored in U1MSR[1] and is a source for a priority level 4 interrupt, if enabled (U1IER[3] = 1).
DSR1 Input
DTR1 Output Data Terminal Ready. Active low signal indicates that the UART1 is ready to establish connection with external modem. The complement value of this signal is stored in U1MCR[0]. The DTR pin can also be used as an RS-485/EIA-485 output enable signal. RI1 Input
Ring Indicator. Active low signal indicates that a telephone ringing signal has been detected by the modem. In normal operation of the modem interface (U1MCR[4] = 0), the complement value of this signal is stored in U1MSR[6]. State change information is stored in U1MSR[2] and is a source for a priority level 4 interrupt, if enabled (U1IER[3] = 1).
RTS1 Output Request To Send. Active low signal indicates that the UART1 would like to transmit data to the external modem. The complement value of this signal is stored in U1MCR[1]. In auto-rts mode, RTS1 is used to control the transmitter FIFO threshold logic. Request to send. RTS1 is an active low signal informing the modem or data set that the UART is ready to receive data. RTS1 is set to the active (low) level by setting the RTS modem control register bit and is set to the inactive (high) level either as a result of a system reset or during loop-back mode operations or by clearing bit 1 (RTS) of the MCR. In the auto-rts mode, RTS1 is controlled by the transmitter FIFO threshold logic. The RTS pin can also be used as an RS-485/EIA-485 output enable signal.
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4. Register description
UART1 contains registers organized as shown in Table 15-289. The Divisor Latch Access Bit (DLAB) is contained in U1LCR[7] and enables access to the Divisor Latches.
Table 289: UART1 register map Name Description Access Reset Address Value[1]
U1RBR (when DLAB =0) U1THR (when DLAB =0) U1DLL (when DLAB =1) U1DLM (when DLAB =1) U1IER (when DLAB =0) U1IIR U1FCR U1LCR U1MCR U1LSR U1MSR U1SCR U1ACR U1FDR U1TER U1RS485CTRL U1ADRMATCH U1RS485DLY U1FIFOLVL
Receiver Buffer Register. Contains the next received character to be read. Transmit Holding Register. The next character to be transmitted is written here. Divisor Latch LSB. Least significant byte of the baud rate divisor value. The full divisor is used to generate a baud rate from the fractional rate divider. Divisor Latch MSB. Most significant byte of the baud rate divisor value. The full divisor is used to generate a baud rate from the fractional rate divider. Interrupt Enable Register. Contains individual interrupt enable bits for the 7 potential UART1 interrupts. Interrupt ID Register. Identifies which interrupt(s) are pending. FIFO Control Register. Controls UART1 FIFO usage and modes. Line Control Register. Contains controls for frame formatting and break generation. Modem Control Register. Contains controls for flow control handshaking and loopback mode.
RO WO R/W
NA NA 0x01
0x4001 0000 (when DLAB=0) 0x4001 0000 (when DLAB=0) 0x4001 0000 (when DLAB=1) 0x4001 0004 (when DLAB=1) 0x4001 0004 (when DLAB=0) 0x4001 0008 0x4001 0008 0x4001 000C 0x4001 0010 0x4001 0014 0x4001 0018 0x4001 001C 0x4001 0020 0x4001 0028 0x4001 0030 0x4001 004C 0x4001 0050 0x4001 0054 0x4001 0058
R/W
0x00
R/W RO WO R/W R/W
0x00 0x01 0x00 0x00 0x00 0x60 0x00 0x00 0x00 0x10 0x80 0x00 0x00 0x00 0x00
Line Status Register. Contains flags for transmit and receive status, RO including line errors. Modem Status Register. Contains handshake signal status flags. Scratch Pad Register. 8-bit temporary storage for software. Auto-baud Control Register. Contains controls for the auto-baud feature. Fractional Divider Register. Generates a clock input for the baud rate divider. Transmit Enable Register. Turns off UART transmitter for use with software flow control. RS-485/EIA-485 Control. Contains controls to configure various aspects of RS-485/EIA-485 modes. RO R/W R/W R/W R/W R/W
RS-485/EIA-485 address match. Contains the address match value R/W for RS-485/EIA-485 mode. RS-485/EIA-485 direction control delay. FIFO Level register. Provides the current fill levels of the transmit and receive FIFOs. R/W RO
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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4.1 UART1 Receiver Buffer Register (U1RBR - 0x4001 0000, when DLAB = 0)
The U1RBR is the top byte of the UART1 RX FIFO. The top byte of the RX FIFO contains the oldest character received and can be read via the bus interface. The LSB (bit 0) represents the "oldest" received data bit. If the character received is less than 8 bits, the unused MSBs are padded with zeroes. The Divisor Latch Access Bit (DLAB) in U1LCR must be zero in order to access the U1RBR. The U1RBR is always read-only. Since PE, FE and BI bits correspond to the byte sitting on the top of the RBR FIFO (i.e. the one that will be read in the next read from the RBR), the right approach for fetching the valid pair of received byte and its status bits is first to read the content of the U1LSR register, and then to read a byte from the U1RBR.
Table 290: UART1 Receiver Buffer Register (U1RBR - address 0x4001 0000 when DLAB = 0) bit description Bit Symbol Description Reset Value
7:0 31:8
RBR -
The UART1 Receiver Buffer Register contains the oldest received byte in the UART1 RX FIFO. Reserved, the value read from a reserved bit is not defined.
undefined NA
4.2 UART1 Transmitter Holding Register (U1THR - 0x4001 0000 when DLAB = 0)
The write-only U1THR is the top byte of the UART1 TX FIFO. The top byte is the newest character in the TX FIFO and can be written via the bus interface. The LSB represents the first bit to transmit. The Divisor Latch Access Bit (DLAB) in U1LCR must be zero in order to access the U1THR. The U1THR is write-only.
Table 291: UART1 Transmitter Holding Register (U1THR - address 0x4001 0000 when DLAB = 0) bit description Bit Symbol Description Reset Value
7:0
THR
Writing to the UART1 Transmit Holding Register causes the data to be stored in the UART1 NA transmit FIFO. The byte will be sent when it reaches the bottom of the FIFO and the transmitter is available. Reserved, user software should not write ones to reserved bits. NA
31:8
-
4.3 UART1 Divisor Latch LSB and MSB Registers (U1DLL - 0x4001 0000 and U1DLM - 0x4001 0004, when DLAB = 1)
The UART1 Divisor Latch is part of the UART1 Baud Rate Generator and holds the value used, along with the Fractional Divider, to divide the APB clock (PCLK) in order to produce the baud rate clock, which must be 16x the desired baud rate. The U1DLL and U1DLM registers together form a 16-bit divisor where U1DLL contains the lower 8 bits of the divisor and U1DLM contains the higher 8 bits of the divisor. A 0x0000 value is treated like a 0x0001 value as division by zero is not allowed.The Divisor Latch Access Bit (DLAB) in U1LCR must be one in order to access the UART1 Divisor Latches. Details on how to select the right value for U1DLL and U1DLM can be found later in this chapter, see Section 15-4.16.
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Table 292: UART1 Divisor Latch LSB Register (U1DLL - address 0x4001 0000 when DLAB = 1) bit description Bit Symbol Description Reset Value
7:0 31:8
DLLSB -
The UART1 Divisor Latch LSB Register, along with the U1DLM register, determines the baud rate of the UART1. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x01 NA
Table 293: UART1 Divisor Latch MSB Register (U1DLM - address 0x4001 0004 when DLAB = 1) bit description Bit Symbol Description Reset Value
7:0 31:8
DLMSB -
The UART1 Divisor Latch MSB Register, along with the U1DLL register, determines the baud rate of the UART1. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
4.4 UART1 Interrupt Enable Register (U1IER - 0x4001 0004, when DLAB = 0)
The U1IER is used to enable the four UART1 interrupt sources.
Table 294: UART1 Interrupt Enable Register (U1IER - address 0x4001 0004 when DLAB = 0) bit description Bit Symbol Value Description Reset Value
0
RBR Interrupt Enable
enables the Receive Data Available interrupt for UART1. It also controls the Character Receive Time-out interrupt. 0 1 Disable the RDA interrupts. Enable the RDA interrupts. enables the THRE interrupt for UART1. The status of this interrupt can be read from U1LSR[5]. 0 1 Disable the THRE interrupts. Enable the THRE interrupts. enables the UART1 RX line status interrupts. The status of this interrupt can be read from U1LSR[4:1]. 0 1 Disable the RX line status interrupts. Enable the RX line status interrupts.
0
1
THRE Interrupt Enable
0
2
RX Line Interrupt Enable
0
3
Modem Status Interrupt Enable CTS Interrupt Enable
enables the modem interrupt. The status of this interrupt can be read from U1MSR[3:0]. 0 0 1 Disable the modem interrupt. Enable the modem interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. If auto-cts mode is enabled this bit enables/disables the modem status interrupt generation on a CTS1 signal transition. If auto-cts mode is disabled a CTS1 transition will generate an interrupt if Modem Status Interrupt Enable (U1IER[3]) is set. In normal operation a CTS1 signal transition will generate a Modem Status Interrupt unless the interrupt has been disabled by clearing the U1IER[3] bit in the U1IER register. In auto-cts mode a transition on the CTS1 bit will trigger an interrupt only if both the U1IER[3] and U1IER[7] bits are set. 0 1 Disable the CTS interrupt. Enable the CTS interrupt.
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NA 0
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Table 294: UART1 Interrupt Enable Register (U1IER - address 0x4001 0004 when DLAB = 0) bit description Bit Symbol Value Description Reset Value
8
ABEOIntEn 0 1
Enables the end of auto-baud interrupt. Disable end of auto-baud Interrupt. Enable end of auto-baud Interrupt. Enables the auto-baud time-out interrupt. 0 1 Disable auto-baud time-out Interrupt. Enable auto-baud time-out Interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
9
ABTOIntEn
0
31:10 -
NA
4.5 UART1 Interrupt Identification Register (U1IIR - 0x4001 0008)
The U1IIR provides a status code that denotes the priority and source of a pending interrupt. The interrupts are frozen during an U1IIR access. If an interrupt occurs during an U1IIR access, the interrupt is recorded for the next U1IIR access.
Table 295: UART1 Interrupt Identification Register (U1IIR - address 0x4001 0008) bit description Bit Symbol Value Description Reset Value
0
IntStatus 0 1
Interrupt status. Note that U1IIR[0] is active low. The pending interrupt can be determined by evaluating U1IIR[3:1]. At least one interrupt is pending. No interrupt is pending. Interrupt identification. U1IER[3:1] identifies an interrupt corresponding to the UART1 Rx or TX FIFO. All other combinations of U1IER[3:1] not listed below are reserved (100,101,111). 011 010 110 001 000 1 - Receive Line Status (RLS). 2a - Receive Data Available (RDA). 2b - Character Time-out Indicator (CTI). 3 - THRE Interrupt. 4 - Modem Interrupt.
1
3:1
IntId
0
5:4 7:6 8 9
FIFO Enable ABEOInt ABTOInt
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. Copies of U1FCR[0]. End of auto-baud interrupt. True if auto-baud has finished successfully and interrupt is enabled. Auto-baud time-out interrupt. True if auto-baud has timed out and interrupt is enabled. Reserved, the value read from a reserved bit is not defined. 0 0 0 NA
31:10 -
Bit U1IIR[9:8] are set by the auto-baud function and signal a time-out or end of auto-baud condition. The auto-baud interrupt conditions are cleared by setting the corresponding Clear bits in the Auto-baud Control Register. If the IntStatus bit is 1 no interrupt is pending and the IntId bits will be zero. If the IntStatus is 0, a non auto-baud interrupt is pending in which case the IntId bits identify the type of interrupt and handling as described in Table 15-296. Given the status of U1IIR[3:0], an
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interrupt handler routine can determine the cause of the interrupt and how to clear the active interrupt. The U1IIR must be read in order to clear the interrupt prior to exiting the Interrupt Service Routine. The UART1 RLS interrupt (U1IIR[3:1] = 011) is the highest priority interrupt and is set whenever any one of four error conditions occur on the UART1RX input: overrun error (OE), parity error (PE), framing error (FE) and break interrupt (BI). The UART1 Rx error condition that set the interrupt can be observed via U1LSR[4:1]. The interrupt is cleared upon an U1LSR read. The UART1 RDA interrupt (U1IIR[3:1] = 010) shares the second level priority with the CTI interrupt (U1IIR[3:1] = 110). The RDA is activated when the UART1 Rx FIFO reaches the trigger level defined in U1FCR7:6 and is reset when the UART1 Rx FIFO depth falls below the trigger level. When the RDA interrupt goes active, the CPU can read a block of data defined by the trigger level. The CTI interrupt (U1IIR[3:1] = 110) is a second level interrupt and is set when the UART1 Rx FIFO contains at least one character and no UART1 Rx FIFO activity has occurred in 3.5 to 4.5 character times. Any UART1 Rx FIFO activity (read or write of UART1 RSR) will clear the interrupt. This interrupt is intended to flush the UART1 RBR after a message has been received that is not a multiple of the trigger level size. For example, if a peripheral wished to send a 105 character message and the trigger level was 10 characters, the CPU would receive 10 RDA interrupts resulting in the transfer of 100 characters and 1 to 5 CTI interrupts (depending on the service routine) resulting in the transfer of the remaining 5 characters.
Table 296: UART1 Interrupt Handling U1IIR[3:0] Priority Interrupt value[1] Type Interrupt Source Interrupt Reset
0001 0110
-
None
None OE[2] or PE[2] or FE[2] or BI[2]
U1LSR Read[2]
Highest RX Line Status / Error Second RX Data Available
0100 1100
Rx data available or trigger level reached in FIFO (U1FCR0=1)
U1RBR Read[3] or UART1 FIFO drops below trigger level
Second Character Minimum of one character in the RX FIFO and no U1RBR Read[3] Time-out character input or removed during a time period depending indication on how many characters are in FIFO and what the trigger level is set at (3.5 to 4.5 character times). The exact time will be: [(word length) x 7 - 2] x 8 + [(trigger level - number of characters) x 8 + 1] RCLKs
0010 0000
Third Fourth
THRE Modem Status
[1] [2] [3] [4]
THRE[2] CTS or DSR or RI or DCD
U1IIR Read[4] (if source of interrupt) or THR write MSR Read
Values "0000", "0011", "0101", "0111", "1000", "1001", "1010", "1011","1101","1110","1111" are reserved. For details see Section 15-4.10 "UART1 Line Status Register (U1LSR - 0x4001 0014)" For details see Section 15-4.1 "UART1 Receiver Buffer Register (U1RBR - 0x4001 0000, when DLAB = 0)" For details see Section 15-4.5 "UART1 Interrupt Identification Register (U1IIR - 0x4001 0008)" and Section 15-4.2 "UART1 Transmitter Holding Register (U1THR - 0x4001 0000 when DLAB = 0)"
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The UART1 THRE interrupt (U1IIR[3:1] = 001) is a third level interrupt and is activated when the UART1 THR FIFO is empty provided certain initialization conditions have been met. These initialization conditions are intended to give the UART1 THR FIFO a chance to fill up with data to eliminate many THRE interrupts from occurring at system start-up. The initialization conditions implement a one character delay minus the stop bit whenever THRE = 1 and there have not been at least two characters in the U1THR at one time since the last THRE = 1 event. This delay is provided to give the CPU time to write data to U1THR without a THRE interrupt to decode and service. A THRE interrupt is set immediately if the UART1 THR FIFO has held two or more characters at one time and currently, the U1THR is empty. The THRE interrupt is reset when a U1THR write occurs or a read of the U1IIR occurs and the THRE is the highest interrupt (U1IIR[3:1] = 001). It is the lowest priority interrupt and is activated whenever there is any state change on modem inputs pins, DCD, DSR or CTS. In addition, a low to high transition on modem input RI will generate a modem interrupt. The source of the modem interrupt can be determined by examining U1MSR[3:0]. A U1MSR read will clear the modem interrupt.
4.6 UART1 FIFO Control Register (U1FCR - 0x4001 0008)
The write-only U1FCR controls the operation of the UART1 RX and TX FIFOs.
Table 297: UART1 FIFO Control Register (U1FCR - address 0x4001 0008) bit description Bit Symbol Value Description Reset Value
0
FIFO Enable
0 1
UART1 FIFOs are disabled. Must not be used in the application. Active high enable for both UART1 Rx and TX FIFOs and U1FCR[7:1] access. This bit must be set for proper UART1 operation. Any transition on this bit will automatically clear the UART1 FIFOs. No impact on either of UART1 FIFOs. Writing a logic 1 to U1FCR[1] will clear all bytes in UART1 Rx FIFO, reset the pointer logic. This bit is self-clearing. No impact on either of UART1 FIFOs. Writing a logic 1 to U1FCR[2] will clear all bytes in UART1 TX FIFO, reset the pointer logic. This bit is self-clearing. When the FIFO enable bit (bit 0 of this register) is set, this bit selects the DMA mode. See Section 15-4.6.1.
0
1
RX FIFO Reset TX FIFO Reset DMA Mode Select RX Trigger Level
0 1 0 1
0
2
0
3 5:4 7:6
0
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. These two bits determine how many receiver UART1 FIFO characters must be 0 written before an interrupt is activated. 00 01 10 11 Trigger level 0 (1 character or 0x01). Trigger level 1 (4 characters or 0x04). Trigger level 2 (8 characters or 0x08). Trigger level 3 (14 characters or 0x0E). Reserved, user software should not write ones to reserved bits. NA
31:8
-
4.6.1 DMA Operation
The user can optionally operate the UART transmit and/or receive using DMA. The DMA mode is determined by the DMA Mode Select bit in the FCR register. This bit only has an affect when the FIFOs are enabled via the FIFO Enable bit in the FCR register.
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UART receiver DMA In DMA mode, the receiver DMA request is asserted on the event of the receiver FIFO level becoming equal to or greater than trigger level, or if a character timeout occurs. See the description of the RX Trigger Level above. The receiver DMA request is cleared by the DMA controller. UART transmitter DMA In DMA mode, the transmitter DMA request is asserted on the event of the transmitter FIFO transitioning to not full. The transmitter DMA request is cleared by the DMA controller.
4.7 UART1 Line Control Register (U1LCR - 0x4001 000C)
The U1LCR determines the format of the data character that is to be transmitted or received.
Table 298: UART1 Line Control Register (U1LCR - address 0x4001 000C) bit description Bit Symbol Value Description Reset Value
1:0
Word Length Select
00 01 10 11
5-bit character length. 6-bit character length. 7-bit character length. 8-bit character length. 1 stop bit. 2 stop bits (1.5 if U1LCR[1:0]=00). Disable parity generation and checking. Enable parity generation and checking. Odd parity. Number of 1s in the transmitted character and the attached parity bit will be odd. Even Parity. Number of 1s in the transmitted character and the attached parity bit will be even. Forced "1" stick parity. Forced "0" stick parity. Disable break transmission. Enable break transmission. Output pin UART1 TXD is forced to logic 0 when U1LCR[6] is active high. Disable access to Divisor Latches. Enable access to Divisor Latches.
0
2 3 5:4
Stop Bit Select Parity Enable Parity Select
0 1 0 1 00 01 10 11
0 0 0
6
Break Control
0 1
0
7 31:8
Divisor Latch 0 Access Bit (DLAB) 1 -
0
Reserved, user software should not write ones to reserved bits. The value NA read from a reserved bit is not defined.
4.8 UART1 Modem Control Register (U1MCR - 0x4001 0010)
The U1MCR enables the modem loopback mode and controls the modem output signals.
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Table 299: UART1 Modem Control Register (U1MCR - address 0x4001 0010) bit description Bit Symbol Value Description Reset value
0 1 3-2 4
DTR Control RTS Control Loopback Mode Select NA
Source for modem output pin, DTR. This bit reads as 0 when modem loopback mode 0 is active. Source for modem output pin RTS. This bit reads as 0 when modem loopback mode is 0 active. Reserved, user software should not write ones to reserved bits. The value read from a 0 reserved bit is not defined. The modem loopback mode provides a mechanism to perform diagnostic loopback 0 testing. Serial data from the transmitter is connected internally to serial input of the receiver. Input pin, RXD1, has no effect on loopback and output pin, TXD1 is held in marking state. The 4 modem inputs (CTS, DSR, RI and DCD) are disconnected externally. Externally, the modem outputs (RTS, DTR) are set inactive. Internally, the 4 modem outputs are connected to the 4 modem inputs. As a result of these connections, the upper 4 bits of the U1MSR will be driven by the lower 4 bits of the U1MCR rather than the 4 modem inputs in normal mode. This permits modem status interrupts to be generated in loopback mode by writing the lower 4 bits of U1MCR. 0 1 Disable modem loopback mode. Enable modem loopback mode. Reserved, user software should not write ones to reserved bits. The value read from a 0 reserved bit is not defined. Disable auto-rts flow control. Enable auto-rts flow control. Disable auto-cts flow control. Enable auto-cts flow control. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. 0 0
5 6 7 31:8
RTSen CTSen -
NA 0 1 0 1
4.9 Auto-flow control
If auto-RTS mode is enabled the UART1`s receiver FIFO hardware controls the RTS1 output of the UART1. If the auto-CTS mode is enabled the UART1`s U1TSR hardware will only start transmitting if the CTS1 input signal is asserted. 15.4.9.1
Auto-RTS
The auto-RTS function is enabled by setting the RTSen bit. Auto-RTS data flow control originates in the U1RBR module and is linked to the programmed receiver FIFO trigger level. If auto-RTS is enabled, the data-flow is controlled as follows: When the receiver FIFO level reaches the programmed trigger level, RTS1 is de-asserted (to a high value). It is possible that the sending UART sends an additional byte after the trigger level is reached (assuming the sending UART has another byte to send) because it might not recognize the de-assertion of RTS1 until after it has begun sending the additional byte. RTS1 is automatically reasserted (to a low value) once the receiver FIFO has reached the previous trigger level. The re-assertion of RTS1 signals to the sending UART to continue transmitting data.
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If Auto-RTS mode is disabled, the RTSen bit controls the RTS1 output of the UART1. If Auto-RTS mode is enabled, hardware controls the RTS1 output, and the actual value of RTS1 will be copied in the RTS Control bit of the UART1. As long as Auto-RTS is enabled, the value of the RTS Control bit is read-only for software. Example: Suppose the UART1 operating in `550 mode has trigger level in U1FCR set to 0x2 then if Auto-RTS is enabled the UART1 will de-assert the RTS1 output as soon as the receive FIFO contains 8 bytes (Table 15-297 on page 323). The RTS1 output will be reasserted as soon as the receive FIFO hits the previous trigger level: 4 bytes.
start
byte N
stop
start
bits0..7
stop
~ ~
UART1 Rx
start
bits0..7
stop
RTS1 pin UART1 Rx FIFO read UART1 Rx FIFO level N-1
N
N-1
N-2
N-1
N-2
~~ ~~
M+2
~ ~
M+1
M
M-1
Fig 47. Auto-RTS Functional Timing
15.4.9.2
Auto-CTS The Auto-CTS function is enabled by setting the CTSen bit. If Auto-CTS is enabled the transmitter circuitry in the U1TSR module checks CTS1 input before sending the next data byte. When CTS1 is active (low), the transmitter sends the next byte. To stop the transmitter from sending the following byte, CTS1 must be released before the middle of the last stop bit that is currently being sent. In Auto-CTS mode a change of the CTS1 signal does not trigger a modem status interrupt unless the CTS Interrupt Enable bit is set, Delta CTS bit in the U1MSR will be set though. Table 15-300 lists the conditions for generating a Modem Status interrupt.
Table 300: Modem status interrupt generation Enable Modem Status Interrupt (U1ER[3]) CTSen CTS Interrupt Delta CTS Delta DCD or Trailing Edge RI Modem Status (U1MCR[7]) Enable (U1IER[7]) (U1MSR[0]) or Delta DSR (U1MSR[3] or Interrupt U1MSR[2] or U1MSR[1])
0 1 1 1 1 1 1 1 1
x 0 0 0 1 1 1 1 1
x x x x 0 0 1 1 1
x 0 1 x x x 0 1 x
x 0 x 1 0 1 0 x 1
~ ~
No No Yes Yes No Yes No Yes Yes
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The auto-CTS function reduces interrupts to the host system. When flow control is enabled, a CTS1 state change does not trigger host interrupts because the device automatically controls its own transmitter. Without Auto-CTS, the transmitter sends any data present in the transmit FIFO and a receiver overrun error can result. Figure 15-48 illustrates the Auto-CTS functional timing.
~ ~
start
bits0..7
stop
start
bits0..7
stop
~ ~
UART1 TX
start
bits0..7
stop
Fig 48. Auto-CTS Functional Timing
While starting transmission of the initial character the CTS1 signal is asserted. Transmission will stall as soon as the pending transmission has completed. The UART will continue transmitting a 1 bit as long as CTS1 is de-asserted (high). As soon as CTS1 gets de-asserted transmission resumes and a start bit is sent followed by the data bits of the next character.
4.10 UART1 Line Status Register (U1LSR - 0x4001 0014)
The U1LSR is a read-only register that provides status information on the UART1 TX and RX blocks.
Table 301: UART1 Line Status Register (U1LSR - address 0x4001 0014) bit description Bit Symbol Value Description Reset Value
0
Receiver Data Ready (RDR) 0 1
U1LSR[0] is set when the U1RBR holds an unread character and is cleared when 0 the UART1 RBR FIFO is empty. The UART1 receiver FIFO is empty. The UART1 receiver FIFO is not empty. The overrun error condition is set as soon as it occurs. An U1LSR read clears U1LSR[1]. U1LSR[1] is set when UART1 RSR has a new character assembled and the UART1 RBR FIFO is full. In this case, the UART1 RBR FIFO will not be overwritten and the character in the UART1 RSR will be lost. 0 1 Overrun error status is inactive. Overrun error status is active. When the parity bit of a received character is in the wrong state, a parity error occurs. An U1LSR read clears U1LSR[2]. Time of parity error detection is dependent on U1FCR[0].
Note: A parity error is associated with the character at the top of the UART1 RBR FIFO.
1
Overrun Error (OE)
~ ~
CTS1 pin
~ ~
0
2
Parity Error (PE)
0
0 1
Parity error status is inactive. Parity error status is active.
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Table 301: UART1 Line Status Register (U1LSR - address 0x4001 0014) bit description Bit Symbol Value Description Reset Value
3
Framing Error (FE)
0 When the stop bit of a received character is a logic 0, a framing error occurs. An U1LSR read clears U1LSR[3]. The time of the framing error detection is dependent on U1FCR0. Upon detection of a framing error, the RX will attempt to resynchronize to the data and assume that the bad stop bit is actually an early start bit. However, it cannot be assumed that the next received byte will be correct even if there is no Framing Error.
Note: A framing error is associated with the character at the top of the UART1 RBR FIFO.
0 1 4 Break Interrupt (BI)
Framing error status is inactive. Framing error status is active. When RXD1 is held in the spacing state (all zeroes) for one full character transmission (start, data, parity, stop), a break interrupt occurs. Once the break condition has been detected, the receiver goes idle until RXD1 goes to marking state (all ones). An U1LSR read clears this status bit. The time of break detection is dependent on U1FCR[0].
Note: The break interrupt is associated with the character at the top of the UART1 RBR FIFO.
0
0 1 5 Transmitter Holding Register Empty (THRE)
Break interrupt status is inactive. Break interrupt status is active. THRE is set immediately upon detection of an empty UART1 THR and is cleared on a U1THR write. 1
0 1
U1THR contains valid data. U1THR is empty. TEMT is set when both U1THR and U1TSR are empty; TEMT is cleared when either the U1TSR or the U1THR contain valid data. 1
6
Transmitter Empty (TEMT) 0 1
U1THR and/or the U1TSR contains valid data. U1THR and the U1TSR are empty. U1LSR[7] is set when a character with a RX error such as framing error, parity error or break interrupt, is loaded into the U1RBR. This bit is cleared when the U1LSR register is read and there are no subsequent errors in the UART1 FIFO. 0
7
Error in RX FIFO (RXFE) 0 1
U1RBR contains no UART1 RX errors or U1FCR[0]=0. UART1 RBR contains at least one UART1 RX error. Reserved, the value read from a reserved bit is not defined. NA
31:8
-
4.11 UART1 Modem Status Register (U1MSR - 0x4001 0018)
The U1MSR is a read-only register that provides status information on the modem input signals. U1MSR[3:0] is cleared on U1MSR read. Note that modem signals have no direct effect on UART1 operation, they facilitate software implementation of modem signal operations.
Table 302: UART1 Modem Status Register (U1MSR - address 0x4001 0018) bit description Bit Symbol Value Description Reset Value
0
Delta CTS 0 1
Set upon state change of input CTS. Cleared on an U1MSR read. No change detected on modem input, CTS. State change detected on modem input, CTS.
0
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Table 302: UART1 Modem Status Register (U1MSR - address 0x4001 0018) bit description Bit Symbol Value Description Reset Value
1
Delta DSR 0 1
Set upon state change of input DSR. Cleared on an U1MSR read. No change detected on modem input, DSR. State change detected on modem input, DSR. Set upon low to high transition of input RI. Cleared on an U1MSR read. 0 1 No change detected on modem input, RI. Low-to-high transition detected on RI. Set upon state change of input DCD. Cleared on an U1MSR read. 0 1 No change detected on modem input, DCD. State change detected on modem input, DCD. Clear To Send State. Complement of input signal CTS. This bit is connected to U1MCR[1] in modem loopback mode. Data Set Ready State. Complement of input signal DSR. This bit is connected to U1MCR[0] in modem loopback mode. Ring Indicator State. Complement of input RI. This bit is connected to U1MCR[2] in modem loopback mode.
0
2
Trailing Edge RI
0
3
Delta DCD
0
4 5 6 7 31:8
CTS DSR RI DCD -
0 0 0
Data Carrier Detect State. Complement of input DCD. This bit is connected 0 to U1MCR[3] in modem loopback mode. Reserved, the value read from a reserved bit is not defined. NA
4.12 UART1 Scratch Pad Register (U1SCR - 0x4001 001C)
The U1SCR has no effect on the UART1 operation. This register can be written and/or read at user's discretion. There is no provision in the interrupt interface that would indicate to the host that a read or write of the U1SCR has occurred.
Table 303: UART1 Scratch Pad Register (U1SCR - address 0x4001 0014) bit description Bit Symbol Description Reset Value
7:0
Pad
A readable, writable byte.
0x00
4.13 UART1 Auto-baud Control Register (U1ACR - 0x4001 0020)
The UART1 Auto-baud Control Register (U1ACR) controls the process of measuring the incoming clock/data rate for the baud rate generation and can be read and written at user's discretion.
Table 304: Auto-baud Control Register (U1ACR - address 0x4001 0020) bit description Bit Symbol Value Description Reset value
0
Start 0 1
This bit is automatically cleared after auto-baud completion. Auto-baud stop (auto-baud is not running). Auto-baud start (auto-baud is running). Auto-baud run bit. This bit is automatically cleared after auto-baud completion. Auto-baud mode select bit. 0 1 Mode 0. Mode 1.
0
1
Mode
0
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Table 304: Auto-baud Control Register (U1ACR - address 0x4001 0020) bit description Bit Symbol Value Description Reset value
2 7:3 8
AutoRestart ABEOIntClr
0 1 NA
No restart Restart in case of time-out (counter restarts at next UART1 Rx falling edge)
0 0
Reserved, user software should not write ones to reserved bits. The value read 0 from a reserved bit is not defined. End of auto-baud interrupt clear bit (write-only accessible). 0 Writing a 0 has no impact. Writing a 1 will clear the corresponding interrupt in the U1IIR. Auto-baud time-out interrupt clear bit (write-only accessible). 0 Writing a 0 has no impact. Writing a 1 will clear the corresponding interrupt in the U1IIR. Reserved, user software should not write ones to reserved bits. The value read 0 from a reserved bit is not defined.
0 1 9 ABTOIntClr 0 1 31:10 NA
4.14 Auto-baud
The UART1 auto-baud function can be used to measure the incoming baud-rate based on the "AT" protocol (Hayes command). If enabled the auto-baud feature will measure the bit time of the receive data stream and set the divisor latch registers U1DLM and U1DLL accordingly. Remark: the fractional rate divider is not connected during auto-baud operations, and therefore should not be used when the auto-baud feature is needed. Auto-baud is started by setting the U1ACR Start bit. Auto-baud can be stopped by clearing the U1ACR Start bit. The Start bit will clear once auto-baud has finished and reading the bit will return the status of auto-baud (pending/finished). Two auto-baud measuring modes are available which can be selected by the U1ACR Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the UART1 Rx pin (the falling edge of the start bit and the falling edge of the least significant bit). In mode 1 the baud-rate is measured between the falling edge and the subsequent rising edge of the UART1 Rx pin (the length of the start bit). The U1ACR AutoRestart bit can be used to automatically restart baud-rate measurement if a time-out occurs (the rate measurement counter overflows). If this bit is set the rate measurement will restart at the next falling edge of the UART1 Rx pin. The auto-baud function can generate two interrupts.
* The U1IIR ABTOInt interrupt will get set if the interrupt is enabled (U1IER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
* The U1IIR ABEOInt interrupt will get set if the interrupt is enabled (U1IER ABEOIntEn
is set and the auto-baud has completed successfully). The auto-baud interrupts have to be cleared by setting the corresponding U1ACR ABTOIntClr and ABEOIntEn bits. Typically the fractional baud-rate generator is disabled (DIVADDVAL = 0) during auto-baud. However, if the fractional baud-rate generator is enabled (DIVADDVAL > 0), it is going to impact the measuring of UART1 Rx pin baud-rate, but the value of the U1FDR
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register is not going to be modified after rate measurement. Also, when auto-baud is used, any write to U1DLM and U1DLL registers should be done before U1ACR register write. The minimum and the maximum baud rates supported by UART1 are function of pclk, number of data bits, stop bits and parity bits. (3)
2 x P CLK PCLK ratemin = ------------------------ UART1 baudrate ----------------------------------------------------------------------------------------------------------- = ratemax 16 x 2 15 16 x ( 2 + databits + paritybits + stopbits )
4.15 Auto-baud modes
When the software is expecting an "AT" command, it configures the UART1 with the expected character format and sets the U1ACR Start bit. The initial values in the divisor latches U1DLM and U1DLM don`t care. Because of the "A" or "a" ASCII coding ("A" = 0x41, "a" = 0x61), the UART1 Rx pin sensed start bit and the LSB of the expected character are delimited by two falling edges. When the U1ACR Start bit is set, the auto-baud protocol will execute the following phases: 1. On U1ACR Start bit setting, the baud-rate measurement counter is reset and the UART1 U1RSR is reset. The U1RSR baud rate is switch to the highest rate. 2. A falling edge on UART1 Rx pin triggers the beginning of the start bit. The rate measuring counter will start counting pclk cycles optionally pre-scaled by the fractional baud-rate generator. 3. During the receipt of the start bit, 16 pulses are generated on the RSR baud input with the frequency of the (fractional baud-rate pre-scaled) UART1 input clock, guaranteeing the start bit is stored in the U1RSR. 4. During the receipt of the start bit (and the character LSB for mode = 0) the rate counter will continue incrementing with the pre-scaled UART1 input clock (pclk). 5. If Mode = 0 then the rate counter will stop on next falling edge of the UART1 Rx pin. If Mode = 1 then the rate counter will stop on the next rising edge of the UART1 Rx pin. 6. The rate counter is loaded into U1DLM/U1DLL and the baud-rate will be switched to normal operation. After setting the U1DLM/U1DLL the end of auto-baud interrupt U1IIR ABEOInt will be set, if enabled. The U1RSR will now continue receiving the remaining bits of the "A/a" character.
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'A' (0x41) or 'a' (0x61) start UARTn RX start bit LSB of 'A' or 'a' bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop
U0ACR start rate counter 16xbaud_rate
16 cycles
16 cycles
a. Mode 0 (start bit and LSB are used for auto-baud)
'A' (0x41) or 'a' (0x61) start UARTn RX start bit LSB of 'A' or 'a' bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop
U1ACR start rate counter 16xbaud_rate
16 cycles
b. Mode 1 (only start bit is used for auto-baud)
Fig 49. Auto-baud a) mode 0 and b) mode 1 waveform
4.16 UART1 Fractional Divider Register (U1FDR - 0x4001 0028)
The UART1 Fractional Divider Register (U1FDR) controls the clock pre-scaler for the baud rate generation and can be read and written at the user's discretion. This pre-scaler takes the APB clock and generates an output clock according to the specified fractional requirements. Important: If the fractional divider is active (DIVADDVAL > 0) and DLM = 0, the value of the DLL register must be greater than 2.
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Table 305: UART1 Fractional Divider Register (U1FDR - address 0x4001 0028) bit description Bit Function Value Description Reset value
3:0 7:4
DIVADDVAL MULVAL
0 1
Baud-rate generation pre-scaler divisor value. If this field is 0, fractional baud-rate generator will not impact the UARTn baudrate. Baud-rate pre-scaler multiplier value. This field must be greater or equal 1 for UARTn to operate properly, regardless of whether the fractional baud-rate generator is used or not.
0 1
31:8
-
NA
Reserved, user software should not write ones to reserved bits. The value read 0 from a reserved bit is not defined.
This register controls the clock pre-scaler for the baud rate generation. The reset value of the register keeps the fractional capabilities of UART1 disabled making sure that UART1 is fully software and hardware compatible with UARTs not equipped with this feature. UART1 baud rate can be calculated as (n = 1): (4)
PCLK UART1 baudrate = ---------------------------------------------------------------------------------------------------------------------------------DivAddVal 16 x ( 256 x U1DLM + U1DLL ) x 1 + ---------------------------- MulVal Where PCLK is the peripheral clock, U1DLM and U1DLL are the standard UART1 baud rate divider registers, and DIVADDVAL and MULVAL are UART1 fractional baud rate generator specific parameters. The value of MULVAL and DIVADDVAL should comply to the following conditions: 1. 1 MULVAL 15 2. 0 DIVADDVAL 14 3. DIVADDVAL < MULVAL The value of the U1FDR should not be modified while transmitting/receiving data or data may be lost or corrupted. If the U1FDR register value does not comply to these two requests, then the fractional divider output is undefined. If DIVADDVAL is zero then the fractional divider is disabled, and the clock will not be divided.
4.16.1 Baud rate calculation
UART1 can operate with or without using the Fractional Divider. In real-life applications it is likely that the desired baud rate can be achieved using several different Fractional Divider settings. The following algorithm illustrates one way of finding a set of DLM, DLL, MULVAL, and DIVADDVAL values. Such set of parameters yields a baud rate with a relative error of less than 1.1% from the desired one.
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Calculating UART baudrate (BR)
PCLK, BR
DL est = PCLK/(16 x BR)
DL est is an integer?
True
False FR est = 1.5
DIVADDVAL = 0 MULVAL = 1
Pick another FR est from the range [1.1, 1.9]
DL est = Int(PCLK/(16 x BR x FR est))
FR est = PCLK/(16 x BR x DL est)
False 1.1 < FR est < 1.9?
True
DIVADDVAL = table(FR est ) MULVAL = table(FR est )
DLM = DL est [15:8] DLL = DLest [7:0]
End
Fig 50. Algorithm for setting UART dividers
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Table 306. Fractional Divider setting look-up table FR DivAddVal/ MulVal FR DivAddVal/ MulVal FR DivAddVal/ MulVal FR DivAddVal/ MulVal
1.000 1.067 1.071 1.077 1.083 1.091 1.100 1.111 1.125 1.133 1.143 1.154 1.167 1.182 1.200 1.214 1.222 1.231
0/1 1/15 1/14 1/13 1/12 1/11 1/10 1/9 1/8 2/15 1/7 2/13 1/6 2/11 1/5 3/14 2/9 3/13
1.250 1.267 1.273 1.286 1.300 1.308 1.333 1.357 1.364 1.375 1.385 1.400 1.417 1.429 1.444 1.455 1.462 1.467
1/4 4/15 3/11 2/7 3/10 4/13 1/3 5/14 4/11 3/8 5/13 2/5 5/12 3/7 4/9 5/11 6/13 7/15
1.500 1.533 1.538 1.545 1.556 1.571 1.583 1.600 1.615 1.625 1.636 1.643 1.667 1.692 1.700 1.714 1.727 1.733
1/2 8/15 7/13 6/11 5/9 4/7 7/12 3/5 8/13 5/8 7/11 9/14 2/3 9/13 7/10 5/7 8/11 11/15
1.750 1.769 1.778 1.786 1.800 1.818 1.833 1.846 1.857 1.867 1.875 1.889 1.900 1.909 1.917 1.923 1.929 1.933
3/4 10/13 7/9 11/14 4/5 9/11 5/6 11/13 6/7 13/15 7/8 8/9 9/10 10/11 11/12 12/13 13/14 14/15
4.16.1.1
Example 1: PCLK = 14.7456 MHz, BR = 9600 According to the provided algorithm DLest = PCLK/(16 x BR) = 14.7456 MHz / (16 x 9600) = 96. Since this DLest is an integer number, DIVADDVAL = 0, MULVAL = 1, DLM = 0, and DLL = 96.
4.16.1.2
Example 2: PCLK = 12 MHz, BR = 115200 According to the provided algorithm DLest = PCLK/(16 x BR) = 12 MHz / (16 x 115200) = 6.51. This DLest is not an integer number and the next step is to estimate the FR parameter. Using an initial estimate of FRest = 1.5 a new DLest = 4 is calculated and FRest is recalculated as FRest = 1.628. Since FRest = 1.628 is within the specified range of 1.1 and 1.9, DIVADDVAL and MULVAL values can be obtained from the attached look-up table. The closest value for FRest = 1.628 in the look-up Table 15-306 is FR = 1.625. It is equivalent to DIVADDVAL = 5 and MULVAL = 8. Based on these findings, the suggested UART setup would be: DLM = 0, DLL = 4, DIVADDVAL = 5, and MULVAL = 8. According to Equation 15-4 the UART rate is 115384. This rate has a relative error of 0.16% from the originally specified 115200.
4.17 UART1 Transmit Enable Register (U1TER - 0x4001 0030)
In addition to being equipped with full hardware flow control (auto-cts and auto-rts mechanisms described above), U1TER enables implementation of software flow control, too. When TxEn=1, UART1 transmitter will keep sending data as long as they are available. As soon as TxEn becomes 0, UART1 transmission will stop.
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Although Table 15-307 describes how to use TxEn bit in order to achieve hardware flow control, it is strongly suggested to let UART1 hardware implemented auto flow control features take care of this, and limit the scope of TxEn to software flow control. U1TER enables implementation of software and hardware flow control. When TXEn=1, UART1 transmitter will keep sending data as long as they are available. As soon as TXEn becomes 0, UART1 transmission will stop. Table 15-307 describes how to use TXEn bit in order to achieve software flow control.
Table 307: UART1 Transmit Enable Register (U1TER - address 0x4001 0030) bit description Bit Symbol Description Reset Value
6:0 7
TXEN
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
When this bit is 1, as it is after a Reset, data written to the THR is output on the TXD pin as 1 soon as any preceding data has been sent. If this bit cleared to 0 while a character is being sent, the transmission of that character is completed, but no further characters are sent until this bit is set again. In other words, a 0 in this bit blocks the transfer of characters from the THR or TX FIFO into the transmit shift register. Software can clear this bit when it detects that the a hardware-handshaking TX-permit signal (CTS) has gone false, or with software handshaking, when it receives an XOFF character (DC3). Software can set this bit again when it detects that the TX-permit signal has gone true, or when it receives an XON (DC1) character. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
31:8
-
4.18 UART1 RS485 Control register (U1RS485CTRL - 0x4001 004C)
The U1RS485CTRL register controls the configuration of the UART in RS-485/EIA-485 mode.
Table 308: UART1 RS485 Control register (U1RS485CTRL - address 0x4001 004C) bit description Bit Symbol Value Description Reset value
0
NMMEN
0 1
RS-485/EIA-485 Normal Multidrop Mode (NMM) is disabled. RS-485/EIA-485 Normal Multidrop Mode (NMM) is enabled. In this mode, an address is detected when a received byte causes the UART to set the parity error and generate an interrupt. The receiver is enabled. The receiver is disabled. Auto Address Detect (AAD) is disabled. Auto Address Detect (AAD) is enabled.
0
1 2 3 4
RXDIS AADEN SEL DCTRL
0 1 0 1 0 1 0 1
0 0
If direction control is enabled (bit DCTRL = 1), pin RTS is used for direction control. 0 If direction control is enabled (bit DCTRL = 1), pin DTR is used for direction control. Disable Auto Direction Control. Enable Auto Direction Control. 0
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Table 308: UART1 RS485 Control register (U1RS485CTRL - address 0x4001 004C) bit description Bit Symbol Value Description Reset value
5
OINV 0 1
This bit reverses the polarity of the direction control signal on the RTS (or DTR) pin. 0 The direction control pin will be driven to logic `0' when the transmitter has data to be sent. It will be driven to logic `1' after the last bit of data has been transmitted. The direction control pin will be driven to logic `1' when the transmitter has data to be sent. It will be driven to logic `0' after the last bit of data has been transmitted. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
31:6
-
-
4.19 UART1 RS-485 Address Match register (U1RS485ADRMATCH 0x4001 0050)
The U1RS485ADRMATCH register contains the address match value for RS-485/EIA-485 mode.
Table 309. UART1 RS-485 Address Match register (U1RS485ADRMATCH - address 0x4001 0050) bit description Bit Symbol Description Reset value
7:0 31:8
ADRMATCH -
Contains the address match value.
0x00
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
4.20 UART1 RS-485 Delay value register (U1RS485DLY - 0x4001 0054)
The user may program the 8-bit RS485DLY register with a delay between the last stop bit leaving the TXFIFO and the de-assertion of RTS (or DTR). This delay time is in periods of the baud clock. Any delay time from 0 to 255 bit times may be programmed.
Table 310. UART1 RS-485 Delay value register (U1RS485DLY - address 0x4001 0054) bit description Bit Symbol Description Reset value
7:0 31:8
DLY -
Contains the direction control (RTS or DTR) delay value. This register works in conjunction with an 8-bit counter.
0x00
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
4.21 RS-485/EIA-485 modes of operation
The RS-485/EIA-485 feature allows the UART to be configured as an addressable slave. The addressable slave is one of multiple slaves controlled by a single master. The UART master transmitter will identify an address character by setting the parity (9th) bit to `1'. For data characters, the parity bit is set to `0'. Each UART slave receiver can be assigned a unique address. The slave can be programmed to either manually or automatically reject data following an address which is not theirs. RS-485/EIA-485 Normal Multidrop Mode (NMM) Setting the RS485CTRL bit 0 enables this mode. In this mode, an address is detected when a received byte causes the UART to set the parity error and generate an interrupt.
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If the receiver is DISABLED (RS485CTRL bit 1 = `1') any received data bytes will be ignored and will not be stored in the RXFIFO. When an address byte is detected (parity bit = `1') it will be placed into the RXFIFO and an Rx Data Ready Interrupt will be generated. The processor can then read the address byte and decide whether or not to enable the receiver to accept the following data. While the receiver is ENABLED (RS485CTRL bit 1 ='0') all received bytes will be accepted and stored in the RXFIFO regardless of whether they are data or address. When an address character is received a parity error interrupt will be generated and the processor can decide whether or not to disable the receiver. RS-485/EIA-485 Auto Address Detection (AAD) mode When both RS485CTRL register bits 0 (9-bit mode enable) and 2 (AAD mode enable) are set, the UART is in auto address detect mode. In this mode, the receiver will compare any address byte received (parity = `1') to the 8-bit value programmed into the RS485ADRMATCH register. If the receiver is DISABLED (RS485CTRL bit 1 = `1') any received byte will be discarded if it is either a data byte OR an address byte which fails to match the RS485ADRMATCH value. When a matching address character is detected it will be pushed onto the RXFIFO along with the parity bit, and the receiver will be automatically enabled (RS485CTRL bit 1 will be cleared by hardware). The receiver will also generate n Rx Data Ready Interrupt. While the receiver is ENABLED (RS485CTRL bit 1 = `0') all bytes received will be accepted and stored in the RXFIFO until an address byte which does not match the RS485ADRMATCH value is received. When this occurs, the receiver will be automatically disabled in hardware (RS485CTRL bit 1 will be set), The received non-matching address character will not be stored in the RXFIFO. RS-485/EIA-485 Auto Direction Control RS485/EIA-485 Mode includes the option of allowing the transmitter to automatically control the state of either the RTS pin or the DTR pin as a direction control output signal. Setting RS485CTRL bit 4 = `1' enables this feature. Direction control, if enabled, will use the RTS pin when RS485CTRL bit 3 = `0'. It will use the DTR pin when RS485CTRL bit 3 = `1'. When Auto Direction Control is enabled, the selected pin will be asserted (driven low) when the CPU writes data into the TXFIFO. The pin will be de-asserted (driven high) once the last bit of data has been transmitted. See bits 4 and 5 in the RS485CTRL register. The RS485CTRL bit 4 takes precedence over all other mechanisms controlling RTS (or DTR) with the exception of loopback mode. RS485/EIA-485 driver delay time The driver delay time is the delay between the last stop bit leaving the TXFIFO and the de-assertion of RTS (or DTR). This delay time can be programmed in the 8-bit RS485DLY register. The delay time is in periods of the baud clock. Any delay time from 0 to 255 bit times may be programmed.
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RS485/EIA-485 output inversion The polarity of the direction control signal on the RTS (or DTR) pins can be reversed by programming bit 5 in the U1RS485CTRL register. When this bit is set, the direction control pin will be driven to logic 1 when the transmitter has data waiting to be sent. The direction control pin will be driven to logic 0 after the last bit of data has been transmitted.
4.22 UART1 FIFO Level register (U1FIFOLVL - 0x4001 0058)
U1FIFOLVL register is a read-only register that allows software to read the current FIFO level status. Both the transmit and receive FIFO levels are present in this register.
Table 311. UART1 FIFO Level register (U1FIFOLVL - address 0x4001 0058) bit description Bit Symbol Description Reset value
3:0 7:4 11:8
RXFIFILVL TXFIFOLVL
Reflects the current level of the UART1 receiver FIFO. 0 = empty, 0xF = FIFO full. Reserved. The value read from a reserved bit is not defined. Reflects the current level of the UART1 transmitter FIFO. 0 = empty, 0xF = FIFO full. Reserved, the value read from a reserved bit is not defined.
0x00 NA 0x00 NA
31:12 -
5. Architecture
The architecture of the UART1 is shown below in the block diagram. The APB interface provides a communications link between the CPU or host and the UART1. The UART1 receiver block, U1RX, monitors the serial input line, RXD1, for valid input. The UART1 RX Shift Register (U1RSR) accepts valid characters via RXD1. After a valid character is assembled in the U1RSR, it is passed to the UART1 RX Buffer Register FIFO to await access by the CPU or host via the generic host interface. The UART1 transmitter block, U1TX, accepts data written by the CPU or host and buffers the data in the UART1 TX Holding Register FIFO (U1THR). The UART1 TX Shift Register (U1TSR) reads the data stored in the U1THR and assembles the data to transmit via the serial output pin, TXD1. The UART1 Baud Rate Generator block, U1BRG, generates the timing enables used by the UART1 TX block. The U1BRG clock input source is the APB clock (PCLK). The main clock is divided down per the divisor specified in the U1DLL and U1DLM registers. This divided down clock is a 16x oversample clock, NBAUDOUT. The modem interface contains registers U1MCR and U1MSR. This interface is responsible for handshaking between a modem peripheral and the UART1. The interrupt interface contains registers U1IER and U1IIR. The interrupt interface receives several one clock wide enables from the U1TX and U1RX blocks. Status information from the U1TX and U1RX is stored in the U1LSR. Control information for the U1TX and U1RX is stored in the U1LCR.
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Transmitter Transmitter Holding Register Transmitter FIFO Transmitter DMA Interface TX_DMA_REQ TX_DMA_CLR Baud Rate Generator Fractional Main Rate Divider Divider (DLM, DLL) FIFO Control & Status Interrupt Control & Status U1_OE Line Control & Status RS485, IrDA, & Auto-baud Receiver Receiver Buffer Register Receiver FIFO Receiver DMA Interface RX_DMA_REQ RX_DMA_CLR Receiver Shift Register U1_RXD Transmitter Shift Register U1_TXD
PCLK
UART1 interrupt U1_CTS U1_RTS U1_DSR U1_DTR U1_DCD U1_RI
Modem Control & Status
Fig 51. UART1 block diagram
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1. Basic configuration
The CAN1/2 peripherals are configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bits PCAN1/2. Remark: On reset, the CAN1/2 blocks are disabled (PCAN1/2 = 0). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_CAN1, PCLK_CAN2, and, for the acceptance filter, PCLK_ACF. Note that these must all be the same value. Remark: If CAN baud rates above 100 kbit/s (see Table 16-323) are needed, do not select the IRC as the clock source (see Table 4-17). 3. Wake-up: CAN controllers are able to wake up the microcontroller from Power-down mode, see Section 4-8.8. 4. Pins: Select CAN1/2 pins through the PINSEL registers and their pin modes through the PINMODE registers (Section 8-5). 5. Interrupts: CAN interrupts are enabled using the CAN1/2IER registers (Table 16-322). Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 6. CAN controller initialization: see CANMOD register (Section 16-7.1).
2. CAN controllers
Controller Area Network (CAN) is the definition of a high performance communication protocol for serial data communication. The CAN Controller is designed to provide a full implementation of the CAN-Protocol according to the CAN Specification Version 2.0B. Microcontrollers with this on-chip CAN controller are used to build powerful local networks by supporting distributed real-time control with a very high level of security. The applications are automotive, industrial environments, and high speed networks as well as low cost multiplex wiring. The result is a strongly reduced wiring harness and enhanced diagnostic and supervisory capabilities. The CAN block is intended to support multiple CAN buses simultaneously, allowing the device to be used as a gateway, switch, or router among a number of CAN buses in various applications. The CAN module consists of two elements: the controller and the Acceptance Filter. All registers and the RAM are accessed as 32-bit words.
3. Features
3.1 General CAN features * Compatible with CAN specification 2.0B, ISO 11898-1. * Multi-master architecture with non destructive bit-wise arbitration.
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* * * * * * *
Bus access priority determined by the message identifier (11-bit or 29-bit). Guaranteed latency time for high priority messages. Programmable transfer rate (up to 1 Mbit/s). Multicast and broadcast message facility. Data length from 0 up to 8 bytes. Powerful error handling capability. Non-return-to-zero (NRZ) encoding/decoding with bit stuffing.
3.2 CAN controller features * * * * * * * *
2 CAN controllers and buses. Supports 11-bit identifier as well as 29-bit identifier. Double Receive Buffer and Triple Transmit Buffer. Programmable Error Warning Limit and Error Counters with read/write access. Arbitration Lost Capture and Error Code Capture with detailed bit position. Single Shot Transmission (no re-transmission). Listen Only Mode (no acknowledge, no active error flags). Reception of "own" messages (Self Reception Request).
3.3 Acceptance filter features * Fast hardware implemented search algorithm supporting a large number of CAN
identifiers.
* Global Acceptance Filter recognizes 11-bit and 29-bit Rx Identifiers for all CAN buses. * Allows definition of explicit and groups for 11-bit and 29-bit CAN identifiers. * Acceptance Filter can provide FullCAN-style automatic reception for selected
Standard Identifiers.
4. Pin description
Table 312. CAN Pin descriptions Pin Name Type Description Serial Inputs. From CAN transceivers. Serial Outputs. To CAN transceivers.
RD1, RD2 TD1, TD2
Input Output
5. CAN controller architecture
The CAN Controller is a complete serial interface with both Transmit and Receive Buffers but without Acceptance Filter. CAN Identifier filtering is done for all CAN channels in a separate block (Acceptance Filter). Except for message buffering and acceptance filtering the functionality is similar to the PeliCAN concept. The CAN Controller Block includes interfaces to the following blocks:
* APB Interface
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Chapter 16: LPC17xx CAN1/2
* * * *
Acceptance Filter Nested Vectored Interrupt Controller (NVIC) CAN Transceiver Common Status Registers
APB BUS
INTERFACE MANAGEMENT LOGIC
CAN CORE BLOCK TX ERROR MANAGEMENT LOGIC RX CAN TRANSCEIVER
NVIC TRANSMIT BUFFERS 1,2 AND 3
COMMON STATUS REGISTER
BIT TIMING LOGIC
ACCEPTANCE FILTER
RECEIVE BUFFERS 1 AND 2
BIT STREAM PROCESSOR
Fig 52. CAN controller block diagram
5.1 APB Interface Block (AIB)
The APB Interface Block provides access to all CAN Controller registers.
5.2 Interface Management Logic (IML)
The Interface Management Logic interprets commands from the CPU, controls internal addressing of the CAN Registers and provides interrupts and status information to the CPU.
5.3 Transmit Buffers (TXB)
The TXB represents a Triple Transmit Buffer, which is the interface between the Interface Management Logic (IML) and the Bit Stream Processor (BSP). Each Transmit Buffer is able to store a complete message which can be transmitted over the CAN network. This buffer is written by the CPU and read out by the BSP.
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Chapter 16: LPC17xx CAN1/2
31
24 23
16 15
87
0
TX
Frame info
unused 0 ... 0
TX DLC
unused
TX Priority ID.28 ... ID.18
TFS TID TDA
Descriptor Field
TX Data 4 TX Data 8
TX Data 3 TX Data 7
TX Data 2 TX Data 6
TX Data 1 TX Data 5
Data Field TDB
Standard Frame Format (11-bit Identifier)
31
24 23
16 15
87
0
TX 000
Frame info ID.28
unused
TX DLC ...
unused
TX Priority ID.00
TFS TID TDA
Descriptor Field
TX Data 4 TX Data 8
TX Data 3 TX Data 7
TX Data 2 TX Data 6
TX Data 1 TX Data 5
Data Field TDB
Extended Frame Format (29-bit Identifier)
Fig 53. Transmit buffer layout for standard and extended frame format configurations
5.4 Receive Buffer (RXB)
The Receive Buffer (RXB) represents a CPU accessible Double Receive Buffer. It is located between the CAN Controller Core Block and APB Interface Block and stores all received messages from the CAN Bus line. With the help of this Double Receive Buffer concept the CPU is able to process one message while another message is being received. The global layout of the Receive Buffer is very similar to the Transmit Buffer described earlier. Identifier, Frame Format, Remote Transmission Request bit and Data Length Code have the same meaning as described for the Transmit Buffer. In addition, the Receive Buffer includes an ID Index field (see Section 16-7.9.1 "ID index field"). The received Data Length Code represents the real transmitted Data Length Code, which may be greater than 8 depending on transmitting CAN node. Nevertheless, the maximum number of received data bytes is 8. This should be taken into account by reading a message from the Receive Buffer. If there is not enough space for a new message within the Receive Buffer, the CAN Controller generates a Data Overrun condition when this message becomes valid and the acceptance test was positive. A message that is partly written into the Receive Buffer (when the Data Overrun situation occurs) is deleted. This situation is signalled to the CPU via the Status Register and the Data Overrun Interrupt, if enabled.
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31
24 23
16 15
10 9 8 7
0
RX
Frame info
unused unused
RX DLC
unused
ID Index ID.28 ... ID.18
RFS RID RDA
Descriptor Field
RX Data 4 RX Data 8
RX Data 3 RX Data 7
RX Data 2 RX Data 6
RX Data 1 RX Data 5
Data Field RDB BPM=bypass message
Standard Frame Format (11-bit Identifier)
31
24 23
16 15
10 9 8 7
0
RX
unused
Frame info ID.28
unused
RX DLC ...
unused
ID Index ID.00
RFS RID RDA
Descriptor Field
RX Data 4 RX Data 8
RX Data 3 RX Data 7
RX Data 2 RX Data 6
RX Data 1 RX Data 5
Data Field RDB
Extended Frame Format (29-bit Identifier)
Fig 54. Receive buffer layout for standard and extended frame format configurations
5.5 Error Management Logic (EML)
The EML is responsible for the error confinement. It gets error announcements from the BSP and then informs the BSP and IML about error statistics.
5.6 Bit Timing Logic (BTL)
The Bit Timing Logic monitors the serial CAN Bus line and handles the Bus line related bit timing. It synchronizes to the bit stream on the CAN Bus on a "recessive" to "dominant" Bus line transition at the beginning of a message (hard synchronization) and re-synchronizes on further transitions during the reception of a message (soft synchronization). The BTL also provides programmable time segments to compensate for the propagation delay times and phase shifts (e.g. due to oscillator drifts) and to define the sample point and the number of samples to be taken within a bit time.
5.7 Bit Stream Processor (BSP)
The Bit Stream Processor is a sequencer, controlling the data stream between the Transmit Buffer, Receive Buffers and the CAN Bus. It also performs the error detection, arbitration, stuffing and error handling on the CAN Bus.
5.8 CAN controller self-tests
The CAN controller supports two different options for self-tests:
* Global Self-Test (setting the self reception request bit in normal Operating Mode) * Local Self-Test (setting the self reception request bit in Self Test Mode)
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Both self-tests are using the `Self Reception' feature of the CAN Controller. With the Self Reception Request, the transmitted message is also received and stored in the receive buffer. Therefore the acceptance filter has to be configured accordingly. As soon as the CAN message is transmitted, a transmit and a receive interrupt are generated, if enabled. Global self test A Global Self-Test can for example be used to verify the chosen configuration of the CAN Controller in a given CAN system. As shown in Figure 16-55, at least one other CAN node, which is acknowledging each CAN message has to be connected to the CAN bus.
TX Buffer TX Buffer TX Buffer
LPC17xx Transceiver
CAN Bus
ack RX Buffer
Fig 55. Global Self-Test (high-speed CAN Bus example)
Initiating a Global Self-Test is similar to a normal CAN transmission. In this case the transmission of a CAN message(s) is initiated by setting Self Reception Request bit (SRR) in conjunction with the selected Message Buffer bits (STB3, STB2, STB1) in the CAN Controller Command register (CANCMR). Local self test The Local Self-Test perfectly fits for single node tests. In this case an acknowledge from other nodes is not needed. As shown in the Figure below, a CAN transceiver with an appropriate CAN bus termination has to be connected to the LPC17xx. The CAN Controller has to be put into the 'Self Test Mode' by setting the STM bit in the CAN Controller Mode register (CANMOD). Hint: Setting the Self Test Mode bit (STM) is possible only when the CAN Controller is in Reset Mode.
TX Buffer TX Buffer TX Buffer LPC17xx Transceiver
RX Buffer
Fig 56. Local self test (high-speed CAN Bus example)
A message transmission is initiated by setting Self Reception Request bit (SRR) in conjunction with the selected Message Buffer(s) (STB3, STB2, STB1).
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Chapter 16: LPC17xx CAN1/2
6. Memory map of the CAN block
The CAN Controllers and Acceptance Filter occupy a number of APB slots, as follows:
Table 313. Memory map of the CAN block Address Range Used for
0x4003 8000 - 0x4003 87FF 0x4003 C000 - 0x4003 C017 0x4004 0000 - 0x4004 000B 0x4004 4000 - 0x4004 405F 0x4004 8000 - 0x4004 805F 0x400F C110 - 0x400F C114
Acceptance Filter RAM. Acceptance Filter Registers. Central CAN Registers. CAN Controller 1 Registers. CAN Controller 2 Registers. CAN Wake and Sleep Registers.
7. CAN controller registers
CAN block implements the registers shown in Table 16-314 and Table 16-315. More detailed descriptions follow.
Table 314. CAN acceptance filter and central CAN registers Name Description Access Reset Value Address
AFMR SFF_sa SFF_GRP_sa EFF_sa EFF_GRP_sa ENDofTable LUTerrAd LUTerr CANTxSR CANRxSR CANMSR
Acceptance Filter Register Standard Frame Individual Start Address Register Standard Frame Group Start Address Register Extended Frame Start Address Register Extended Frame Group Start Address Register End of AF Tables register LUT Error Address register LUT Error Register CAN Central Transmit Status Register CAN Central Receive Status Register CAN Central Miscellaneous Register
R/W R/W R/W R/W R/W R/W RO RO RO RO RO
1 0 0 0 0 0 0 0 0x0003 0300 0 0
0x4003 C000 0x4003 C004 0x4003 C008 0x4003 C00C 0x4003 C010 0x4003 C014 0x4003 C018 0x4003 C01C 0x4004 0000 0x4004 0004 0x4004 0008
Table 315. CAN1 and CAN2 controller register map Generic Description Name Access Reset value CAN1 & 2 Register Name & Address
MOD CMR GSR ICR IER
Controls the operating mode of the CAN Controller. Command bits that affect the state of the CAN Controller Global Controller Status and Error Counters
R/W WO RO[1]
1 0 0x3C 0 0
CAN1MOD - 0x4004 4000 CAN2MOD - 0x4004 8000 CAN1CMR - 0x4004 4004 CAN2CMR - 0x4004 8004 CAN1GSR - 0x4004 4008 CAN2GSR - 0x4004 8008 CAN1ICR - 0x4004 400C CAN2ICR - 0x4004 800C CAN1IER - 0x4004 4010 CAN2IER - 0x4004 8010
Interrupt status, Arbitration Lost Capture, Error Code Capture RO Interrupt Enable R/W
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Table 315. CAN1 and CAN2 controller register map Generic Description Name Access Reset value CAN1 & 2 Register Name & Address
BTR EWL SR RFS RID RDA RDB TFI1 TID1 TDA1 TDB1 TFI2 TID2 TDA2 TDB2 TFI3 TID3 TDA3 TDB3
Bus Timing Error Warning Limit Status Register Receive frame status Received Identifier Received data bytes 1-4 Received data bytes 5-8 Transmit frame info (Tx Buffer 1) Transmit Identifier (Tx Buffer 1) Transmit data bytes 1-4 (Tx Buffer 1) Transmit data bytes 5-8 (Tx Buffer 1) Transmit frame info (Tx Buffer 2) Transmit Identifier (Tx Buffer 2) Transmit data bytes 1-4 (Tx Buffer 2) Transmit data bytes 5-8 (Tx Buffer 2) Transmit frame info (Tx Buffer 3) Transmit Identifier (Tx Buffer 3) Transmit data bytes 1-4 (Tx Buffer 3) Transmit data bytes 5-8 (Tx Buffer 3)
R/W[2] R/W[2] RO R/W[2] R/W[2] R/W[2] R/W[2] R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
0x1C0000 0x60
CAN1BTR - 0x4004 4014 CAN2BTR - 0x4004 8014 CAN1EWL - 0x4004 4018 CAN2EWL - 0x4004 8018
0x3C3C3C CAN1SR - 0x4004 401C CAN2SR - 0x4004 801C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CAN1RFS - 0x4004 4020 CAN2RFS - 0x4004 8020 CAN1RID - 0x4004 4024 CAN2RID - 0x4004 8024 CAN1RDA - 0x4004 4028 CAN2RDA - 0x4004 8028 CAN1RDB - 0x4004 402C CAN2RDB - 0x4004 802C CAN1TFI1 - 0x4004 4030 CAN2TFI1 - 0x4004 8030 CAN1TID1 - 0x4004 4034 CAN2TID1 - 0x4004 8034 CAN1TDA1 - 0x4004 4038 CAN2TDA1 - 0x4004 8038 CAN1TDB1- 0x4004 403C CAN2TDB1 - 0x4004 803C CAN1TFI2 - 0x4004 4040 CAN2TFI2 - 0x4004 8040 CAN1TID2 - 0x4004 4044 CAN2TID2 - 0x4004 8044 CAN1TDA2 - 0x4004 4048 CAN2TDA2 - 0x4004 8048 CAN1TDB2 - 0x4004 404C CAN2TDB2 - 0x4004 804C CAN1TFI3 - 0x4004 4050 CAN2TFI3 - 0x4004 8050 CAN1TID3 - 0x4004 4054 CAN2TID3 - 0x4004 8054 CAN1TDA3 - 0x4004 4058 CAN2TDA3 - 0x4004 8058 CAN1TDB3 - 0x4004 405C CAN2TDB3 - 0x4004 805C
[1] [2]
The error counters can only be written when RM in CANMOD is 1. These registers can only be written when RM in CANMOD is 1.
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The internal registers of each CAN Controller appear to the CPU as on-chip memory mapped peripheral registers. Because the CAN Controller can operate in different modes (Operating/Reset, see also Section 16-7.1 "CAN Mode register (CAN1MOD 0x4004 4000, CAN2MOD - 0x4004 8000)"), one has to distinguish between different internal address definitions. Note that write access to some registers is only allowed in Reset Mode.
Table 316. CAN1 and CAN2 controller register summary Generic Name Operating Mode Read Write Reset Mode Read Write
MOD CMR GSR ICR IER BTR EWL SR RFS RID RDA RDB TFI1 TID1 TDA1 TDB1
Mode 0x00 Global Status and Error Counters Interrupt and Capture Interrupt Enable Bus Timing Error Warning Limit Status Rx Info and Index Rx Identifier Rx Data Rx Info and Index Tx Info1 Tx Identifier Tx Data Tx Data
Mode Command Interrupt Enable Tx Info Tx Identifier Tx Data Tx Data
Mode 0x00 Global Status and Error Counters Interrupt and Capture Interrupt Enable Bus Timing Error Warning Limit Status Rx Info and Index Rx Identifier Rx Data Rx Info and Index Tx Info Tx Identifier Tx Data Tx Data
Mode Command Error Counters only Interrupt Enable Bus Timing Error Warning Limit Rx Info and Index Rx Identifier Rx Data Rx Info and Index Tx Info Tx Identifier Tx Data Tx Data
Table 317. CAN Wake and Sleep registers Name Description Access Reset Value Address
CANSLEEPCLR
Allows clearing the current CAN channel sleep state as well as R/W reading that state. R/W
0 0
0x400F C110 0x400F C114
CANWAKEFLAGS Allows reading the wake-up state of the CAN channels.
In the following register tables, the column "Reset Value" shows how a hardware reset affects each bit or field, while the column "RM Set" indicates how each bit or field is affected if software sets the RM bit, or RM is set because of a Bus-Off condition. Note that while hardware reset sets RM, in this case the setting noted in the "Reset Value" column prevails over that shown in the "RM Set" column, in the few bits where they differ. In both columns, X indicates the bit or field is unchanged.
7.1 CAN Mode register (CAN1MOD - 0x4004 4000, CAN2MOD 0x4004 8000)
The contents of the Mode Register are used to change the behavior of the CAN Controller. Bits may be set or reset by the CPU that uses the Mode Register as a read/write memory.
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Table 318. CAN Mode register (CAN1MOD - address 0x4004 4000, CAN2MOD - address 0x4004 8000) bit description Bit Symbol Value Function Reset RM Value Set
0
RM[1][6] 0 (normal) 1 (reset)
Reset Mode. The CAN Controller is in the Operating Mode, and certain registers can not be written. CAN operation is disabled, writable registers can be written and the current transmission/reception of a message is aborted. Listen Only Mode. 0 (normal) 1 (listen only) The CAN controller acknowledges a successfully received message on the CAN bus. The error counters are stopped at the current value. The controller gives no acknowledgment, even if a message is successfully received. Messages cannot be sent, and the controller operates in "error passive" mode. This mode is intended for software bit rate detection and "hot plugging". Self Test Mode. 0 (normal) 1 (self test) A transmitted message must be acknowledged to be considered successful. The controller will consider a Tx message successful even if there is no acknowledgment received. In this mode a full node test is possible without any other active node on the bus using the SRR bit in CANxCMR.
1
1
1
LOM[3][2]
[6]
0
x
2
STM[3][6]
0
x
3
TPM[4] 0 (CAN ID) 1 (local prio)
Transmit Priority Mode. The transmit priority for 3 Transmit Buffers depends on the CAN Identifier. The transmit priority for 3 Transmit Buffers depends on the contents of the Tx Priority register within the Transmit Buffer. Sleep Mode. 0 (wake-up) 1 (sleep) Normal operation. The CAN controller enters Sleep Mode if no CAN interrupt is pending and there is no bus activity. See the Sleep Mode description Section 16-8.2 on page 369. Receive Polarity Mode. 0 (low active) 1 (high active) RD input is active Low (dominant bit = 0). RD input is active High (dominant bit = 1) -- reverse polarity. Reserved, user software should not write ones to reserved bits. Test Mode. 0 (disabled) 1 (enabled) Normal operation. The TD pin will reflect the bit, detected on RD pin, with the next positive edge of the system clock. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
x
4
SM[5]
0
0
5
RPM
0
x
6 7
TM
-
0 0
0 x
31:8
-
NA
[1]
During a Hardware reset or when the Bus Status bit is set '1' (Bus-Off), the Reset Mode bit is set '1' (present). After the Reset Mode bit is set '0' the CAN Controller will wait for: - one occurrence of Bus-Free signal (11 recessive bits), if the preceding reset has been caused by a Hardware reset or a CPU-initiated reset. - 128 occurrences of Bus-Free, if the preceding reset has been caused by a CAN Controller initiated Bus-Off, before re-entering the Bus-On mode.
[2]
This mode of operation forces the CAN Controller to be error passive. Message Transmission is not possible. The Listen Only Mode can be used e.g. for software driven bit rate detection and "hot plugging".
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[3] [4] [5]
A write access to the bits MOD.1 and MOD.2 is possible only if the Reset Mode is entered previously. Transmit Priority Mode is explained in more detail in Section 16-5.3 "Transmit Buffers (TXB)". The CAN Controller will enter Sleep Mode, if the Sleep Mode bit is set '1' (sleep), there is no bus activity, and none of the CAN interrupts is pending. Setting of SM with at least one of the previously mentioned exceptions valid will result in a wake-up interrupt. The CAN Controller will wake up if SM is set LOW (wake-up) or there is bus activity. On wake-up, a Wake-up Interrupt is generated. A sleeping CAN Controller which wakes up due to bus activity will not be able to receive this message until it detects 11 consecutive recessive bits (Bus-Free sequence). Note that setting of SM is not possible in Reset Mode. After clearing of Reset Mode, setting of SM is possible only when Bus-Free is detected again. The LOM and STM bits can only be written if the RM bit is 1 prior to the write operation.
[6]
7.2 CAN Command Register (CAN1CMR - 0x4004 x004, CAN2CMR 0x4004 8004)
Writing to this write-only register initiates an action within the transfer layer of the CAN Controller. Reading this register yields zeroes. At least one internal clock cycle is needed for processing between two commands.
Table 319. CAN Command Register (CAN1CMR - address 0x4004 4004, CAN2CMR - address 0x4004 8004) bit description Bit Symbol Value Function Reset RM Value Set
0[1][2]
TR 0 (absent) 1 (present)
Transmission Request. No transmission request. The message, previously written to the CANxTFI, CANxTID, and optionally the CANxTDA and CANxTDB registers, is queued for transmission from the selected Transmit Buffer. If at two or all three of STB1, STB2 and STB3 bits are selected when TR=1 is written, Transmit Buffer will be selected based on the chosen priority scheme (for details see Section 16-5.3 "Transmit Buffers (TXB)") Abort Transmission. 0 (no action) 1 (present) Do not abort the transmission. if not already in progress, a pending Transmission Request for the selected Transmit Buffer is cancelled. Release Receive Buffer. 0 (no action) 1 (released) Do not release the receive buffer. The information in the Receive Buffer (consisting of CANxRFS, CANxRID, and if applicable the CANxRDA and CANxRDB registers) is released, and becomes eligible for replacement by the next received frame. If the next received frame is not available, writing this command clears the RBS bit in the Status Register(s). Clear Data Overrun. 0 (no action) 1 (clear) Do not clear the data overrun bit. The Data Overrun bit in Status Register(s) is cleared. Self Reception Request. 0 (absent) 1 (present) No self reception request. The message, previously written to the CANxTFS, CANxTID, and optionally the CANxTDA and CANxTDB registers, is queued for transmission from the selected Transmit Buffer and received simultaneously. This differs from the TR bit above in that the receiver is not disabled during the transmission, so that it receives the message if its Identifier is recognized by the Acceptance Filter.
0
0
1[1][3]
AT
0
0
2[4]
RRB
0
0
3[5]
CDO
0
0
4[1][6]
SRR
0
0
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Table 319. CAN Command Register (CAN1CMR - address 0x4004 4004, CAN2CMR - address 0x4004 8004) bit description Bit Symbol Value Function Reset RM Value Set
5
STB1 0 (not selected) 1 (selected)
Select Tx Buffer 1. Tx Buffer 1 is not selected for transmission. Tx Buffer 1 is selected for transmission. Select Tx Buffer 2. 0 (not selected) 1 (selected) Tx Buffer 2 is not selected for transmission. Tx Buffer 2 is selected for transmission. Select Tx Buffer 3. 0 (not selected) 1 (selected) Tx Buffer 3 is not selected for transmission. Tx Buffer 3 is selected for transmission. Reserved, user software should not write ones to reserved bits.
0
0
6
STB2
0
0
7
STB3
0
0
31:8
[1]
-
NA
- Setting the command bits TR and AT simultaneously results in transmitting a message once. No re-transmission will be performed in case of an error or arbitration lost (single shot transmission). - Setting the command bits SRR and TR simultaneously results in sending the transmit message once using the self-reception feature. No re-transmission will be performed in case of an error or arbitration lost. - Setting the command bits TR, AT and SRR simultaneously results in transmitting a message once as described for TR and AT. The moment the Transmit Status bit is set within the Status Register, the internal Transmission Request Bit is cleared automatically. - Setting TR and SRR simultaneously will ignore the set SRR bit. If the Transmission Request or the Self-Reception Request bit was set '1' in a previous command, it cannot be cancelled by resetting the bits. The requested transmission may only be cancelled by setting the Abort Transmission bit. The Abort Transmission bit is used when the CPU requires the suspension of the previously requested transmission, e.g. to transmit a more urgent message before. A transmission already in progress is not stopped. In order to see if the original message has been either transmitted successfully or aborted, the Transmission Complete Status bit should be checked. This should be done after the Transmit Buffer Status bit has been set to '1' or a Transmit Interrupt has been generated. After reading the contents of the Receive Buffer, the CPU can release this memory space by setting the Release Receive Buffer bit '1'. This may result in another message becoming immediately available. If there is no other message available, the Receive Interrupt bit is reset. If the RRB command is given, it will take at least 2 internal clock cycles before a new interrupt is generated. This command bit is used to clear the Data Overrun condition signalled by the Data Overrun Status bit. As long as the Data Overrun Status bit is set no further Data Overrun Interrupt is generated. Upon Self Reception Request, a message is transmitted and simultaneously received if the Acceptance Filter is set to the corresponding identifier. A receive and a transmit interrupt will indicate correct self reception (see also Self Test Mode in Section 16-7.1 "CAN Mode register (CAN1MOD - 0x4004 4000, CAN2MOD - 0x4004 8000)").
[2] [3]
[4]
[5] [6]
7.3 CAN Global Status Register (CAN1GSR - 0x4004 x008, CAN2GSR 0x4004 8008)
The content of the Global Status Register reflects the status of the CAN Controller. This register is read-only, except that the Error Counters can be written when the RM bit in the CANMOD register is 1. Bits not listed read as 0 and should be written as 0.
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Table 320. CAN Global Status Register (CAN1GSR - address 0x4004 4008, CAN2GSR - address 0x4004 8008) bit description Bit Symbol Value Function Reset RM Value Set
0
RBS[1] 0 (empty) 1 (full)
Receive Buffer Status. No message is available. At least one complete message is received by the Double Receive Buffer and available in the CANxRFS, CANxRID, and if applicable the CANxRDA and CANxRDB registers. This bit is cleared by the Release Receive Buffer command in CANxCMR, if no subsequent received message is available. Data Overrun Status. 0 (absent) 1 (overrun) No data overrun has occurred since the last Clear Data Overrun command was given/written to CANxCMR (or since Reset). A message was lost because the preceding message to this CAN controller was not read and released quickly enough (there was not enough space for a new message in the Double Receive Buffer). Transmit Buffer Status. 0 (locked) At least one of the Transmit Buffers is not available for the CPU, i.e. at least one previously queued message for this CAN controller has not yet been sent, and therefore software should not write to the CANxTFI, CANxTID, CANxTDA, nor CANxTDB registers of that (those) Tx buffer(s). All three Transmit Buffers are available for the CPU. No transmit message is pending for this CAN controller (in any of the 3 Tx buffers), and software may write to any of the CANxTFI, CANxTID, CANxTDA, and CANxTDB registers. Transmit Complete Status. 0 (incomplete) 1 (complete) At least one requested transmission has not been successfully completed yet. All requested transmission(s) has (have) been successfully completed. Receive Status. 0 (idle) 1 (receive) The CAN controller is idle. The CAN controller is receiving a message. Transmit Status. 0 (idle) 1 (transmit) The CAN controller is idle. The CAN controller is sending a message. Error Status. 0 (ok) 1 (error) Both error counters are below the Error Warning Limit. One or both of the Transmit and Receive Error Counters has reached the limit set in the Error Warning Limit register. Bus Status. 0 (Bus-On) 1 (Bus-Off) The CAN Controller is involved in bus activities The CAN controller is currently not involved/prohibited from bus activity because the Transmit Error Counter reached its limiting value of 255. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. The current value of the Rx Error Counter (an 8-bit value). The current value of the Tx Error Counter (an 8-bit value).
0
0
1
DOS[2]
0
0
2
TBS
1
1
1 (released)
3
TCS[3]
1
x
4
RS[4]
1
0
5
TS[4]
1
0
6
ES[5]
0
0
7
BS[6]
0
0
15:8
-
-
NA 0 0 X X
23:16 RXERR 31:24 TXERR [1]
After reading all messages and releasing their memory space with the command 'Release Receive Buffer,' this bit is cleared.
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[2]
If there is not enough space to store the message within the Receive Buffer, that message is dropped and the Data Overrun condition is signalled to the CPU in the moment this message becomes valid. If this message is not completed successfully (e.g. because of an error), no overrun condition is signalled. The Transmission Complete Status bit is set '0' (incomplete) whenever the Transmission Request bit or the Self Reception Request bit is set '1' at least for one of the three Transmit Buffers. The Transmission Complete Status bit will remain '0' until all messages are transmitted successfully. If both the Receive Status and the Transmit Status bits are '0' (idle), the CAN-Bus is idle. If both bits are set, the controller is waiting to become idle again. After hardware reset 11 consecutive recessive bits have to be detected until idle status is reached. After Bus-off this will take 128 times of 11 consecutive recessive bits. Errors detected during reception or transmission will effect the error counters according to the CAN specification. The Error Status bit is set when at least one of the error counters has reached or exceeded the Error Warning Limit. An Error Warning Interrupt is generated, if enabled. The default value of the Error Warning Limit after hardware reset is 96 decimal, see also Section 16-7.7 "CAN Error Warning Limit register (CAN1EWL - 0x4004 4018, CAN2EWL - 0x4004 8018)". Mode bit '1' (present) and an Error Warning Interrupt is generated, if enabled. Afterwards the Transmit Error Counter is set to '127', and the Receive Error Counter is cleared. It will stay in this mode until the CPU clears the Reset Mode bit. Once this is completed the CAN Controller will wait the minimum protocol-defined time (128 occurrences of the Bus-Free signal) counting down the Transmit Error Counter. After that, the Bus Status bit is cleared (Bus-On), the Error Status bit is set '0' (ok), the Error Counters are reset, and an Error Warning Interrupt is generated, if enabled. Reading the TX Error Counter during this time gives information about the status of the Bus-Off recovery.
[3]
[4]
[5]
[6]
RX error counter The RX Error Counter Register, which is part of the Status Register, reflects the current value of the Receive Error Counter. After hardware reset this register is initialized to 0. In Operating Mode this register appears to the CPU as a read-only memory. A write access to this register is possible only in Reset Mode. If a Bus Off event occurs, the RX Error Counter is initialized to 0. As long as Bus Off is valid, writing to this register has no effect.The Rx Error Counter is determined as follows: RX Error Counter = (CANxGSR AND 0x00FF0000) / 0x00010000 Note that a CPU-forced content change of the RX Error Counter is possible only if the Reset Mode was entered previously. An Error Status change (Status Register), an Error Warning or an Error Passive Interrupt forced by the new register content will not occur until the Reset Mode is cancelled again. TX error counter The TX Error Counter Register, which is part of the Status Register, reflects the current value of the Transmit Error Counter. In Operating Mode this register appears to the CPU as a read-only memory. After hardware reset this register is initialized to 0. A write access to this register is possible only in Reset Mode. If a bus-off event occurs, the TX Error Counter is initialized to 127 to count the minimum protocol-defined time (128 occurrences of the Bus-Free signal). Reading the TX Error Counter during this time gives information about the status of the Bus-Off recovery. If Bus Off is active, a write access to TXERR in the range of 0 to 254 clears the Bus Off Flag and the controller will wait for one occurrence of 11 consecutive recessive bits (bus free) after clearing of Reset Mode. The Tx error counter is determined as follows: TX Error Counter = (CANxGSR AND 0xFF000000) / 0x01000000 Writing 255 to TXERR allows initiation of a CPU-driven Bus Off event. Note that a CPU-forced content change of the TX Error Counter is possible only if the Reset Mode was entered previously. An Error or Bus Status change (Status Register), an Error
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Warning, or an Error Passive Interrupt forced by the new register content will not occur until the Reset Mode is cancelled again. After leaving the Reset Mode, the new TX Counter content is interpreted and the Bus Off event is performed in the same way as if it was forced by a bus error event. That means, that the Reset Mode is entered again, the TX Error Counter is initialized to 127, the RX Counter is cleared, and all concerned Status and Interrupt Register bits are set. Clearing of Reset Mode now will perform the protocol defined Bus Off recovery sequence (waiting for 128 occurrences of the Bus-Free signal). If the Reset Mode is entered again before the end of Bus Off recovery (TXERR>0), Bus Off keeps active and TXERR is frozen.
7.4 CAN Interrupt and Capture Register (CAN1ICR - 0x4004 400C, CAN2ICR - 0x4004 800C)
Bits in this register indicate information about events on the CAN bus. This register is read-only. The Interrupt flags of the Interrupt and Capture Register allow the identification of an interrupt source. When one or more bits are set, a CAN interrupt will be indicated to the CPU. After this register is read from the CPU all interrupt bits are reset except of the Receive Interrupt bit. The Interrupt Register appears to the CPU as a read-only memory. Bits 1 through 10 clear when they are read. Bits 16-23 are captured when a bus error occurs. At the same time, if the BEIE bit in CANIER is 1, the BEI bit in this register is set, and a CAN interrupt can occur. Bits 24-31 are captured when CAN arbitration is lost. At the same time, if the ALIE bit in CANIER is 1, the ALI bit in this register is set, and a CAN interrupt can occur. Once either of these bytes is captured, its value will remain the same until it is read, at which time it is released to capture a new value. The clearing of bits 1 to 10 and the releasing of bits 16-23 and 24-31 all occur on any read from CANxICR, regardless of whether part or all of the register is read. This means that software should always read CANxICR as a word, and process and deal with all bits of the register as appropriate for the application.
Table 321. CAN Interrupt and Capture Register (CAN1ICR - address 0x4004 400C, CAN2ICR - address 0x4004 800C) bit description Bit Symbol Value Function Reset RM Value Set
0
RI[1]
0 (reset) 1 (set) 0 (reset) 1 (set) 0 (reset) 1 (set) 0 (reset) 1 (set) 0 (reset) 1 (set)
Receive Interrupt. This bit is set whenever the RBS bit in CANxSR and the RIE bit in CANxIER are both 1, indicating that a new message was received and stored in the Receive Buffer.
0
0
1
TI1
Transmit Interrupt 1. This bit is set when the TBS1 bit in CANxSR goes from 0 to 0 1 (whenever a message out of TXB1 was successfully transmitted or aborted), indicating that Transmit buffer 1 is available, and the TIE1 bit in CANxIER is 1. Error Warning Interrupt. This bit is set on every change (set or clear) of either the 0 Error Status or Bus Status bit in CANxSR and the EIE bit bit is set within the Interrupt Enable Register at the time of the change. Data Overrun Interrupt. This bit is set when the DOS bit in CANxSR goes from 0 0 to 1 and the DOIE bit in CANxIER is 1. Wake-Up Interrupt. This bit is set if the CAN controller is sleeping and bus activity 0 is detected and the WUIE bit in CANxIER is 1.
0
2
EI
X
3 4
DOI WUI[2]
0 0
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Table 321. CAN Interrupt and Capture Register (CAN1ICR - address 0x4004 400C, CAN2ICR - address 0x4004 800C) bit description Bit Symbol Value Function Reset RM Value Set
5
EPI
0 (reset) 1 (set)
Error Passive Interrupt. This bit is set if the EPIE bit in CANxIER is 1, and the CAN controller switches between Error Passive and Error Active mode in either direction. This is the case when the CAN Controller has reached the Error Passive Status (at least one error counter exceeds the CAN protocol defined level of 127) or if the CAN Controller is in Error Passive Status and enters the Error Active Status again.
0
0
6
ALI
0 (reset) 1 (set) 0 (reset) 1 (set) 0 (reset) 1 (set)
Arbitration Lost Interrupt. This bit is set if the ALIE bit in CANxIER is 1, and the CAN controller loses arbitration while attempting to transmit. In this case the CAN node becomes a receiver. Bus Error Interrupt -- this bit is set if the BEIE bit in CANxIER is 1, and the CAN controller detects an error on the bus. ID Ready Interrupt -- this bit is set if the IDIE bit in CANxIER is 1, and a CAN Identifier has been received (a message was successfully transmitted or aborted). This bit is set whenever a message was successfully transmitted or aborted and the IDIE bit is set in the IER register.
0
0
7 8
BEI IDI
0 0
X 0
9
TI2
0 (reset) 1 (set) 0 (reset) 1 (set) -
Transmit Interrupt 2. This bit is set when the TBS2 bit in CANxSR goes from 0 to 0 1 (whenever a message out of TXB2 was successfully transmitted or aborted), indicating that Transmit buffer 2 is available, and the TIE2 bit in CANxIER is 1. Transmit Interrupt 3. This bit is set when the TBS3 bit in CANxSR goes from 0 to 0 1 (whenever a message out of TXB3 was successfully transmitted or aborted), indicating that Transmit buffer 3 is available, and the TIE3 bit in CANxIER is 1. Reserved, user software should not write ones to reserved bits. 0
0
10
TI3
0
15:11 -
0
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Table 321. CAN Interrupt and Capture Register (CAN1ICR - address 0x4004 400C, CAN2ICR - address 0x4004 800C) bit description Bit Symbol Value Function Reset RM Value Set
20:16 ERRBIT 4:0[3] 00011 00010 00110 00100 00101 00111 01111 01110 01100 01101 01001 01011 01010 01000 11000 11001 11011 11010 10010 10001 10110 10011 10111 11100 21 ERRDIR 0 1 23:22 ERRC1:0 00 01 10 11
Error Code Capture: when the CAN controller detects a bus error, the location of 0 the error within the frame is captured in this field. The value reflects an internal state variable, and as a result is not very linear: Start of Frame ID28 ... ID21 ID20 ... ID18 SRTR Bit IDE bit ID17 ... 13 ID12 ... ID5 ID4 ... ID0 RTR Bit Reserved Bit 1 Reserved Bit 0 Data Length Code Data Field CRC Sequence CRC Delimiter Acknowledge Slot Acknowledge Delimiter End of Frame Intermission Active Error Flag Passive Error Flag Tolerate Dominant Bits Error Delimiter Overload flag When the CAN controller detects a bus error, the direction of the current bit is captured in this bit. Error occurred during transmitting. Error occurred during receiving. When the CAN controller detects a bus error, the type of error is captured in this 0 field: Bit error Form error Stuff error Other error 0
X
X
X
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Table 321. CAN Interrupt and Capture Register (CAN1ICR - address 0x4004 400C, CAN2ICR - address 0x4004 800C) bit description Bit Symbol Value Function Reset RM Value Set
31:24 ALCBIT[4] -
Each time arbitration is lost while trying to send on the CAN, the bit number within the frame is captured into this field. After the content of ALCBIT is read, the ALI bit is cleared and a new Arbitration Lost interrupt can occur. arbitration lost in the first bit (MS) of identifier arbitration lost in SRTS bit (RTR bit for standard frame messages) arbitration lost in IDE bit arbitration lost in 12th bit of identifier (extended frame only) arbitration lost in last bit of identifier (extended frame only) arbitration lost in RTR bit (extended frame only)
[1]
0
X
00 ... 11 12 13 ... 30 31
The Receive Interrupt Bit is not cleared upon a read access to the Interrupt Register. Giving the Command "Release Receive Buffer" will clear RI temporarily. If there is another message available within the Receive Buffer after the release command, RI is set again. Otherwise RI remains cleared. A Wake-Up Interrupt is also generated if the CPU tries to set the Sleep bit while the CAN controller is involved in bus activities or a CAN Interrupt is pending. The WUI flag can also get asserted when the according enable bit WUIE is not set. In this case a Wake-Up Interrupt does not get asserted. Whenever a bus error occurs, the corresponding bus error interrupt is forced, if enabled. At the same time, the current position of the Bit Stream Processor is captured into the Error Code Capture Register. The content within this register is fixed until the user software has read out its content once. From now on, the capture mechanism is activated again, i.e. reading the CANxICR enables another Bus Error Interrupt. On arbitration lost, the corresponding arbitration lost interrupt is forced, if enabled. At that time, the current bit position of the Bit Stream Processor is captured into the Arbitration Lost Capture Register. The content within this register is fixed until the user application has read out its contents once. From now on, the capture mechanism is activated again.
[2]
[3]
[4]
7.5 CAN Interrupt Enable Register (CAN1IER - 0x4004 4010, CAN2IER 0x4004 8010)
This read/write register controls whether various events on the CAN controller will result in an interrupt or not. Bits 10:0 in this register correspond 1-to-1 with bits 10:0 in the CANxICR register. If a bit in the CANxIER register is 0 the corresponding interrupt is disabled; if a bit in the CANxIER register is 1 the corresponding source is enabled to trigger an interrupt.
Table 322. CAN Interrupt Enable Register (CAN1IER - address 0x4004 4010, CAN2IER - address 0x4004 8010) bit description Bit Symbol Function Reset RM Value Set
0 1
RIE TIE1
Receiver Interrupt Enable. When the Receive Buffer Status is 'full', the CAN Controller requests the respective interrupt. Transmit Interrupt Enable for Buffer1. When a message has been successfully transmitted out of TXB1 or Transmit Buffer 1 is accessible again (e.g. after an Abort Transmission command), the CAN Controller requests the respective interrupt. Error Warning Interrupt Enable. If the Error or Bus Status change (see Status Register), the CAN Controller requests the respective interrupt.
0 0
X X
2
EIE
0
X
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Table 322. CAN Interrupt Enable Register (CAN1IER - address 0x4004 4010, CAN2IER - address 0x4004 8010) bit description Bit Symbol Function Reset RM Value Set
3 4 5 6 7 8 9
DOIE WUIE EPIE ALIE BEIE IDIE TIE2
Data Overrun Interrupt Enable. If the Data Overrun Status bit is set (see Status Register), the 0 CAN Controller requests the respective interrupt. Wake-Up Interrupt Enable. If the sleeping CAN controller wakes up, the respective interrupt is requested. Error Passive Interrupt Enable. If the error status of the CAN Controller changes from error active to error passive or vice versa, the respective interrupt is requested. Arbitration Lost Interrupt Enable. If the CAN Controller has lost arbitration, the respective interrupt is requested. 0 0 0
X X X X X X X
Bus Error Interrupt Enable. If a bus error has been detected, the CAN Controller requests the 0 respective interrupt. ID Ready Interrupt Enable. When a CAN identifier has been received, the CAN Controller requests the respective interrupt. Transmit Interrupt Enable for Buffer2. When a message has been successfully transmitted out of TXB2 or Transmit Buffer 2 is accessible again (e.g. after an Abort Transmission command), the CAN Controller requests the respective interrupt. Transmit Interrupt Enable for Buffer3. When a message has been successfully transmitted out of TXB3 or Transmit Buffer 3 is accessible again (e.g. after an Abort Transmission command), the CAN Controller requests the respective interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 0
10
TIE3
0
X
31:11 -
NA
7.6 CAN Bus Timing Register (CAN1BTR - 0x4004 4014, CAN2BTR 0x4004 8014)
This register controls how various CAN timings are derived from the APB clock. It defines the values of the Baud Rate Prescaler (BRP) and the Synchronization Jump Width (SJW). Furthermore, it defines the length of the bit period, the location of the sample point and the number of samples to be taken at each sample point. It can be read at any time but can only be written if the RM bit in CANmod is 1.
Table 323. CAN Bus Timing Register (CAN1BTR - address 0x4004 4014, CAN2BTR - address 0x4004 8014) bit description Bit Symbol Value Function Reset RM Value Set
9:0
BRP
Baud Rate Prescaler. The APB clock is divided by (this value plus one) to produce the 0 CAN clock. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. The Synchronization Jump Width is (this value plus one) CAN clocks. The delay from the nominal Sync point to the sample point is (this value plus one) CAN clocks. 0 1100
X
13:10 15:14 SJW 19:16 TESG1 22:20 TESG2
X X X
The delay from the sample point to the next nominal sync point is (this value plus one) 001 CAN clocks. The nominal CAN bit time is (this value plus the value in TSEG1 plus 3) CAN clocks.
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Table 323. CAN Bus Timing Register (CAN1BTR - address 0x4004 4014, CAN2BTR - address 0x4004 8014) bit description Bit Symbol Value Function Reset RM Value Set
23
SAM 0 1
Sampling The bus is sampled once (recommended for high speed buses) The bus is sampled 3 times (recommended for low to medium speed buses to filter spikes on the bus-line) Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. 0 X
31:24 -
Baud rate prescaler The period of the CAN system clock tSCL is programmable and determines the individual bit timing. The CAN system clock tSCL is calculated using the following equation: (5) t SCL = t CANsuppliedCLK x ( BRP + 1 ) Synchronization jump width To compensate for phase shifts between clock oscillators of different bus controllers, any bus controller must re-synchronize on any relevant signal edge of the current transmission. The synchronization jump width tSJW defines the maximum number of clock cycles a certain bit period may be shortened or lengthened by one re-synchronization: (6) t SJW = t SCL x ( SJW + 1 ) Time segment 1 and time segment 2 Time segments TSEG1 and TSEG2 determine the number of clock cycles per bit period and the location of the sample point: (7) t SYNCSEG = t SCL (8) t TSEG1 = t SCL x ( TSEG1 + 1 ) (9) t TSEG2 = t SCL x ( TSEG2 + 1 )
7.7 CAN Error Warning Limit register (CAN1EWL - 0x4004 4018, CAN2EWL - 0x4004 8018)
This register sets a limit on Tx or Rx errors at which an interrupt can occur. It can be read at any time but can only be written if the RM bit in CANmod is 1.
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Table 324. CAN Error Warning Limit register (CAN1EWL - address 0x4004 4018, CAN2EWL - address 0x4004 8018) bit description Bit Symbol Function Reset Value RM Set
7:0 31:8
EWL -
During CAN operation, this value is compared to both the Tx and Rx Error Counters. If either of these counter matches this value, the Error Status (ES) bit in CANSR is set. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
9610 = 0x60 X NA
Note that a content change of the Error Warning Limit Register is possible only if the Reset Mode was entered previously. An Error Status change (Status Register) and an Error Warning Interrupt forced by the new register content will not occur until the Reset Mode is cancelled again.
7.8 CAN Status Register (CAN1SR - 0x4004 401C, CAN2SR 0x4004 801C)
This read-only register contains three status bytes in which the bits not related to transmission are identical to the corresponding bits in the Global Status Register, while those relating to transmission reflect the status of each of the 3 Tx Buffers.
Table 325. CAN Status Register (CAN1SR - address 0x4004 401C, CAN2SR - address 0x4004 801C) bit description Bit Symbol Value Function Reset RM Value Set
0 1 2
RBS DOS TBS1[1] 0(locked)
Receive Buffer Status. This bit is identical to the RBS bit in the CANxGSR. Data Overrun Status. This bit is identical to the DOS bit in the CANxGSR. Transmit Buffer Status 1. Software cannot access the Tx Buffer 1 nor write to the corresponding CANxTFI, CANxTID, CANxTDA, and CANxTDB registers because a message is either waiting for transmission or is in transmitting process. Software may write a message into the Transmit Buffer 1 and its CANxTFI, CANxTID, CANxTDA, and CANxTDB registers. Transmission Complete Status. 0(incomplete) 1(complete) The previously requested transmission for Tx Buffer 1 is not complete. The previously requested transmission for Tx Buffer 1 has been successfully completed. Receive Status. This bit is identical to the RS bit in the GSR. Transmit Status 1. 0(idle) 1(transmit) There is no transmission from Tx Buffer 1. The CAN Controller is transmitting a message from Tx Buffer 1. Error Status. This bit is identical to the ES bit in the CANxGSR. Bus Status. This bit is identical to the BS bit in the CANxGSR. Receive Buffer Status. This bit is identical to the RBS bit in the CANxGSR. Data Overrun Status. This bit is identical to the DOS bit in the CANxGSR.
0 0 1
0 0 1
1(released) 3 TCS1[2]
1
x
4 5
RS TS1
1 1
0 0
6 7 8 9
ES BS RBS DOS
0 0 0 0
0 0 0 0
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Table 325. CAN Status Register (CAN1SR - address 0x4004 401C, CAN2SR - address 0x4004 801C) bit description Bit Symbol Value Function Reset RM Value Set
10
TBS2[1] 0(locked)
Transmit Buffer Status 2. Software cannot access the Tx Buffer 2 nor write to the corresponding CANxTFI, CANxTID, CANxTDA, and CANxTDB registers because a message is either waiting for transmission or is in transmitting process. Software may write a message into the Transmit Buffer 2 and its CANxTFI, CANxTID, CANxTDA, and CANxTDB registers. Transmission Complete Status. 0(incomplete) 1(complete) The previously requested transmission for Tx Buffer 2 is not complete. The previously requested transmission for Tx Buffer 2 has been successfully completed. Receive Status. This bit is identical to the RS bit in the GSR. Transmit Status 2. 0(idle) 1(transmit) There is no transmission from Tx Buffer 2. The CAN Controller is transmitting a message from Tx Buffer 2. Error Status. This bit is identical to the ES bit in the CANxGSR. Bus Status. This bit is identical to the BS bit in the CANxGSR. Receive Buffer Status. This bit is identical to the RBS bit in the CANxGSR. Data Overrun Status. This bit is identical to the DOS bit in the CANxGSR. Transmit Buffer Status 3. 0(locked) Software cannot access the Tx Buffer 3 nor write to the corresponding CANxTFI, CANxTID, CANxTDA, and CANxTDB registers because a message is either waiting for transmission or is in transmitting process. Software may write a message into the Transmit Buffer 3 and its CANxTFI, CANxTID, CANxTDA, and CANxTDB registers. Transmission Complete Status. 0(incomplete) 1(complete) The previously requested transmission for Tx Buffer 3 is not complete. The previously requested transmission for Tx Buffer 3 has been successfully completed. Receive Status. This bit is identical to the RS bit in the GSR. Transmit Status 3. 0(idle) 1(transmit) There is no transmission from Tx Buffer 3. The CAN Controller is transmitting a message from Tx Buffer 3. Error Status. This bit is identical to the ES bit in the CANxGSR. Bus Status. This bit is identical to the BS bit in the CANxGSR. Reserved, the value read from a reserved bit is not defined.
1
1
1(released) 11 TCS2[2]
1
x
12 13
RS TS2
1 1
0 0
14 15 16 17 18
ES BS RBS DOS TBS3[1]
0 0 0 0 1
0 0 0 0 1
1(released) 19 TCS3[2]
1
x
20 21
RS TS3
1 1
0 0
22 23
ES BS
0 0 NA
0 0
31:24 [1] [2]
If the CPU tries to write to this Transmit Buffer when the Transmit Buffer Status bit is '0' (locked), the written byte is not accepted and is lost without this being signalled. The Transmission Complete Status bit is set '0' (incomplete) whenever the Transmission Request bit or the Self Reception Request bit is set '1' for this TX buffer. The Transmission Complete Status bit remains '0' until a message is transmitted successfully.
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7.9 CAN Receive Frame Status register (CAN1RFS - 0x4004 4020, CAN2RFS - 0x4004 8020)
This register defines the characteristics of the current received message. It is read-only in normal operation but can be written for testing purposes if the RM bit in CANxMOD is 1.
Table 326. CAN Receive Frame Status register (CAN1RFS - address 0x4004 4020, CAN2RFS - address 0x4004 8020) bit description Bit Symbol Function Reset RM Value Set
9:0
ID Index
If the BP bit (below) is 0, this value is the zero-based number of the Lookup Table RAM entry 0 at which the Acceptance Filter matched the received Identifier. Disabled entries in the Standard tables are included in this numbering, but will not be matched. See Section 16-17 "Examples of acceptance filter tables and ID index values" on page 391 for examples of ID Index values. If this bit is 1, the current message was received in AF Bypass mode, and the ID Index field (above) is meaningless. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 NA
X
10
BP
X
15:11 19:16 DLC
The field contains the Data Length Code (DLC) field of the current received message. When 0 RTR = 0, this is related to the number of data bytes available in the CANRDA and CANRDB registers as follows: 0000-0111 = 0 to 7 bytes1000-1111 = 8 bytes With RTR = 1, this value indicates the number of data bytes requested to be sent back, with the same encoding.
X
29:20 30 RTR
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. This bit contains the Remote Transmission Request bit of the current received message. 0 indicates a Data Frame, in which (if DLC is non-zero) data can be read from the CANRDA and possibly the CANRDB registers. 1 indicates a Remote frame, in which case the DLC value identifies the number of data bytes requested to be sent using the same Identifier.
NA 0 X
31
FF
A 0 in this bit indicates that the current received message included an 11-bit Identifier, while 0 a 1 indicates a 29-bit Identifier. This affects the contents of the CANid register described below.
X
7.9.1 ID index field
The ID Index is a 10-bit field in the Info Register that contains the table position of the ID Look-up Table if the currently received message was accepted. The software can use this index to simplify message transfers from the Receive Buffer into the Shared Message Memory. Whenever bit 10 (BP) of the ID Index in the CANRFS register is 1, the current CAN message was received in acceptance filter bypass mode.
7.10 CAN Receive Identifier register (CAN1RID - 0x4004 4024, CAN2RID 0x4004 8024)
This register contains the Identifier field of the current received message. It is read-only in normal operation but can be written for testing purposes if the RM bit in CANmod is 1. It has two different formats depending on the FF bit in CANRFS. See Table 16-314 for details on specific CAN channel register address.
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Table 327. CAN Receive Identifier register (CAN1RID - address 0x4004 4024, CAN2RID - address 0x4004 8024) bit description Bit Symbol Function Reset Value RM Set
10:0
ID
The 11-bit Identifier field of the current received message. In CAN 2.0A, these bits are called ID10-0, while in CAN 2.0B they're called ID29-18. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
X
31:11 -
Table 328. RX Identifier register when FF = 1 Bit Symbol Function Reset Value RM Set
28:0
ID
The 29-bit Identifier field of the current received message. In CAN 2.0B these bits 0 are called ID29-0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
X
31:29 -
7.11 CAN Receive Data register A (CAN1RDA - 0x4004 4028, CAN2RDA 0x4004 8028)
This register contains the first 1-4 Data bytes of the current received message. It is read-only in normal operation, but can be written for testing purposes if the RM bit in CANMOD is 1. See Table 16-314 for details on specific CAN channel register address.
Table 329. CAN Receive Data register A (CAN1RDA - address 0x4004 4028, CAN2RDA - address 0x4004 8028) bit description Bit Symbol Function Reset Value RM Set
7:0 15:8
Data 1 Data 2
If the DLC field in CANRFS 0001, this contains the first Data byte of the current 0 received message. If the DLC field in CANRFS 0010, this contains the first Data byte of the current 0 received message. If the DLC field in CANRFS 0011, this contains the first Data byte of the current 0 received message. If the DLC field in CANRFS 0100, this contains the first Data byte of the current 0 received message.
X X X X
23:16 Data 3 31:24 Data 4
7.12 CAN Receive Data register B (CAN1RDB - 0x4004 402C, CAN2RDB 0x4004 802C)
This register contains the 5th through 8th Data bytes of the current received message. It is read-only in normal operation, but can be written for testing purposes if the RM bit in CANMOD is 1. See Table 16-314 for details on specific CAN channel register address.
Table 330. CAN Receive Data register B (CAN1RDB - address 0x4004 402C, CAN2RDB - address 0x4004 802C) bit description Bit Symbol Function Reset Value RM Set
7:0
Data 5
If the DLC field in CANRFS 0101, this contains the first Data byte of the current 0 received message.
X
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Table 330. CAN Receive Data register B (CAN1RDB - address 0x4004 402C, CAN2RDB - address 0x4004 802C) bit description Bit Symbol Function Reset Value RM Set
15:8
Data 6
If the DLC field in CANRFS 0110, this contains the first Data byte of the current 0 received message. If the DLC field in CANRFS 0111, this contains the first Data byte of the current 0 received message. If the DLC field in CANRFS 1000, this contains the first Data byte of the current 0 received message.
X X X
23:16 Data 7 31:24 Data 8
7.13 CAN Transmit Frame Information register (CAN1TFI[1/2/3] 0x4004 40[30/ 40/50], CAN2TFI[1/2/3] - 0x4004 80[30/40/50])
When the corresponding TBS bit in CANSR is 1, software can write to one of these registers to define the format of the next transmit message for that Tx buffer. Bits not listed read as 0 and should be written as 0. The values for the reserved bits of the CANxTFI register in the Transmit Buffer should be set to the values expected in the Receive Buffer for an easy comparison, when using the Self Reception facility (self test), otherwise they are not defined. The CAN Controller consist of three Transmit Buffers. Each of them has a length of 4 words and is able to store one complete CAN message as shown in Figure 16-53. The buffer layout is subdivided into Descriptor and Data Field where the first word of the Descriptor Field includes the TX Frame Info that describes the Frame Format, the Data Length and whether it is a Remote or Data Frame. In addition, a TX Priority register allows the definition of a certain priority for each transmit message. Depending on the chosen Frame Format, an 11-bit identifier for Standard Frame Format (SFF) or an 29-bit identifier for Extended Frame Format (EFF) follows. Note that unused bits in the TID field have to be defined as 0. The Data Field in TDA and TDB contains up to eight data bytes.
Table 331. CAN Transmit Frame Information register (CAN1TFI[1/2/3] - address 0x4004 40[30/40/50], CAN2TFI[1/2/3] 0x4004 80[30/40/50]) bit description Bit Symbol Function Reset RM Value Set
7:0
PRIO
If the TPM (Transmit Priority Mode) bit in the CANxMOD register is set to 1, enabled Tx Buffers contend for the right to send their messages based on this field. The buffer with the lowest TX Priority value wins the prioritization and is sent first. Reserved. Data Length Code. This value is sent in the DLC field of the next transmit message. In addition, if RTR = 0, this value controls the number of Data bytes sent in the next transmit message, from the CANxTDA and CANxTDB registers: 0000-0111 = 0-7 bytes 1xxx = 8 bytes 0 0
x
15:8
-
19:16 DLC
X
29:20 30 RTR
Reserved. This value is sent in the RTR bit of the next transmit message. If this bit is 0, the number of data bytes called out by the DLC field are sent from the CANxTDA and CANxTDB registers. If this bit is 1, a Remote Frame is sent, containing a request for that number of bytes.
0 0 X
31
FF
If this bit is 0, the next transmit message will be sent with an 11-bit Identifier (standard frame 0 format), while if it's 1, the message will be sent with a 29-bit Identifier (extended frame format).
X
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Automatic transmit priority detection To allow uninterrupted streams of transmit messages, the CAN Controller provides Automatic Transmit Priority Detection for all Transmit Buffers. Depending on the selected Transmit Priority Mode, internal prioritization is based on the CAN Identifier or a user defined "local priority". If more than one message is enabled for transmission (TR=1) the internal transmit message queue is organized such as that the transmit buffer with the lowest CAN Identifier (TID) or the lowest "local priority" (TX Priority) wins the prioritization and is sent first. The result of the internal scheduling process is taken into account short before a new CAN message is sent on the bus. This is also true after the occurrence of a transmission error and right before a re-transmission. Tx DLC The number of bytes in the Data Field of a message is coded with the Data Length Code (DLC). At the start of a Remote Frame transmission the DLC is not considered due to the RTR bit being '1 ' (remote). This forces the number of transmitted/received data bytes to be 0. Nevertheless, the DLC must be specified correctly to avoid bus errors, if two CAN Controllers start a Remote Frame transmission with the same identifier simultaneously. For reasons of compatibility no DLC > 8 should be used. If a value greater than 8 is selected, 8 bytes are transmitted in the data frame with the Data Length Code specified in DLC. The range of the Data Byte Count is 0 to 8 bytes and is coded as follows: (10) DataByteCount = DLC
7.14 CAN Transmit Identifier register (CAN1TID[1/2/3] 0x4004 40[34/44/54], CAN2TID[1/2/3] - 0x4004 80[34/44/54])
When the corresponding TBS bit in CANxSR is 1, software can write to one of these registers to define the Identifier field of the next transmit message. Bits not listed read as 0 and should be written as 0. The register assumes two different formats depending on the FF bit in CANTFI. In Standard Frame Format messages, the CAN Identifier consists of 11 bits (ID.28 to ID.18), and in Extended Frame Format messages, the CAN identifier consists of 29 bits (ID.28 to ID.0). ID.28 is the most significant bit, and it is transmitted first on the bus during the arbitration process. The Identifier acts as the message's name, used in a receiver for acceptance filtering, and also determines the bus access priority during the arbitration process.
Table 332. CAN Transfer Identifier register (CAN1TID[1/2/3] - address 0x4004 40[34/44/54], CAN2TID[1/2/3] - address 0x4004 80[34/44/54]) bit description Bit Symbol Function Reset Value RM Set
10:0
ID
The 11-bit Identifier to be sent in the next transmit message. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
X
31:11 -
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Table 333. Transfer Identifier register when FF = 1 Bit Symbol Function Reset Value RM Set
28:0
ID
The 29-bit Identifier to be sent in the next transmit message. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
X
31:29 -
7.15 CAN Transmit Data register A (CAN1TDA[1/2/3] - 0x4004 40[38/48/58], CAN2TDA[1/2/3] - 0x4004 80[38/48/58])
When the corresponding TBS bit in CANSR is 1, software can write to one of these registers to define the first 1 - 4 data bytes of the next transmit message. The Data Length Code defines the number of transferred data bytes. The first bit transmitted is the most significant bit of TX Data Byte 1.
Table 334. CAN Transmit Data register A (CAN1TDA[1/2/3] - address 0x4004 40[38/48/58], CAN2TDA[1/2/3] - address 0x4004 80[38/48/58]) bit description Bit Symbol Function Reset Value RM Set
7:0 15;8
Data 1 Data 2
If RTR = 0 and DLC 0001 in the corresponding CANxTFI, this byte is sent as the first Data byte of the next transmit message. If RTR = 0 and DLC 0010 in the corresponding CANxTFI, this byte is sent as the 2nd Data byte of the next transmit message. If RTR = 0 and DLC 0011 in the corresponding CANxTFI, this byte is sent as the 3rd Data byte of the next transmit message. If RTR = 0 and DLC 0100 in the corresponding CANxTFI, this byte is sent as the 4th Data byte of the next transmit message.
0 0 0 0
X X X X
23:16 Data 3 31:24 Data 4
7.16 CAN Transmit Data register B (CAN1TDB[1/2/3] - 0x4004 40[3C/4C/5C], CAN2TDB[1/2/3] - 0x4004 80[3C/4C/5C])
When the corresponding TBS bit in CANSR is 1, software can write to one of these registers to define the 5th through 8th data bytes of the next transmit message. The Data Length Code defines the number of transferred data bytes. The first bit transmitted is the most significant bit of TX Data Byte 1.
Table 335. CAN Transmit Data register B (CAN1TDB[1/2/3] - address 0x4004 40[3C/4C/5C], CAN2TDB[1/2/3] - address 0x4004 80[3C/4C/5C]) bit description Bit Symbol Function Reset Value RM Set
7:0 15;8
Data 5 Data 6
If RTR = 0 and DLC 0101 in the corresponding CANTFI, this byte is sent as the 0 5th Data byte of the next transmit message. If RTR = 0 and DLC 0110 in the corresponding CANTFI, this byte is sent as the 0 6th Data byte of the next transmit message. If RTR = 0 and DLC 0111 in the corresponding CANTFI, this byte is sent as the 0 7th Data byte of the next transmit message. If RTR = 0 and DLC 1000 in the corresponding CANTFI, this byte is sent as the 0 8th Data byte of the next transmit message.
X X X X
23:16 Data 7 31:24 Data 8
7.17 CAN Sleep Clear register (CANSLEEPCLR - 0x400F C110)
This register provides the current sleep state of the two CAN channels and provides a means to restore the clocks to that channel following wake-up. Refer to Section 16-8.2 "Sleep mode" for more information on the CAN sleep feature.
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Table 336. CAN Sleep Clear register (CANSLEEPCLR - address 0x400F C110) bit description Bit Symbol Function Reset Value
0 1
CAN1SLEEP
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. Sleep status and control for CAN channel 1. Read: when 1, indicates that CAN channel 1 is in the sleep mode. Write: writing a 1 causes clocks to be restored to CAN channel 1. 0
2
CAN2SLEEP
Sleep status and control for CAN channel 2. Read: when 1, indicates that CAN channel 2 is in the sleep mode. Write: writing a 1 causes clocks to be restored to CAN channel 2.
0
31:3
-
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
7.18 CAN Wake-up Flags register (CANWAKEFLAGS - 0x400F C114)
This register provides the wake-up status for the two CAN channels and allows clearing wake-up events. Refer to Section 16-8.2 "Sleep mode" for more information on the CAN sleep feature.
Table 337. CAN Wake-up Flags register (CANWAKEFLAGS - address 0x400F C114) bit description Bit Symbol Function Reset Value
0 1
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
CAN1WAKE
Wake-up status for CAN channel 1.
Read: when 1, indicates that a falling edge has occurred on the receive data line of CAN channel 1. Write: writing a 1 clears this bit.
0
2
CAN2WAKE
Wake-up status for CAN channel 2.
Read: when 1, indicates that a falling edge has occurred on the receive data line of CAN channel 2. Write: writing a 1 clears this bit.
0
31:3
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
8. CAN controller operation
8.1 Error handling
The CAN Controllers count and handle transmit and receive errors as specified in CAN Spec 2.0B. The Transmit and Receive Error Counters are incriminated for each detected error and are decremented when operation is error-free. If the Transmit Error counter contains 255 and another error occurs, the CAN Controller is forced into a state called Bus-Off. In this state, the following register bits are set: BS in CANxSR, BEI and EI in CANxIR if these are enabled, and RM in CANxMOD. RM resets and disables much of the CAN Controller. Also at this time the Transmit Error Counter is set to 127 and the Receive Error Counter is cleared. Software must next clear the RM bit. Thereafter the Transmit Error Counter will count down 128 occurrences of the Bus Free condition (11 consecutive
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recessive bits). Software can monitor this countdown by reading the Tx Error Counter. When this countdown is complete, the CAN Controller clears BS and ES in CANxSR, and sets EI in CANxSR if EIE in IER is 1. The Tx and Rx error counters can be written if RM in CANxMOD is 1. Writing 255 to the Tx Error Counter forces the CAN Controller to Bus-Off state. If Bus-Off (BS in CANxSR) is 1, writing any value 0 through 254 to the Tx Error Counter clears Bus-Off. When software clears RM in CANxMOD thereafter, only one Bus Free condition (11 consecutive recessive bits) is needed before operation resumes.
8.2 Sleep mode
The CAN Controller will enter sleep mode if the SM bit in the CAN Mode register is 1, no CAN interrupt is pending, and there is no activity on the CAN bus. Software can only set SM when RM in the CAN Mode register is 0; it can also set the WUIE bit in the CAN Interrupt Enable register to enable an interrupt on any wake-up condition. The CAN Controller wakes up (and sets WUI in the CAN Interrupt register if WUIE in the CAN Interrupt Enable register is 1) in response to a) a dominant bit on the CAN bus, or b) software clearing SM in the CAN Mode register. A sleeping CAN Controller that wakes up in response to bus activity is not able to receive an initial message until after it detects Bus_Free (11 consecutive recessive bits). If an interrupt is pending or the CAN bus is active when software sets SM, the wake-up is immediate. Upon wake-up, software needs to do the following things: 1. Write a 1 to the relevant bit(s) in the CANSLEEPCLR register. 2. Write a 0 to the SM bit in the CAN1MOD and/or CAN2MOD register. 3. Write a 1 to the relevant bit(s) in the CANWAKEFLAGS register. Failure to perform this step will prevent subsequent entry into Power-down mode. If the LPC17xx is in Deep Sleep or Power-down mode, CAN activity will wake up the device if the CAN activity interrupt is enabled. See Section 4-8 "Power control".
8.3 Interrupts
Each CAN Controller produces 3 interrupt requests, Receive, Transmit, and "other status". The Transmit interrupt is the OR of the Transmit interrupts from the three Tx Buffers. Each Receive and Transmit interrupt request from each controller is assigned its own channel in the NVIC, and can have its own interrupt service routine. The "other status" interrupts from all of the CAN controllers, and the Acceptance Filter LUTerr condition, are ORed into one NVIC channel.
8.4 Transmit priority
If the TPM bit in the CANxMOD register is 0, multiple enabled Tx Buffers contend for the right to send their messages based on the value of their CAN Identifier (TID). If TPM is 1, they contend based on the PRIO fields in bits 7:0 of their CANxTFS registers. In both cases the smallest binary value has priority. If two (or three) transmit-enabled buffers have the same smallest value, the lowest-numbered buffer sends first. The CAN controller selects among multiple enabled Tx Buffers dynamically, just before it sends each message.
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9. Centralized CAN registers
For easy and fast access, all CAN Controller Status bits from each CAN Controller Status register are bundled together. Each defined byte of the following registers contains one particular status bit from each of the CAN controllers, in its LS bits. All Status registers are read-only and allow byte, half word and word access.
9.1 Central Transmit Status Register (CANTxSR - 0x4004 0000)
Table 338. Central Transit Status Register (CANTxSR - address 0x4004 0000) bit description Bit Symbol Description Reset Value
0 1 7:2 8 9
TS1 TS2 TBS1 TBS2
When 1, the CAN controller 1 is sending a message (same as TS in the CAN1GSR). When 1, the CAN controller 2 is sending a message (same as TS in the CAN2GSR) Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 1, all 3 Tx Buffers of the CAN1 controller are available to the CPU (same as TBS in CAN1GSR). When 1, all 3 Tx Buffers of the CAN2 controller are available to the CPU (same as TBS in CAN2GSR). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 1, all requested transmissions have been completed successfully by the CAN1 controller (same as TCS in CAN1GSR). When 1, all requested transmissions have been completed successfully by the CAN2 controller (same as TCS in CAN2GSR). Reserved, the value read from a reserved bit is not defined.
0 0 NA 1 1 NA 1 1 NA
15:10 16 TCS1
17:16 TCS2 31:18 -
9.2 Central Receive Status Register (CANRxSR - 0x4004 0004)
Table 339. Central Receive Status Register (CANRxSR - address 0x4004 0004) bit description Bit Symbol Description Reset Value
0 1 7:2 8 9
RS1 RS2 RB1 RB2
When 1, CAN1 is receiving a message (same as RS in CAN1GSR). When 1, CAN2 is receiving a message (same as RS in CAN2GSR). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 1, a received message is available in the CAN1 controller (same as RBS in CAN1GSR). When 1, a received message is available in the CAN2 controller (same as RBS in CAN2GSR). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 1, a message was lost because the preceding message to CAN1 controller was not read out quickly enough (same as DOS in CAN1GSR). When 1, a message was lost because the preceding message to CAN2 controller was not read out quickly enough (same as DOS in CAN2GSR). Reserved, the value read from a reserved bit is not defined.
0 0 NA 0 0 NA 0 0 NA
15:10 16 DOS1
17:16 DOS2 31:18 -
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9.3 Central Miscellaneous Status Register (CANMSR - 0x4004 0008)
Table 340. Central Miscellaneous Status Register (CANMSR - address 0x4004 0008) bit description Bit Symbol Description Reset Value
0 1 7:2 8 9
E1 E2 BS1 BS2
When 1, one or both of the CAN1 Tx and Rx Error Counters has reached the limit set in the 0 CAN1EWL register (same as ES in CAN1GSR) When 1, one or both of the CAN2 Tx and Rx Error Counters has reached the limit set in the 0 CAN2EWL register (same as ES in CAN2GSR) Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 1, the CAN1 controller is currently involved in bus activities (same as BS in CAN1GSR). When 1, the CAN2 controller is currently involved in bus activities (same as BS in CAN2GSR). Reserved, the value read from a reserved bit is not defined. NA 0 0 NA
31:10 -
10. Global acceptance filter
This block provides lookup for received Identifiers (called Acceptance Filtering in CAN terminology) for all the CAN Controllers. It includes a 512 x 32 (2 kB) RAM in which software maintains one to five tables of Identifiers. This RAM can contain up to 1024 Standard Identifiers or 512 Extended Identifiers, or a mixture of both types.
11. Acceptance filter modes
The Acceptance Filter can be put into different modes by setting the according AccOff, AccBP, and eFCAN bits in the Acceptance Filter Mode Register (Section 16-14.1 "Acceptance Filter Mode Register (AFMR - 0x4003 C000)"). During each mode the access to the Configuration Register and the ID Look-up table is handled differently.
Table 341. Acceptance filter modes and access control Acceptance Bit Bit Acceptance filter mode AccOff AccBP filter state ID Look-up table RAM[1] Acceptanc e filter config. registers CAN controller message receive interrupt
Off Mode Bypass Mode Operating Mode and FullCAN Mode
[1] [2]
1 X 0
0 1 0
reset & halted reset & halted running
r/w access from CPU r/w access from CPU read-only from CPU[2]
r/w access from CPU r/w access from CPU
no messages accepted all messages accepted
access from hardware Acceptance acceptance filtering filter only
The whole ID Look-up Table RAM is only word accessible. During the Operating Mode of the Acceptance Filter the Look-up Table can be accessed only to disable or enable Messages.
A write access to all section configuration registers is only possible during the Acceptance Filter Off and Bypass Mode. Read access is allowed in all Acceptance Filter Modes.
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11.1 Acceptance filter Off mode
The Acceptance Filter Off Mode is typically used during initialization. During this mode an unconditional access to all registers and to the Look-up Table RAM is possible. With the Acceptance Filter Off Mode, CAN messages are not accepted and therefore not stored in the Receive Buffers of active CAN Controllers.
11.2 Acceptance filter Bypass mode
The Acceptance Filter Bypass Mode can be used for example to change the acceptance filter configuration during a running system, e.g. change of identifiers in the ID-Look-up Table memory. During this re-configuration, software acceptance filtering has to be used. It is recommended to use the ID ready Interrupt (ID Index) and the Receive Interrupt (RI). In this mode all CAN message are accepted and stored in the Receive Buffers of active CAN Controllers.
11.3 Acceptance filter Operating mode
The Acceptance Filter is in Operating Mode when neither the AccOff nor the AccBP in the Configuration Register is set and the eFCAN = 0.
11.4 FullCAN mode
The Acceptance Filter is in Operating Mode when neither the AccOff nor the AccBP in the Configuration Register is set and the eFCAN = 1. More details on FullCAN mode are available in Section 16-16 "FullCAN mode".
12. Sections of the ID look-up table RAM
Four 12-bit section configuration registers (SFF_sa, SFF_GRP_sa, EFF_sa, EFF_GRP_sa) are used to define the boundaries of the different identifier sections in the ID-Look-up Table Memory. The fifth 12-bit section configuration register, the End of Table address register (ENDofTable) is used to define the end of all identifier sections. The End of Table address is also used to assign the start address of the section where FullCAN Message Objects, if enabled are stored.
Table 342. Section configuration register settings ID-Look up Table Section Register Value Section status
FullCAN (Standard Frame Format) Identifier Section Explicit Standard Frame Format Identifier Section Group of Standard Frame Format Identifier Section Explicit Extended Frame Format Identifier Section Group of Extended Frame Format Identifier Section
SFF_sa
= 0x000 > 0x000
disabled enabled disabled enabled
SFF_GRP_sa = SFF_sa > SFF_sa EFF_sa
= SFF_GRP_sa disabled > SFF_GRP_sa enabled disabled enabled
EFF_GRP_sa = EFF_sa > EFF_sa ENDofTable
= EFF_GRP_sa disabled > EFF_GRP_sa enabled
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13. ID look-up table RAM
The Whole ID Look-up Table RAM is only word accessible. A write access is only possible during the Acceptance Filter Off or Bypass Mode. Read access is allowed in all Acceptance Filter Modes. If Standard (11-bit) Identifiers are used in the application, at least one of 3 tables in Acceptance Filter RAM must not be empty. If the optional "FullCAN mode" is enabled, the first table contains Standard identifiers for which reception is to be handled in this mode. The next table contains individual Standard Identifiers and the third contains ranges of Standard Identifiers, for which messages are to be received via the CAN Controllers. The tables of FullCAN and individual Standard Identifiers must be arranged in ascending numerical order, one per halfword, two per word. Since each CAN bus has its own address map, each entry also contains the number of the CAN Controller (001-010) to which it applies.
31 15
29 13
26 10
16 0
CONTROLLER #
DIS NOT ABLE USED
IDENTIFIER
Fig 57. Entry in FullCAN and individual standard identifier tables
The table of Standard Identifier Ranges contains paired upper and lower (inclusive) bounds, one pair per word. These must also be arranged in ascending numerical order.
31
29 NOT US ED DISABLE
26 LOWER IDENTIFIER BOUND
16 CONTROLLER # DISABLE NOT US ED
10 UPPER IDENTIFIER BOUND
0
CONTROLLER #
Fig 58. Entry in standard identifier range table
The disable bits in Standard entries provide a means to turn response, to particular CAN Identifiers or ranges of Identifiers, on and off dynamically. When the Acceptance Filter function is enabled, only the disable bits in Acceptance Filter RAM can be changed by software. Response to a range of Standard addresses can be enabled by writing 32 zero bits to its word in RAM, and turned off by writing 32 one bits (0xFFFF FFFF) to its word in RAM. Only the disable bits are actually changed. Disabled entries must maintain the ascending sequence of Identifiers. If Extended (29-bit) Identifiers are used in the application, at least one of the other two tables in Acceptance Filter RAM must not be empty, one for individual Extended Identifiers and one for ranges of Extended Identifiers. The table of individual Extended Identifiers must be arranged in ascending numerical order.
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31
29 28
0
CONTROLLER #
IDENTIFIER
Fig 59. Entry in either extended identifier table
The table of ranges of Extended Identifiers must contain an even number of entries, of the same form as in the individual Extended Identifier table. Like the Individual Extended table, the Extended Range must be arranged in ascending numerical order. The first and second (3rd and 4th ...) entries in the table are implicitly paired as an inclusive range of Extended addresses, such that any received address that falls in the inclusive range is received (accepted). Software must maintain the table to consist of such word pairs. There is no facility to receive messages to Extended identifiers using the FullCAN method. Five address registers point to the boundaries between the tables in Acceptance Filter RAM: FullCAN Standard addresses, Standard Individual addresses, Standard address ranges, Extended Individual addresses, and Extended address ranges. These tables must be consecutive in memory. The start of each of the latter four tables is implicitly the end of the preceding table. The end of the Extended range table is given in an End of Tables register. If the start address of a table equals the start of the next table or the End Of Tables register, that table is empty. When the Receive side of a CAN controller has received a complete Identifier, it signals the Acceptance Filter of this fact. The Acceptance Filter responds to this signal, and reads the Controller number, the size of the Identifier, and the Identifier itself from the Controller. It then proceeds to search its RAM to determine whether the message should be received or ignored. If FullCAN mode is enabled and the CAN controller signals that the current message contains a Standard identifier, the Acceptance Filter first searches the table of identifiers for which reception is to be done in FullCAN mode. Otherwise, or if the AF doesn't find a match in the FullCAN table, it searches its individual Identifier table for the size of Identifier signalled by the CAN controller. If it finds an equal match, the AF signals the CAN controller to retain the message, and provides it with an ID Index value to store in its Receive Frame Status register. If the Acceptance Filter does not find a match in the appropriate individual Identifier table, it then searches the Identifier Range table for the size of Identifier signalled by the CAN controller. If the AF finds a match to a range in the table, it similarly signals the CAN controller to retain the message, and provides it with an ID Index value to store in its Receive Frame Status register. If the Acceptance Filter does not find a match in either the individual or Range table for the size of Identifier received, it signals the CAN controller to discard/ignore the received message.
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14. Acceptance filter registers
14.1 Acceptance Filter Mode Register (AFMR - 0x4003 C000)
The AccBP and AccOff bits of the acceptance filter mode register are used for putting the acceptance filter into the Bypass and Off mode. The eFCAN bit of the mode register can be used to activate a FullCAN mode enhancement for received 11-bit CAN ID messages.
Table 343. Acceptance Filter Mode Register (AFMR - address 0x4003 C000) bit description Bit Symbol Value Description Reset Value
0 1
AccOff[2] AccBP[1]
1 1
if AccBP is 0, the Acceptance Filter is not operational. All Rx messages on all CAN 1 buses are ignored. All Rx messages are accepted on enabled CAN controllers. Software must set this 0 bit before modifying the contents of any of the registers described below, and before modifying the contents of Lookup Table RAM in any way other than setting or clearing Disable bits in Standard Identifier entries. When both this bit and AccOff are 0, the Acceptance filter operates to screen received CAN Identifiers. Software must read all messages for all enabled IDs on all enabled CAN buses, from the receiving CAN controllers. The Acceptance Filter itself will take care of receiving and storing messages for selected Standard ID values on selected CAN buses. See Section 16-16 "FullCAN mode" on page 380. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
[1]
2
eFCAN[3] 0 1
0
31:3
-
NA
Acceptance Filter Bypass Mode (AccBP): By setting the AccBP bit in the Acceptance Filter Mode Register, the Acceptance filter is put into the Acceptance Filter Bypass mode. During bypass mode, the internal state machine of the Acceptance Filter is reset and halted. All received CAN messages are accepted, and acceptance filtering can be done by software. Acceptance Filter Off mode (AccOff): After power-up or hardware reset, the Acceptance filter will be in Off mode, the AccOff bit in the Acceptance filter Mode register 0 will be set to 1. The internal state machine of the acceptance filter is reset and halted. If not in Off mode, setting the AccOff bit, either by hardware or by software, will force the acceptance filter into Off mode. FullCAN Mode Enhancements: A FullCAN mode for received CAN messages can be enabled by setting the eFCAN bit in the acceptance filter mode register.
[2]
[3]
14.2 Section configuration registers
The 10-bit section configuration registers are used for the ID look-up table RAM to indicate the boundaries of the different sections for explicit and group of CAN identifiers for 11-bit CAN and 29-bit CAN identifiers, respectively. The 10-bit wide section configuration registers allow the use of a 512x32 (2 kB) look-up table RAM. The whole ID Look-up Table RAM is only word accessible. All five section configuration registers contain APB addresses for the acceptance filter RAM and do not include the APB base address. A write access to all section configuration registers is only possible during the Acceptance filter off and Bypass modes. Read access is allowed in all acceptance filter modes.
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14.3 Standard Frame Individual Start Address register (SFF_sa 0x4003 C004)
Table 344. Standard Frame Individual Start Address register (SFF_sa - address 0x4003 C004) bit description Bit Symbol Description Reset Value
1:0 10:2
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
SFF_sa[1] The start address of the table of individual Standard Identifiers in AF Lookup RAM. If the 0 table is empty, write the same value in this register and the SFF_GRP_sa register described below. For compatibility with possible future devices, write zeroes in bits 31:11 and 1:0 of this register. If the eFCAN bit in the AFMR is 1, this value also indicates the size of the table of Standard IDs which the Acceptance Filter will search and (if found) automatically store received messages in Acceptance Filter RAM. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
[1]
31:11 -
NA
Write access to the look-up table section configuration registers are possible only during the Acceptance filter bypass mode or the Acceptance filter off mode.
14.4 Standard Frame Group Start Address register (SFF_GRP_sa 0x4003 C008)
Table 345. Standard Frame Group Start Address register (SFF_GRP_sa - address 0x4003 C008) bit description Bit Symbol Description Reset Value
1:0 11:2
-
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
SFF_GRP_sa[1] The start address of the table of grouped Standard Identifiers in AF Lookup RAM. If 0 the table is empty, write the same value in this register and the EFF_sa register described below. The largest value that should be written to this register is 0x800, when only the Standard Individual table is used, and the last word (address 0x7FC) in AF Lookup Table RAM is used. For compatibility with possible future devices, please write zeroes in bits 31:12 and 1:0 of this register. Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
[1] Write access to the look-up table section configuration registers are possible only during the Acceptance filter bypass mode or the Acceptance filter off mode.
31:12 -
14.5 Extended Frame Start Address register (EFF_sa - 0x4003 C00C)
Table 346. Extended Frame Start Address register (EFF_sa - address 0x4003 C00C) bit description Bit Symbol Description Reset Value
1:0 10:2
EFF_sa[1]
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
The start address of the table of individual Extended Identifiers in AF Lookup RAM. If the 0 table is empty, write the same value in this register and the EFF_GRP_sa register described below. The largest value that should be written to this register is 0x800, when both Extended Tables are empty and the last word (address 0x7FC) in AF Lookup Table RAM is used. For compatibility with possible future devices, please write zeroes in bits 31:11 and 1:0 of this register. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
31:11 -
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[1]
Write access to the look-up table section configuration registers are possible only during the Acceptance filter bypass mode or the Acceptance filter off mode.
14.6 Extended Frame Group Start Address register (EFF_GRP_sa 0x4003 C010)
Table 347. Extended Frame Group Start Address register (EFF_GRP_sa - address 0x4003 C010) bit description Bit Symbol Description Reset Value
1:0 11:2
Eff_GRP_sa[1]
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined. The start address of the table of grouped Extended Identifiers in AF Lookup RAM. If 0 the table is empty, write the same value in this register and the ENDofTable register described below. The largest value that should be written to this register is 0x800, when this table is empty and the last word (address 0x7FC) in AF Lookup Table RAM is used. For compatibility with possible future devices, please write zeroes in bits 31:12 and 1:0 of this register. Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
[1] Write access to the look-up table section configuration registers are possible only during the Acceptance filter bypass mode or the Acceptance filter off mode.
31:12 -
14.7 End of AF Tables register (ENDofTable - 0x4003 C014)
Table 348. End of AF Tables register (ENDofTable - address 0x4003 C014) bit description Bit Symbol Description Reset Value
1:0 11:2
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0
EndofTable[1] The address above the last active address in the last active AF table. For compatibility with possible future devices, please write zeroes in bits 31:12 and 1:0 of this register. If the eFCAN bit in the AFMR is 0, the largest value that should be written to this register is 0x800, which allows the last word (address 0x7FC) in AF Lookup Table RAM to be used. If the eFCAN bit in the AFMR is 1, this value marks the start of the area of Acceptance Filter RAM, into which the Acceptance Filter will automatically receive messages for selected IDs on selected CAN buses. In this case, the maximum value that should be written to this register is 0x800 minus 6 times the value in SFF_sa. This allows 12 bytes of message storage between this address and the end of Acceptance Filter RAM, for each Standard ID that is specified between the start of Acceptance Filter RAM, and the next active AF table.
31:12 -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
[1]
NA
Write access to the look-up table section configuration registers are possible only during the Acceptance filter bypass mode or the Acceptance filter off mode.
14.8 Status registers
The look-up table error status registers, the error addresses, and the flag register provide information if a programming error in the look-up table RAM during the ID screening was encountered. The look-up table error address and flag register have only read access. If an error is detected, the LUTerror flag is set, and the LUTerrorAddr register provides the
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information under which address during an ID screening an error in the look-up table was encountered. Any read of the LUTerrorAddr Filter block can be used for a look-up table interrupt.
14.9 LUT Error Address register (LUTerrAd - 0x4003 C018)
Table 349. LUT Error Address register (LUTerrAd - address 0x4003 C018) bit description Bit Symbol Description Reset Value
1:0 10:2
LUTerrAd
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. It the LUT Error bit (below) is 1, this read-only field contains the address in AF Lookup Table RAM, at which the Acceptance Filter encountered an error in the content of the tables. Reserved, the value read from a reserved bit is not defined.
NA 0
31:11 -
NA
14.10 LUT Error register (LUTerr - 0x4003 C01C)
Table 350. LUT Error register (LUTerr - address 0x4003 C01C) bit description Bit Symbol Description Reset Value
0
LUTerr
This read-only bit is set to 1 if the Acceptance Filter encounters an error in the content of the tables in AF RAM. It is cleared when software reads the LUTerrAd register. This condition is ORed with the "other CAN" interrupts from the CAN controllers, to produce the request that is connected to the NVIC. Reserved, the value read from a reserved bit is not defined.
0
31:1
-
NA
14.11 Global FullCANInterrupt Enable register (FCANIE - 0x4003 C020)
A write access to the Global FullCAN Interrupt Enable register is only possible when the Acceptance Filter is in the off mode.
Table 351. Global FullCAN Enable register (FCANIE - address 0x4003 C020) bit description Bit Symbol Description Reset Value
0 31:1
FCANIE -
Global FullCAN Interrupt Enable. When 1, this interrupt is enabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
14.12 FullCAN Interrupt and Capture registers (FCANIC0 - 0x4003 C024 and FCANIC1 - 0x4003 C028)
For detailed description on these two registers, see Section 16-16.2 "FullCAN interrupts".
Table 352. FullCAN Interrupt and Capture register 0 (FCANIC0 - address 0x4003 C024) bit description Bit Symbol Description Reset Value
0 ... 31
IntPnd0 IntPndx (0FullCan Interrupt Pending bit 0. FullCan Interrupt Pending bit x. FullCan Interrupt Pending bit 31.
0 0 0
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Table 353. FullCAN Interrupt and Capture register 1 (FCANIC1 - address 0x4003 C028) bit description Bit Symbol Description Reset Value
0 ... 31
IntPnd32 IntPndx (32FullCan Interrupt Pending bit 32. FullCan Interrupt Pending bit x. FullCan Interrupt Pending bit 63.
0 0 0
15. Configuration and search algorithm
The CAN Identifier Look-up Table Memory can contain explicit identifiers and groups of CAN identifiers for Standard and Extended CAN Frame Formats. They are organized as a sorted list or table with an increasing order of the Source CAN Channel (SCC) together with CAN Identifier in each section. SCC value equals CAN_controller - 1, i.e., SCC = 0 matches CAN1 and SCC = 1 matches CAN2. Every CAN identifier is linked to an ID Index number. In case of a CAN Identifier match, the matching ID Index is stored in the Identifier Index of the Frame Status Register (CANRFS) of the according CAN Controller.
15.1 Acceptance filter search algorithm
The identifier screening process of the acceptance filter starts in the following order: 1. FullCAN (Standard Frame Format) Identifier Section 2. Explicit Standard Frame Format Identifier Section 3. Group of Standard Frame Format Identifier Section 4. Explicit Extended Frame Format Identifier Section 5. Group of Extended Frame Format Identifier Section Note: Only activated sections will take part in the screening process. In cases where equal message identifiers of same frame format are defined in more than one section, the first match will end the screening process for this identifier. For example, if the same Source CAN Channel in conjunction with the identifier is defined in the FullCAN, the Explicit Standard Frame Format and the Group of Standard Frame Format Identifier Sections, the screening will already be finished with the match in the FullCAN section. In the example of Figure 16-60, Identifiers with their Source CAN Channel have been defined in the FullCAN, Explicit and Group of Standard Frame Format Identifier Sections. This example corresponds part with 6 CAN controllers.
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Message disable bit
Message disable bit
Index 0, 1 Index 2, 3 Index 4, 5 Index 6, 7
SCC = 1 SCC = 2 SCC = 4 SCC = 6
0
ID = 0x5A ... ... ...
SCC = 1 SCC = 3 SCC = 5 SCC = 6
0
... ... ... ...
0
0
0
0
0
0
FullCAN Explicit Standard Frame Format Identifier Section
Index 8, 9 Index 10, 11 Index 12, 13
SCC = 1 SCC = 2 SCC = 4
0
ID = 0x5A ... ...
SCC = 1 SCC = 3 SCC = 5
0
... ... ...
0
0
0
0
Explicit Standard Frame Format Identifier Section Group of Standard Frame Format Identifier Section
Index 14 Index 15
SCC = 1 SCC = 2
0
ID = 0x5A ...
SCC = 1 SCC = 2
0
ID = 0x5A 0x5F ...
0
0
Fig 60. ID Look-up table example explaining the search algorithm
The identifier 0x5A of the CAN Controller 1 with the Source CAN Channel SCC = 1, is defined in all three sections. With this configuration incoming CAN messages on CAN Controller 1 with a 0x5A identifier will find a match in the FullCAN section. It is possible to disable the `0x5A identifier' in the FullCAN section. With that, the screening process would be finished with the match in the Explicit Identifier Section. The first group in the Group Identifier Section has been defined in that way, that incoming CAN messages with identifiers of 0x5A up to 0x5F are accepted on CAN Controller 1 with the Source CAN Channel SCC = 1. As stated above, the identifier 0x5A would find a match already in the FullCAN or in the Explicit Identifier section if enabled. The rest of the defined identifiers of this group (0x5B to 0x5F) will find a match in this Group Identifier Section. This way the user can switch dynamically between different filter modes for same identifiers.
16. FullCAN mode
The FullCAN mode is based on capabilities provided by the CAN Gateway module used in the LPC2000 family of products. This block uses the Acceptance Filter to provide filtering for both CAN channels. The concept of the CAN Gateway block is mainly based on a BasicCAN functionality. This concept fits perfectly in systems where a gateway is used to transfer messages or message data between different CAN channels. A BasicCAN device is generating a
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receive interrupt whenever a CAN message is accepted and received. Software has to move the received message out of the receive buffer from the according CAN controller into the user RAM. To cover dashboard like applications where the controller typically receives data from several CAN channels for further processing, the CAN Gateway block was extended by a so-called FullCAN receive function. This additional feature uses an internal message handler to move received FullCAN messages from the receive buffer of the according CAN controller into the FullCAN message object data space of Look-up Table RAM. When FullCAN mode is enabled, the Acceptance Filter itself takes care of receiving and storing messages for selected Standard ID values on selected CAN buses, in the style of "FullCAN" controllers. In order to set this bit and use this mode, two other conditions must be met with respect to the contents of Acceptance Filter RAM and the pointers into it:
* The Standard Frame Individual Start Address Register (SFF_sa) must be greater than
or equal to the number of IDs for which automatic receive storage is to be done, times two. SFF_sa must be rounded up to a multiple of 4 if necessary.
* The EndOfTable register must be less than or equal to 0x800 minus 6 times the
SFF_sa value, to allow 12 bytes of message storage for each ID for which automatic receive storage will be done. When these conditions are met and eFCAN is set:
* The area between the start of Acceptance Filter RAM and the SFF_sa address, is
used for a table of individual Standard IDs and CAN Controller/bus identification, sorted in ascending order and in the same format as in the Individual Standard ID table (see Figure 16-57 "Entry in FullCAN and individual standard identifier tables" on page 373). Entries can be marked as "disabled" as in the other Standard tables. If there are an odd number of "FullCAN" ID's, at least one entry in this table must be so marked.
* The first (SFF_sa)/2 IDindex values are assigned to these automatically-stored ID's.
That is, IDindex values stored in the Rx Frame Status Register, for IDs not handled in this way, are increased by (SFF_sa)/2 compared to the values they would have when eFCAN is 0.
* When a Standard ID is received, the Acceptance Filter searches this table before the
Standard Individual and Group tables.
* When a message is received for a controller and ID in this table, the Acceptance filter
reads the received message out of the CAN controller and stores it in Acceptance Filter RAM, starting at (EndOfTable) + its IDindex*12.
* The format of such messages is shown in Table 16-354.
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16.1 FullCAN message layout
Table 354. Format of automatically stored Rx messages Address 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8 7 6 5 4 3 2 1 0
0
F R 0000 FT R Rx Data 4 Rx Data 8
SEM [1:0]
0000
DLC
00000
ID.28 ... ID.18
+4 +8
Rx Data 3 Rx Data 7
Rx Data 2 Rx Data 6
Rx Data 1 Rx Data 5
The FF, RTR, and DLC fields are as described in Table 16-326. Since the FullCAN message object section of the Look-up table RAM can be accessed both by the Acceptance Filter and the CPU, there is a method for insuring that no CPU reads from FullCAN message object occurs while the Acceptance Filter hardware is writing to that object. For this purpose the Acceptance Filter uses a 3-state semaphore, encoded with the two semaphore bits SEM1 and SEM0 (see Table 16-354 "Format of automatically stored Rx messages") for each message object. This mechanism provides the CPU with information about the current state of the Acceptance Filter activity in the FullCAN message object section. The semaphore operates in the following manner:
Table 355. FullCAN semaphore operation SEM1 SEM0 activity
0 1 0
1 1 0
Acceptance Filter is updating the content Acceptance Filter has finished updating the content CPU is in process of reading from the Acceptance Filter
Prior to writing the first data byte into a message object, the Acceptance Filter will write the FrameInfo byte into the according buffer location with SEM[1:0] = 01. After having written the last data byte into the message object, the Acceptance Filter will update the semaphore bits by setting SEM[1:0] = 11. Before reading a message object, the CPU should read SEM[1:0] to determine the current state of the Acceptance Filter activity therein. If SEM[1:0] = 01, then the Acceptance Filter is currently active in this message object. If SEM[1:0] = 11, then the message object is available to be read. Before the CPU begins reading from the message object, it should clear SEM[1:0] = 00. When the CPU is finished reading, it can check SEM[1:0] again. At the time of this final check, if SEM[1:0] = 01 or 11, then the Acceptance Filter has updated the message object during the time when the CPU reads were taking place, and the CPU should discard the data. If, on the other hand, SEM[1:0] = 00 as expected, then valid data has been successfully read by the CPU. Figure 16-61 shows how software should use the SEM field to ensure that all three words read from the message are all from the same received message.
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START
read 1st word
SEM == 01?
SEM == 11?
this message has not been received since last check
clear SEM, write back 1 word st
read 2nd and 3rd words
read 1st word
SEM == 00?
most recently read 1 2nd, and st, 3rd words are from the same message
Fig 61. Semaphore procedure for reading an auto-stored message
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16.2 FullCAN interrupts
The CAN Gateway Block contains a 2 kB ID Look-up Table RAM. With this size a maximum number of 146 FullCAN objects can be defined if the whole Look-up Table RAM is used for FullCAN objects only. Only the first 64 FullCAN objects can be configured to participate in the interrupt scheme. It is still possible to define more than 64 FullCAN objects. The only difference is, that the remaining FullCAN objects will not provide a FullCAN interrupt. The FullCAN Interrupt Register-set contains interrupt flags (IntPndx) for (pending) FullCAN receive interrupts. As soon as a FullCAN message is received, the according interrupt bit (IntPndx) in the FCAN Interrupt Register gets asserted. In case that the Global FullCAN Interrupt Enable bit is set, the FullCAN Receive Interrupt is passed to the Vectored Interrupt Controller. Application Software has to solve the following: 1. Index/Object number calculation based on the bit position in the FCANIC Interrupt Register for more than one pending interrupt. 2. Interrupt priority handling if more than one FullCAN receive interrupt is pending. The software that covers the interrupt priority handling has to assign a receive interrupt priority to every FullCAN object. If more than one interrupt is pending, then the software has to decide, which received FullCAN object has to be served next. To each FullCAN object a new FullCAN Interrupt Enable bit (FCANIntxEn) is added, so that it is possible to enable or disable FullCAN interrupts for each object individually. The new Message Lost flag (MsgLstx) is introduced to indicate whether more than one FullCAN message has been received since last time this message object was read by the CPU. The Interrupt Enable and the Message Lost bits reside in the existing Look-up Table RAM.
16.2.1 FullCAN message interrupt enable bit
In Figure 16-62 8 FullCAN Identifiers with their Source CAN Channel are defined in the FullCAN, Section. The new introduced FullCAN Message Interrupt enable bit can be used to enable for each FullCAN message an Interrupt.
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Message disable bit
Message disable bit
3 1 0 9 8 0 0 0 0 7 6 54 3 2 1
2 0 9 8 7 6 5 4 3 2 0 0 0 0 1
1 0 9 8 7 6 5 4 3 2 1 0
Index 0, 1 Index 2, 3 Index 4, 5 Index 6, 7
SCC SCC SCC SCC
11-bit CAN ID 11-bit CAN ID 11-bit CAN ID 11-bit CAN ID
SCC SCC SCC SCC
11-bit CAN ID 11-bit CAN ID 11-bit CAN ID 11-bit CAN ID
FullCAN Explicit Standard Frame Format Identifier Section
New: FullCAN Message Interrupt enable bit
New: FullCAN Message Interrupt enable bit
Fig 62. FullCAN section example of the ID look-up table
16.2.2 Message lost bit and CAN channel number
Figure 16-63 is the detailed layout structure of one FullCAN message stored in the FullCAN message object section of the Look-up Table.
New: FullCAN Message lost bit APB Base + F F
R T R unused S E M 1 S E M 0 31 24 23 16
New:
CAN
Source Channel
15 10 9 8 7 0
Msg_ObjAddr + 0 Msg_ObjAddr + 4 Msg_ObjAddr + 8
unused
RX DLC
SCC
unused
ID.2 8
............................
ID.1 8
RX Data 4 RX Data 8
RX Data 3 RX Data 7
RX Data 2 RX Data 6
RX Data 1 RX Data 5
Fig 63. FullCAN message object layout
The new message lost bit (MsgLst) is introduced to indicate whether more than one FullCAN message has been received since last time this message object was read. For more information the CAN Source Channel (SCC) of the received FullCAN message is added to Message Object.
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16.2.3 Setting the interrupt pending bits (IntPnd 63 to 0)
The interrupt pending bit (IntPndx) gets asserted in case of an accepted FullCAN message and if the interrupt of the according FullCAN Object is enabled (enable bit FCANIntxEn) is set). During the last write access from the data storage of a FullCAN message object the interrupt pending bit of a FullCAN object (IntPndx) gets asserted.
16.2.4 Clearing the interrupt pending bits (IntPnd 63 to 0)
Each of the FullCAN Interrupt Pending requests gets cleared when the semaphore bits of a message object are cleared by Software (ARM CPU).
16.2.5 Setting the message lost bit of a FullCAN message object (MsgLost 63 to 0)
The Message Lost bit of a FullCAN message object gets asserted in case of an accepted FullCAN message and when the FullCAN Interrupt of the same object is asserted already. During the first write access from the data storage of a FullCAN message object the Message Lost bit of a FullCAN object (MsgLostx) gets asserted if the interrupt pending bit is set already.
16.2.6 Clearing the message lost bit of a FullCAN message object (MsgLost 63 to 0)
The Message Lost bit of a FullCAN message object gets cleared when the FullCAN Interrupt of the same object is not asserted. During the first write access from the data storage of a FullCAN message object the Message Lost bit of a FullCAN object (MsgLostx) gets cleared if the interrupt pending bit is not set.
16.3 Set and clear mechanism of the FullCAN interrupt
Special precaution is needed for the built-in set and clear mechanism of the FullCAN Interrupts. The following text illustrates how the already existing Semaphore Bits (see Section 16-16.1 "FullCAN message layout" for more details) and how the new introduced features (IntPndx, MsgLstx) will behave.
16.3.1 Scenario 1: Normal case, no message lost
Figure 16-64 below shows a typical "normal" scenario in which an accepted FullCAN message is stored in the FullCAN Message Object Section. After storage the message is read out by Software (ARM CPU).
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semaphore bits
01
11
00
IntPndx
look-up table access MsgLostx
Write ID, SEM
write D1
write D2
write SEM
read clear SEM SEM
read D1
read read D2 SEM
message handler access
ARM processor access
Fig 64. Normal case, no messages lost
16.3.2 Scenario 2: Message lost
In this scenario a first FullCAN Message is stored and read out by Software (1st Object write and read). In a second course a second message is stored (2nd Object write) but not read out before a third message gets stored (3rd Object write). Since the FullCAN Interrupt of that Object (IntPndx) is already asserted, the Message Lost Signal gets asserted.
semaphore bits
01
11
00
01
11
11
IntPndx look-up table access
write write write write ID, D1 D2 SEM SEM 1st Object write 1st Object read write read read read ID, write write write D1 D2 SEM SEM D1 D2 SEM 2nd Object write write write write write ID, D1 D2 SEM SEM 3rd Object write
read clear SEM SEM
MsgLostx
message handler access
ARM processor access
Fig 65. Message lost
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16.3.3 Scenario 3: Message gets overwritten indicated by Semaphore bits
This scenario is a special case in which the lost message is indicated by the existing semaphore bits. The scenario is entered, if during a Software read of a message object another new message gets stored by the message handler. In this case, the FullCAN Interrupt bit gets set for a second time with the 2nd Object write.
semaphore bits
01
11
00
01
11
00
IntPndx look-up table access
write write write ID, D1 D2 SEM 1st Object write write ID, write write write D2 SEM SEM D1 2nd Object write 1st Object read Interrupt Service Routine 2nd Object read
write SEM
read clear SEM SEM
read read read D1 D2 SEM
clear SEM
read read read D1 D2 SEM
MsgLostx
message handler access
ARM processor access
Fig 66. Message gets overwritten
16.3.4 Scenario 3.1: Message gets overwritten indicated by Semaphore bits and Message Lost
This scenario is a sub-case to Scenario 3 in which the lost message is indicated by the existing semaphore bits and by Message Lost.
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semaphore bits
01
11
00
01
11
00
IntPndx
write write write write ID, D1 D2 SEM SEM 1st Object write write write write write ID, D1 D2 SEM SEM 2nd Object write 1st Object read Interrupt Service Routine 2nd Object read
look-up table access
read clear SEM SEM
read read read D1 D2 SEM
clear SEM
read read read D1 D2 SEM
MsgLostx
message handler access
ARM processor access
Fig 67. Message overwritten indicated by semaphore bits and message lost
16.3.5 Scenario 3.2: Message gets overwritten indicated by Message Lost
This scenario is a sub-case to Scenario 3 in which the lost message is indicated by Message Lost.
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semaphore bits
01
11
01
11
00
01
11
IntPndx
look-up table access
write write write write read ID, D1 D2 SEM SEM SEM 1st Object write
write write write write ID, D1 D2 SEM SEM 2nd Object write 1st Object read Interrupt Service Routine
clear SEM
read read read D1 D2 SEM
write write write write ID, D1 D2 SEM SEM 3rd Object write
MsgLostx
message handler access
ARM processor access
Fig 68. Message overwritten indicated by message lost
16.3.6 Scenario 4: Clearing Message Lost bit
This scenario is a special case in which the lost message bit of an object gets set during an overwrite of a none read message object (2nd Object write). The subsequent read out of that object by Software (1st Object read) clears the pending Interrupt. The 3rd Object write clears the Message Lost bit. Every "write ID, SEM" clears Message Lost bit if no pending Interrupt of that object is set.
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semaphore bits
01
11
01
11
00
11
IntPndx
write write write write ID, D1 D2 SEM SEM 1st Object write write write write write ID, D1 D2 SEM SEM 2nd Object write 1st Object read write write write write ID, D1 D2 SEM SEM 3rd Object write
look-up table access
read clear SEM SEM
read read read D1 D2 SEM
MsgLostx
message handler access
ARM processor access
Fig 69. Clearing message lost
17. Examples of acceptance filter tables and ID index values
17.1 Example 1: only one section is used
SFF_sa SFF_GRP_sa EFF_sa EFF_GRP_sa < < < < ENDofTable ENDofTable ENDofTable ENDofTable OR OR OR
The start address of a section is lower than the end address of all programmed CAN identifiers.
17.2 Example 2: all sections are used
SFF_sa SFF_GRP_sa EFF_sa EFF_GRP_sa < < < < SFF_GRP_sa EFF_sa EFF_GRP_sa ENDofTable AND AND AND
In cases of a section not being used, the start address has to be set onto the value of the next section start address.
17.3 Example 3: more than one but not all sections are used
If the SFF group is not used, the start address of the SFF Group Section (SFF_GRP_sa register) has to be set to the same value of the next section start address, in this case the start address of the Explicit SFF Section (SFF_sa register).
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In cases where explicit identifiers as well as groups of the identifiers are programmed, a CAN identifier search has to start in the explicit identifier section first. If no match is found, it continues the search in the group of identifier section. By this order it can be guaranteed that in case where an explicit identifier match is found, the succeeding software can directly proceed on this certain message whereas in case of a group of identifier match the succeeding software needs more steps to identify the message.
17.4 Configuration example 4
Suppose that the five Acceptance Filter address registers contain the values shown in the third column below. In this case each table contains the decimal number of words and entries shown in the next two columns, and the ID Index field of the CANRFS register can return the decimal values shown in the column ID Indexes for CAN messages whose Identifiers match the entries in that table.
Table 356. Example of Acceptance Filter Tables and ID index Values Table Register Value # Words # Entire ID Indexes
Standard Individual Standard Group Extended Individual Extended Group
SFF_sa SFF_GRP_sa EFF_sa EFF_GRP_sa ENDofTable
0x040 0x060 0x070 0x100 0x110
810 410 810 810
1610 410 1610 1610
0-1510 16-1910 20-5510 56-5710
17.5 Configuration example 5
Figure 16-70 below is a more detailed and graphic example of the address registers, table layout, and ID Index values. It shows:
* A Standard Individual table starting at the start of Acceptance Filter RAM and
containing 26 Identifiers, followed by:
* A Standard Group table containing 12 ranges of Identifiers, followed by: * An Extended Individual table containing 3 Identifiers, followed by: * An Extended Group table containing 2 ranges of Identifiers.
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SFF_sa APB base + address 00d = 00h 04d = 04h
000 d := 000 h := 0 0000 0000 b
look-up table RAM column_lower 0 2 column_upper 1 3
ID index #
44d = 2Ch 48d = 30h 52d = 34h SFF_GRP_sa 52 d := 034 h := 0 0011 0100 b
22 24 26
23 25
22 23 24 25 26 d
84d = 54h 88d = 58h 92d = 5Ch
lower_boundary 3 4 upper_boundary 34 d lower_boundary 3 5 upper_boundary 35 d lower_boundary 3 6 upper_boundary 36 d
EFF_sa
100 d := 064 h := 0 0110 0100 b
100d = 64h 104d = 68h
39
39 d
EFF_GRP_sa 112 d := 070 h := 0 0111 0000 b
116d = 74h 120d = 78h 124d = 7Ch
upper_boundary lower_boundary upper_boundary 42 42 d
ENDofTable
128 d := 080 h := 0 1000 0000 b
Fig 70. Detailed example of acceptance filter tables and ID index values
17.6 Configuration example 6
The Table below shows which sections and therefore which types of CAN identifiers are used and activated. The ID-Look-up Table configuration of this example is shown in Figure 16-71.
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group EFF table
112d = 70h
lower_boundary
41
41 d
explicit EFF table
38
38 d
group SFF table
explicit SFF table
0 1 2 3
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Table 357. Used ID-Look-up Table sections ID-Look-up Table Section Status
FullCAN Explicit Standard Frame Format Group of Standard Frame Format Explicit Extended Frame Format Group of Extended Frame Format
not activated activated activated activated activated
Explicit standard frame format identifier section (11-bit CAN ID): The start address of the Explicit Standard Frame Format section is defined in the SFF_sa register with the value of 0x00. The end of this section is defined in the SFF_GRP_sa register. In the Explicit Standard Frame Format section of the ID Look-up Table two CAN Identifiers with their Source CAN Channels (SCC) share one 32-bit word. Not used or disabled CAN Identifiers can be marked by setting the message disable bit. Group of standard frame format identifier section (11-bit CAN ID): The start address of the Group of Standard Frame Format section is defined with the SFF_GRP_sa register with the value of 0x10. The end of this section is defined with the EFF_sa register. In the Group of Standard Frame Format section two CAN Identifiers with the same Source CAN Channel (SCC) share one 32-bit word and represent a range of CAN Identifiers to be accepted. Bit 31 down to 16 represents the lower boundary and bit 15 down to 0 represents the upper boundary of the range of CAN Identifiers. All Identifiers within this range (including the boundary identifiers) will be accepted. A whole group can be disabled and not used by the acceptance filter by setting the message disable bit in the upper and lower boundary identifier. To provide memory space for four Groups of Standard Frame Format identifiers, the EFF_sa register value is set to 0x20. The identifier group with the Index 9 of this section is not used and therefore disabled. Explicit extended frame format identifier section (29-bit CAN ID, Figure 16-71) The start address of the Explicit Extended Frame Format section is defined with the EFF_sa register with the value of 0x20. The end of this section is defined with the EFF_GRP_sa register. In the explicit Extended Frame Format section only one CAN Identifier with its Source CAN Channel (SCC) is programmed per address line. To provide memory space for four Explicit Extended Frame Format identifiers, the EFF_GRP_sa register value is set to 0x30. Group of extended frame format identifier section (29-bit CAN ID, Figure 16-71) The start address of the Group of Extended Frame Format is defined with the EFF_GRP_sa register with the value of 0x30. The end of this section is defined with the End of Table address register (ENDofTable). In the Group of Extended Frame Format section the boundaries are programmed with a pair of address lines; the first is the lower boundary, the second the upper boundary. To provide memory space for two Groups of Extended Frame Format Identifiers, the ENDofTable register value is set to 0x40.
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Message disable bit Index SFF_sa = 0x00 SCC 0 Explicit Standard Frame ... Format Identifier Section SCC 0 SCC 0 SCC 0 SCC 0 Group of Standard Frame Format ... Identifier Section SCC 1 SCC 1 SCC 0 SCC Explicit Extended Frame Format Identifier Section SCC
MSB ID28 MSB ID28 MSB MSB MSB MSB MSB MSB MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28
Message disable bit
0 2 4 6 8 Disabled, 9 10 11
LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18
SCC SCC SCC SCC SCC SCC SCC SCC 12 13 14 15 16 16 17 17
0 0 0 1 0 1 1 0
MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28
1 3 5 Disabled, 7 8 Disabled, 9 10 11
LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID0 LSB ID0 LSB ID0 LSB ID0 LSB ID0 LSB ID0 LSB ID0 LSB ID0
SFF_GRP_sa = 0x10
Group 8 Disabled Group 9 Group 10 Group 11
EFF_sa = 0x20
SCC ID28 SCC ID28 SCC ID28 SCC ID28 SCC ID28
EFF_GRP_sa = 0x30
Group of Extended Frame Format Identifier Section
Group 16
Group 17
SCC ID28
ENDofTable = 0x40
Fig 71. ID Look-up table configuration example (no FullCAN)
17.7 Configuration example 7
The Table below shows which sections and therefore which types of CAN identifiers are used and activated. The ID-Look-up Table configuration of this example is shown in Figure 16-72. This example uses a typical configuration in which FullCAN as well as Explicit Standard Frame Format messages are defined. As described in Section 16-15.1 "Acceptance filter search algorithm", acceptance filtering takes place in a certain order. With the enabled FullCAN section, the identifier screening process of the acceptance filter starts always in the FullCAN section first, before it continues with the rest of enabled sections.e disabled.
Table 358. Used ID-Look-up Table sections ID-Look-up Table Section Status
FullCAN Explicit Standard Frame Format Group of Standard Frame Format Explicit Extended Frame Format Group of Extended Frame Format
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FullCAN explicit standard frame format identifier section (11-bit CAN ID) The start address of the FullCAN Explicit Standard Frame Format Identifier section is (automatically) set to 0x00. The end of this section is defined in the SFF_sa register. In the FullCAN ID section only identifiers of FullCAN Object are stored for acceptance filtering. In this section two CAN Identifiers with their Source CAN Channels (SCC) share one 32-bit word. Not used or disabled CAN Identifiers can be marked by setting the message disable bit. The FullCAN Object data for each defined identifier can be found in the FullCAN Message Object section. In case of an identifier match during the acceptance filter process, the received FullCAN message object data is moved from the Receive Buffer of the appropriate CAN Controller into the FullCAN Message Object section. To provide memory space for eight FullCAN, Explicit Standard Frame Format identifiers, the SFF_sa register value is set to 0x10. The identifier with the Index 1 of this section is not used and therefore disabled. Explicit standard frame format identifier section (11-bit CAN ID) The start address of the Explicit Standard Frame Format section is defined in the SFF_sa register with the value of 0x10. The end of this section is defined in the End of Table address register (ENDofTable). In the explicit Standard Frame Format section of the ID Look-up Table two CAN Identifiers with their Source CAN Channel (SCC) share one 32-bit word. Not used or disabled CAN Identifiers can be marked by setting the message disable bit. To provide memory space for eight Explicit Standard Frame Format identifiers, the ENDofTable register value is set to 0x20. FullCAN message object data section The start address of the FullCAN Message Object Data section is defined with the ENDofTable register. The number of enabled FullCAN identifiers is limited to the available memory space in the FullCAN Message Object Data section. Each defined FullCAN Message needs three address lines for the Message Data in the FullCAN Message Object Data section. The FullCAN Message Object section is organized in that way, that each Index number of the FullCAN Identifier section corresponds to a Message Object Number in the FullCAN Message Object section.
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Message Disable bit
FullCAN Interrupt Enable bit
Message Disable bit Index LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18
1 1 MSB 00 00 00 00 00 00 00
FullCAN Interrupt Enable bit LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18 LSB ID18
FullCAN Explicit Standard Frame ... Format Identifier Section SFF_sa = 0x10
SCC SCC SCC SCC SCC
MSB ID28 MSB 01 ID28
00 01 01 00 00 00 00
0 2 4 6 8 10 12 14
SCC SCC SCC SCC SCC SCC SCC SCC
Explicit Standard Frame ...Format Identifier Section
SCC SCC SCC
MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28
ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28 MSB ID28
Disabled, 1 3 5 7 9 11 13 15
ENDofTable = SFF_GRP_sa = EFF_sa = EFF_GRP_sa = 0x20
FF RTR SEM DLC CAN-ID FullCAN Message Object section Section RXDATA 4, 3, 2, 1 RXDATA 8, 7, 6, 5 No Message Data, disabled. No Message Data, disabled. No Message Data, disabled. FF RTR SEM DLC CAN-ID RXDATA 4, 3, 2, 1 RXDATA 8, 7, 6, 5 Message Object Data 2 Message Object Data 1 Message Object Data 0
Fig 72. ID Look-up table configuration example (FullCAN activated and enabled)
17.8 Look-up table programming guidelines
All identifier sections of the ID Look-up Table have to be programmed in such a way, that each active section is organized as a sorted list or table with an increasing order of the Source CAN Channel (SCC) together with CAN Identifier in each section. SCC value equals CAN_controller - 1, i.e., SCC = 0 matches CAN1 and SCC = 1 matches CAN2. In cases, where a syntax error in the ID Look-up Table is encountered, the Look-up Table address of the incorrect line is made available in the Look-up Table Error Address Register (LUTerrAd). The reporting process in the Look-up Table Error Address Register (LUTerrAd) is a "run-time" process. Only those address lines with syntax error are reported, which were passed through the acceptance filtering process. The following general rules for programming the Look-up Table apply:
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* Each section has to be organized as a sorted list or table with an increasing order of
the Source CAN Channel (SCC) in conjunction with the CAN Identifier (there is no exception for disabled identifiers).
* The upper and lower bound in a Group of Identifiers definition has to be from the
same Source CAN Channel.
* To disable a Group of Identifiers the message disable bit has to be set for both, the
upper and lower bound.
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Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The SPI is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCSPI. Remark: On reset, the SPI is enabled (PCSPI = 1). 2. Clock: In the PCLKSEL0 register (Table 4-40), set bit PCLK_SPI. In master mode, the clock must be an even number greater than or equal to 8 (see Section 17-7.4). 3. Pins: The SPI pins are configured using both PINSEL0 (Table 8-78) and PINSEL1 (Table 8-79), as well as the PINMODE (Section 8-4) register. PINSEL0[31:30] is used to configure the SPI CLK pin. PINSEL1[1:0], PINSEL1[3:2] and PINSEL1[5:4] are used to configure the pins SSEL, MISO and MOSI, respectively. 4. Interrupts: The SPI interrupt flag is enabled using the S0SPINT[0] bit (Section 17-7.7). The SPI interrupt flag must be enabled in the NVIC, see Table 6-50. Remark: SSP0 is intended to be used as an alternative for the SPI interface, which is included as a legacy peripheral. Only one of these peripherals can be used at the any one time.
2. Features
* * * * *
Compliant with Serial Peripheral Interface (SPI) specification. Synchronous, Serial, Full Duplex Communication. SPI master or slave. Maximum data bit rate of one eighth of the peripheral clock rate. 8 to 16 bits per transfer.
3. SPI overview
SPI is a full duplex serial interface. It can handle multiple masters and slaves being connected to a given bus. Only a single master and a single slave can communicate on the interface during a given data transfer. During a data transfer the master always sends 8 to 16 bits of data to the slave, and the slave always sends a byte of data to the master.
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4. Pin description
Table 359. SPI pin description Pin Name Type Pin Description Serial Clock. The SPI clock signal (SCK) is used to synchronize the transfer of data across the SPI interface. The SPI is always driven by the master and received by the slave. The clock is programmable to be active high or active low. The SPI is only active during a data transfer. Any other time, it is either in its inactive state, or tri-stated. Slave Select. The SPI slave select signal (SSEL) is an active low signal that indicates which slave is currently selected to participate in a data transfer. Each slave has its own unique slave select signal input. The SSEL must be low before data transactions begin and normally stays low for the duration of the transaction. If the SSEL signal goes high any time during a data transfer, the transfer is considered to be aborted. In this event, the slave returns to idle, and any data that was received is thrown away. There are no other indications of this exception. This signal is not directly driven by the master. It could be driven by a simple general purpose I/O under software control. Master In Slave Out. The SPI Master In Slave Out signal (MISO) is a unidirectional signal used to transfer serial data from an SPI slave to an SPI master. When a device is a slave, serial data is output on this pin. When a device is a master, serial data is input on this pin. When a slave device is not selected, the slave drives the signal high-impedance. Master Out Slave In. The SPI Master Out Slave In signal (MOSI) is a unidirectional signal used to transfer serial data from an SPI master to an SPI slave. When a device is a master, serial data is output on this pin. When a device is a slave, serial data is input on this pin.
SCK
Input/ Output
SSEL
Input
MISO
Input/ Output
MOSI
Input/ Output
5. SPI data transfers
Figure 17-73 is a timing diagram that illustrates the four different data transfer formats that are available with the SPI port. This timing diagram illustrates a single 8-bit data transfer. The first thing you should notice in this timing diagram is that it is divided into three horizontal parts. The first part describes the SCK and SSEL signals. The second part describes the MOSI and MISO signals when the Clock Phase control bit (CPHA) in the SPI Control Register is 0. The third part describes the MOSI and MISO signals when the CPHA variable is 1. In the first part of the timing diagram, note two points. First, the SPI is illustrated with the Clock Polarity control bit (CPOL) in the SPI Control Register set to both 0 and 1. The second point to note is the activation and de-activation of the SSEL signal. When CPHA = 0, the SSEL signal will always go inactive between data transfers. This is not guaranteed when CPHA = 1 (the signal can remain active).
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SCK (CPOL = 0)
SCK (CPOL = 1)
SSEL
CPHA = 0
Cycle # CPHA = 0
1
2
3
4
5
6
7
8
MOSI (CPHA = 0)
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
MISO (CPHA = 0)
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
CPHA = 1
Cycle # CPHA = 1
1
2
3
4
5
6
7
8
MOSI (CPHA = 1)
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
MISO (CPHA = 1)
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
Fig 73. SPI data transfer format (CPHA = 0 and CPHA = 1)
The data and clock phase relationships are summarized in Table 17-360.
Table 360. SPI Data To Clock Phase Relationship CPOL and CPHA settings When the first data bit is driven When all other data bits are driven When data is sampled
CPOL = 0, CPHA = 0 CPOL = 0, CPHA = 1 CPOL = 1, CPHA = 0 CPOL = 1, CPHA = 1
Prior to first SCK rising edge First SCK rising edge Prior to first SCK falling edge First SCK falling edge
SCK falling edge SCK rising edge SCK rising edge SCK falling edge
SCK rising edge SCK falling edge SCK falling edge SCK rising edge
The definition of when a transfer starts and stops is dependent on whether a device is a master or a slave, and the setting of the CPHA variable. When a device is a master, the start of a transfer is indicated by the master having a byte of data that is ready to be transmitted. At this point, the master can activate the clock, and begin the transfer. The transfer ends when the last clock cycle of the transfer is complete. When a device is a slave and CPHA is set to 0, the transfer starts when the SSEL signal goes active, and ends when SSEL goes inactive. When a device is a slave, and CPHA is set to 1, the transfer starts on the first clock edge when the slave is selected, and ends on the last clock edge where data is sampled.
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6. SPI peripheral details
6.1 General information
There are five control and status registers for the SPI port. They are described in detail in Section 17-7 "Register description" on page 404. The SPI Control Register (S0SPCR) contains a number of programmable bits used to control the function of the SPI block. The settings for this register must be set up prior to a given data transfer taking place. The SPI Status Register (S0SPSR) contains read-only bits that are used to monitor the status of the SPI interface, including normal functions, and exception conditions. The primary purpose of this register is to detect completion of a data transfer. This is indicated by the SPI Interrupt Flag (SPIF) in the S0SPINT register. The remaining bits in the register are exception condition indicators. These exceptions will be described later in this section. The SPI Data Register (S0SPDR) is used to provide the transmit and receive data bytes. An internal shift register in the SPI block logic is used for the actual transmission and reception of the serial data. Data is written to the SPI Data Register for the transmit case. There is no buffer between the data register and the internal shift register. A write to the data register goes directly into the internal shift register. Therefore, data should only be written to this register when a transmit is not currently in progress. Read data is buffered. When a transfer is complete, the receive data is transferred to a single byte data buffer, where it is later read. A read of the SPI Data Register returns the value of the read data buffer. The SPI Clock Counter Register (S0SPCCR) controls the clock rate when the SPI block is in master mode. This needs to be set prior to a transfer taking place, when the SPI block is a master. This register has no function when the SPI block is a slave. Prior to use, SPI configurations such as the master/slave settings, clock polarity, clock rate, etc. must be set up in the SPI Control Register and SPI Clock Counter Register. The I/Os for this implementation of SPI are standard CMOS I/Os. The open drain SPI option is not implemented in this design. When a device is set up to be a slave, its I/Os are only active when it is selected by the SSEL signal being active.
6.2 Master operation
The following sequence can be followed to set up the SPI prior to its first use as a master. This is typically done during program initialization. 1. Set the SPI Clock Counter Register to the desired clock rate. 2. Set the SPI Control Register to the desired settings for master mode. The following sequence describes how one should process a data transfer with the SPI block when it is set up to be the master. This process assumes that any prior data transfer has already completed. 1. Optionally, verify the SPI setup before starting the transfer. 2. Write the data to transmitted to the SPI Data Register. This write starts the SPI data transfer.
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3. Wait for the SPIF bit in the SPI Status Register to be set to 1. The SPIF bit will be set after the last cycle of the SPI data transfer. 4. Read the SPI Status Register. 5. Read the received data from the SPI Data Register (optional). 6. Go to step 2 if more data is to be transmitted. Note: A read or write of the SPI Data Register is required in order to clear the SPIF status bit. Therefore, if the optional read of the SPI Data Register does not take place, a write to this register is required in order to clear the SPIF status bit.
6.3 Slave operation
The following sequence can be followed to set up the SPI prior to its first use as a slave. This is typically done during program initialization. 1. Set the SPI Control Register to the desired settings for slave mode. The following sequence describes how one should process a data transfer with the SPI block when it is set up to be a slave. This process assumes that any prior data transfer has already completed. It is required that the system clock driving the SPI logic be at least 8X faster than the SPI. 1. Optionally, verify the SPI setup before starting the transfer. 2. Write the data to transmitted to the SPI Data Register (optional). Note that this can only be done when a slave SPI transfer is not in progress. 3. Wait for the SPIF bit in the SPI Status Register to be set to 1. The SPIF bit will be set after the last sampling clock edge of the SPI data transfer. 4. Read the SPI Status Register. 5. Read the received data from the SPI Data Register (optional). 6. Go to step 2 if more data is to be transferred. Note: A read or write of the SPI Data Register is required in order to clear the SPIF status bit. Therefore, at least one of the optional reads or writes of the SPI Data Register must take place, in order to clear the SPIF status bit.
6.4 Exception conditions
Read Overrun A read overrun occurs when the SPI block internal read buffer contains data that has not been read by the processor, and a new transfer has completed. The read buffer containing valid data is indicated by the SPIF bit in the SPI Interrupt Register being active. When a transfer completes, the SPI block needs to move the received data to the read buffer. If the SPIF bit is active (the read buffer is full), the new receive data will be lost, and the read overrun (ROVR) bit in the SPI Status Register will be activated. Write Collision As stated previously, there is no write buffer between the SPI block bus interface, and the internal shift register. As a result, data must not be written to the SPI Data Register when a SPI data transfer is currently in progress. The time frame where data cannot be written to the SPI Data Register is from when the transfer starts, until after the SPI Status
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Register has been read when the SPIF status is active. If the SPI Data Register is written in this time frame, the write data will be lost, and the write collision (WCOL) bit in the SPI Status Register will be activated. Mode Fault If the SSEL signal goes active when the SPI block is a master, this indicates another master has selected the device to be a slave. This condition is known as a mode fault. When a mode fault is detected, the mode fault (MODF) bit in the SPI Status Register will be activated, the SPI signal drivers will be de-activated, and the SPI mode will be changed to be a slave. If the SSEL function is assigned to its related pin in the relevant Pin Function Select Register, the SSEL signal must always be inactive when the SPI controller is a master. Slave Abort A slave transfer is considered to be aborted if the SSEL signal goes inactive before the transfer is complete. In the event of a slave abort, the transmit and receive data for the transfer that was in progress are lost, and the slave abort (ABRT) bit in the SPI Status Register will be activated.
7. Register description
The SPI contains 5 registers as shown in Table 17-361. All registers are byte, half word and word accessible.
Table 361. SPI register map Name Description Access Reset Value[1] Address
S0SPCR S0SPSR S0SPDR
SPI Control Register. This register controls the operation of the SPI. SPI Status Register. This register shows the status of the SPI.
R/W RO
0x00 0x00 0x00
0x4002 0000 0x4002 0004 0x4002 0008
SPI Data Register. This bi-directional register R/W provides the transmit and receive data for the SPI. Transmit data is provided to the SPI0 by writing to this register. Data received by the SPI0 can be read from this register. R/W R/W
S0SPCCR SPI Clock Counter Register. This register controls the frequency of a master's SCK0. S0SPINT
[1]
0x00 0x00
0x4002 000C 0x4002 001C
SPI Interrupt Flag. This register contains the interrupt flag for the SPI interface.
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
7.1 SPI Control Register (S0SPCR - 0x4002 0000)
The S0SPCR register controls the operation of SPI0 as per the configuration bits setting shown in Table 17-362.
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Table 362: SPI Control Register (S0SPCR - address 0x4002 0000) bit description Bit Symbol Value Description Reset Value
1:0 2
BitEnable 0 1
Reserved, user software should not write ones to reserved bits. NA The value read from a reserved bit is not defined. The SPI controller sends and receives 8 bits of data per transfer. The SPI controller sends and receives the number of bits selected by bits 11:8. Clock phase control determines the relationship between the 0 data and the clock on SPI transfers, and controls when a slave transfer is defined as starting and ending. 0 1 Data is sampled on the first clock edge of SCK. A transfer starts and ends with activation and deactivation of the SSEL signal. Data is sampled on the second clock edge of the SCK. A transfer starts with the first clock edge, and ends with the last sampling edge when the SSEL signal is active. Clock polarity control. 0 1 SCK is active high. SCK is active low. Master mode select. 0 1 The SPI operates in Slave mode. The SPI operates in Master mode. LSB First controls which direction each byte is shifted when transferred. 0 1 SPI data is transferred MSB (bit 7) first. SPI data is transferred LSB (bit 0) first. Serial peripheral interrupt enable. 0 1 SPI interrupts are inhibited. A hardware interrupt is generated each time the SPIF or MODF bits are activated. When bit 2 of this register is 1, this field controls the number of 0000 bits per transfer: 1000 1001 1010 1011 1100 1101 1110 1111 0000 8 bits per transfer 9 bits per transfer 10 bits per transfer 11 bits per transfer 12 bits per transfer 13 bits per transfer 14 bits per transfer 15 bits per transfer 16 bits per transfer Reserved, user software should not write ones to reserved bits. NA The value read from a reserved bit is not defined. 0 0 0 0 0
3
CPHA
4
CPOL
5
MSTR
6
LSBF
7
SPIE
11:8
BITS
31:12 -
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7.2 SPI Status Register (S0SPSR - 0x4002 0004)
The S0SPSR register controls the operation of SPI0 as per the configuration bits setting shown in Table 17-363.
Table 363: SPI Status Register (S0SPSR - address 0x4002 0004) bit description Bit Symbol Description Reset Value
2:0 3 4
ABRT MODF
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Slave abort. When 1, this bit indicates that a slave abort has occurred. This bit is cleared by reading this register. Mode fault. when 1, this bit indicates that a Mode fault error has occurred. This bit is cleared by reading this register, then writing the SPI0 control register. Read overrun. When 1, this bit indicates that a read overrun has occurred. This bit is cleared by reading this register. Write collision. When 1, this bit indicates that a write collision has occurred. This bit is cleared by reading this register, then accessing the SPI Data Register. SPI transfer complete flag. When 1, this bit indicates when a SPI data transfer is complete. When a master, this bit is set at the end of the last cycle of the transfer. When a slave, this bit is set on the last data sampling edge of the SCK. This bit is cleared by first reading this register, then accessing the SPI Data Register.
Note: this is not the SPI interrupt flag. This flag is found in the SPINT register.
NA 0 0
5 6
ROVR WCOL
0 0
7
SPIF
0
31:8
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
7.3 SPI Data Register (S0SPDR - 0x4002 0008)
This bi-directional data register provides the transmit and receive data for the SPI. Transmit data is provided to the SPI by writing to this register. Data received by the SPI can be read from this register. When used as a master, a write to this register will start an SPI data transfer. Writes to this register will be blocked when a data transfer starts, or when the SPIF status bit is set, and the SPI Status Register has not been read.
Table 364: SPI Data Register (S0SPDR - address 0x4002 0008) bit description Bit Symbol Description Reset Value
7:0 15:8
DataLow DataHigh
SPI Bi-directional data port.
0x00
If bit 2 of the SPCR is 1 and bits 11:8 are other than 1000, some or all 0x00 of these bits contain the additional transmit and receive bits. When less than 16 bits are selected, the more significant among these bits read as zeroes. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
31:16 -
7.4 SPI Clock Counter Register (S0SPCCR - 0x4002 000C)
This register controls the frequency of a master's SCK. The register indicates the number of SPI peripheral clock cycles that make up an SPI clock.
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In Master mode, this register must be an even number greater than or equal to 8. Violations of this can result in unpredictable behavior. The SPI0 SCK rate may be calculated as: PCLK_SPI / SPCCR0 value. The SPI peripheral clock is determined by the PCLKSEL0 register contents for PCLK_SPI as described in Section 4-7.3. In Slave mode, the SPI clock rate provided by the master must not exceed 1/8 of the SPI peripheral clock selected in Section 4-7.3. The content of the S0SPCCR register is not relevant.
Table 365: SPI Clock Counter Register (S0SPCCR - address 0x4002 000C) bit description Bit Symbol Description Reset Value
7:0 31:8
Counter -
SPI0 Clock counter setting. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0x00 NA
7.5 SPI Test Control Register (SPTCR - 0x4002 0010)
Note that the bits in this register are intended for functional verification only. This register should not be used for normal operation.
Table 366: SPI Test Control Register (SPTCR - address 0x4002 0010) bit description Bit Symbol Description Reset Value
0 7:1
Test
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. SPI test mode. When 0, the SPI operates normally. When 1, SCK will always be on, independent of master mode select, and data availability setting. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0
31:8
-
NA
7.6 SPI Test Status Register (SPTSR - 0x4002 0014)
Note: The bits in this register are intended for functional verification only. This register should not be used for normal operation. This register is a replication of the SPI Status Register. The difference between the registers is that a read of this register will not start the sequence of events required to clear these status bits. A write to this register will set an interrupt if the write data for the respective bit is a 1.
Table 367: SPI Test Status Register (SPTSR - address 0x4002 0014) bit description Bit Symbol Description Reset Value
2:0 3 4 5
ABRT MODF ROVR
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Slave abort. Mode fault. Read overrun.
NA 0 0 0
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Table 367: SPI Test Status Register (SPTSR - address 0x4002 0014) bit description Bit Symbol Description Reset Value
6 7 31:8
WCOL SPIF -
Write collision. SPI transfer complete flag. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 NA
7.7 SPI Interrupt Register (S0SPINT - 0x4002 001C)
This register contains the interrupt flag for the SPI0 interface.
Table 368: SPI Interrupt Register (S0SPINT - address 0x4002 001C) bit description Bit Symbol Description Reset Value
0
SPIF
SPI interrupt flag. Set by the SPI interface to generate an interrupt. Cleared by writing a 1 to this bit.
Note: this bit will be set once when SPIE = 1 and at least one of SPIF and WCOL bits is 1. However, only when the SPI Interrupt bit is set and SPI0 Interrupt is enabled in the NVIC, SPI based interrupt can be processed by interrupt handling software.
0
7:1 31:8
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA NA
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8. Architecture
The block diagram of the SPI solution implemented in SPI0 interface is shown in the Figure 17-74.
MOSI_IN MOSI_OUT MISO_IN MISO_OUT SPI SHIFT REGISTER
SPI CLOCK GENERATOR & SPI Interrupt SPI REGISTER INTERFACE DETECTOR
SCK_IN SCK_OUT SS_IN
APB Bus
SPI STATE CONTROL
OUTPUT ENABLE LOGIC
SCK_OUT_EN MOSI_OUT_EN MISO_OUT_EN
Fig 74. SPI block diagram
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1. Basic configuration
The two SSP interfaces, SSP0 and SSP1 are configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCSSP0 to enable SSP0 and bit PCSSP1 to enable SSP1. Remark: On reset, both SSP interfaces are enabled (PCSSP0/1 = 1). 2. Clock: In PCLKSEL0 select PCLK_SSP1; in PCLKSEL1 select PCLK_SSP0 (see Section 4-7.3. In master mode, the clock must be scaled down (see Section 18-6.5). 3. Pins: Select the SSP pins through the PINSEL registers (Section 8-5) and pin modes through the PINMODE registers (Section 8-4). 4. Interrupts: Interrupts are enabled in the SSP0IMSC register for SSP0 and SSP1IMSC register for SSP1 Table 18-376. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register, see Table 6-50. 5. Initialization: There are two control registers for each of the SSP ports to be configured: SSP0CR0 and SSP0CR1 for SSP0, SSP1CR0 and SSP1CR1 for SSP1. See Section 18-6.1 and Section 18-6.2. 6. DMA: The Rx and Tx FIFOs of the SSP interfaces can be connected to the GPDMA controller (see Section 18-6.10). For GPDMA system connections, see Table 31-544. Remark: SSP0 is intended to be used as an alternative for the SPI interface, which is included as a legacy peripheral. Only one of these peripherals can be used at the any one time.
2. Features
* Compatible with Motorola SPI, 4-wire TI SSI, and National Semiconductor Microwire
buses.
* * * * *
Synchronous Serial Communication. Master or slave operation. 8 frame FIFOs for both transmit and receive. 4 to 16 bit data frame. DMA transfers supported by GPDMA.
3. Description
The SSP is a Synchronous Serial Port (SSP) controller capable of operation on a SPI, 4-wire SSI, or Microwire bus. It can interact with multiple masters and slaves on the bus. Only a single master and a single slave can communicate on the bus during a given data transfer. Data transfers are in principle full duplex, with frames of 4 to 16 bits of data flowing from the master to the slave and from the slave to the master. In practice it is often the case that only one of these data flows carries meaningful data.
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The LPC17xx has two Synchronous Serial Port controllers -- SSP0 and SSP1.
4. Pin descriptions
Table 369. SSP pin descriptions Pin Name Interface pin Type name/function Pin Description SPI SSI Microwire
SCK0/1
I/O
SCK
CLK
SK
Serial Clock. SCK/CLK/SK is a clock signal used to synchronize the transfer of data. It is driven by the master and received by the slave. When the SPI interface is used, the clock is programmable to be active-high or active-low, otherwise it is always active-high. SCK1 only switches during a data transfer. Any other time, the SSPn interface either holds it in its inactive state, or does not drive it (leaves it in high-impedance state). Frame Sync/Slave Select. When the SSPn interface is a bus master, it drives this signal to an active state before the start of serial data, and then releases it to an inactive state after the serial data has been sent. The active state of this signal can be high or low depending upon the selected bus and mode. When the SSPn is a bus slave, this signal qualifies the presence of data from the Master, according to the protocol in use.
SSEL0/1 I/O
SSEL FS
CS
When there is just one bus master and one bus slave, the Frame Sync or Slave Select signal from the Master can be connected directly to the slave's corresponding input. When there is more than one slave on the bus, further qualification of their Frame Select/Slave Select inputs will typically be necessary to prevent more than one slave from responding to a transfer. MISO0/1 I/O MISO DR(M) SI(M) DX(S) SO(S)
Master In Slave Out. The MISO signal transfers serial data from the slave to the master. When the SSPn is a slave, serial data is output on this signal. When the SSPn is a master, it clocks in serial data from this signal. When the SSPn is a slave and is not selected by FS/SSEL, it does not drive this signal (leaves it in high-impedance state). Master Out Slave In. The MOSI signal transfers serial data from the master to the slave. When the SSPn is a master, it outputs serial data on this signal. When the SSPn is a slave, it clocks in serial data from this signal.
MOSI0/1 I/O
MOSI DX(M) SO(M) DR(S) SI(S)
5. Bus description
5.1 Texas Instruments synchronous serial frame format
Figure 18-75 shows the 4-wire Texas Instruments synchronous serial frame format supported by the SSP module.
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CLK FS DX/DR MSB 4 to 16 bits LSB
a. Single frame transfer
CLK FS DX/DR MSB 4 to 16 bits LSB MSB 4 to 16 bits LSB
b. Continuous/back-to-back frames transfer
Fig 75. Texas Instruments Synchronous Serial Frame Format: a) Single and b) Continuous/back-to-back Two Frames Transfer
For device configured as a master in this mode, CLK and FS are forced LOW, and the transmit data line DX is tri-stated whenever the SSP is idle. Once the bottom entry of the transmit FIFO contains data, FS is pulsed HIGH for one CLK period. The value to be transmitted is also transferred from the transmit FIFO to the serial shift register of the transmit logic. On the next rising edge of CLK, the MSB of the 4-bit to 16-bit data frame is shifted out on the DX pin. Likewise, the MSB of the received data is shifted onto the DR pin by the off-chip serial slave device. Both the SSP and the off-chip serial slave device then clock each data bit into their serial shifter on the falling edge of each CLK. The received data is transferred from the serial shifter to the receive FIFO on the first rising edge of CLK after the LSB has been latched.
5.2 SPI frame format
The SPI interface is a four-wire interface where the SSEL signal behaves as a slave select. The main feature of the SPI format is that the inactive state and phase of the SCK signal are programmable through the CPOL and CPHA bits within the SSPCR0 control register.
5.2.1 Clock Polarity (CPOL) and Phase (CPHA) control
When the CPOL clock polarity control bit is 0, it produces a steady state low value on the SCK pin. If the CPOL clock polarity control bit is 1, a steady state high value is placed on the CLK pin when data is not being transferred.
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The CPHA control bit selects the clock edge that captures data and allows it to change state. It has the most impact on the first bit transmitted by either allowing or not allowing a clock transition before the first data capture edge. When the CPHA phase control bit is 0, data is captured on the first clock edge transition. If the CPHA clock phase control bit is 1, data is captured on the second clock edge transition.
5.2.2 SPI format with CPOL=0,CPHA=0
Single and continuous transmission signal sequences for SPI format with CPOL = 0, CPHA = 0 are shown in Figure 18-76.
SCK SSEL
MOSI MISO
MSB MSB 4 to 16 bits
LSB LSB Q
a. Single transfer with CPOL=0 and CPHA=0
SCK SSEL
MOSI MISO
MSB MSB 4 to 16 bits
LSB LSB Q
MSB MSB 4 to 16 bits
LSB LSB Q
b. Continuous transfer with CPOL=0 and CPHA=0
Fig 76. SPI frame format with CPOL=0 and CPHA=0 (a) Single and b) Continuous Transfer)
In this configuration, during idle periods:
* The CLK signal is forced LOW. * SSEL is forced HIGH. * The transmit MOSI/MISO pad is in high impedance.
If the SSP is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSEL master signal being driven LOW. This causes slave data to be enabled onto the MISO input line of the master. Master's MOSI is enabled. One half SCK period later, valid master data is transferred to the MOSI pin. Now that both the master and slave data have been set, the SCK master clock pin goes HIGH after one further half SCK period. The data is now captured on the rising and propagated on the falling edges of the SCK signal.
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In the case of a single word transmission, after all bits of the data word have been transferred, the SSEL line is returned to its idle HIGH state one SCK period after the last bit has been captured. However, in the case of continuous back-to-back transmissions, the SSEL signal must be pulsed HIGH between each data word transfer. This is because the slave select pin freezes the data in its serial peripheral register and does not allow it to be altered if the CPHA bit is logic zero. Therefore the master device must raise the SSEL pin of the slave device between each data transfer to enable the serial peripheral data write. On completion of the continuous transfer, the SSEL pin is returned to its idle state one SCK period after the last bit has been captured.
5.2.3 SPI format with CPOL=0,CPHA=1
The transfer signal sequence for SPI format with CPOL = 0, CPHA = 1 is shown in Figure 18-77, which covers both single and continuous transfers.
SCK SSEL
MOSI MISO Q
MSB MSB 4 to 16 bits
LSB LSB Q
Fig 77. SPI frame format with CPOL=0 and CPHA=1
In this configuration, during idle periods:
* The CLK signal is forced LOW. * SSEL is forced HIGH. * The transmit MOSI/MISO pad is in high impedance.
If the SSP is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSEL master signal being driven LOW. Master's MOSI pin is enabled. After a further one half SCK period, both master and slave valid data is enabled onto their respective transmission lines. At the same time, the SCK is enabled with a rising edge transition. Data is then captured on the falling edges and propagated on the rising edges of the SCK signal. In the case of a single word transfer, after all bits have been transferred, the SSEL line is returned to its idle HIGH state one SCK period after the last bit has been captured. For continuous back-to-back transfers, the SSEL pin is held LOW between successive data words and termination is the same as that of the single word transfer.
5.2.4 SPI format with CPOL = 1,CPHA = 0
Single and continuous transmission signal sequences for SPI format with CPOL=1, CPHA=0 are shown in Figure 18-78.
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SCK SSEL
MOSI MISO
MSB MSB 4 to 16 bits
LSB LSB Q
a. Single transfer with CPOL=1 and CPHA=0
SCK SSEL
MOSI MISO
MSB MSB 4 to 16 bits
LSB LSB Q
MSB MSB 4 to 16 bits
LSB LSB Q
b. Continuous transfer with CPOL=1 and CPHA=0
Fig 78. SPI frame format with CPOL = 1 and CPHA = 0 (a) Single and b) Continuous Transfer)
In this configuration, during idle periods:
* The CLK signal is forced HIGH. * SSEL is forced HIGH. * The transmit MOSI/MISO pad is in high impedance.
If the SSP is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSEL master signal being driven LOW, which causes slave data to be immediately transferred onto the MISO line of the master. Master's MOSI pin is enabled. One half period later, valid master data is transferred to the MOSI line. Now that both the master and slave data have been set, the SCK master clock pin becomes LOW after one further half SCK period. This means that data is captured on the falling edges and be propagated on the rising edges of the SCK signal. In the case of a single word transmission, after all bits of the data word are transferred, the SSEL line is returned to its idle HIGH state one SCK period after the last bit has been captured. However, in the case of continuous back-to-back transmissions, the SSEL signal must be pulsed HIGH between each data word transfer. This is because the slave select pin freezes the data in its serial peripheral register and does not allow it to be altered if the CPHA bit is logic zero. Therefore the master device must raise the SSEL pin of the slave device between each data transfer to enable the serial peripheral data write. On completion of the continuous transfer, the SSEL pin is returned to its idle state one SCK period after the last bit has been captured.
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5.2.5 SPI format with CPOL = 1,CPHA = 1
The transfer signal sequence for SPI format with CPOL = 1, CPHA = 1 is shown in Figure 18-79, which covers both single and continuous transfers.
SCK SSEL
MOSI MISO Q
MSB MSB 4 to 16 bits
LSB LSB Q
Fig 79. SPI Frame Format with CPOL = 1 and CPHA = 1
In this configuration, during idle periods:
* The CLK signal is forced HIGH. * SSEL is forced HIGH. * The transmit MOSI/MISO pad is in high impedance.
If the SSP is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSEL master signal being driven LOW. Master's MOSI is enabled. After a further one half SCK period, both master and slave data are enabled onto their respective transmission lines. At the same time, the SCK is enabled with a falling edge transition. Data is then captured on the rising edges and propagated on the falling edges of the SCK signal. After all bits have been transferred, in the case of a single word transmission, the SSEL line is returned to its idle HIGH state one SCK period after the last bit has been captured. For continuous back-to-back transmissions, the SSEL pins remains in its active LOW state, until the final bit of the last word has been captured, and then returns to its idle state as described above. In general, for continuous back-to-back transfers the SSEL pin is held LOW between successive data words and termination is the same as that of the single word transfer.
5.3 National Semiconductor Microwire frame format
Figure 18-80 shows the Microwire frame format for a single frame. Figure 18-81 shows the same format when back-to-back frames are transmitted.
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SK CS
SO SI
MSB
LSB
8-bit control 0 MSB
LSB
4 to 16 bits output data
Fig 80. Microwire frame format (single transfer)
Microwire format is very similar to SPI format, except that transmission is half-duplex instead of full-duplex, using a master-slave message passing technique. Each serial transmission begins with an 8-bit control word that is transmitted from the SSP to the off-chip slave device. During this transmission, no incoming data is received by the SSP. After the message has been sent, the off-chip slave decodes it and, after waiting one serial clock after the last bit of the 8-bit control message has been sent, responds with the required data. The returned data is 4 to 16 bits in length, making the total frame length anywhere from 13 to 25 bits. In this configuration, during idle periods:
* The SK signal is forced LOW. * CS is forced HIGH. * The transmit data line SO is arbitrarily forced LOW.
A transmission is triggered by writing a control byte to the transmit FIFO.The falling edge of CS causes the value contained in the bottom entry of the transmit FIFO to be transferred to the serial shift register of the transmit logic, and the MSB of the 8-bit control frame to be shifted out onto the SO pin. CS remains LOW for the duration of the frame transmission. The SI pin remains tristated during this transmission. The off-chip serial slave device latches each control bit into its serial shifter on the rising edge of each SK. After the last bit is latched by the slave device, the control byte is decoded during a one clock wait-state, and the slave responds by transmitting data back to the SSP. Each bit is driven onto SI line on the falling edge of SK. The SSP in turn latches each bit on the rising edge of SK. At the end of the frame, for single transfers, the CS signal is pulled HIGH one clock period after the last bit has been latched in the receive serial shifter, that causes the data to be transferred to the receive FIFO. Note: The off-chip slave device can tristate the receive line either on the falling edge of SK after the LSB has been latched by the receive shiftier, or when the CS pin goes HIGH. For continuous transfers, data transmission begins and ends in the same manner as a single transfer. However, the CS line is continuously asserted (held LOW) and transmission of data occurs back to back. The control byte of the next frame follows directly after the LSB of the received data from the current frame. Each of the received values is transferred from the receive shifter on the falling edge SK, after the LSB of the frame has been latched into the SSP.
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SK CS SO SI
LSB MSB LSB
8-bit control 0 MSB
LSB MSB LSB
4 to 16 bits output data
4 to 16 bits output data
Fig 81. Microwire frame format (continuos transfers)
5.3.1 Setup and hold time requirements on CS with respect to SK in Microwire mode
In the Microwire mode, the SSP slave samples the first bit of receive data on the rising edge of SK after CS has gone LOW. Masters that drive a free-running SK must ensure that the CS signal has sufficient setup and hold margins with respect to the rising edge of SK. Figure 18-82 illustrates these setup and hold time requirements. With respect to the SK rising edge on which the first bit of receive data is to be sampled by the SSP slave, CS must have a setup of at least two times the period of SK on which the SSP operates. With respect to the SK rising edge previous to this edge, CS must have a hold of at least one SK period.
t HOLD= tSK
tSETUP=2*tSK
SK CS
SI
Fig 82. Microwire frame format setup and hold details
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6. Register description
The register addresses of the SSP controllers addresses are shown in Table 18-370.
Table 370. SSP Register Map Generic Name Description Access Reset Value[1] SSPn Register Name & Address
CR0
Control Register 0. Selects the R/W serial clock rate, bus type, and data size. Control Register 1. Selects master/slave and other modes. Data Register. Writes fill the transmit FIFO, and reads empty the receive FIFO. Status Register Clock Prescale Register Interrupt Mask Set and Clear Register Raw Interrupt Status Register Masked Interrupt Status Register SSPICR Interrupt Clear Register DMA Control Register R/W R/W
0
SSP0CR0 - 0x4008 8000 SSP1CR0 - 0x4003 0000 SSP0CR1 - 0x4008 8004 SSP1CR1 - 0x4003 0004 SSP0DR - 0x4008 8008 SSP1DR - 0x4003 0008 SSP0SR - 0x4008 800C SSP1SR - 0x4003 000C
CR1 DR
0 0
SR CPSR IMSC RIS MIS ICR DMACR
RO R/W R/W R/W R/W R/W R/W 0 NA 0 0 0
SSP0CPSR - 0x4008 8010 SSP1CPSR - 0x4003 0010 SSP0IMSC - 0x4008 8014 SSP1IMSC - 0x4003 0014 SSP0RIS - 0x4008 8018 SSP1RIS - 0x4003 0018 SSP0MIS - 0x4008 801C SSP1MIS - 0x4003 001C SSP0ICR - 0x4008 8020 SSP1ICR - 0x4003 0020 SSP0DMACR - 0x4008 8024 SSP1DMACR - 0x4003 0024
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
6.1 SSPn Control Register 0 (SSP0CR0 - 0x4008 8000, SSP1CR0 - 0x4003 0000)
This register controls the basic operation of the SSP controller.
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Table 371: SSPn Control Register 0 (SSP0CR0 - address 0x4008 8000, SSP1CR0 0x4003 0000) bit description Bit Symbol Value Description Reset Value
3:0
DSS
Data Size Select. This field controls the number of bits transferred in each frame. Values 0000-0010 are not supported and should not be used. 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 4-bit transfer 5-bit transfer 6-bit transfer 7-bit transfer 8-bit transfer 9-bit transfer 10-bit transfer 11-bit transfer 12-bit transfer 13-bit transfer 14-bit transfer 15-bit transfer 16-bit transfer Frame Format. 00 01 10 11 SPI TI Microwire This combination is not supported and should not be used. Clock Out Polarity. This bit is only used in SPI mode. 0 1 SSP controller maintains the bus clock low between frames. SSP controller maintains the bus clock high between frames. Clock Out Phase. This bit is only used in SPI mode. 0 SSP controller captures serial data on the first clock transition of the frame, that is, the transition away from the inter-frame state of the clock line. SSP controller captures serial data on the second clock transition of the frame, that is, the transition back to the inter-frame state of the clock line.
0000
5:4
FRF
00
6
CPOL
0
7
CPHA
0
1
15:8
SCR
Serial Clock Rate. The number of prescaler-output clocks per bit 0x00 on the bus, minus one. Given that CPSDVSR is the prescale divider, and the APB clock PCLK clocks the prescaler, the bit frequency is PCLK / (CPSDVSR x [SCR+1]). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
31:8
-
6.2 SSPn Control Register 1 (SSP0CR1 - 0x4008 8004, SSP1CR1 0x4003 0004)
This register controls certain aspects of the operation of the SSP controller.
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Table 372: SSPn Control Register 1 (SSP0CR1 - address 0x4008 8004, SSP1CR1 0x4003 0004) bit description Bit Symbol Value Description Reset Value
0
LBM 0 1
Loop Back Mode. During normal operation. Serial input is taken from the serial output (MOSI or MISO) rather than the serial input pin (MISO or MOSI respectively). SSP Enable. 0 1 The SSP controller is disabled. The SSP controller will interact with other devices on the serial bus. Software should write the appropriate control information to the other SSP registers and interrupt controller registers, before setting this bit.
0
1
SSE
0
2
MS 0 1
Master/Slave Mode.This bit can only be written when the SSE bit 0 is 0. The SSP controller acts as a master on the bus, driving the SCLK, MOSI, and SSEL lines and receiving the MISO line. The SSP controller acts as a slave on the bus, driving MISO line and receiving SCLK, MOSI, and SSEL lines. Slave Output Disable. This bit is relevant only in slave mode 0 (MS = 1). If it is 1, this blocks this SSP controller from driving the transmit data line (MISO). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
3
SOD
31:4
-
6.3 SSPn Data Register (SSP0DR - 0x4008 8008, SSP1DR - 0x4003 0008)
Software can write data to be transmitted to this register, and read data that has been received.
Table 373: SSPn Data Register (SSP0DR - address 0x4008 8008, SSP1DR - 0x4003 0008) bit description Bit Symbol Description Reset Value
15:0
DATA
Write: software can write data to be sent in a future frame to this 0x0000 register whenever the TNF bit in the Status register is 1, indicating that the Tx FIFO is not full. If the Tx FIFO was previously empty and the SSP controller is not busy on the bus, transmission of the data will begin immediately. Otherwise the data written to this register will be sent as soon as all previous data has been sent (and received). If the data length is less than 16 bits, software must right-justify the data written to this register. Read: software can read data from this register whenever the RNE bit in the Status register is 1, indicating that the Rx FIFO is not empty. When software reads this register, the SSP controller returns data from the least recent frame in the Rx FIFO. If the data length is less than 16 bits, the data is right-justified in this field with higher order bits filled with 0s.
31:16 -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
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6.4 SSPn Status Register (SSP0SR - 0x4008 800C, SSP1SR 0x4003 000C)
This read-only register reflects the current status of the SSP controller.
Table 374: SSPn Status Register (SSP0SR - address 0x4008 800C, SSP1SR - 0x4003 000C) bit description Bit Symbol Description Reset Value
0 1 2 3 4 31:5
TFE TNF RNE RFF BSY -
Transmit FIFO Empty. This bit is 1 is the Transmit FIFO is empty, 0 if not. 1 Transmit FIFO Not Full. This bit is 0 if the Tx FIFO is full, 1 if not. Receive FIFO Not Empty. This bit is 0 if the Receive FIFO is empty, 1 if not. Receive FIFO Full. This bit is 1 if the Receive FIFO is full, 0 if not. Busy. This bit is 0 if the SSPn controller is idle, or 1 if it is currently sending/receiving a frame and/or the Tx FIFO is not empty. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 1 0 0 0 NA
6.5 SSPn Clock Prescale Register (SSP0CPSR - 0x4008 8010, SSP1CPSR - 0x4003 0010)
This register controls the factor by which the Prescaler divides the SSP peripheral clock SSP_PCLK to yield the prescaler clock that is, in turn, divided by the SCR factor in SSPnCR0, to determine the bit clock.
Table 375: SSPn Clock Prescale Register (SSP0CPSR - address 0x4008 8010, SSP1CPSR 0x4003 0010) bit description Bit Symbol Description Reset Value
7:0 31:8
CPSDVSR -
This even value between 2 and 254, by which SSP_PCLK is divided to yield the prescaler output clock. Bit 0 always reads as 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
Important: the SSPnCPSR value must be properly initialized or the SSP controller will not be able to transmit data correctly. In Slave mode, the SSP clock rate provided by the master must not exceed 1/12 of the SSP peripheral clock selected in Section 4-7.3. The content of the SSPnCPSR register is not relevant. In master mode, CPSDVSRmin = 2 or larger (even numbers only).
6.6 SSPn Interrupt Mask Set/Clear Register (SSP0IMSC - 0x4008 8014, SSP1IMSC - 0x4003 0014)
This register controls whether each of the four possible interrupt conditions in the SSP controller are enabled. Note that ARM uses the word "masked" in the opposite sense from classic computer terminology, in which "masked" meant "disabled". ARM uses the word "masked" to mean "enabled". To avoid confusion we will not use the word "masked".
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Table 376: SSPn Interrupt Mask Set/Clear register (SSP0IMSC - address 0x4008 8014, SSP1IMSC - 0x4003 0014) bit description Bit Symbol Description Reset Value
0
RORIM
Software should set this bit to enable interrupt when a Receive Overrun 0 occurs, that is, when the Rx FIFO is full and another frame is completely received. The ARM spec implies that the preceding frame data is overwritten by the new frame data when this occurs. Software should set this bit to enable interrupt when a Receive Timeout condition occurs. A Receive Timeout occurs when the Rx FIFO is not empty, and no has not been read for a "timeout period". Software should set this bit to enable interrupt when the Rx FIFO is at least half full. Software should set this bit to enable interrupt when the Tx FIFO is at least half empty. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0
1
RTIM
2 3 31:4
RXIM TXIM -
0 0 NA
6.7 SSPn Raw Interrupt Status Register (SSP0RIS - 0x4008 8018, SSP1RIS - 0x4003 0018)
This read-only register contains a 1 for each interrupt condition that is asserted, regardless of whether or not the interrupt is enabled in the SSPnIMSC.
Table 377: SSPn Raw Interrupt Status register (SSP0RIS - address 0x4008 8018, SSP1RIS 0x4003 0018) bit description Bit Symbol Description Reset Value
0
RORRIS
This bit is 1 if another frame was completely received while the RxFIFO 0 was full. The ARM spec implies that the preceding frame data is overwritten by the new frame data when this occurs. This bit is 1 if the Rx FIFO is not empty, and has not been read for a "timeout period". This bit is 1 if the Rx FIFO is at least half full. This bit is 1 if the Tx FIFO is at least half empty. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 0 1 NA
1 2 3 31:4
RTRIS RXRIS TXRIS -
6.8 SSPn Masked Interrupt Status Register (SSP0MIS - 0x4008 801C, SSP1MIS - 0x4003 001C)
This read-only register contains a 1 for each interrupt condition that is asserted and enabled in the SSPnIMSC. When an SSP interrupt occurs, the interrupt service routine should read this register to determine the cause(s) of the interrupt.
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Table 378: SSPn Masked Interrupt Status register (SSPnMIS -address 0x4008 801C, SSP1MIS - 0x4003 001C) bit description Bit Symbol Description Reset Value
0 1 2 3 31:4
RORMIS RTMIS RXMIS TXMIS -
This bit is 1 if another frame was completely received while the RxFIFO 0 was full, and this interrupt is enabled. This bit is 1 if the Rx FIFO is not empty, has not been read for a "timeout period", and this interrupt is enabled. This bit is 1 if the Rx FIFO is at least half full, and this interrupt is enabled. This bit is 1 if the Tx FIFO is at least half empty, and this interrupt is enabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. 0 0 0 NA
6.9 SSPn Interrupt Clear Register (SSP0ICR - 0x4008 8020, SSP1ICR 0x4003 0020)
Software can write one or more one(s) to this write-only register, to clear the corresponding interrupt condition(s) in the SSP controller. Note that the other two interrupt conditions can be cleared by writing or reading the appropriate FIFO, or disabled by clearing the corresponding bit in SSPnIMSC.
Table 379: SSPn interrupt Clear Register (SSP0ICR - address 0x4008 8020, SSP1ICR 0x4003 0020) bit description Bit Symbol Description Reset Value
0 1 31:2
RORIC RTIC -
Writing a 1 to this bit clears the "frame was received when RxFIFO was full" interrupt. Writing a 1 to this bit clears the "Rx FIFO was not empty and has not been read for a timeout period" interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA NA NA
6.10 SSPn DMA Control Register (SSP0DMACR - 0x4008 8024, SSP1DMACR - 0x4003 0024)
The SSPnDMACR register is the DMA control register. It is a read/write register.
Table 380: SSPn DMA Control Register (SSP0DMACR - address 0x4008 8024, SSP1DMACR 0x4003 0024) bit description Bit Symbol Description Reset Value
0 1 31:2
Receive DMA Enable (RXDMAE) Transmit DMA Enable (TXDMAE) -
When this bit is set to one 1, DMA for the receive FIFO is enabled, otherwise receive DMA is disabled.
0
When this bit is set to one 1, DMA for the transmit FIFO is 0 enabled, otherwise transmit DMA is disabled Reserved, user software should not write ones to reserved NA bits. The value read from a reserved bit is not defined.
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1. Basic configuration
The I2C0/1/2 interfaces are configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCI2C0/1/2. Remark: On reset, all I2C interfaces are enabled (PCI2C0/1/2 = 1). 2. Clock: In PCLKSEL0 select PCLK_I2C0; in PCLKSEL1 select PCLK_I2C1 or PCLK_I2C2 (see Section 4-7.3). 3. Pins: Select I2C0, I2C1, or I2C2 pins through the PINSEL registers. Select the pin modes for the port pins with I2C1 or I2C2 functions through the PINMODE registers (no pull-up, no pull-down resistors) and the PINMODE_OD registers (open drain) (See Section 8-5). Remark: I2C0 pins SDA0 and SCL0 are open-drain outputs and fully I2C-bus compliant (see Table 7-72). I2C0 can be further configured through the I2CPADCFG register to support Fast Mode Plus (See Table 8-98). Remark: I2C0 is not available in the 80-pin package. Remark: I2C1 and I2C2 pins are not fully I2C-bus compliant open-drain pins but can be configured to be open-drain via the PINMODE and PINMODE_OD registers. The non-compliance is in the I2C-bus ability to turn off power to the device without pulling down the I2C-bus itself. 4. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 5. Initialization: see Section 19-9.8.1 and Section 19-10.1.
2. Features
* Standard I2C compliant bus interfaces may be configured as Master, Slave, or
Master/Slave.
* Arbitration is handled between simultaneously transmitting masters without corruption
of serial data on the bus.
* Programmable clock allows adjustment of I2C transfer rates. * Data transfer is bidirectional between masters and slaves. * Serial clock synchronization allows devices with different bit rates to communicate via
one serial bus.
* Serial clock synchronization is used as a handshake mechanism to suspend and
resume serial transfer.
* Supports Fast Mode Plus (I2C0 only). * Optional recognition of up to 4 distinct slave addresses. * Monitor mode allows observing all I2C-bus traffic, regardless of slave address, without
affecting the actual I2C-bus traffic.
* The I2C-bus can be used for test and diagnostic purposes.
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* I2C0 is a standard I2C compliant bus interface with open-drain pins. This interface
supports functions described in the I2C specification for speeds up to 1 MHz. This includes multi-master operation and allows powering off this device in a working system while leaving the I2C-bus functional.
* I2C1 and I2C2 use standard I/O pins and are intended for use with a single-master
I2C-bus and do not support powering off of this device while leaving the I2C-bus functional, and do not support multi-master I2C implementations.
3. Applications
Interfaces to external I2C standard parts, such as serial RAMs, LCDs, tone generators, other microcontrollers, etc.
4. Description
A typical I2C-bus configuration is shown in Figure 19-83. Depending on the state of the direction bit (R/W), two types of data transfers are possible on the I2C-bus:
* Data transfer from a master transmitter to a slave receiver. The first byte transmitted
by the master is the slave address. Next follows a number of data bytes. The slave returns an acknowledge bit after each received byte, unless the slave device is unable to accept more data.
* Data transfer from a slave transmitter to a master receiver. The first byte (the slave
address) is transmitted by the master. The slave then returns an acknowledge bit. Next follows the data bytes transmitted by the slave to the master. The master returns an acknowledge bit after all received bytes other than the last byte. At the end of the last received byte, a "not acknowledge" is returned. The master device generates all of the serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or with a repeated START condition. Since a repeated START condition is also the beginning of the next serial transfer, the I2C-bus will not be released. The LPC17xx I2C interfaces are byte oriented and have four operating modes: master transmitter mode, master receiver mode, slave transmitter mode and slave receiver mode. I2C0 complies with the entire I2C specification, supporting the ability to have the LPC17xx powered off and not interfere with other powered devices on the same I2C-bus. I2C1 and I2C2 do not support the ability to have the power to the LPC17xx turned off without interfering with other powered devices on the same I2C-bus. Since I2C1 and I2C2 use standard port pins, internal pull-ups could (in theory) be enabled in order to pull I2C-bus signals high when they are not driven low. However, these internal pull-ups are far weaker than what would normally be used for I2C, so this practice is not recommended. Refer to the "I2C-bus specification and user manual" for information on proper pull-up values for a specific case.
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pull-up resistor
pull-up resistor
SDA I 2C bus SCL
SDA
SCL OTHER DEVICE WITH I 2C INTERFACE OTHER DEVICE WITH I 2C INTERFACE
LPCXXXX
Fig 83. I2C-bus configuration
4.1 I2C FAST Mode Plus
Fast Mode Plus is a 1 Mbit/sec transfer rate to communicate with the I2C products which the NXP Semiconductors is now providing. In order to use Fast Mode Plus, the I2C0 pins must be configured, then rates above 400 kHz and up to 1 Mhz may be selected, see Table 19-395. To configure the pins for Fast Mode Plus, the SDADRV0 and SCLDRV0 bits in the I2CPADCFG register must be set, see Section 8-5.21.
5. Pin description
Table 381. I2C Pin Description Pin Type Description
SDA0[1] SCL0[1] SDA1 SCL1 SDA2 SCL2
[1]
Input/Output Input/Output Input/Output Input/Output Input/Output Input/Output
I2C0 Serial Data I2C0 Serial Clock I2C1 Serial Data I2C1 Serial Clock I2C2 Serial Data I2C2 Serial Clock
I2C0 is only available in 100-pin LPC17xx devices. The SDA0 and SCL0 pins are open-drain pins to comply with I2C specifications. The pins must be configured in the I2CPADCFG register for Fast Mode Plus.
The three I2C interfaces are identical except for the pin I/O characteristics. I2C0 complies with the entire I2C specification, supporting the ability to turn power off to the device without causing a problem with other devices on the same I2C-bus (see "The I2C-bus specification" description under the heading "Fast Mode", and notes for the table titled "Characteristics of the SDA and SCL I/O stages for F/S-mode I2C-bus devices"). This is sometimes a useful capability, but intrinsically limits alternate uses for the same pins if the I2C interface is not used. Seldom is this capability needed on multiple I2C interfaces within
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the same microcontroller. Therefore, I2C1 and I2C2 are implemented using standard port pins, and do not support the ability to turn power off to the device while leaving the I2C-bus functioning between other devices. Standard I/Os also change I2C-bus pull-up characteristics and do not support multi-master I2C implementations. This difference should be considered during system design while assigning uses for the I2C interfaces. The pins associated with I2C1 and I2C2 should be switched to the open drain mode when the pins are used for I2C communications.
6. I2C operating modes
In a given application, the I2C block may operate as a master, a slave, or both. In the slave mode, the I2C hardware looks for any one of its four slave addresses and the General Call address. If one of these addresses is detected, an interrupt is requested. If the processor wishes to become the bus master, the hardware waits until the bus is free before the master mode is entered so that a possible slave operation is not interrupted. If bus arbitration is lost in the master mode, the I2C block switches to the slave mode immediately and can detect any of its own configured slave addresses in the same serial transfer.
6.1 Master Transmitter mode
In this mode data is transmitted from master to slave. Before the master transmitter mode can be entered, the I2CONSET register must be initialized as shown in Table 19-382. I2EN must be set to 1 to enable the I2C function. If the AA bit is 0, the I2C interface will not acknowledge any address when another device is master of the bus, so it can not enter slave mode. The STA, STO and SI bits must be 0. The SI bit is cleared by writing 1 to the SIC bit in the I2CONCLR register. THe STA bit should be cleared after writing the slave address.
Table 382. I2C0CONSET and I2C1CONSET used to configure Master mode Bit 7 6 5 4 3 2 1 0
Symbol Value
-
I2EN 1
STA 0
STO 0
SI 0
AA 0
-
-
The first byte transmitted contains the slave address of the receiving device (7 bits) and the data direction bit. In this mode the data direction bit (R/W) should be 0 which means Write. The first byte transmitted contains the slave address and Write bit. Data is transmitted 8 bits at a time. After each byte is transmitted, an acknowledge bit is received. START and STOP conditions are output to indicate the beginning and the end of a serial transfer. The I2C interface will enter master transmitter mode when software sets the STA bit. The I2C logic will send the START condition as soon as the bus is free. After the START condition is transmitted, the SI bit is set, and the status code in the I2STAT register is 0x08. This status code is used to vector to a state service routine which will load the slave address and Write bit to the I2DAT register, and then clear the SI bit. SI is cleared by writing a 1 to the SIC bit in the I2CONCLR register.
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When the slave address and R/W bit have been transmitted and an acknowledgment bit has been received, the SI bit is set again, and the possible status codes now are 0x18, 0x20, or 0x38 for the master mode, or 0x68, 0x78, or 0xB0 if the slave mode was enabled (by setting AA to 1). The appropriate actions to be taken for each of these status codes are shown in Table 19-399 to Table 19-402.
S
SLAVE ADDRESS
RW=0
A
DATA
A
DATA
A/A
P
n bytes data transmitted
A = Acknowledge (SDA low) from Master to Slave from Slave to Master A = Not acknowledge (SDA high) S = START condition P = STOP condition
Fig 84. Format in the Master Transmitter mode
6.2 Master Receiver mode
In the master receiver mode, data is received from a slave transmitter. The transfer is initiated in the same way as in the master transmitter mode. When the START condition has been transmitted, the interrupt service routine must load the slave address and the data direction bit to the I2C Data register (I2DAT), and then clear the SI bit. In this case, the data direction bit (R/W) should be 1 to indicate a read. When the slave address and data direction bit have been transmitted and an acknowledge bit has been received, the SI bit is set, and the Status Register will show the status code. For master mode, the possible status codes are 0x40, 0x48, or 0x38. For slave mode, the possible status codes are 0x68, 0x78, or 0xB0. For details, refer to Table 19-400. When the LPC17xx needs to acknowledge a received byte, the AA bit needs to be set accordingly prior to clearing the SI bit and initiating the byte read. When the LPC17xx needs to not acknowledge a received byte, the AA bit needs to be cleared prior to clearing the SI bit and initiating the byte read. Note that the last received byte is always followed by a "Not Acknowledge" from the LPC17xx so that the master can signal the slave that the reading sequence is finished and that it needs to issue a STOP or repeated START Command. Once the "Not Acknowledge has been sent and the SI bit is set, the LPC17xx can send either a STOP (STO bit is set) or a repeated START (STA bit is set). Then the SI bit is cleared to initiate the requested operation.
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S
SLAVE ADDRESS
RW=1
A
DATA
A
DATA
A
P
n bytes data received
A = Acknowledge (SDA low) from Master to Slave from Slave to Master A = Not acknowledge (SDA high) S = START condition P = STOP condition
Fig 85. Format of Master Receiver mode
After a repeated START condition, I2C may switch to the master transmitter mode.
S
SLA
R
A
DATA
A
DATA
A
Sr
SLA
W
A
DATA
A
P
n bytes data transmitted A = Acknowledge (SDA low) A = Not acknowledge (SDA high) From master to slave From slave to master S = START condition P = STOP condition SLA = Slave Address Sr = Repeated START condition
Fig 86. A Master Receiver switches to Master Transmitter after sending repeated START
6.3 Slave Receiver mode
In the slave receiver mode, data bytes are received from a master transmitter. To initialize the slave receiver mode, write any of the Slave Address registers (I2ADR0-3) and Slave Mask registers (I2MASK0-3) and write the I2C Control Set register (I2CONSET) as shown in Table 19-383.
Table 383. I2C0CONSET and I2C1CONSET used to configure Slave mode Bit 7 6 5 4 3 2 1 0
Symbol Value
-
I2EN 1
STA 0
STO 0
SI 0
AA 1
-
-
I2EN must be set to 1 to enable the I2C function. AA bit must be set to 1 to acknowledge any of its own slave addresses or the General Call address. The STA, STO and SI bits are set to 0. After I2ADR and I2CONSET are initialized, the I2C interface waits until it is addressed by its any of its own slave addresses or General Call address followed by the data direction bit. If the direction bit is 0 (W), it enters slave receiver mode. If the direction bit is 1 (R), it
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enters slave transmitter mode. After the address and direction bit have been received, the SI bit is set and a valid status code can be read from the Status register (I2STAT). Refer to Table 19-401 for the status codes and actions.
S
SLAVE ADDRESS
RW=0
A
DATA
A
DATA
A/A
P/Sr
n bytes data received
A = Acknowledge (SDA low) from Master to Slave from Slave to Master A = Not acknowledge (SDA high) S = START condition P = STOP condition Sr = Repeated START condition
Fig 87. Format of Slave Receiver mode
6.4 Slave Transmitter mode
The first byte is received and handled as in the slave receiver mode. However, in this mode, the direction bit will be 1, indicating a read operation. Serial data is transmitted via SDA while the serial clock is input through SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer. In a given application, I2C may operate as a master and as a slave. In the slave mode, the I2C hardware looks for any of its own slave addresses and the General Call address. If one of these addresses is detected, an interrupt is requested. When the microcontrollers wishes to become the bus master, the hardware waits until the bus is free before the master mode is entered so that a possible slave action is not interrupted. If bus arbitration is lost in the master mode, the I2C interface switches to the slave mode immediately and can detect any of its own slave addresses in the same serial transfer.
S
SLAVE ADDRESS
RW=1
A
DATA
A
DATA
A
P
n bytes data transmitted
A = Acknowledge (SDA low) from Master to Slave from Slave to Master A = Not acknowledge (SDA high) S = START condition P = STOP condition
Fig 88. Format of Slave Transmitter mode
7. I2C implementation and operation
Figure 19-89 shows how the on-chip I2C-bus interface is implemented, and the following text describes the individual blocks.
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7.1 Input filters and output stages
Input signals are synchronized with the internal clock, and spikes shorter than three clocks are filtered out. The output for I2C is a special pad designed to conform to the I2C specification.
8
ADDRESS REGISTERS I2CnADDR0 to I2CnADDR3 MATCHALL I2CnMMCTRL[3] MASK and COMPARE INPUT FILTER SDA OUTPUT STAGE SHIFT REGISTER I2CnDAT ACK 8 MASK REGISTERS I2CnMASK0 to I2CnMASK3 I2CnDATABUFFER
MONITOR MODE REGISTER I2CnMMCTRL APB BUS PCLK TIMING and CONTROL LOGIC OUTPUT STAGE SERIAL CLOCK GENERATOR interrupt 16 8
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INPUT FILTER SCL
BIT COUNTER/ ARBITRATION and SYNC LOGIC
CONTROL REGISTER and SCL DUTY CYLE REGISTERS I2CnCONSET, I2CnCONCLR, I2CnSCLH, I2CnSCLL
status bus
STATUS DECODER
STATUS REGISTER I2CnSTAT
Fig 89. I2C serial interface block diagram
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7.2 Address Registers, I2ADR0 to I2ADR3
These registers may be loaded with the 7-bit slave address (7 most significant bits) to which the I2C block will respond when programmed as a slave transmitter or receiver. The LSB (GC) is used to enable General Call address (0x00) recognition. When multiple slave addresses are enabled, the actual address received may be read from the I2DAT register at the state where the "own slave address" has just been received. Remark: in the remainder of this chapter, when the phrase "own slave address" is used, it refers to any of the four configured slave addresses after address masking.
7.3 Address mask registers, I2MASK0 to I2MASK3
The four mask registers each contain seven active bits (7:1). Any bit in these registers which is set to `1' will cause an automatic compare on the corresponding bit of the received address when it is compared to the I2ADRn register associated with that mask register. In other words, bits in an I2ADRn register which are masked are not taken into account in determining an address match. When an address-match interrupt occurs, the processor will have to read the data register (I2DAT) to determine which received address actually caused the match.
7.4 Comparator
The comparator compares the received 7-bit slave address with any of the four configured slave addresses in I2ADR0 through I2ADR3 after masking. It also compares the first received 8-bit byte with the General Call address (0x00). If an a match is found, the appropriate status bits are set and an interrupt is requested.
7.5 Shift register, I2DAT
This 8-bit register contains a byte of serial data to be transmitted or a byte which has just been received. Data in I2DAT is always shifted from right to left; the first bit to be transmitted is the MSB (bit 7) and, after a byte has been received, the first bit of received data is located at the MSB of I2DAT. While data is being shifted out, data on the bus is simultaneously being shifted in; I2DAT always contains the last byte present on the bus. Thus, in the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data in I2DAT.
7.6 Arbitration and synchronization logic
In the master transmitter mode, the arbitration logic checks that every transmitted logic 1 actually appears as a logic 1 on the I2C-bus. If another device on the bus overrules a logic 1 and pulls the SDA line low, arbitration is lost, and the I2C block immediately changes from master transmitter to slave receiver. The I2C block will continue to output clock pulses (on SCL) until transmission of the current serial byte is complete. Arbitration may also be lost in the master receiver mode. Loss of arbitration in this mode can only occur while the I2C block is returning a "not acknowledge: (logic 1) to the bus. Arbitration is lost when another device on the bus pulls this signal low. Since this can occur only at the end of a serial byte, the I2C block generates no further clock pulses. Figure 19-90 shows the arbitration procedure.
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(1) SDA line
(1)
(2)
(3)
SCL line
1
2
3
4
8
9 ACK
(1) Another device transmits serial data. (2) Another device overrules a logic (dotted line) transmitted this I2C master by pulling the SDA line low. Arbitration is lost, and this I2C enters Slave Receiver mode. (3) This I2C is in Slave Receiver mode but still generates clock pulses until the current byte has been transmitted. This I2C will not generate clock pulses for the next byte. Data on SDA originates from the new master once it has won arbitration.
Fig 90. Arbitration procedure
The synchronization logic will synchronize the serial clock generator with the clock pulses on the SCL line from another device. If two or more master devices generate clock pulses, the "mark" duration is determined by the device that generates the shortest "marks," and the "space" duration is determined by the device that generates the longest "spaces". Figure 19-91 shows the synchronization procedure.
SDA line (1) SCL line (2) high period low period (3) (1)
(1) Another device pulls the SCL line low before this I2C has timed a complete high time. The other device effectively determines the (shorter) HIGH period. (2) Another device continues to pull the SCL line low after this I2C has timed a complete low time and released SCL. The I2C clock generator is forced to wait until SCL goes HIGH. The other device effectively determines the (longer) LOW period. (3) The SCL line is released , and the clock generator begins timing the HIGH time.
Fig 91. Serial clock synchronization
A slave may stretch the space duration to slow down the bus master. The space duration may also be stretched for handshaking purposes. This can be done after each bit or after a complete byte transfer. the I2C block will stretch the SCL space duration after a byte has been transmitted or received and the acknowledge bit has been transferred. The serial interrupt flag (SI) is set, and the stretching continues until the serial interrupt flag is cleared.
7.7 Serial clock generator
This programmable clock pulse generator provides the SCL clock pulses when the I2C block is in the master transmitter or master receiver mode. It is switched off when the I2C block is in a slave mode. The I2C output clock frequency and duty cycle is programmable
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via the I2C Clock Control Registers. See the description of the I2CSCLL and I2CSCLH registers for details. The output clock pulses have a duty cycle as programmed unless the bus is synchronizing with other SCL clock sources as described above.
7.8 Timing and control
The timing and control logic generates the timing and control signals for serial byte handling. This logic block provides the shift pulses for I2DAT, enables the comparator, generates and detects START and STOP conditions, receives and transmits acknowledge bits, controls the master and slave modes, contains interrupt request logic, and monitors the I2C-bus status.
7.9 Control register, I2CONSET and I2CONCLR
The I2C control register contains bits used to control the following I2C block functions: start and restart of a serial transfer, termination of a serial transfer, bit rate, address recognition, and acknowledgment. The contents of the I2C control register may be read as I2CONSET. Writing to I2CONSET will set bits in the I2C control register that correspond to ones in the value written. Conversely, writing to I2CONCLR will clear bits in the I2C control register that correspond to ones in the value written.
7.10 Status decoder and status register
The status decoder takes all of the internal status bits and compresses them into a 5-bit code. This code is unique for each I2C-bus status. The 5-bit code may be used to generate vector addresses for fast processing of the various service routines. Each service routine processes a particular bus status. There are 26 possible bus states if all four modes of the I2C block are used. The 5-bit status code is latched into the five most significant bits of the status register when the serial interrupt flag is set (by hardware) and remains stable until the interrupt flag is cleared by software. The three least significant bits of the status register are always zero. If the status code is used as a vector to service routines, then the routines are displaced by eight address locations. Eight bytes of code is sufficient for most of the service routines (see the software example in this section).
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8. Register description
Each I2C interface contains 16 registers as shown in Table 19-384 below. Remark: In the LPC17xx, the following registers have been added to support response to multiple addresses in Slave mode and a new Monitor mode: I2ADR1 to 3, I2MASK0 To 3, MMCTRL, and I2DATA_BUFFER.
Table 384. I2C register map Generic Name Description Access Reset I2Cn Name & Address value[1]
I2CONSET I2C Control Set Register. When a one is written to R/W a bit of this register, the corresponding bit in the I2C control register is set. Writing a zero has no effect on the corresponding bit in the I2C control register. I2STAT
I2C Status Register. During I2C operation, this register provides detailed status codes that allow software to determine the next action needed. I2 C Data Register. During master or slave transmit mode, data to be transmitted is written to this register. During master or slave receive mode, data that has been received may be read from this register.
0x00
I2C0CONSET - 0x4001 C000 I2C1CONSET - 0x4005 C000 I2C2CONSET - 0x400A 0000
RO
0xF8
I2C0STAT - 0x4001 C004 I2C1STAT - 0x4005 C004 I2C2STAT - 0x400A 0004
I2DAT
R/W
0x00
I2C0DAT - 0x4001 C008 I2C1DAT - 0x4005 C008 I2C2DAT - 0x400A 0008
I2ADR0
I2C Slave Address Register 0. Contains the 7-bit slave address for operation of the I2C interface in slave mode, and is not used in master mode. The least significant bit determines whether a slave responds to the General Call address. SCH Duty Cycle Register High Half Word. Determines the high time of the I2C clock.
R/W
0x00
I2C0ADR0 - 0x4001 C00C I2C1ADR0 - 0x4005 C00C I2C2ADR0 - 0x400A 000C
I2SCLH
R/W
0x04
I2C0SCLH - 0x4001 C010 I2C1SCLH - 0x4005 C010 I2C2SCLH - 0x400A 0010
I2SCLL
SCL Duty Cycle Register Low Half Word. Determines the low time of the I2C clock. I2nSCLL and I2nSCLH together determine the clock frequency generated by an I2C master and certain times used in slave mode.
R/W
0x04
I2C0SCLL - 0x4001 C014 I2C1SCLL - 0x4005 C014 I2C2SCLL - 0x400A 0014
I2CONCLR I2C Control Clear Register. When a one is written WO to a bit of this register, the corresponding bit in the I2C control register is cleared. Writing a zero has no effect on the corresponding bit in the I2C control register. MMCTRL
Monitor mode control register.
NA
I2C0CONCLR - 0x4001 C018 I2C1CONCLR - 0x4005 C018 I2C2CONCLR - 0x400A 0018
R/W
0x00
I2C0MMCTRL - 0x4001 C01C I2C1MMCTRL - 0x4005 C01C I2C2MMCTRL - 0x400A 001C
I2ADR1
Slave Address Register 1. Contains the 7-bit slave address for operation of the I2C interface in slave mode, and is not used in master mode. The least significant bit determines whether a slave responds to the General Call address.
I2 C
R/W
0x00
I2C0ADR1 - 0x4001 C020 I2C1ADR1 - 0x4005 C020 I2C2ADR1 - 0x400A 0020
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Table 384. I2C register map Generic Name Description I2C Slave Address Register 2. Contains the 7-bit slave address for operation of the I2C interface in slave mode, and is not used in master mode. The least significant bit determines whether a slave responds to the General Call address. I2C Slave Address Register 3. Contains the 7-bit slave address for operation of the I2C interface in slave mode, and is not used in master mode. The least significant bit determines whether a slave responds to the General Call address. Access Reset I2Cn Name & Address value[1]
I2ADR2
R/W
0x00
I2C0ADR2 - 0x4001 C024 I2C1ADR2 - 0x4005 C024 I2C2ADR2 - 0x400A 0024
I2ADR3
R/W
0x00
I2C0ADR3 - 0x4001 C028 I2C1ADR3 - 0x4005 C028 I2C2ADR3 - 0x400A 0028
I2DATA_ BUFFER
Data buffer register. The contents of the 8 MSBs of RO the I2DAT shift register will be transferred to the I2DATA_BUFFER automatically after every 9 bits (8 bits of data plus ACK or NACK) has been received on the bus. I2C Slave address mask register 0. This mask register is associated with I2ADR0 to determine an address match. The mask register has no effect when comparing to the General Call address (`0000000'). I2C Slave address mask register 1. This mask register is associated with I2ADR0 to determine an address match. The mask register has no effect when comparing to the General Call address (`0000000'). I2C Slave address mask register 2. This mask register is associated with I2ADR0 to determine an address match. The mask register has no effect when comparing to the General Call address (`0000000'). I2C Slave address mask register 3. This mask register is associated with I2ADR0 to determine an address match. The mask register has no effect when comparing to the General Call address (`0000000').
0x00
I2C0DATA_ BUFFER - 0x4001 C02C I2C1DATA_ BUFFER - 0x4005 C02C I2C2DATA_ BUFFER - 0x400A 002C
I2MASK0
R/W
0x00
I2C0MASK0 - 0x4001 C030 I2C1MASK0 - 0x4005 C030 I2C2MASK0 - 0x400A 0030
I2MASK1
R/W
0x00
I2C0MASK1 - 0x4001 C034 I2C1MASK1 - 0x4005 C034 I2C2MASK1 - 0x400A 0034
I2MASK2
R/W
0x00
I2C0MASK2 - 0x4001 C038 I2C1MASK2 - 0x4005 C038 I2C2MASK2 - 0x400A 0038
I2MASK3
R/W
0x00
I2C0MASK3 - 0x4001 C03C I2C1MASK3 - 0x4005 C03C I2C2MASK3 - 0x400A 003C
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
8.1 I2C Control Set register (I2CONSET: I2C0, I2C0CONSET 0x4001 C000; I2C1, I2C1CONSET - 0x4005 C000; I2C2, I2C2CONSET 0x400A 0000)
The I2CONSET registers control setting of bits in the I2CON register that controls operation of the I2C interface. Writing a one to a bit of this register causes the corresponding bit in the I2C control register to be set. Writing a zero has no effect. Reading this register provides the current values of the control and flag bits.
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Table 385. I2C Control Set register (I2CONSET: I2C0, I2C0CONSET - address 0x4001 C000, I2C1, I2C1CONSET - address 0x4005 C000, I2C2, I2C2CONSET - address 0x400A 0000) bit description Bit Symbol Description Reset value
1:0 2 3 4 5 6 31:7
AA SI STO STA I2EN -
Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. Assert acknowledge flag. I2C interrupt flag. STOP flag. START flag. I2C interface enable. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0 0 0 0 0 NA
I2EN I2C Interface Enable. When I2EN is 1, the I2C interface is enabled. I2EN can be cleared by writing 1 to the I2ENC bit in the I2CONCLR register. When I2EN is 0, the I2C interface is disabled. When I2EN is "0", the SDA and SCL input signals are ignored, the I2C block is in the "not addressed" slave state, and the STO bit is forced to "0". I2EN should not be used to temporarily release the I2C-bus since, when I2EN is reset, the I2C-bus status is lost. The AA flag should be used instead. STA is the START flag. Setting this bit causes the I2C interface to enter master mode and transmit a START condition or transmit a repeated START condition if it is already in master mode. When STA is 1 and the I2C interface is not already in master mode, it enters master mode, checks the bus and generates a START condition if the bus is free. If the bus is not free, it waits for a STOP condition (which will free the bus) and generates a START condition after a delay of a half clock period of the internal clock generator. If the I2C interface is already in master mode and data has been transmitted or received, it transmits a repeated START condition. STA may be set at any time, including when the I2C interface is in an addressed slave mode. STA can be cleared by writing 1 to the STAC bit in the I2CONCLR register. When STA is 0, no START condition or repeated START condition will be generated. If STA and STO are both set, then a STOP condition is transmitted on the I2C-bus if it the interface is in master mode, and transmits a START condition thereafter. If the I2C interface is in slave mode, an internal STOP condition is generated, but is not transmitted on the bus. STO is the STOP flag. Setting this bit causes the I2C interface to transmit a STOP condition in master mode, or recover from an error condition in slave mode. When STO is 1 in master mode, a STOP condition is transmitted on the I2C-bus. When the bus detects the STOP condition, STO is cleared automatically.
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In slave mode, setting this bit can recover from an error condition. In this case, no STOP condition is transmitted to the bus. The hardware behaves as if a STOP condition has been received and it switches to "not addressed" slave receiver mode. The STO flag is cleared by hardware automatically. SI is the I2C Interrupt Flag. This bit is set when the I2C state changes. However, entering state F8 does not set SI since there is nothing for an interrupt service routine to do in that case. While SI is set, the low period of the serial clock on the SCL line is stretched, and the serial transfer is suspended. When SCL is HIGH, it is unaffected by the state of the SI flag. SI must be reset by software, by writing a 1 to the SIC bit in I2CONCLR register. The SI bit should be cleared only after the required bit(s) has (have) been set and the value in I2DAT has been loaded or read. AA is the Assert Acknowledge Flag. When set to 1, an acknowledge (low level to SDA) will be returned during the acknowledge clock pulse on the SCL line on the following situations: 1. A matching address defined by registers I2ADR0 through I2ADR3, masked by I2MASK0 though I2MASK3, has been received. 2. The General Call address has been received while the General Call bit (GC) in I2ADR is set. 3. A data byte has been received while the I2C is in the master receiver mode. 4. A data byte has been received while the I2C is in the addressed slave receiver mode The AA bit can be cleared by writing 1 to the AAC bit in the I2CONCLR register. When AA is 0, a not acknowledge (HIGH level to SDA) will be returned during the acknowledge clock pulse on the SCL line on the following situations: 1. A data byte has been received while the I2C is in the master receiver mode. 2. A data byte has been received while the I2C is in the addressed slave receiver mode.
8.2 I2C Control Clear register (I2CONCLR: I2C0, I2C0CONCLR 0x4001 C018; I2C1, I2C1CONCLR - 0x4005 C018; I2C2, I2C2CONCLR 0x400A 0018)
The I2CONCLR registers control clearing of bits in the I2CON register that controls operation of the I2C interface. Writing a one to a bit of this register causes the corresponding bit in the I2C control register to be cleared. Writing a zero has no effect. I2CONCLR is a write-only register. The value of the related bits can be read from the I2CONSET register.
Table 386. I2C Control Clear register (I2CONCLR: I2C0, I2C0CONCLR - 0x4001 C018; I2C1, I2C1CONCLR - 0x4005 C018; I2C2, I2C2CONCLR - 0x400A 0018) bit description Bit Symbol Description
1:0 2 3
AAC SIC
Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. Assert acknowledge Clear bit. I2C interrupt Clear bit.
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Table 386. I2C Control Clear register (I2CONCLR: I2C0, I2C0CONCLR - 0x4001 C018; I2C1, I2C1CONCLR - 0x4005 C018; I2C2, I2C2CONCLR - 0x400A 0018) bit description Bit Symbol Description
4 5 6 31:7
STAC I2ENC -
Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined. START flag Clear bit. I2C interface Disable bit. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
AAC is the Assert Acknowledge Clear bit. Writing a 1 to this bit clears the AA bit in the I2CONSET register. Writing 0 has no effect. SIC is the I2C Interrupt Clear bit. Writing a 1 to this bit clears the SI bit in the I2CONSET register. Writing 0 has no effect. STAC is the START flag Clear bit. Writing a 1 to this bit clears the STA bit in the I2CONSET register. Writing 0 has no effect. I2ENC is the I2C Interface Disable bit. Writing a 1 to this bit clears the I2EN bit in the I2CONSET register. Writing 0 has no effect.
8.3 I2C Status register (I2STAT: I2C0, I2C0STAT - 0x4001 C004; I2C1, I2C1STAT - 0x4005 C004; I2C2, I2C2STAT - 0x400A 0004)
Each I2C Status register reflects the condition of the corresponding I2C interface. The I2C Status register is read-only.
Table 387. I2C Status register (I2STAT: I2C0, I2C0STAT - 0x4001 C004; I2C1, I2C1STAT 0x4005 C004; I2C2, I2C2STAT - 0x400A 0004) bit description Bit Symbol Description Reset value
2:0 7:3 31:8
Status -
These bits are unused and are always 0. These bits give the actual status information about the I2C interface. Reserved. The value read from a reserved bit is not defined.
0 0x1F NA
The three least significant bits are always 0. Taken as a byte, the status register contents represent a status code. There are 26 possible status codes. When the status code is 0xF8, there is no relevant information available and the SI bit is not set. All other 25 status codes correspond to defined I2C states. When any of these states entered, the SI bit will be set. For a complete list of status codes, refer to tables from Table 19-399 to Table 19-402.
8.4 I2C Data register (I2DAT: I2C0, I2C0DAT - 0x4001 C008; I2C1, I2C1DAT 0x4005 C008; I2C2, I2C2DAT - 0x400A 0008)
This register contains the data to be transmitted or the data just received. The CPU can read and write to this register only while it is not in the process of shifting a byte, when the SI bit is set. Data in I2DAT remains stable as long as the SI bit is set. Data in I2DAT is always shifted from right to left: the first bit to be transmitted is the MSB (bit 7), and after a byte has been received, the first bit of received data is located at the MSB of I2DAT.
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Table 388. I2C Data register (I2DAT: I2C0, I2C0DAT - 0x4001 C008; I2C1, I2C1DAT 0x4005 C008; I2C2, I2C2DAT - 0x400A 0008) bit description Bit Symbol Description Reset value
7:0 31:8
Data -
This register holds data values that have been received or are to be transmitted. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
8.5 I2C Monitor mode control register (I2MMCTRL: I2C0, I2C0MMCTRL 0x4001 C01C; I2C1, I2C1MMCTRL- 0x4005 C01C; I2C2, I2C2MMCTRL0x400A 001C)
This register controls the Monitor mode which allows the I2C module to monitor traffic on the I2C-bus without actually participating in traffic or interfering with the I2C-bus.
Table 389. I2C Monitor mode control register (I2MMCTRL: I2C0, I2C0MMCTRL - 0x4001 C01C; I2C1, I2C1MMCTRL- 0x4005 C01C; I2C2, I2C2MMCTRL- 0x400A 001C) bit description Bit Symbol Value Description Reset value
0
MM_ENA 0 1
Monitor mode enable. Monitor mode disabled. The I2C module will enter monitor mode. In this mode the SDA output will be put in high impedance mode. This prevents the I2C module from outputting data of any kind (including ACK) onto the I2C data bus. Depending on the state of the ENA_SCL bit, the output may be also forced high, preventing the module from having control over the I2C clock line.
0
1
ENA_SCL 0
SCL output enable. When this bit is cleared to `0', the SCL output will be forced high when the module is in monitor mode. As described above, this will prevent the module from having any control over the I2C clock line. When this bit is set, the I2C module may exercise the same control over the clock line that it would in normal operation. This means that, acting as a slave peripheral, the I2C module can "stretch" the clock line (hold it low) until it has had time to respond to an I2C interrupt.[1]
0
1
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Table 389. I2C Monitor mode control register (I2MMCTRL: I2C0, I2C0MMCTRL - 0x4001 C01C; I2C1, I2C1MMCTRL- 0x4005 C01C; I2C2, I2C2MMCTRL- 0x400A 001C) bit description Bit Symbol Value Description Reset value
2
MATCH_ALL 0
Select interrupt register match. When this bit is cleared, an interrupt will only be generated when a match occurs to one of the (up-to) four address registers, I2ADR0 through I2ADR3. That is, the module will respond as a normal slave as far as address-recognition is concerned. When this bit is set to `1' and the I2C is in monitor mode, an interrupt will be generated on ANY address received. This will enable the part to monitor all traffic on the bus. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
31:3
-
NA
[1]
When the ENA_SCL bit is cleared and the I2C no longer has the ability to stretch the clock, interrupt response time becomes important. To give the part more time to respond to an I2C interrupt under these conditions, an I2DATA_BUFFER register is used (Section 19-8.6) to hold received data for a full 9-bit word transmission time.
Remark: The ENA_SCL and MATCH_ALL bits have no effect if the MM_ENA is `0' (i.e. if the module is NOT in monitor mode).
8.5.1 Interrupt in Monitor mode
All interrupts will occur as normal when the module is in monitor mode. This means that the first interrupt will occur when an address-match is detected (any address received if the MATCH_ALL bit is set, otherwise an address matching one of the four address registers). Subsequent to an address-match detection, interrupts will be generated after each data byte is received for a slave-write transfer, or after each byte that the module believes it has transmitted for a slave-read transfer. In this second case, the data register will actually contain data transmitted by some other slave on the bus which was actually addressed by the master. Following all of these interrupts, the processor may read the data register to see what was actually transmitted on the bus.
8.5.2 Loss of arbitration in Monitor mode
In monitor mode, the I2C module will not be able to respond to a request for information by the bus master or issue an ACK. Some other slave on the bus will respond instead. Software should be aware of the fact that the module is in monitor mode and should not respond to any loss of arbitration state that is detected.
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8.6 I2C Data buffer register (I2DATA_BUFFER: I2C0, I2CDATA_BUFFER 0x4001 C02C; I2C1, I2C1DATA_BUFFER- 0x4005 C02C; I2C2, I2C2DATA_BUFFER- 0x400A 002C)
In monitor mode, the I2C module may lose the ability to stretch the clock if the ENA_SCL bit is not set. This means that the processor will have a limited amount of time to read the contents of the data received on the bus. If the processor reads the I2DAT shift register, as it ordinarily would, it could have only one bit-time to respond to the interrupt before the received data is overwritten by new data. To give the processor more time to respond, a new 8-bit, read-only I2DATA_BUFFER register will be added. The contents of the 8 MSBs of the I2DAT shift register will be transferred to the I2DATA_BUFFER automatically after every 9 bits (8 bits of data plus ACK or NACK) has been received on the bus. This means that the processor will have 9 bit transmission times to respond to the interrupt and read the data before it is overwritten. The processor will still have the ability to read I2DAT directly, as usual, and the behavior of I2DAT will not be altered in any way. Although the I2DATA_BUFFER register is primarily intended for use in monitor mode with the ENA_SCL bit = `0', it will be available for reading at any time under any mode of operation.
Table 390. I2C Data buffer register (I2DATA_BUFFER: I2C0, I2CDATA_BUFFER 0x4001 C02C; I2C1, I2C1DATA_BUFFER- 0x4005 C02C; I2C2, I2C2DATA_BUFFER0x400A 002C) bit description Bit Symbol Description Reset value
7:0 31:8
Data -
This register holds contents of the 8 MSBs of the I2DAT shift register. Reserved. The value read from a reserved bit is not defined.
0 NA
8.7 I2C Slave Address registers (I2ADR0 to 3: I2C0, I2C0ADR[0, 1, 2, 3]0x4001 C0[0C, 20, 24, 28]; I2C1, I2C1ADR[0, 1, 2, 3] - address 0x4005 C0[0C, 20, 24, 28]; I2C2, I2C2ADR[0, 1, 2, 3] - address 0x400A 00[0C, 20, 24, 28])
These registers are readable and writable and are only used when an I2C interface is set to slave mode. In master mode, this register has no effect. The LSB of I2ADR is the General Call bit. When this bit is set, the General Call address (0x00) is recognized. If these registers contain 0x00, the I2C will not acknowledge any address on the bus. All four registers will be cleared to this disabled state on reset.
Table 391. I2C Slave Address registers (I2ADR0 to 3: I2C0, I2C0ADR[0, 1, 2, 3]- 0x4001 C0[0C, 20, 24, 28]; I2C1, I2C1ADR[0, 1, 2, 3] - address 0x4005 C0[0C, 20, 24, 28]; I2C2, I2C2ADR[0, 1, 2, 3] - address 0x400A 00[0C, 20, 24, 28]) bit description Bit Symbol Description Reset value
0 7:1 31:8
GC Address -
General Call enable bit. The I2C device address for slave mode. Reserved. User software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0x00 NA
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8.8 I2C Mask registers (I2MASK0 to 3: I2C0, I2C0MASK[0, 1, 2, 3] 0x4001 C0[30, 34, 38, 3C]; I2C1, I2C1MASK[0, 1, 2, 3] - address 0x4005 C0[30, 34, 38, 3C]; I2C2, I2C2MASK[0, 1, 2, 3] - address 0x400A 00[30, 34, 38, 3C])
The four mask registers each contain seven active bits (7:1). Any bit in these registers which is set to `1' will cause an automatic compare on the corresponding bit of the received address when it is compared to the I2ADRn register associated with that mask register. In other words, bits in an I2ADRn register which are masked are not taken into account in determining an address match. The mask register has no effect on comparison to the General Call address ("0000000"). When an address-match interrupt occurs, the processor will have to read the data register (I2DAT) to determine which received address actually caused the match.
Table 392. I2C Mask registers (I2MASK0 to 3: I2C0, I2C0MASK[0, 1, 2, 3] - 0x4001 C0[30, 34, 38, 3C]; I2C1, I2C1MASK[0, 1, 2, 3] - address 0x4005 C0[30, 34, 38, 3C]; I2C2, I2C2MASK[0, 1, 2, 3] - address 0x400A 00[30, 34, 38, 3C]) bit description Bit Symbol Description Reset value
0 7:1 31:8
MASK -
Reserved. User software should not write ones to reserved bits. This bit reads always back as 0. Mask bits. Reserved. User software should not write ones to reserved bits. These bits read always back as zeroes.
0 0x00 0
8.9 I2C SCL HIGH duty cycle register (I2SCLH: I2C0, I2C0SCLH 0x4001 C010; I2C1, I2C1SCLH - 0x4005 C010; I2C2, I2C2SCLH 0x400A 0010)
Table 393. I2C SCL HIGH Duty Cycle register (I2SCLH: I2C0, I2C0SCLH - address 0x4001 C010; I2C1, I2C1SCLH - address 0x4005 C010; I2C2, I2C2SCLH 0x400A 0010) bit description Bit Symbol Description Reset value
15:0
SCLH
Count for SCL HIGH time period selection. Reserved. The value read from a reserved bit is not defined.
0x0004 NA
31:16 -
8.10 I2C SCL Low duty cycle register (I2SCLL: I2C0 - I2C0SCLL: 0x4001 C014; I2C1 - I2C1SCLL: 0x4005 C014; I2C2 - I2C2SCLL: 0x400A 0014)
Table 394. I2C SCL Low duty cycle register (I2SCLL: I2C0 - I2C0SCLL: 0x4001 C014; I2C1 I2C1SCLL: 0x4005 C014; I2C2 - I2C2SCLL: 0x400A 0014) bit description Bit Symbol Description Reset value
15:0
SCLL
Count for SCL low time period selection. Reserved. The value read from a reserved bit is not defined.
0x0004 NA
31:16 -
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8.11 Selecting the appropriate I2C data rate and duty cycle
Software must set values for the registers I2SCLH and I2SCLL to select the appropriate data rate and duty cycle. I2SCLH defines the number of PCLK_I2C cycles for the SCL HIGH time, I2SCLL defines the number of PCLK_I2C cycles for the SCL low time. The frequency is determined by the following formula (PCLK_I2C is the frequency of the peripheral bus APB): (11)
PCLKI2C I 2 C bitfrequency = -------------------------------------------------------I2CSCLH + I2CSCLL
The values for I2SCLL and I2SCLH must ensure that the data rate is in the appropriate I2C data rate range. Each register value must be greater than or equal to 4. Table 19-395 gives some examples of I2C-bus rates based on PCLK_I2C frequency and I2SCLL and I2SCLH values.
Table 395. Example I2C clock rates
I2C Rate
100 kHz (Standard) 400 kHz (Fast Mode) 1 MHz (Fast Mode Plus)
I2SCLL + I2SCLH values at PCLK_I2C (MHz) 6 8 10 12 16 20 30 40 50 60 70 80 90 100
60 15 -
80 20 8
100 25 10
120 30 12
160 40 16
200 50 20
300 75 30
400 100 40
500 125 50
600 150 60
700 175 70
800 200 80
900 225 90
1000 250 100
I2SCLL and I2SCLH values should not necessarily be the same. Software can set different duty cycles on SCL by setting these two registers. For example, the I2C-bus specification defines the SCL low time and high time at different values for a Fast Mode and Fast Mode Plus I2C.
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9. Details of I2C operating modes
The four operating modes are:
* * * *
Master Transmitter Master Receiver Slave Receiver Slave Transmitter
Data transfers in each mode of operation are shown in Figure 19-92, Figure 19-93, Figure 19-94, Figure 19-95, and Figure 19-96. Table 19-396 lists abbreviations used in these figures when describing the I2C operating modes.
Table 396. Abbreviations used to describe an I2C operation Abbreviation Explanation
S SLA R W A A Data P Sr
START condition 7-bit slave address Read bit (HIGH level at SDA) Write bit (LOW level at SDA) Acknowledge bit (LOW level at SDA) Not acknowledge bit (HIGH level at SDA) 8-bit data byte STOP condition Repeated START condition
In Figure 19-92 to Figure 19-96, circles are used to indicate when the serial interrupt flag is set. The numbers in the circles show the status code held in the I2STAT register. At these points, a service routine must be executed to continue or complete the serial transfer. These service routines are not critical since the serial transfer is suspended until the serial interrupt flag is cleared by software. When a serial interrupt routine is entered, the status code in I2STAT is used to branch to the appropriate service routine. For each status code, the required software action and details of the following serial transfer are given in tables from Table 19-399 to Table 19-403.
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9.1 Master Transmitter mode
In the master transmitter mode, a number of data bytes are transmitted to a slave receiver (see Figure 19-92). Before the master transmitter mode can be entered, I2CON must be initialized as follows:
Table 397. I2CONSET used to initialize Master Transmitter mode Bit 7 6 5 4 3 2 1 0
Symbol Value
-
I2EN 1
STA 0
STO 0
SI 0
AA x
-
-
The I2C rate must also be configured in the I2SCLL and I2SCLH registers. I2EN must be set to logic 1 to enable the I2C block. If the AA bit is reset, the I2C block will not acknowledge its own slave address or the General Call address in the event of another device becoming master of the bus. In other words, if AA is reset, the I2C interface cannot enter a slave mode. STA, STO, and SI must be reset. The master transmitter mode may now be entered by setting the STA bit. The I2C logic will now test the I2C-bus and generate a START condition as soon as the bus becomes free. When a START condition is transmitted, the serial interrupt flag (SI) is set, and the status code in the status register (I2STAT) will be 0x08. This status code is used by the interrupt service routine to enter the appropriate state service routine that loads I2DAT with the slave address and the data direction bit (SLA+W). The SI bit in I2CON must then be reset before the serial transfer can continue. When the slave address and the direction bit have been transmitted and an acknowledgment bit has been received, the serial interrupt flag (SI) is set again, and a number of status codes in I2STAT are possible. There are 0x18, 0x20, or 0x38 for the master mode and also 0x68, 0x78, or 0xB0 if the slave mode was enabled (AA = logic 1). The appropriate action to be taken for each of these status codes is detailed in Table 19-399. After a repeated START condition (state 0x10). The I2C block may switch to the master receiver mode by loading I2DAT with SLA+R).
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MT successful transmission to a Slave Receiver
S
SLA
W
A
DATA
A
P
08H
18H
28H
next transfer started with a Repeated Start condition Not Acknowledge received after the Slave address
S
SLA
W
10H A P R
20H to Master receive mode, entry = MR
Not Acknowledge received after a Data byte
A
P
30H
arbitration lost in Slave address or Data byte
A OR A
other Master continues
A OR A
other Master continues
38H
38H
arbitration lost and addressed as Slave
A
other Master continues to corresponding states in Slave mode
68H 78H B0H
from Master to Slave
from Slave to Master
DATA
any number of data bytes and their associated Acknowledge bits
n
this number (contained in I2STA) corresponds to a defined state of the I2C bus
Fig 92. Format and states in the Master Transmitter mode
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9.2 Master Receiver mode
In the master receiver mode, a number of data bytes are received from a slave transmitter (see Figure 19-93). The transfer is initialized as in the master transmitter mode. When the START condition has been transmitted, the interrupt service routine must load I2DAT with the 7-bit slave address and the data direction bit (SLA+R). The SI bit in I2CON must then be cleared before the serial transfer can continue. When the slave address and the data direction bit have been transmitted and an acknowledgment bit has been received, the serial interrupt flag (SI) is set again, and a number of status codes in I2STAT are possible. These are 0x40, 0x48, or 0x38 for the master mode and also 0x68, 0x78, or 0xB0 if the slave mode was enabled (AA = 1). The appropriate action to be taken for each of these status codes is detailed in Table 19-400. After a repeated START condition (state 0x10), the I2C block may switch to the master transmitter mode by loading I2DAT with SLA+W.
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MR
successful transmission to a Slave transmitter
S
SLA
R
A
DATA
A
DATA
A
P
08H
40H
50H
58H
next transfer started with a Repeated Start condition
S
SLA
R
10H Not Acknowledge received after the Slave address A P W
48H to Master transmit mode, entry = MT
arbitration lost in Slave address or Acknowledge bit
A OR A
other Master continues
A
other Master continues
38H
38H
arbitration lost and addressed as Slave
A
other Master continues to corresponding states in Slave mode
68H 78H B0H
from Master to Slave
from Slave to Master
DATA
A
any number of data bytes and their associated Acknowledge bits this number (contained in I2STA) corresponds to a defined state of the I2C bus
n
Fig 93. Format and states in the Master Receiver mode
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9.3 Slave Receiver mode
In the slave receiver mode, a number of data bytes are received from a master transmitter (see Figure 19-94). To initiate the slave receiver mode, I2CON register, the I2ADR registers, and the I2MASK registers must be configured. The values on the four I2ADR registers combined with the values on the four I2MASK registers determines which address(es) the I2C block will respond to when slave functions are enabled. See sections 7.2, 7.3, 8.7, and 8.8 for details.
Table 398. I2CONSET used to initialize Slave Receiver mode Bit 7 6 5 4 3 2 1 0
Symbol Value
-
I2EN 1
STA 0
STO 0
SI 0
AA 1
-
-
The I2C-bus rate settings do not affect the I2C block in the slave mode. I2EN must be set to logic 1 to enable the I2C block. The AA bit must be set to enable the I2C block to acknowledge its own slave address or the General Call address. STA, STO, and SI must be reset. When the I2ADR, I2MASK, and I2CON registers have been initialized, the I2C block waits until it is addressed by its own slave address followed by the data direction bit which must be "0" (W) for the I2C block to operate in the slave receiver mode. After its own slave address and the W bit have been received, the serial interrupt flag (SI) is set and a valid status code can be read from I2STAT. This status code is used to vector to a state service routine. The appropriate action to be taken for each of these status codes is detailed in Table 19-401. The slave receiver mode may also be entered if arbitration is lost while the I2C block is in the master mode (see status 0x68 and 0x78). If the AA bit is reset during a transfer, the I2C block will return a not acknowledge (logic 1) to SDA after the next received data byte. While AA is reset, the I2C block does not respond to its own slave address or a General Call address. However, the I2C-bus is still monitored and address recognition may be resumed at any time by setting AA. This means that the AA bit may be used to temporarily isolate the I2C block from the I2C-bus.
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reception of the own Slave address and one or more Data bytes all are acknowledged
S
SLA
R
A
DATA
A
DATA
A
P OR S
60H
80H
80H
A0H
last data byte received is Not acknowledged
A
P OR S
88H arbitration lost as Master and addressed as Slave A
68H
reception of the General Call address and one or more Data bytes
GENERAL CALL
A
DATA
A
DATA
A
P OR S
70h
90h
90h
A0H
last data byte is Not acknowledged
A
P OR S
98h arbitration lost as Master and addressed as Slave by General Call A
78h
from Master to Slave
from Slave to Master
DATA
A
any number of data bytes and their associated Acknowledge bits
n
this number (contained in I2STA) corresponds to a defined state of the 2C I bus
Fig 94. Format and states in the Slave Receiver mode
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9.4 Slave Transmitter mode
In the slave transmitter mode, a number of data bytes are transmitted to a master receiver (see Figure 19-95). Data transfer is initialized as in the slave receiver mode. When I2ADR and I2CON have been initialized, the I2C block waits until it is addressed by its own slave address followed by the data direction bit which must be "1" (R) for the I2C block to operate in the slave transmitter mode. After its own slave address and the R bit have been received, the serial interrupt flag (SI) is set and a valid status code can be read from I2STAT. This status code is used to vector to a state service routine, and the appropriate action to be taken for each of these status codes is detailed in Table 19-402. The slave transmitter mode may also be entered if arbitration is lost while the I2C block is in the master mode (see state 0xB0). If the AA bit is reset during a transfer, the I2C block will transmit the last byte of the transfer and enter state 0xC0 or 0xC8. The I2C block is switched to the not addressed slave mode and will ignore the master receiver if it continues the transfer. Thus the master receiver receives all 1s as serial data. While AA is reset, the I2C block does not respond to its own slave address or a General Call address. However, the I2C-bus is still monitored, and address recognition may be resumed at any time by setting AA. This means that the AA bit may be used to temporarily isolate the I2C block from the I2C-bus.
reception of the own Slave address and one or more Data bytes all are acknowledged
S
SLA
R
A
DATA
A
DATA
A
P OR S
A8H
B8H
C0H
arbitration lost as Master and addressed as Slave last data byte transmitted. Switched to Not Addressed Slave (AA bit in I2CON = "0")
A
B0H A ALL ONES P OR S
C8H
from Master to Slave
from Slave to Master
DATA
A
any number of data bytes and their associated Acknowledge bits
n
this number (contained in I2STA) corresponds to a defined state of the I2C bus
Fig 95. Format and states in the Slave Transmitter mode
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9.5 Detailed state tables
The following tables show detailed state information for the four I2C operating modes.
Table 399. Master Transmitter mode I2CSTAT Status of the Status I2C-bus and Code hardware Application software response To/From I2DAT To I2CON STA STO SI AA Next action taken by I2C hardware
0x08 0x10
A START condition Load SLA+W; clear has been transmitted. STA A repeated START condition has been transmitted. Load SLA+W or Load SLA+R; Clear STA
X X X 0 1 0 1
0 0 0 0 0 1 1
0 0 0 0 0 0 0
X X X X X X X
SLA+W will be transmitted; ACK bit will be received. As above. SLA+W will be transmitted; the I2C block will be switched to MST/REC mode. Data byte will be transmitted; ACK bit will be received. Repeated START will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset. Data byte will be transmitted; ACK bit will be received. Repeated START will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset. Data byte will be transmitted; ACK bit will be received. Repeated START will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset. Data byte will be transmitted; ACK bit will be received. Repeated START will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset. I2C-bus will be released; not addressed slave will be entered. A START condition will be transmitted when the bus becomes free.
0x18
SLA+W has been Load data byte or transmitted; ACK has been received. No I2DAT action or No I2DAT action or No I2DAT action
0x20
SLA+W has been transmitted; NOT ACK has been received.
Load data byte or No I2DAT action or No I2DAT action or No I2DAT action
0 1 0 1
0 0 1 1
0 0 0 0
X X X X
0x28
Data byte in I2DAT Load data byte or has been transmitted; ACK has been No I2DAT action or received. No I2DAT action or No I2DAT action
0 1 0 1
0 0 1 1
0 0 0 0
X X X X
0x30
Data byte in I2DAT Load data byte or has been transmitted; NOT ACK has been No I2DAT action or received. No I2DAT action or No I2DAT action
0 1 0 1
0 0 1 1
0 0 0 0
X X X X
0x38
Arbitration lost in SLA+R/W or Data bytes.
No I2DAT action or No I2DAT action
0 1
0 0
0 0
X X
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Table 400. Master Receiver mode I2CSTAT Status of the Status I2C-bus and Code hardware Application software response To/From I2DAT To I2CON STA STO SI AA Next action taken by I2C hardware
0x08 0x10
A START condition Load SLA+R has been transmitted. A repeated START condition has been transmitted. Arbitration lost in NOT ACK bit. Load SLA+R or Load SLA+W No I2DAT action or No I2DAT action
X X X 0 1 0 0 1 0 1
0 0 0 0 0 0 0 0 1 1
0 0 0 0 0 0 0 0 0 0
X X X X X 0 1 X X X
SLA+R will be transmitted; ACK bit will be received. As above. SLA+W will be transmitted; the I2C block will be switched to MST/TRX mode. I2C-bus will be released; the I2C block will enter a slave mode. A START condition will be transmitted when the bus becomes free. Data byte will be received; NOT ACK bit will be returned. Data byte will be received; ACK bit will be returned. Repeated START condition will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset. Data byte will be received; NOT ACK bit will be returned. Data byte will be received; ACK bit will be returned. Repeated START condition will be transmitted. STOP condition will be transmitted; STO flag will be reset. STOP condition followed by a START condition will be transmitted; STO flag will be reset.
0x38
0x40
SLA+R has been No I2DAT action or transmitted; ACK has been received. No I2DAT action SLA+R has been transmitted; NOT ACK has been received. No I2DAT action or No I2DAT action or No I2DAT action
0x48
0x50
Data byte has been received; ACK has been returned. Data byte has been received; NOT ACK has been returned.
Read data byte or Read data byte Read data byte or Read data byte or Read data byte
0 0 1 0 1
0 0 0 1 1
0 0 0 0 0
0 1 X X X
0x58
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Table 401. Slave Receiver mode I2CSTAT Status of the I2C-bus Status and hardware Code Application software response To/From I2DAT To I2CON STA STO SI AA Next action taken by I2C hardware
0x60
Own SLA+W has been received; ACK has been returned. Arbitration lost in SLA+R/W as master; Own SLA+W has been received, ACK returned. General Call address (0x00) has been received; ACK has been returned. Arbitration lost in SLA+R/W as master; General Call address has been received, ACK has been returned.
No I2DAT action X or No I2DAT action X No I2DAT action X or No I2DAT action X No I2DAT action X or No I2DAT action X No I2DAT action X or No I2DAT action X
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 1 0 1 0 1 0 1
Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned. Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned. Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned. Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned. Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. A START condition will be transmitted when the bus becomes free. Data byte will be received and NOT ACK will be returned. Data byte will be received and ACK will be returned.
0x68
0x70
0x78
0x80
Previously addressed Read data byte with own SLA address; or DATA has been received; Read data byte ACK has been returned. Previously addressed with own SLA; DATA byte has been received; NOT ACK has been returned. Read data byte or Read data byte or
X X 0
0 0 0
0 0 0
0 1 0
0x88
0
0
0
1
Read data byte or
1
0
0
0
Read data byte
1
0
0
1
0x90
Previously addressed with General Call; DATA byte has been received; ACK has been returned.
Read data byte or Read data byte
X X
0 0
0 0
0 1
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Table 401. Slave Receiver mode I2CSTAT Status of the I2C-bus Status and hardware Code Application software response To/From I2DAT To I2CON STA STO SI AA Next action taken by I2C hardware
0x98
Previously addressed with General Call; DATA byte has been received; NOT ACK has been returned.
Read data byte or Read data byte or
0
0
0
0
Switched to not addressed SLV mode; no recognition of own SLA or General Call address. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. A START condition will be transmitted when the bus becomes free.
0
0
0
1
Read data byte or
1
0
0
0
Read data byte
1
0
0
1
0xA0
A STOP condition or repeated START condition has been received while still addressed as Slave Receiver or Slave Transmitter.
No STDAT action or No STDAT action or
0
0
0
0
0
0
0
1
No STDAT action or
1
0
0
0
No STDAT action
1
0
0
1
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Table 402. Slave Transmitter mode I2CSTAT Status of the I2C-bus Status and hardware Code Application software response To/From I2DAT To I2CON STA STO SI AA Next action taken by I2C hardware
0xA8
Own SLA+R has been Load data byte or received; ACK has been returned. Load data byte Arbitration lost in Load data byte or SLA+R/W as master; Own SLA+R has been Load data byte received, ACK has been returned. Data byte in I2DAT has Load data byte or been transmitted; ACK has been received. Load data byte Data byte in I2DAT has No I2DAT action been transmitted; NOT or ACK has been received. No I2DAT action or
X X X X
0 0 0 0
0 0 0 0
0 1 0 1
Last data byte will be transmitted and ACK bit will be received. Data byte will be transmitted; ACK will be received. Last data byte will be transmitted and ACK bit will be received. Data byte will be transmitted; ACK bit will be received. Last data byte will be transmitted and ACK bit will be received. Data byte will be transmitted; ACK bit will be received. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR[0] = logic 1. Switched to not addressed SLV mode; no recognition of own SLA or General Call address. A START condition will be transmitted when the bus becomes free. Switched to not addressed SLV mode; Own SLA will be recognized; General Call address will be recognized if I2ADR.0 = logic 1. A START condition will be transmitted when the bus becomes free.
0xB0
0xB8
X X 0
0 0 0
0 0 0
0 1 0
0xC0
0
0
0
1
No I2DAT action or
1
0
0
0
No I2DAT action
1
0
0
1
0xC8
Last data byte in I2DAT has been transmitted (AA = 0); ACK has been received.
No I2DAT action or No I2DAT action or
0
0
0
0
0
0
0
1
No I2DAT action or
1
0
0
0
No I2DAT action
1
0
0
01
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9.6 Miscellaneous states
There are two I2STAT codes that do not correspond to a defined I2C hardware state (see Table 19-403). These are discussed below.
9.6.1 I2STAT = 0xF8
This status code indicates that no relevant information is available because the serial interrupt flag, SI, is not yet set. This occurs between other states and when the I2C block is not involved in a serial transfer.
9.6.2 I2STAT = 0x00
This status code indicates that a bus error has occurred during an I2C serial transfer. A bus error is caused when a START or STOP condition occurs at an illegal position in the format frame. Examples of such illegal positions are during the serial transfer of an address byte, a data byte, or an acknowledge bit. A bus error may also be caused when external interference disturbs the internal I2C block signals. When a bus error occurs, SI is set. To recover from a bus error, the STO flag must be set and SI must be cleared. This causes the I2C block to enter the "not addressed" slave mode (a defined state) and to clear the STO flag (no other bits in I2CON are affected). The SDA and SCL lines are released (a STOP condition is not transmitted).
Table 403. Miscellaneous States Status Status of the I2C-bus Application software response Code and hardware To/From I2DAT To I2CON (I2CSTAT) STA STO SI Next action taken by I2C hardware AA
0xF8
No relevant state information available; SI = 0.
No I2DAT action
No I2CON action
Wait or proceed current transfer.
0x00
Bus error during MST No I2DAT action or selected slave modes, due to an illegal START or STOP condition. State 0x00 can also occur when interference causes the I2C block to enter an undefined state.
0
1
0
X
Only the internal hardware is affected in the MST or addressed SLV modes. In all cases, the bus is released and the I2C block is switched to the not addressed SLV mode. STO is reset.
9.7 Some special cases
The I2C hardware has facilities to handle the following special cases that may occur during a serial transfer:
9.7.1 Simultaneous repeated START conditions from two masters
A repeated START condition may be generated in the master transmitter or master receiver modes. A special case occurs if another master simultaneously generates a repeated START condition (see Figure 19-96). Until this occurs, arbitration is not lost by either master since they were both transmitting the same data.
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If the I2C hardware detects a repeated START condition on the I2C-bus before generating a repeated START condition itself, it will release the bus, and no interrupt request is generated. If another master frees the bus by generating a STOP condition, the I2C block will transmit a normal START condition (state 0x08), and a retry of the total serial data transfer can commence.
9.7.2 Data transfer after loss of arbitration
Arbitration may be lost in the master transmitter and master receiver modes (see Figure 19-90). Loss of arbitration is indicated by the following states in I2STAT; 0x38, 0x68, 0x78, and 0xB0 (see Figure 19-92 and Figure 19-93). If the STA flag in I2CON is set by the routines which service these states, then, if the bus is free again, a START condition (state 0x08) is transmitted without intervention by the CPU, and a retry of the total serial transfer can commence.
9.7.3 Forced access to the I2C-bus
In some applications, it may be possible for an uncontrolled source to cause a bus hang-up. In such situations, the problem may be caused by interference, temporary interruption of the bus or a temporary short-circuit between SDA and SCL. If an uncontrolled source generates a superfluous START or masks a STOP condition, then the I2C-bus stays busy indefinitely. If the STA flag is set and bus access is not obtained within a reasonable amount of time, then a forced access to the I2C-bus is possible. This is achieved by setting the STO flag while the STA flag is still set. No STOP condition is transmitted. The I2C hardware behaves as if a STOP condition was received and is able to transmit a START condition. The STO flag is cleared by hardware Figure 19-97.
9.7.4 I2C-bus obstructed by a LOW level on SCL or SDA
An I2C-bus hang-up can occur if either the SDA or SCL line is held LOW by any device on the bus. If the SCL line is obstructed (pulled LOW) by a device on the bus, no further serial transfer is possible, and the problem must be resolved by the device that is pulling the SCL bus line LOW. Typically, the SDA line may be obstructed by another device on the bus that has become out of synchronization with the current bus master by either missing a clock, or by sensing a noise pulse as a clock. In this case, the problem can be solved by transmitting additional clock pulses on the SCL line Figure 19-98. The I2C interface does not include a dedicated timeout timer to detect an obstructed bus, but this can be implemented using another timer in the system. When detected, software can force clocks (up to 9 may be required) on SCL until SDA is released by the offending device. At that point, the slave may still be out of synchronization, so a START should be generated to insure that all I2C peripherals are synchronized.
9.7.5 Bus error
A bus error occurs when a START or STOP condition is detected at an illegal position in the format frame. Examples of illegal positions are during the serial transfer of an address byte, a data bit, or an acknowledge bit.
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The I2C hardware only reacts to a bus error when it is involved in a serial transfer either as a master or an addressed slave. When a bus error is detected, the I2C block immediately switches to the not addressed slave mode, releases the SDA and SCL lines, sets the interrupt flag, and loads the status register with 0x00. This status code may be used to vector to a state service routine which either attempts the aborted serial transfer again or simply recovers from the error condition as shown in Table 19-403.
S 08H
SLA
W
A 18H
DATA
A 28H
S
OTHER MASTER CONTINUES
P 08H
S
SLA
other Master sends repeated START earlier
retry
Fig 96. Simultaneous repeated START conditions from two masters
time limit STA flag
STO flag SDA line
SCL line start condition
Fig 97. Forced access to a busy I2C-bus
STA flag (2) SDA line (1) (1) (3)
SCL line start condition
(1) Unsuccessful attempt to send a START condition. (2) SDA line is released. (3) Successful attempt to send a START condition. State 08H is entered.
Fig 98. Recovering from a bus obstruction caused by a LOW level on SDA
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9.8 I2C state service routines
This section provides examples of operations that must be performed by various I2C state service routines. This includes:
* Initialization of the I2C block after a Reset. * I2C Interrupt Service * The 26 state service routines providing support for all four I2C operating modes.
9.8.1 Initialization
In the initialization example, the I2C block is enabled for both master and slave modes. For each mode, a buffer is used for transmission and reception. The initialization routine performs the following functions:
* The I2ADR registers and I2MASK registers are loaded with values to configure the
part's own slave address(es) and the General Call bit (GC)
* The I2C interrupt enable and interrupt priority bits are set * The slave mode is enabled by simultaneously setting the I2EN and AA bits in I2CON
and the serial clock frequency (for master modes) is defined by loading the I2SCLH and I2SCLL registers. The master routines must be started in the main program. The I2C hardware now begins checking the I2C-bus for its own slave address and General Call. If the General Call or the own slave address is detected, an interrupt is requested and I2STAT is loaded with the appropriate state information.
9.8.2 I2C interrupt service
When the I2C interrupt is entered, I2STAT contains a status code which identifies one of the 26 state services to be executed.
9.8.3 The state service routines
Each state routine is part of the I2C interrupt routine and handles one of the 26 states.
9.8.4 Adapting state services to an application
The state service examples show the typical actions that must be performed in response to the 26 I2C state codes. If one or more of the four I2C operating modes are not used, the associated state services can be omitted, as long as care is taken that the those states can never occur. In an application, it may be desirable to implement some kind of timeout during I2C operations, in order to trap an inoperative bus or a lost service routine.
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10. Software example
10.1 Initialization routine
Example to initialize I2C Interface as a Slave and/or Master. 1. Load the I2ADR registers and I2MASK registers with values to configure the own Slave Address, enable General Call recognition if needed. 2. Enable I2C interrupt. 3. Write 0x44 to I2CONSET to set the I2EN and AA bits, enabling Slave functions. For Master only functions, write 0x40 to I2CONSET.
10.2 Start Master Transmit function
Begin a Master Transmit operation by setting up the buffer, pointer, and data count, then initiating a START. 1. Initialize Master data counter. 2. Set up the Slave Address to which data will be transmitted, and add the Write bit. 3. Write 0x20 to I2CONSET to set the STA bit. 4. Set up data to be transmitted in Master Transmit buffer. 5. Initialize the Master data counter to match the length of the message being sent. 6. Exit
10.3 Start Master Receive function
Begin a Master Receive operation by setting up the buffer, pointer, and data count, then initiating a START. 1. Initialize Master data counter. 2. Set up the Slave Address to which data will be transmitted, and add the Read bit. 3. Write 0x20 to I2CONSET to set the STA bit. 4. Set up the Master Receive buffer. 5. Initialize the Master data counter to match the length of the message to be received. 6. Exit
10.4 I2C interrupt routine
Determine the I2C state and which state routine will be used to handle it. 1. Read the I2C status from I2STA. 2. Use the status value to branch to one of 26 possible state routines.
10.5 Non mode specific states
10.5.1 State: 0x00
Bus Error. Enter not addressed Slave mode and release bus.
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1. Write 0x14 to I2CONSET to set the STO and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.5.2 Master States
State 0x08 and State 0x10 are for both Master Transmit and Master Receive modes. The R/W bit decides whether the next state is within Master Transmit mode or Master Receive mode.
10.5.3 State: 0x08
A START condition has been transmitted. The Slave Address + R/W bit will now be transmitted. 1. Write Slave Address with R/W bit to I2DAT. 2. Write 0x04 to I2CONSET to set the AA bit. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Set up Master Transmit mode data buffer. 5. Set up Master Receive mode data buffer. 6. Initialize Master data counter. 7. Exit
10.5.4 State: 0x10
A repeated START condition has been transmitted. The Slave Address + R/W bit will now be transmitted. 1. Write Slave Address with R/W bit to I2DAT. 2. Write 0x04 to I2CONSET to set the AA bit. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Set up Master Transmit mode data buffer. 5. Set up Master Receive mode data buffer. 6. Initialize Master data counter. 7. Exit
10.6 Master Transmitter states
10.6.1 State: 0x18
Previous state was State 0x08 or State 0x10, Slave Address + Write has been transmitted, ACK has been received. The first data byte will be transmitted. 1. Load I2DAT with first data byte from Master Transmit buffer. 2. Write 0x04 to I2CONSET to set the AA bit. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Increment Master Transmit buffer pointer. 5. Exit
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10.6.2 State: 0x20
Slave Address + Write has been transmitted, NOT ACK has been received. A STOP condition will be transmitted. 1. Write 0x14 to I2CONSET to set the STO and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.6.3 State: 0x28
Data has been transmitted, ACK has been received. If the transmitted data was the last data byte then transmit a STOP condition, otherwise transmit the next data byte. 1. Decrement the Master data counter, skip to step 5 if not the last data byte. 2. Write 0x14 to I2CONSET to set the STO and AA bits. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Exit 5. Load I2DAT with next data byte from Master Transmit buffer. 6. Write 0x04 to I2CONSET to set the AA bit. 7. Write 0x08 to I2CONCLR to clear the SI flag. 8. Increment Master Transmit buffer pointer 9. Exit
10.6.4 State: 0x30
Data has been transmitted, NOT ACK received. A STOP condition will be transmitted. 1. Write 0x14 to I2CONSET to set the STO and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.6.5 State: 0x38
Arbitration has been lost during Slave Address + Write or data. The bus has been released and not addressed Slave mode is entered. A new START condition will be transmitted when the bus is free again. 1. Write 0x24 to I2CONSET to set the STA and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.7 Master Receive states
10.7.1 State: 0x40
Previous state was State 08 or State 10. Slave Address + Read has been transmitted, ACK has been received. Data will be received and ACK returned. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag.
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3. Exit
10.7.2 State: 0x48
Slave Address + Read has been transmitted, NOT ACK has been received. A STOP condition will be transmitted. 1. Write 0x14 to I2CONSET to set the STO and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.7.3 State: 0x50
Data has been received, ACK has been returned. Data will be read from I2DAT. Additional data will be received. If this is the last data byte then NOT ACK will be returned, otherwise ACK will be returned. 1. Read data byte from I2DAT into Master Receive buffer. 2. Decrement the Master data counter, skip to step 5 if not the last data byte. 3. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit. 4. Exit 5. Write 0x04 to I2CONSET to set the AA bit. 6. Write 0x08 to I2CONCLR to clear the SI flag. 7. Increment Master Receive buffer pointer 8. Exit
10.7.4 State: 0x58
Data has been received, NOT ACK has been returned. Data will be read from I2DAT. A STOP condition will be transmitted. 1. Read data byte from I2DAT into Master Receive buffer. 2. Write 0x14 to I2CONSET to set the STO and AA bits. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Exit
10.8 Slave Receiver states
10.8.1 State: 0x60
Own Slave Address + Write has been received, ACK has been returned. Data will be received and ACK returned. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Set up Slave Receive mode data buffer. 4. Initialize Slave data counter. 5. Exit
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10.8.2 State: 0x68
Arbitration has been lost in Slave Address and R/W bit as bus Master. Own Slave Address + Write has been received, ACK has been returned. Data will be received and ACK will be returned. STA is set to restart Master mode after the bus is free again. 1. Write 0x24 to I2CONSET to set the STA and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Set up Slave Receive mode data buffer. 4. Initialize Slave data counter. 5. Exit.
10.8.3 State: 0x70
General Call has been received, ACK has been returned. Data will be received and ACK returned. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Set up Slave Receive mode data buffer. 4. Initialize Slave data counter. 5. Exit
10.8.4 State: 0x78
Arbitration has been lost in Slave Address + R/W bit as bus Master. General Call has been received and ACK has been returned. Data will be received and ACK returned. STA is set to restart Master mode after the bus is free again. 1. Write 0x24 to I2CONSET to set the STA and AA bits. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Set up Slave Receive mode data buffer. 4. Initialize Slave data counter. 5. Exit
10.8.5 State: 0x80
Previously addressed with own Slave Address. Data has been received and ACK has been returned. Additional data will be read. 1. Read data byte from I2DAT into the Slave Receive buffer. 2. Decrement the Slave data counter, skip to step 5 if not the last data byte. 3. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit. 4. Exit. 5. Write 0x04 to I2CONSET to set the AA bit. 6. Write 0x08 to I2CONCLR to clear the SI flag. 7. Increment Slave Receive buffer pointer. 8. Exit
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10.8.6 State: 0x88
Previously addressed with own Slave Address. Data has been received and NOT ACK has been returned. Received data will not be saved. Not addressed Slave mode is entered. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.8.7 State: 0x90
Previously addressed with General Call. Data has been received, ACK has been returned. Received data will be saved. Only the first data byte will be received with ACK. Additional data will be received with NOT ACK. 1. Read data byte from I2DAT into the Slave Receive buffer. 2. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit. 3. Exit
10.8.8 State: 0x98
Previously addressed with General Call. Data has been received, NOT ACK has been returned. Received data will not be saved. Not addressed Slave mode is entered. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.8.9 State: 0xA0
A STOP condition or repeated START has been received, while still addressed as a Slave. Data will not be saved. Not addressed Slave mode is entered. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
10.9 Slave Transmitter states
10.9.1 State: 0xA8
Own Slave Address + Read has been received, ACK has been returned. Data will be transmitted, ACK bit will be received. 1. Load I2DAT from Slave Transmit buffer with first data byte. 2. Write 0x04 to I2CONSET to set the AA bit. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Set up Slave Transmit mode data buffer. 5. Increment Slave Transmit buffer pointer. 6. Exit
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10.9.2 State: 0xB0
Arbitration lost in Slave Address and R/W bit as bus Master. Own Slave Address + Read has been received, ACK has been returned. Data will be transmitted, ACK bit will be received. STA is set to restart Master mode after the bus is free again. 1. Load I2DAT from Slave Transmit buffer with first data byte. 2. Write 0x24 to I2CONSET to set the STA and AA bits. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Set up Slave Transmit mode data buffer. 5. Increment Slave Transmit buffer pointer. 6. Exit
10.9.3 State: 0xB8
Data has been transmitted, ACK has been received. Data will be transmitted, ACK bit will be received. 1. Load I2DAT from Slave Transmit buffer with data byte. 2. Write 0x04 to I2CONSET to set the AA bit. 3. Write 0x08 to I2CONCLR to clear the SI flag. 4. Increment Slave Transmit buffer pointer. 5. Exit
10.9.4 State: 0xC0
Data has been transmitted, NOT ACK has been received. Not addressed Slave mode is entered. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit.
10.9.5 State: 0xC8
The last data byte has been transmitted, ACK has been received. Not addressed Slave mode is entered. 1. Write 0x04 to I2CONSET to set the AA bit. 2. Write 0x08 to I2CONCLR to clear the SI flag. 3. Exit
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Chapter 20: LPC17xx I2S interface
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1. Basic configuration
The I2S interface is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCI2S. Remark: On reset, the I2S interface is disabled (PCI2S = 0). 2. Clock: In PCLKSEL1 select PCLK_I2S, see Table 4-41. 3. Pins: Select I2S pins and their modes in PINSEL0 to PINSEL4 and PINMODE0 to PINMODE4 (see Section 8-5). 4. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 5. DMA: The I2S interface supports two DMA requests, see Table 20-411 and Table 20-412, and Table 31-544.
2. Features
The I2S bus provides a standard communication interface for digital audio applications. The I2S bus specification defines a 3-wire serial bus, having one data, one clock, and one word select signal. The basic I2S connection has one master, which is always the master, and one slave. The I2S interface on the LPC17xx provides a separate transmit and receive channel, each of which can operate as either a master or a slave.
* The I2S input can operate in both master and slave mode.
The I2S output can operate in both master and slave mode, independent of the I2S input.
* Capable of handling 8-bit, 16-bit, and 32-bit word sizes. * Mono and stereo audio data supported. * Versatile clocking includes independent transmit and receive fractional rate
generators, and an ability to use a single clock input or output for a 4-wire mode.
* The sampling frequency (fs) can range (in practice) from 16 to 96 kHz. (16, 22.05, 32,
44.1, 48, or 96 kHz) for audio applications.
* Separate Master Clock outputs for both transmit and receive channels support a clock
up to 512 times the I2S sampling frequency.
* Word Select period in master mode is configurable (separately for I2S input and I2S
output).
* Two 8 word (32 byte) FIFO data buffers are provided, one for transmit and one for
receive.
* Generates interrupt requests when buffer levels cross a programmable boundary. * Two DMA requests, controlled by programmable buffer levels. These are connected
to the General Purpose DMA block.
* Controls include reset, stop and mute options separately for I2S input and I2S output.
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3. Description
The I2S performs serial data out via the transmit channel and serial data in via the receive channel. These support the NXP Inter IC Audio format for 8-bit, 16-bit and 32-bit audio data, both for stereo and mono modes. Configuration, data access and control is performed by a APB register set. Data streams are buffered by FIFOs with a depth of 8 words. The I2S receive and transmit stage can operate independently in either slave or master mode. Within the I2S module the difference between these modes lies in the word select (WS) signal which determines the timing of data transmissions. Data words start on the next falling edge of the transmitting clock after a WS change. In stereo mode when WS is low left data is transmitted and right data when WS is high. In mono mode the same data is transmitted twice, once when WS is low and again when WS is high.
* In master mode, word select is generated internally with a 9-bit counter. The half
period count value of this counter can be set in the control register.
* In slave mode, word select is input from the relevant bus pin. * When an I2S bus is active, the word select, receive clock and transmit clock signals
are sent continuously by the bus master, while data is sent continuously by the transmitter.
* Disabling the I2S can be done with the stop or mute control bits separately for the
transmit and receive.
* The stop bit will disable accesses by the transmit channel or the receive channel to
the FIFOs and will place the transmit channel in mute mode.
* The mute control bit will place the transmit channel in mute mode. In mute mode, the
transmit channel FIFO operates normally, but the output is discarded and replaced by zeroes. This bit does not affect the receive channel, data reception can occur normally.
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4. Pin descriptions
Table 404. Pin descriptions Pin Name Type Description
I2SRX_CLK
Input/ Output Input/ Output
Receive Clock. A clock signal used to synchronize the transfer of data on the receive channel. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification. Receive Word Select. Selects the channel from which data is to be received. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. WS = 0 indicates that data is being received by channel 1 (left channel). WS = 1 indicates that data is being received by channel 2 (right channel).
I2SRX_WS
I2SRX_SDA RX_MCLK I2STX_CLK
Input/ Output Output Input/ Output Input/ Output
Receive Data. Serial data, received MSB first. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. Optional master clock output for the I2S receive function. Transmit Clock. A clock signal used to synchronize the transfer of data on the transmit channel. It is driven by the master and received by the slave. Corresponds to the signal SCK in the I2S bus specification. Transmit Word Select. Selects the channel to which data is being sent. It is driven by the master and received by the slave. Corresponds to the signal WS in the I2S bus specification. WS = 0 indicates that data is being sent to channel 1 (left channel). WS = 1 indicates that data is being sent to channel 2 (right channel).
I2STX_WS
I2STX_SDA TX_MCLK
Input/ Output Output
Transmit Data. Serial data, sent MSB first. It is driven by the transmitter and read by the receiver. Corresponds to the signal SD in the I2S bus specification. Optional master clock output for the I2S transmit function.
SCK: serial clock TRANSMITTER (MASTER) WS: word select SD: serial data RECEIVER (SLAVE) TRANSMITTER (SLAVE)
SCK: serial clock WS: word select SD: serial data RECEIVER (MASTER)
CONTROLLER (MASTER) SCK TRANSMITTER (SLAVE) WS SD RECEIVER (SLAVE)
SCK
WS
SD word n-1 right channel
MSB word n left channel
LSB
MSB word n+1 right channel
Fig 99. Simple I2S configurations and bus timing
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Chapter 20: LPC17xx I2S interface
5. Register description
Table 20-405 shows the registers associated with the I2S interface and a summary of their functions. Following the table are details for each register.
Table 405. I2S register map Name Description Access Reset Address Value[1]
I2SDAO I2SDAI I2STXFIFO I2SRXFIFO I2SSTATE I2SDMA1 I2SDMA2 I2SIRQ I2STXRATE I2SRXRATE
Digital Audio Output Register. Contains control bits for the I2S transmit channel. Digital Audio Input Register. Contains control bits for the I2S receive channel. Transmit FIFO. Access register for the 8 x 32-bit transmitter FIFO. Receive FIFO. Access register for the 8 x 32-bit receiver FIFO. Status Feedback Register. Contains status information about the I2S interface. DMA Configuration Register 1. Contains control information for DMA request 1. DMA Configuration Register 2. Contains control information for DMA request 2. Interrupt Request Control Register. Contains bits that control how the I2S interrupt request is generated.
R/W R/W WO RO RO R/W R/W R/W
0x87E1 0x400A 8000 0x07E1 0x400A 8004 0 0 0x7 0 0 0 0 0 0 0x400A 8008 0x400A 800C 0x400A 8010 0x400A 8014 0x400A 8018 0x400A 801C 0x400A 8020 0x400A 8024 0x400A 8028
Transmit MCLK divider. This register determines the I2S TX MCLK rate R/W by specifying the value to divide PCLK by in order to produce MCLK. Receive MCLK divider. This register determines the I2S RX MCLK rate R/W by specifying the value to divide PCLK by in order to produce MCLK. R/W
I2STXBITRATE Transmit bit rate divider. This register determines the I2S transmit bit rate by specifying the value to divide TX_MCLK by in order to produce the transmit bit clock.
I2SRXBITRATE Receive bit rate divider. This register determines the I2S receive bit rate R/W by specifying the value to divide RX_MCLK by in order to produce the receive bit clock. I2STXMODE I2SRXMODE Transmit mode control. Receive mode control.
[1]
0
0x400A 802C
R/W R/W
0 0
0x400A 8030 0x400A 8034
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
5.1 Digital Audio Output register (I2SDAO - 0x400A 8000)
The I2SDAO register controls the operation of the I2S transmit channel. The function of bits in DAO are shown in Table 20-406.
Table 406: Digital Audio Output register (I2SDAO - address 0x400A 8000) bit description Bit Symbol Value Description Reset Value
1:0
wordwidth 00 01 10 11
Selects the number of bytes in data as follows: 8-bit data 16-bit data Reserved, do not use this setting 32-bit data
01
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Table 406: Digital Audio Output register (I2SDAO - address 0x400A 8000) bit description Bit Symbol Value Description Reset Value
2 3 4 5 14:6 15
mono stop reset ws_sel ws_halfperiod mute
When 1, data is of monaural format. When 0, the data is in stereo format. When 1, disables accesses on FIFOs, places the transmit channel in mute mode. When 1, asynchronously resets the transmit channel and FIFO.
0 0 0
When 0, the interface is in master mode. When 1, the interface is in slave mode. See 1 Section 20-7 for a summary of useful combinations for this bit with I2STXMODE. Word select half period minus 1, i.e. WS 64clk period -> ws_halfperiod = 31. When 1, the transmit channel sends only zeroes. 0x1F 1
31:16 -
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
5.2 Digital Audio Input register (I2SDAI - 0x400A 8004)
The I2SDAI register controls the operation of the I2S receive channel. The function of bits in DAI are shown in Table 20-407.
Table 407: Digital Audio Input register (I2SDAI - address 0x400A 8004) bit description Bit Symbol Value Description Reset Value
1:0
wordwidth 00 01 10 11
Selects the number of bytes in data as follows: 8-bit data 16-bit data Reserved, do not use this setting 32-bit data When 1, data is of monaural format. When 0, the data is in stereo format. When 1, disables accesses on FIFOs, places the transmit channel in mute mode. When 1, asynchronously reset the transmit channel and FIFO.
01
2 3 4 5 14:6 31:15
mono stop reset ws_sel ws_halfperiod -
0 0 0
When 0, the interface is in master mode. When 1, the interface is in slave mode. See 1 Section 20-7 for a summary of useful combinations for this bit with I2SRXMODE. Word select half period minus 1, i.e. WS 64clk period -> ws_halfperiod = 31. 0x1F Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
5.3 Transmit FIFO register (I2STXFIFO - 0x400A 8008)
The I2STXFIFO register provides access to the transmit FIFO. The function of bits in I2STXFIFO are shown in Table 20-408.
Table 408: Transmit FIFO register (I2STXFIFO - address 0x400A 8008) bit description Bit Symbol Description Reset Value
31:0
I2STXFIFO
8 x 32-bit transmit FIFO.
Level = 0
5.4 Receive FIFO register (I2SRXFIFO - 0x400A 800C)
The I2SRXFIFO register provides access to the receive FIFO. The function of bits in I2SRXFIFO are shown in Table 20-409.
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Table 409: Receive FIFO register (I2RXFIFO - address 0x400A 800C) bit description Bit Symbol Description Reset Value
31:0 I2SRXFIFO
8 x 32-bit transmit FIFO.
level = 0
5.5 Status Feedback register (I2SSTATE - 0x400A 8010)
The I2SSTATE register provides status information about the I2S interface. The meaning of bits in I2SSTATE are shown in Table 20-410.
Table 410: Status Feedback register (I2SSTATE - address 0x400A 8010) bit description Bit Symbol Description Reset Value
0
irq
This bit reflects the presence of Receive Interrupt or Transmit Interrupt. This is determined by comparing the current FIFO levels to the rx_depth_irq and tx_depth_irq fields in the I2SIRQ register. This bit reflects the presence of Receive or Transmit DMA Request 1. This is determined by comparing the current FIFO levels to the rx_depth_dma1 and tx_depth_dma1 fields in the I2SDMA1 register. This bit reflects the presence of Receive or Transmit DMA Request 2. This is determined by comparing the current FIFO levels to the rx_depth_dma2 and tx_depth_dma2 fields in the I2SDMA2 register. Unused. Reflects the current level of the Receive FIFO.
1
1
dmareq1
1
2
dmareq2
1
7:3 11:8 15:12 19:16 31:20
Unused rx_level tx_level -
0 0
Reserved, user software should not write ones to reserved bits. The value read from a reserved NA bit is not defined. Reflects the current level of the Transmit FIFO. 0 Reserved, user software should not write ones to reserved bits. The value read from a reserved NA bit is not defined.
5.6 DMA Configuration Register 1 (I2SDMA1 - 0x400A 8014)
The I2SDMA1 register controls the operation of DMA request 1. The function of bits in I2SDMA1 are shown in Table 20-411. Refer to the General Purpose DMA Controller chapter for details of DMA operation.
Table 411: DMA Configuration register 1 (I2SDMA1 - address 0x400A 8014) bit description Bit Symbol Description Reset Value
0 1 7:2 11:8 15:12 19:16 31:20
rx_dma1_enable tx_dma1_enable rx_depth_dma1 tx_depth_dma1 -
When 1, enables DMA1 for I2S receive. When 1, enables DMA1 for I2S transmit.
0 0
Reserved, user software should not write ones to reserved bits. The value read from a 0 reserved bit is not defined. Set the FIFO level that triggers a receive DMA request on DMA1. 0 Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. Set the FIFO level that triggers a transmit DMA request on DMA1. 0 Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
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5.7 DMA Configuration Register 2 (I2SDMA2 - 0x400A 8018)
The I2SDMA2 register controls the operation of DMA request 2. The function of bits in I2SDMA2 are shown in Table 20-406.
Table 412: DMA Configuration register 2 (I2SDMA2 - address 0x400A 8018) bit description Bit Symbol Description Reset Value
0 1 7:2 11:8 15:12 19:16 31:20
rx_dma2_enable tx_dma2_enable Unused rx_depth_dma2 tx_depth_dma2 -
When 1, enables DMA1 for I2S receive. When 1, enables DMA1 for Unused. Set the FIFO level that triggers a receive DMA request on DMA2. I2S transmit.
0 0 0 0
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. Set the FIFO level that triggers a transmit DMA request on DMA2. 0 Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
5.8 Interrupt Request Control register (I2SIRQ - 0x400A 801C)
The I2SIRQ register controls the operation of the I2S interrupt request. The function of bits in I2SIRQ are shown in Table 20-406.
Table 413: Interrupt Request Control register (I2SIRQ - address 0x400A 801C) bit description Bit Symbol Description Reset Value
0 1 7:2 11:8 15:12 19:16 31:20
rx_Irq_enable tx_Irq_enable Unused rx_depth_irq tx_depth_irq -
When 1, enables I2S receive interrupt. When 1, enables Unused. Set the FIFO level on which to create an irq request.
0 0 0 0
I2S
transmit interrupt.
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. Set the FIFO level on which to create an irq request. 0 Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
5.9 Transmit Clock Rate register (I2STXRATE - 0x400A 8020)
The MCLK rate for the I2S transmitter is determined by the values in the I2STXRATE register. The required I2STXRATE setting depends on the desired audio sample rate desired, the format (stereo/mono) used, and the data size. The transmitter MCLK rate is generated using a fractional rate generator, dividing down the frequency of PCLK_I2S. Values of the numerator (X) and the denominator (Y) must be chosen to produce a frequency twice that desired for the transmitter MCLK, which must be an integer multiple of the transmitter bit clock rate. Fractional rate generators have some aspects that the user should be aware of when choosing settings. These are discussed in Section 20-5.9.1. The equation for the fractional rate generator is: I2STXMCLK = PCLK_I2S * (X/Y) /2
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Note: If the value of X or Y is 0, then no clock is generated. Also, the value of Y must be greater than or equal to X.
Table 414: Transmit Clock Rate register (I2TXRATE - address 0x400A 8020) bit description Bit Symbol Description Reset Value
7:0
Y_divider
I2S transmit MCLK rate denominator. This value is used to divide PCLK to produce the
transmit MCLK. Eight bits of fractional divide supports a wide range of possibilities. A value of 0 stops the clock.
0
15:8
X_divider
I2S transmit MCLK rate numerator. This value is used to multiply PCLK by to produce the
transmit MCLK. A value of 0 stops the clock. Eight bits of fractional divide supports a wide range of possibilities. Note: the resulting ratio X/Y is divided by 2.
0
31:16
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
5.9.1 Notes on fractional rate generators
The nature of a fractional rate generator is that there will be some output jitter with some divide settings. This is because the fractional rate generator is a fully digital function, so output clock transitions are synchronous with the source clock, whereas a theoretical perfect fractional rate may have edges that are not related to the source clock. So, output jitter will not be greater than plus or minus one source clock between consecutive clock edges. For example, if X = 0x07 and Y = 0x11, the fractional rate generator will output 7 clocks for every 17 (11 hex) input clocks, distributed as evenly as it can. In this example, there is no way to distribute the output clocks in a perfectly even fashion, so some clocks will be longer than others. The output is divided by 2 in order to square it up, which also helps with the jitter. The frequency averages out to exactly (7/17) / 2, but some clocks will be a slightly different length than their neighbors. It is possible to avoid jitter entirely by choosing fractions such that X divides evenly into Y, such as 2/4, 2/6, 3/9, 1/N, etc.
5.10 Receive Clock Rate register (I2SRXRATE - 0x400A 8024)
The MCLK rate for the I2S receiver is determined by the values in the I2SRXRATE register. The required I2SRXRATE setting depends on the peripheral clock rate (PCLK_I2S) and the desired MCLK rate (such as 256 fs). The receiver MCLK rate is generated using a fractional rate generator, dividing down the frequency of PCLK_I2S. Values of the numerator (X) and the denominator (Y) must be chosen to produce a frequency twice that desired for the receiver MCLK, which must be an integer multiple of the receiver bit clock rate. Fractional rate generators have some aspects that the user should be aware of when choosing settings. These are discussed in Section 20-5.9.1. The equation for the fractional rate generator is: I2SRXMCLK = PCLK_I2S * (X/Y) /2 Note: If the value of X or Y is 0, then no clock is generated. Also, the value of Y must be greater than or equal to X.
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Table 415: Receive Clock Rate register (I2SRXRATE - address 0x400A 8024) bit description Bit Symbol Description Reset Value
7:0
Y_divider
0 I2S receive MCLK rate denominator. This value is used to divide PCLK to produce the receive MCLK. Eight bits of fractional divide supports a wide range of possibilities. A value of 0 stops the clock.
15:8
X_divider
I2S receive MCLK rate numerator. This value is used to multiply PCLK by to produce the receive MCLK. A value of 0 stops the clock. Eight bits of fractional divide supports a wide
range of possibilities. Note: the resulting ratio X/Y is divided by 2. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
31:16
-
NA
5.11 Transmit Clock Bit Rate register (I2STXBITRATE - 0x400A 8028)
The bit rate for the I2S transmitter is determined by the value of the I2STXBITRATE register. The value depends on the audio sample rate desired, and the data size and format (stereo/mono) used. For example, a 48 kHz sample rate for 16-bit stereo data requires a bit rate of 48,000x16x2 = 1.536 MHz.
Table 416: Transmit Clock Rate register (I2TXBITRATE - address 0x400A 8028) bit description Bit Symbol Description Reset Value
5:0 31:6
tx_bitrate -
I2S transmit bit rate. This value plus one is used to divide TX_MCLK to produce the transmit bit 0 clock. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
5.12 Receive Clock Bit Rate register (I2SRXBITRATE - 0x400A 802C)
The bit rate for the I2S receiver is determined by the value of the I2SRXBITRATE register. The value depends on the audio sample rate, as well as the data size and format used. The calculation is the same as for I2SRXBITRATE.
Table 417: Receive Clock Rate register (I2SRXBITRATE - address 0x400A 802C) bit description Bit Symbol Description Reset Value
5:0 31:6
rx_bitrate -
I2S receive bit rate. This value plus one is used to divide RX_MCLK to produce the receive bit 0 clock. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
5.13 Transmit Mode Control register (I2STXMODE - 0x400A 8030)
The Transmit Mode Control register contains additional controls for transmit clock source, enabling the 4-pin mode, and how MCLK is used. See Section 20-7 for a summary of useful mode combinations.
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Table 418: Transmit Mode Control register (I2STXMODE - 0x400A 8030) bit description Bit Symbol Value Description Reset Value
1:0
TXCLKSEL 00 01 10 11
Clock source selection for the transmit bit clock divider. Select the TX fractional rate divider clock output as the source Reserved Select the RX_MCLK signal as the TX_MCLK clock source Reserved Transmit 4-pin mode selection. When 1, enables 4-pin mode.
0
2 3 31:4
TX4PIN TXMCENA -
0
Enable for the TX_MCLK output. When 0, output of TX_MCLK is not enabled. When 1, 0 output of TX_MCLK is enabled. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
5.14 Receive Mode Control register (I2SRXMODE - 0x400A 8034)
The Receive Mode Control register contains additional controls for receive clock source, enabling the 4-pin mode, and how MCLK is used. See Section 20-7 for a summary of useful mode combinations.
Table 419: Receive Mode Control register (I2SRXMODE - 0x400A 8034) bit description Bit Symbol Value Description Reset Value
1:0
RXCLKSEL 00 01 10 11
Clock source selection for the receive bit clock divider. Select the RX fractional rate divider clock output as the source Reserved Select the TX_MCLK signal as the RX_MCLK clock source Reserved Receive 4-pin mode selection. When 1, enables 4-pin mode.
0
2 3 31:4
RX4PIN RXMCENA -
0
Enable for the RX_MCLK output. When 0, output of RX_MCLK is not enabled. When 1, 0 output of RX_MCLK is enabled. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
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6. I2S transmit and receive interfaces
The I2S interface can transmit and receive 8-bit, 16-bit or 32-bit stereo or mono audio information. Some details of I2S implementation are:
* When the FIFO is empty, the transmit channel will repeat transmitting the same data
until new data is written to the FIFO.
* When mute is true, the data value 0 is transmitted. * When mono is false, two successive data words are respectively left and right data. * Data word length is determined by the wordwidth value in the configuration register.
There is a separate wordwidth value for the receive channel and the transmit channel. - 0: word is considered to contain four 8-bit data words. - 1: word is considered to contain two 16-bit data words. - 3: word is considered to contain one 32-bit data word.
* When the transmit FIFO contains insufficient data the transmit channel will repeat
transmitting the last data until new data is available. This can occur when the microprocessor or the DMA at some time is unable to provide new data fast enough. Because of this delay in new data there is a need to fill the gap, which is accomplished by continuing to transmit the last sample. The data is not muted as this would produce an noticeable and undesirable effect in the sound.
* The transmit channel and the receive channel only handle 32-bit aligned words, data
chunks must be clipped or extended to a multiple of 32 bits. When switching between data width or modes the I2S must be reset via the reset bit in the control register in order to ensure correct synchronization. It is advisable to set the stop bit also until sufficient data has been written in the transmit FIFO. Note that when stopped data output is muted. All data accesses to FIFOs are 32 bits. Figure 20-112 shows the possible data sequences. A data sample in the FIFO consists of:
* 1x32 bits in 8-bit or 16-bit stereo modes. * 1x32 bits in mono modes. * 2x32 bits, first left data, second right data, in 32-bit stereo modes.
Data is read from the transmit FIFO after the falling edge of WS, it will be transferred to the transmit clock domain after the rising edge of WS. On the next falling edge of WS the left data will be loaded in the shift register and transmitted and on the following rising edge of WS the right data is loaded and transmitted. The receive channel will start receiving data after a change of WS. When word select becomes low it expects this data to be left data, when WS is high received data is expected to be right data. Reception will stop when the bit counter has reached the limit set by wordwidth. On the next change of WS the received data will be stored in the appropriate hold register. When complete data is available it will be written into the receive FIFO.
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7. I2S operating modes
The clocking and WS usage of the I2S interface is configurable. In addition to master and slave modes, which are independently configurable for the transmitter and the receiver, several different clock sources are possible, including variations that share the clock and/or WS between the transmitter and receiver. This last option allows using I2S with fewer pins, typically four. Many configurations are possible that are not considered useful, the following tables and figures give details of the configurations that are most likely to be useful.
Table 420: I2S transmit modes I2SDAO I2STXMODE Description [5] [3:0]
0
0000
Typical transmitter master mode. See Figure 20-100. The I2S transmit function operates as a master. The transmit clock source is the fractional rate divider. The WS used is the internally generated TX_WS. The TX_MCLK pin is not enabled for output.
0
0010
Transmitter master mode sharing the receiver reference clock. See Figure 20-101. The I2S transmit function operates as a master. The transmit clock source is RX_REF. The WS used is the internally generated TX_WS. The TX_MCLK pin is not enabled for output.
0
0100
4-wire transmitter master mode sharing the receiver bit clock and WS. See Figure 20-102. The I2S transmit function operates as a master. The transmit clock source is the RX bit clock. The WS used is the internally generated RX_WS. The TX_MCLK pin is not enabled for output.
0
1000
Transmitter master mode with TX_MCLK output. See Figure 20-100. The I2S transmit function operates as a master. The transmit clock source is the fractional rate divider. The WS used is the internally generated TX_WS. The TX_MCLK pin is enabled for output.
1
0000
Typical transmitter slave mode. See Figure 20-103. The I2S transmit function operates as a slave. The transmit clock source is the TX_CLK pin. The WS used is the TX_WS pin.
1
0010
Transmitter slave mode sharing the receiver reference clock. See Figure 20-104. The I2S transmit function operates as a slave. The transmit clock source is RX_REF. The WS used is the TX_WS pin.
1
0100
4-wire transmitter slave mode sharing the receiver bit clock and WS. See Figure 20-105. The I2S transmit function operates as a slave. The transmit clock source is the RX bit clock. The WS used is RX_WS ref.
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I2STXMODE[3]
(Pin OE)
I2STX_MCLK
I2STX_RATE[15:8] I2STX_RATE[7:0]
X Y
I2STXBITRATE[5:0] TX_REF
I2STX_CLK I2S peripheral block (transmit) I2STX_SDA
TX_WS ref
I2S_PCLK
8-bit Fractional Rate Divider
/2
/N
(1 to 64)
TX bit clock
I2STX_WS
Fig 100. Typical transmitter master mode, with or without MCLK output
I2STXBITRATE[5:0] RX_REF
I2STX_CLK I2S peripheral block (transmit) I2STX_SDA
TX_WS ref
/N
(1 to 64)
TX bit clock
I2STX_WS
Fig 101. Transmitter master mode sharing the receiver reference clock
I2STX_CLK I2S peripheral block (transmit)
RX_WS ref
RX bit clock
I2STX_SDA I2STX_WS
Fig 102. 4-wire transmitter master mode sharing the receiver bit clock and WS
I2STXBITRATE[5:0] TX_REF
I2STX_CLK I2S peripheral block (transmit) I2STX_SDA I2STX_WS
/N
(1 to 64)
TX bit clock
Fig 103. Typical transmitter slave mode
I2STXBITRATE[5:0] RX_REF
/N
(1 to 64)
TX bit clock
I2S peripheral block (transmit)
I2STX_SDA I2STX_WS
Fig 104. Transmitter slave mode sharing the receiver reference clock
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RX bit clock
I2S peripheral block (transmit)
RX_WS ref
I2STX_SDA I2STX_WS
Fig 105. 4-wire transmitter slave mode sharing the receiver bit clock and WS Table 421: I2S receive modes I2SDAI [5] I2SRXMODE Description [3:0]
0
0000
Typical receiver master mode. See Figure 20-106. The I2S receive function operates as a master. The receive clock source is the fractional rate divider. The WS used is the internally generated RX_WS. The RX_MCLK pin is not enabled for output.
0
0010
Receiver master mode sharing the transmitter reference clock. See Figure 20-107. The I2S receive function operates as a master. The receive clock source is TX_REF. The WS used is the internally generated RX_WS. The RX_MCLK pin is not enabled for output.
0
0100
4-wire receiver master mode sharing the transmitter bit clock and WS. See Figure 20-108. The I2S receive function operates as a master. The receive clock source is the TX bit clock. The WS used is the internally generated TX_WS. The RX_MCLK pin is not enabled for output.
0
1000
Receiver master mode with RX_MCLK output. See Figure 20-106. The I2S receive function operates as a master. The receive clock source is the fractional rate divider. The WS used is the internally generated RX_WS. The RX_MCLK pin is enabled for output.
1
0000
Typical receiver slave mode. See Figure 20-109. The I2S receive function operates as a slave. The receive clock source is the RX_CLK pin. The WS used is the RX_WS pin.
1
0010
Receiver slave mode sharing the transmitter reference clock. See Figure 20-110. The I2S receive function operates as a slave. The receive clock source is TX_REF. The WS used is the RX_WS pin.
1
0100
This is a 4-wire receiver slave mode sharing the transmitter bit clock and WS. See Figure 20-111. The I2S receive function operates as a slave. The receive clock source is the TX bit clock. The WS used is TX_WS ref.
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I2SRXMODE[3]
(Pin OE)
I2SRX_MCLK
I2SRX_RATE[15:8] I2SRX_RATE[7:0]
X Y
I2SRXBITRATE[5:0] RX_REF
I2SRX_CLK I2S peripheral block (receive) RX_WS ref I2SRX_SDA I2SRX_WS
I2S_PCLK
8-bit Fractional Rate Divider
/2
/N
(1 to 64)
RX bit clock
Fig 106. Typical receiver master mode, with or without MCLK output
I2SRXBITRATE[5:0] TX_REF
I2SRX_CLK I2S peripheral block (receive) RX_WS ref I2SRX_SDA I2SRX_WS
/N
(1 to 64)
RX bit clock
Fig 107. Receiver master mode sharing the transmitter reference clock
I2SRX_CLK I2S peripheral block (receive)
TX_WS ref
TX bit clock
I2SRX_SDA I2SRX_WS
Fig 108. 4-wire receiver master mode sharing the transmitter bit clock and WS
I2SRXBITRATE[5:0] RX_REF
I2SRX_CLK I2S peripheral block (receive) I2SRX_SDA I2SRX_WS
/N
(1 to 64)
RX bit clock
Fig 109. Typical receiver slave mode
I2SRXBITRATE[5:0] TX_REF
/N
(1 to 64)
RX bit clock
I2S peripheral block (receive)
I2SRX_SDA I2SRX_WS
Fig 110. Receiver slave mode sharing the transmitter reference clock
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TX bit clock
I2S peripheral block (receive)
TX_WS ref
I2SRX_SDA I2SRX_WS
Fig 111. 4-wire receiver slave mode sharing the transmitter bit clock and WS
8. FIFO controller
Handling of data for transmission and reception is performed via the FIFO controller which can generate two DMA requests and an interrupt request. The controller consists of a set of comparators which compare FIFO levels with depth settings contained in registers. The current status of the level comparators can be seen in the APB status register.
Table 422. Conditions for FIFO level comparison Level Comparison Condition
dmareq_tx_1 dmareq_rx_1 dmareq_tx_2 dmareq_rx_2 irq_tx irq_rx
tx_depth_dma1 >= tx_level rx_depth_dma1 <= rx_level tx_depth_dma2 >= tx_level rx_depth_dma2 <= rx_level tx_depth_irq >= tx_level rx_depth_irq <= rx_level
System signaling occurs when a level detection is true and enabled.
Table 423. DMA and interrupt request generation System Signaling Condition
irq dmareq[0] dmareq[1]
(irq_rx & rx_irq_enable) | (irq_tx & tx_irq_enable) (dmareq_tx_1 & tx_dma1_enable ) | (dmareq_rx_1 & rx_dma1_enable ) ( dmareq_tx_2 & tx_dma2_enable ) | (dmareq_rx_2 & rx_dma2_enable )
Table 424. Status feedback in the I2SSTATE register Status Feedback Status
irq dmareq1 dmareq2
irq_rx | irq_tx (dmareq_tx_1 | dmareq_rx_1) (dmareq_rx_2 | dmareq_tx_2)
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Mono 8-bit data mode 7 N+3 0 7 N+2 0 7 N+1 0 7 N 0
Stereo 8-bit data mode 7 LEFT + 1 0 7 RIGHT + 1 0 7 LEFT 0 7 RIGHT 0
Mono 16-bit data mode 15 N+1 0 15 N 0
Stereo 16-bit data mode 15 LEFT 0 15 RIGHT 0
Mono 32-bit data mode 31 N 0
Stereo 32-bit data mode 31 LEFT 0 N
31
RIGHT
0
N+1
Fig 112. FIFO contents for various I2S modes
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Chapter 21: LPC17xx Timer 0/1/2/3
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1. Basic configuration
The Timer 0, 1, 2, and 3 peripherals are configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bits PCTIM0/1/2/3. Remark: On reset, Timer0/1 are enabled (PCTIM0/1 = 1), and Timer2/3 are disabled (PCTIM2/3 = 0). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_TIMER0/1; in the PCLKSEL1 register (Table 4-41), select PCLK_TIMER2/3. 3. Pins: Select timer pins through the PINSEL registers. Select the pin modes for the port pins with timer functions through the PINMODE registers (Section 8-5). 4. Interrupts: See register T0/1/2/3MCR (Table 21-430) and T0/1/2/3CCR (Table 21-431) for match and capture events. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 5. DMA: Up to two match conditions can be used to generate timed DMA requests, see Table 31-544.
2. Features
Remark: The four Timer/Counters are identical except for the peripheral base address. A minimum of two Capture inputs and two Match outputs are pinned out for all four timers, with a choice of multiple pins for each. Timer 2 brings out all four Match outputs.
* A 32-bit Timer/Counter with a programmable 32-bit Prescaler. * Counter or Timer operation * Up to two 32-bit capture channels per timer, that can take a snapshot of the timer
value when an input signal transitions. A capture event may also optionally generate an interrupt.
* Four 32-bit match registers that allow:
- Continuous operation with optional interrupt generation on match. - Stop timer on match with optional interrupt generation. - Reset timer on match with optional interrupt generation.
* Up to four external outputs corresponding to match registers, with the following
capabilities: - Set low on match. - Set high on match. - Toggle on match. - Do nothing on match.
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3. Applications
* Interval Timer for counting internal events. * Pulse Width Demodulator via Capture inputs. * Free running timer.
4. Description
The Timer/Counter is designed to count cycles of the peripheral clock (PCLK) or an externally-supplied clock, and can optionally generate interrupts or perform other actions at specified timer values, based on four match registers. It also includes four capture inputs to trap the timer value when an input signal transitions, optionally generating an interrupt.
5. Pin description
Table 21-425 gives a brief summary of each of the Timer/Counter related pins.
Table 425. Timer/Counter pin description Pin Type Description
CAP0[1:0] Input CAP1[1:0] CAP2[1:0] CAP3[1:0]
Capture Signals- A transition on a capture pin can be configured to load one of the Capture Registers with the value in the Timer Counter and optionally generate an interrupt. Capture functionality can be selected from a number of pins. When more than one pin is selected for a Capture input on a single TIMER0/1 channel, the pin with the lowest Port number is used Timer/Counter block can select a capture signal as a clock source instead of the PCLK derived clock. For more details see Section 21-6.3.
MAT0[1:0] Output MAT1[1:0] MAT2[3:0] MAT3[1:0]
External Match Output - When a match register (MR3:0) equals the timer counter (TC) this output can either toggle, go low, go high, or do nothing. The External Match Register (EMR) controls the functionality of this output. Match Output functionality can be selected on a number of pins in parallel.
5.1 Multiple CAP and MAT pins
Software can select from multiple pins for the CAP or MAT functions in the Pin Select registers, which are described in Section 8-5. When more than one pin is selected for a MAT output, all such pins are driven identically. When more than one pin is selected for a CAP input, the pin with the lowest Port number is used. Note that match conditions may be used internally without the use of a device pin.
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6. Register description
Each Timer/Counter contains the registers shown in Table 21-426 ("Reset Value" refers to the data stored in used bits only; it does not include reserved bits content). More detailed descriptions follow.
Table 426. TIMER/COUNTER0-3 register map Generic Description Name Access Reset TIMERn Register/ Value[1] Name & Address
IR
Interrupt Register. The IR can be written to clear interrupts. The IR R/W can be read to identify which of eight possible interrupt sources are pending. Timer Control Register. The TCR is used to control the Timer Counter functions. The Timer Counter can be disabled or reset through the TCR. Timer Counter. The 32-bit TC is incremented every PR+1 cycles of PCLK. The TC is controlled through the TCR. R/W
0
T0IR - 0x4000 4000 T1IR - 0x4000 8000 T2IR - 0x4009 0000 T3IR - 0x4009 4000 T0TCR - 0x4000 4004 T1TCR - 0x4000 8004 T2TCR - 0x4009 0004 T3TCR - 0x4009 4004 T0TC - 0x4000 4008 T1TC - 0x4000 8008 T2TC - 0x4009 0008 T3TC - 0x4009 4008 T0PR - 0x4000 400C T1PR - 0x4000 800C T2PR - 0x4009 000C T3PR - 0x4009 400C T0PC - 0x4000 4010 T1PC - 0x4000 8010 T2PC - 0x4009 0010 T3PC - 0x4009 4010 T0MCR - 0x4000 4014 T1MCR - 0x4000 8014 T2MCR - 0x4009 0014 T3MCR - 0x4009 4014 T0MR0 - 0x4000 4018 T1MR0 - 0x4000 8018 T2MR0 - 0x4009 0018 T3MR0 - 0x4009 4018 T0MR1 - 0x4000 401C T1MR1 - 0x4000 801C T2MR1 - 0x4009 001C T3MR1 - 0x4009 401C T0MR2 - 0x4000 4020 T1MR2 - 0x4000 8020 T2MR2 - 0x4009 0020 T3MR2 - 0x4009 4020 T0MR3 - 0x4000 4024 T1MR3 - 0x4000 8024 T2MR3 - 0x4009 0024 T3MR3 - 0x4009 4024 T0CCR - 0x4000 4028 T1CCR - 0x4000 8028 T2CCR - 0x4009 0028 T3CCR - 0x4009 4028
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TCR
0
TC
R/W
0
PR
Prescale Register. When the Prescale Counter (below) is equal to this value, the next clock increments the TC and clears the PC.
R/W
0
PC
Prescale Counter. The 32-bit PC is a counter which is incremented R/W to the value stored in PR. When the value in PR is reached, the TC is incremented and the PC is cleared. The PC is observable and controllable through the bus interface. Match Control Register. The MCR is used to control if an interrupt is R/W generated and if the TC is reset when a Match occurs.
0
MCR
0
MR0
Match Register 0. MR0 can be enabled through the MCR to reset the TC, stop both the TC and PC, and/or generate an interrupt every time MR0 matches the TC. Match Register 1. See MR0 description.
R/W
0
MR1
R/W
0
MR2
Match Register 2. See MR0 description.
R/W
0
MR3
Match Register 3. See MR0 description.
R/W
0
CCR
Capture Control Register. The CCR controls which edges of the R/W capture inputs are used to load the Capture Registers and whether or not an interrupt is generated when a capture takes place.
0
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Chapter 21: LPC17xx Timer 0/1/2/3
Table 426. TIMER/COUNTER0-3 register map Generic Description Name Access Reset TIMERn Register/ Value[1] Name & Address
CR0
Capture Register 0. CR0 is loaded with the value of TC when there RO is an event on the CAPn.0(CAP0.0 or CAP1.0 respectively) input.
0
T0CR0 - 0x4000 402C T1CR0 - 0x4000 802C T2CR0 - 0x4009 002C T3CR0 - 0x4009 402C T0CR1 - 0x4000 4030 T1CR1 - 0x4000 8030 T2CR1 - 0x4009 0030 T3CR1 - 0x4009 4030 T0EMR - 0x4000 403C T1EMR - 0x4000 803C T2EMR - 0x4009 003C T3EMR - 0x4009 403C T0CTCR - 0x4000 4070 T1CTCR - 0x4000 8070 T2CTCR - 0x4009 0070 T3CTCR - 0x4009 4070
CR1
Capture Register 1. See CR0 description.
RO
0
EMR
External Match Register. The EMR controls the external match pins R/W MATn.0-3 (MAT0.0-3 and MAT1.0-3 respectively).
0
CTCR
Count Control Register. The CTCR selects between Timer and R/W Counter mode, and in Counter mode selects the signal and edge(s) for counting.
0
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
6.1 Interrupt Register (T[0/1/2/3]IR - 0x4000 4000, 0x4000 8000, 0x4009 0000, 0x4009 4000)
The Interrupt Register consists of 4 bits for the match interrupts and 4 bits for the capture interrupts. If an interrupt is generated then the corresponding bit in the IR will be high. Otherwise, the bit will be low. Writing a logic one to the corresponding IR bit will reset the interrupt. Writing a zero has no effect. The act of clearing an interrupt for a timer match also clears any corresponding DMA request.
Table 427. Interrupt Register (T[0/1/2/3]IR - addresses 0x4000 4000, 0x4000 8000, 0x4009 0000, 0x4009 4000) bit description Bit Symbol Description Reset Value
0 1 2 3 4 5 31:6
MR0 Interrupt MR1 Interrupt MR2 Interrupt MR3 Interrupt CR0 Interrupt CR1 Interrupt -
Interrupt flag for match channel 0. Interrupt flag for match channel 1. Interrupt flag for match channel 2. Interrupt flag for match channel 3. Interrupt flag for capture channel 0 event. Interrupt flag for capture channel 1 event. Reserved
0 0 0 0 0 0 -
6.2 Timer Control Register (T[0/1/2/3]CR - 0x4000 4004, 0x4000 8004, 0x4009 0004, 0x4009 4004)
The Timer Control Register (TCR) is used to control the operation of the Timer/Counter.
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Table 428. Timer Control Register (TCR, TIMERn: TnTCR - addresses 0x4000 4004, 0x4000 8004, 0x4009 0004, 0x4009 4004) bit description Bit Symbol Description Reset Value
0 1 31:2
Counter Enable Counter Reset -
When one, the Timer Counter and Prescale Counter are enabled for counting. When 1, the counters are disabled. When one, the Timer Counter and the Prescale Counter are synchronously reset on the next positive edge of PCLK. The counters remain reset until TCR[1] is returned to zero. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 NA
6.3 Count Control Register (T[0/1/2/3]CTCR - 0x4000 4070, 0x4000 8070, 0x4009 0070, 0x4009 4070)
The Count Control Register (CTCR) is used to select between Timer and Counter mode, and in Counter mode to select the pin and edge(s) for counting. When Counter Mode is chosen as a mode of operation, the CAP input (selected by the CTCR bits 3:2) is sampled on every rising edge of the PCLK clock. After comparing two consecutive samples of this CAP input, one of the following four events is recognized: rising edge, falling edge, either of edges or no changes in the level of the selected CAP input. Only if the identified event occurs and the event corresponds to the one selected by bits 1:0 in the CTCR register, will the Timer Counter register be incremented. Effective processing of the externally supplied clock to the counter has some limitations. Since two successive rising edges of the PCLK clock are used to identify only one edge on the CAP selected input, the frequency of the CAP input can not exceed one quarter of the PCLK clock. Consequently, duration of the high/low levels on the same CAP input in this case can not be shorter than 1/(2 PCLK).
Table 429. Count Control Register (T[0/1/2/3]CTCR - addresses 0x4000 4070, 0x4000 8070, 0x4009 0070, 0x4009 4070) bit description Bit Symbol Value Description Reset Value
1:0
Counter/ Timer Mode
This field selects which rising PCLK edges can increment the Timer's Prescale Counter (PC), or clear the PC and increment the Timer Counter (TC). 00 01 10 11 Timer Mode: the TC is incremented when the Prescale Counter matches the Prescale Register. The Prescale Counter is incremented on every rising PCLK edge. Counter Mode: TC is incremented on rising edges on the CAP input selected by bits 3:2. Counter Mode: TC is incremented on falling edges on the CAP input selected by bits 3:2. Counter Mode: TC is incremented on both edges on the CAP input selected by bits 3:2.
00
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Table 429. Count Control Register (T[0/1/2/3]CTCR - addresses 0x4000 4070, 0x4000 8070, 0x4009 0070, 0x4009 4070) bit description Bit Symbol Value Description Reset Value
3:2
Count Input Select
When bits 1:0 in this register are not 00, these bits select which CAP pin is sampled for clocking. 00 01 10 11 CAPn.0 for TIMERn CAPn.1 for TIMERn Reserved Reserved
Note: If Counter mode is selected for a particular CAPn input in the TnCTCR, the 3 bits for that input in the Capture Control Register (TnCCR) must be programmed as 000. However, capture and/or interrupt can be selected for the other 3 CAPn inputs in the same timer.
00
31:4
-
-
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA
6.4 Timer Counter registers (T0TC - T3TC, 0x4000 4008, 0x4000 8008, 0x4009 0008, 0x4009 4008)
The 32-bit Timer Counter register is incremented when the prescale counter reaches its terminal count. Unless it is reset before reaching its upper limit, the Timer Counter will count up through the value 0xFFFF FFFF and then wrap back to the value 0x0000 0000. This event does not cause an interrupt, but a match register can be used to detect an overflow if needed.
6.5 Prescale register (T0PR - T3PR, 0x4000 400C, 0x4000 800C, 0x4009 000C, 0x4009 400C)
The 32-bit Prescale register specifies the maximum value for the Prescale Counter.
6.6 Prescale Counter register (T0PC - T3PC, 0x4000 4010, 0x4000 8010, 0x4009 0010, 0x4009 4010)
The 32-bit Prescale Counter controls division of PCLK by some constant value before it is applied to the Timer Counter. This allows control of the relationship of the resolution of the timer versus the maximum time before the timer overflows. The Prescale Counter is incremented on every PCLK. When it reaches the value stored in the Prescale register, the Timer Counter is incremented and the Prescale Counter is reset on the next PCLK. This causes the Timer Counter to increment on every PCLK when PR = 0, every 2 pclks when PR = 1, etc.
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Chapter 21: LPC17xx Timer 0/1/2/3
6.7 Match Registers (MR0 - MR3)
The Match register values are continuously compared to the Timer Counter value. When the two values are equal, actions can be triggered automatically. The action possibilities are to generate an interrupt, reset the Timer Counter, or stop the timer. Actions are controlled by the settings in the MCR register.
6.8 Match Control Register (T[0/1/2/3]MCR - 0x4000 4014, 0x4000 8014, 0x4009 0014, 0x4009 4014)
The Match Control Register is used to control what operations are performed when one of the Match Registers matches the Timer Counter. The function of each of the bits is shown in Table 21-430.
Table 430. Match Control Register (T[0/1/2/3]MCR - addresses 0x4000 4014, 0x4000 8014, 0x4009 0014, 0x4009 4014) bit description Bit Symbol Value Description Reset Value
0 1 2
MR0I MR0R MR0S
1 0 1 0 1 0
Interrupt on MR0: an interrupt is generated when MR0 matches the value in the TC. This interrupt is disabled Reset on MR0: the TC will be reset if MR0 matches it. Feature disabled. Stop on MR0: the TC and PC will be stopped and TCR[0] will be set to 0 if MR0 matches the TC. Feature disabled. Interrupt on MR1: an interrupt is generated when MR1 matches the value in the TC. This interrupt is disabled Reset on MR1: the TC will be reset if MR1 matches it. Feature disabled. Stop on MR1: the TC and PC will be stopped and TCR[0] will be set to 0 if MR1 matches the TC. Feature disabled. Interrupt on MR2: an interrupt is generated when MR2 matches the value in the TC. This interrupt is disabled Reset on MR2: the TC will be reset if MR2 matches it. Feature disabled. Stop on MR2: the TC and PC will be stopped and TCR[0] will be set to 0 if MR2 matches the TC. Feature disabled. Interrupt on MR3: an interrupt is generated when MR3 matches the value in the TC. This interrupt is disabled Reset on MR3: the TC will be reset if MR3 matches it. Feature disabled. Stop on MR3: the TC and PC will be stopped and TCR[0] will be set to 0 if MR3 matches the TC. Feature disabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 0 0
3 4 5
MR1I MR1R MR1S
1 0 1 0 1 0
0 0 0
6 7 8
MR2I MR2R MR2S
1 0 1 0 1 0
0 0 0
9 10 11
MR3I MR3R MR3S
1 0 1 0 1 0
0 0 0
31:12 -
NA
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Chapter 21: LPC17xx Timer 0/1/2/3
6.9 Capture Registers (CR0 - CR1)
Each Capture register is associated with a device pin and may be loaded with the Timer Counter value when a specified event occurs on that pin. The settings in the Capture Control Register register determine whether the capture function is enabled, and whether a capture event happens on the rising edge of the associated pin, the falling edge, or on both edges.
6.10 Capture Control Register (T[0/1/2/3]CCR - 0x4000 4028, 0x4000 8028, 0x4009 0028, 0x4009 4028)
The Capture Control Register is used to control whether one of the four Capture Registers is loaded with the value in the Timer Counter when the capture event occurs, and whether an interrupt is generated by the capture event. Setting both the rising and falling bits at the same time is a valid configuration, resulting in a capture event for both edges. In the description below, "n" represents the Timer number, 0 or 1. Note: If Counter mode is selected for a particular CAP input in the CTCR, the 3 bits for that input in this register should be programmed as 000, but capture and/or interrupt can be selected for the other 3 CAP inputs.
Table 431. Capture Control Register (T[0/1/2/3]CCR - addresses 0x4000 4028, 0x4000 8020, 0x4009 0028, 0x4009 4028) bit description Bit Symbol Value Description Reset Value
0
CAP0RE 1 0
Capture on CAPn.0 rising edge: a sequence of 0 then 1 on CAPn.0 will cause CR0 to be loaded with the contents of TC. This feature is disabled. Capture on CAPn.0 falling edge: a sequence of 1 then 0 on CAPn.0 will cause CR0 to be loaded with the contents of TC. This feature is disabled. Interrupt on CAPn.0 event: a CR0 load due to a CAPn.0 event will generate an interrupt. This feature is disabled. Capture on CAPn.1 rising edge: a sequence of 0 then 1 on CAPn.1 will cause CR1 to be loaded with the contents of TC. This feature is disabled. Capture on CAPn.1 falling edge: a sequence of 1 then 0 on CAPn.1 will cause CR1 to be loaded with the contents of TC. This feature is disabled. Interrupt on CAPn.1 event: a CR1 load due to a CAPn.1 event will generate an interrupt. This feature is disabled. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
CAP0FE 1 0
0
2 3
CAP0I
1 0
0 0
CAP1RE 1 0
4
CAP1FE 1 0
0
5 31:6
CAP1I -
1 0
0 NA
6.11 External Match Register (T[0/1/2/3]EMR - 0x4000 403C, 0x4000 803C, 0x4009 003C, 0x4009 403C)
The External Match Register provides both control and status of the external match pins. In the descriptions below, "n" represents the Timer number, 0 or 1, and "m" represent a Match number, 0 through 3.
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Chapter 21: LPC17xx Timer 0/1/2/3
Match events for Match 0 and Match 1 in each timer can cause a DMA request, see Section 21-6.12.
Table 432. External Match Register (T[0/1/2/3]EMR - addresses 0x4000 403C, 0x4000 803C, 0x4009 003C, 0x4009 403C) bit description Bit Symbol Description Reset Value
0
EM0
External Match 0. When a match occurs between the TC and MR0, this bit can either toggle, go low, go high, or do nothing, depending on bits 5:4 of this register. This bit can be driven onto a MATn.0 pin, in a positive-logic manner (0 = low, 1 = high). External Match 1. When a match occurs between the TC and MR1, this bit can either toggle, go low, go high, or do nothing, depending on bits 7:6 of this register. This bit can be driven onto a MATn.1 pin, in a positive-logic manner (0 = low, 1 = high). External Match 2. When a match occurs between the TC and MR2, this bit can either toggle, go low, go high, or do nothing, depending on bits 9:8 of this register. This bit can be driven onto a MATn.0 pin, in a positive-logic manner (0 = low, 1 = high). External Match 3. When a match occurs between the TC and MR3, this bit can either toggle, go low, go high, or do nothing, depending on bits 11:10 of this register. This bit can be driven onto a MATn.0 pin, in a positive-logic manner (0 = low, 1 = high). External Match Control 0. Determines the functionality of External Match 0. Table 21-433 shows the encoding of these bits. External Match Control 1. Determines the functionality of External Match 1. Table 21-433 shows the encoding of these bits. External Match Control 2. Determines the functionality of External Match 2. Table 21-433 shows the encoding of these bits. External Match Control 3. Determines the functionality of External Match 3. Table 21-433 shows the encoding of these bits. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
1
EM1
0
2
EM2
0
3
EM3
0
5:4 7:6 9:8
EMC0 EMC1 EMC2
00 00 00 00 NA
11:10 EMC3 15:12 -
Table 433. External Match Control EMR[11:10], EMR[9:8], EMR[7:6], or EMR[5:4] Function
00 01 10 11
Do Nothing. Clear the corresponding External Match bit/output to 0 (MATn.m pin is LOW if pinned out). Set the corresponding External Match bit/output to 1 (MATn.m pin is HIGH if pinned out). Toggle the corresponding External Match bit/output.
6.12 DMA operation
DMA requests are generated by 0 to 1 transitions of the External Match 0 and 1 bits of each timer. In order to have an effect, the GPDMA must be configured and the relevant timer DMA request selected as a DMA source via the DMAREQSEL register, see Section 31-5.15. When a timer is initially set up to generate a DMA request, the request may already be asserted before a match condition occurs. An initial DMA request may be avoided by having software write a one to the interrupt flag location, as if clearing a timer interrupt. See Section 21-6.1. A DMA request will be cleared automatically when it is acted upon by the GPDMA controller.
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Chapter 21: LPC17xx Timer 0/1/2/3
7. Example timer operation
Figure 21-113 shows a timer configured to reset the count and generate an interrupt on match. The prescaler is set to 2 and the match register set to 6. At the end of the timer cycle where the match occurs, the timer count is reset. This gives a full length cycle to the match value. The interrupt indicating that a match occurred is generated in the next clock after the timer reached the match value. Figure 21-114 shows a timer configured to stop and generate an interrupt on match. The prescaler is again set to 2 and the match register set to 6. In the next clock after the timer reaches the match value, the timer enable bit in TCR is cleared, and the interrupt indicating that a match occurred is generated.
PCLK prescale counter timer counter timer counter reset interrupt 2 4 0 1 5 2 0 1 6 2 0 1 0 2 0 1 1
Fig 113. A timer cycle in which PR=2, MRx=6, and both interrupt and reset on match are enabled.
PCLK prescale counter timer counter TCR[0] (counter enable) interrupt 2 4 0 1 5 1 2 0 6 0
Fig 114. A timer Cycle in Which PR=2, MRx=6, and both interrupt and stop on match are enabled
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Chapter 21: LPC17xx Timer 0/1/2/3
8. Architecture
The block diagram for TIMER/COUNTER0 and TIMER/COUNTER1 is shown in Figure 21-115.
MATCH REGISTER 0 MATCH REGISTER 1 MATCH REGISTER 2 MATCH REGISTER 3 MATCH CONTROL REGISTER EXTERNAL MATCH REGISTER INTERRUPT REGISTER
CONTROL MAT[3:0] INTERRUPT CAP[3:0] DMA REQUEST[1:0] DMA CLEAR[1:0] STOP ON MATCH RESET ON MATCH LOAD[3:0] = = = =
CAPTURE CONTROL REGISTER
CAPTURE REGISTER 0 CAPTURE REGISTER 1 RESERVED RESERVED
CSN
TIMER COUNTER CE
TCI PCLK PRESCALE COUNTER reset enable MAXVAL PRESCALE REGISTER
TIMER CONTROL REGISTER
Fig 115. Timer block diagram
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Chapter 22: LPC17xx Repetitive Interrupt Timer (RIT)
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1. Features
* 32-bit counter running from PCLK. Counter can be free-running, or be reset by a
generated interrupt.
* 32-bit compare value. * 32-bit compare mask. An interrupt is generated when the counter value equals the
compare value, after masking. This allows for combinations not possible with a simple compare.
2. Description
The Repetitive Interrupt Timer provides a versatile means of generating interrupts at specified time intervals, without using a standard timer. It is intended for repeating interrupts that aren't related to Operating System interrupts. However, it could be used as an alternative to the Cortex-M3 System Tick Timer (Section 23-1) if there are different system requirements.
3. Register description
Table 434. Repetitive Interrupt Timer register map Name Description Access Reset value[1] Address
RICOMPVAL RIMASK
Compare register
R/W
0xFFFF FFFF 0x400B 0000 0 0x400B 0004
R/W Mask register. This register holds the 32-bit mask value. A `1' written to any bit will force a compare on the corresponding bit of the counter and compare register. Control register. 32-bit counter R/W R/W
RICTRL RICOUNTER
[1]
0xC 0
0x400B 0008 0x400B 000C
Reset Value reflects the data stored in used bits only. It does not include content of reserved bits.
3.1 RI Compare Value register (RICOMPVAL - 0x400B 0000)
Table 435. RI Compare Value register (RICOMPVAL - address 0x400B 0000) bit description Bit Symbol Description Reset value
31:0
RICOMP
Compare register. Holds the compare value which is compared to the counter.
0xFFFF FFFF
3.2 RI Mask register (RIMASK - 0x400B 0004)
Table 436. RI Compare Value register (RICOMPVAL - address 0x400B 0004) bit description Bit Symbol Description Reset value
31:0
RIMASK
Mask register. This register holds the 32-bit mask value. A `1' written to any bit will force a 0 compare on the corresponding bit of the counter and compare register.
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Chapter 22: LPC17xx Repetitive Interrupt Timer (RIT)
3.3 RI Control register (RICTRL - 0x400B 0008)
Table 437. RI Control register (RICTRL - address 0x400B 0008) bit description Bit Symbol Value Description Reset value
0
RITINT 1
Interrupt flag This bit is set to 1 by hardware whenever the counter value equals the masked compare value specified by the contents of RICOMPVAL and RIMASK registers. Writing a 1 to this bit will clear it to 0. Writing a 0 has no effect. 0 The counter value does not equal the masked compare value. Timer enable clear 1
0
1
RITENCLR
The timer will be cleared to 0 whenever the counter value equals the masked compare 0 value specified by the contents of RICOMPVAL and RIMASK registers. This will occur on the same clock that sets the interrupt flag. The timer will not be cleared to 0. Timer enable for debug 1 The timer is halted when the processor is halted for debugging. Debug has no effect on the timer operation. Timer enable. 1 Timer enabled.
Remark: This can be overruled by a debug halt if enabled in bit 2.
0 2 RITENBR 1 0 3 RITEN 1 0 31:4 -
Timer disabled. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
3.4 RI Counter register (RICOUNTER - 0x400B 000C)
Table 438. RI Counter register (RICOUNTER - address 0x400B 000C) bit description Bit Symbol Description Reset value
31:0
RICOUNTER
32-bit up counter. Counts continuously unless RITEN bit in RICTRL register is cleared or debug mode is entered (if enabled by the RITNEBR bit in RICTRL). Can be loaded to any value in software.
0
4. RI timer operation
Following reset, the counter begins counting up from 00000000h. Whenever the counter value equals the value programmed into the RICOMPVAL register the interrupt flag will be set. Any bit or combination of bits can be removed from this comparison (i.e. forced to compare) by writing a `1' to the corresponding bit(s) in the RIMASK register. If the enable_clr bit is low (default state), a valid comparison ONLY causes the interrupt flag to be set. It has no effect on the count sequence. Counting continues as usual. When the counter reaches FFFFFFFFh it rolls-over to 00000000h on the next clock and continues counting. If the enable_clr bit is set to `1' a valid comparison will also cause the counter to be reset to zero. Counting will resume from there on the next clock edge.
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Counting can be halted in software by writing a `0' to the Enable_Timer bit - RICTRL(2). Counting will also be halted when the processor is halted for debugging provided the Enable_Break bit - RICTRL(1) is set. Both the Enable_Timer and Enable_Break bits are set on reset. The interrupt flag can be cleared in software by writing a `1' to the Interrupt bit - RICTRL(0). Software can load the counter to any value at any time by writing to RICOUNTER. The counter (RICOUNTER), RICOMPVAL register, RIMASK register and RICTRL register can all be read by software at any time.
RESET CNT_ENA
PBUS
ENA CLR 32-bit COUNTER
RESET SET ENABLE_TIMER 3 PBUS ENABLE_BREAK BREAK ENABLE_CLK
32
2 PBUS
PBUS
CLR RESET COMPARATOR EQ
32
SET_INT S
32
0 PBUS write '1' to clear RESET PBUS C CLR CTRL register
INTR
PBUS
32
RESET SET COMPARE REGISTER CLR
PBUS
MASK REGISTER
PBUS
PBUS
OperatingSystemTimer
Fig 116. RI timer block diagram
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Chapter 23: LPC17xx System Tick Timer
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1. Basic configuration
The System Tick Timer is configured using the following registers: 1. Clock Source: Select either the internal CCLK or external STCLK (P3.26) clock as the source in the STCTRL register. 2. Pins: If STCLK (P3.26) was selected as clock source enable the STCLK pin function in the PINMODE register (Section 8-5). 3. Interrupt: The System Tick Timer Interrupt is enabled in the NVIC using the appropriate Interrupt Set Enable register.
2. Features
* Times intervals of 10 milliseconds * Dedicated exception vector * Can be clocked internally by the CPU clock or by a clock input from a pin (STCLK)
3. Description
The System Tick Timer is an integral part of the Cortex-M3. The System Tick Timer is intended to generate a fixed 10 millisecond interrupt for use by an operating system or other system management software. Since the System Tick Timer is a part of the Cortex-M3, it facilitates porting of software by providing a standard timer that is available on Cortex-M3 based devices. Refer to the Cortex-M3 User Guide appended to this manual (Section 34-4.4) for details of System Tick Timer operation.
4. Operation
The System Tick Timer is a 24-bit timer that counts down to zero and generates an interrupt. The intent is to provide a fixed 10 millisecond time interval between interrupts. The System Tick Timer may be clocked either from the CPU clock or from the external pin STCLK. The STCLK function shares pin P3.26 with other functions, and must be selected for use as the System Tick Timer clock. In order to generate recurring interrupts at a specific interval, the STRELOAD register must be initialized with the correct value for the desired interval. A default value is provided in the STCALIB register and may be changed by software. The default value gives a 10 millisecond interrupt rate if the CPU clock is set to 100 MHz. The block diagram of the System Tick Timer is shown below in the Figure 23-117.
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STCALIB STRELOAD
load data
cclk STCLK pin
D Q
STCURR 24-bit down counter
clock load under- count flow enable
private peripheral bus
ENABLE CLKSOURCE STCTRL COUNTFLAG TICKINT System Tick interrupt
Fig 117. System Tick Timer block diagram
5. Register description
Table 439. System Tick Timer register map Name Description Access Reset value[1] Address
STCTRL STRELOAD STCURR STCALIB
[1]
System Timer Control and status register System Timer Reload value register System Timer Current value register System Timer Calibration value register
R/W R/W R/W R/W
0x4 0 0 0x000F 423F
0xE000 E010 0xE000 E014 0xE000 E018 0xE000 E01C
Reset Value reflects the data stored in used bits only. It does not include content of reserved bits.
5.1 System Timer Control and status register (STCTRL - 0xE000 E010)
The STCTRL register contains control information for the System Tick Timer, and provides a status flag.
Table 440. System Timer Control and status register (STCTRL - 0xE000 E010) bit description Bit Symbol Description Reset value
0 1
ENABLE TICKINT
System Tick counter enable. When 1, the counter is enabled. When 0, the counter is disabled.
0
System Tick interrupt enable. When 1, the System Tick interrupt is 0 enabled. When 0, the System Tick interrupt is disabled. When enabled, the interrupt is generated when the System Tick counter counts down to 0. System Tick clock source selection. When 1, the CPU clock is selected. When 0, the external clock pin (STCLK) is selected. 1
2
CLKSOURCE
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Table 440. System Timer Control and status register (STCTRL - 0xE000 E010) bit description Bit Symbol Description Reset value
15:3 16 31:17
COUNTFLAG -
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. System Tick counter flag. This flag is set when the System Tick counter counts down to 0, and is cleared by reading this register. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
NA 0 NA
5.2 System Timer Reload value register (STRELOAD - 0xE000 E014)
The STRELOAD register is set to the value that will be loaded into the System Tick Timer whenever it counts down to zero. This register is loaded by software as part of timer initialization. The STCALIB register may be read and used as the value for STRELOAD if the CPU or external clock is running at the frequency intended for use with the STCALIB value.
Table 441. System Timer Reload value register (STRELOAD - 0xE000 E014) bit description Bit Symbol Description Reset value
23:0 31:24
RELOAD -
This is the value that is loaded into the System Tick counter when it counts down to 0. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0 NA
5.3 System Timer Current value register (STCURR - 0xE000 E018)
The STCURR register returns the current count from the System Tick counter when it is read by software.
Table 442. System Timer Current value register (STCURR - 0xE000 E018) bit description Bit Symbol Description Reset value
23:0
CURRENT
Reading this register returns the current value of the System Tick counter. Writing any value clears the System Tick counter and the COUNTFLAG bit in STCTRL. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
31:24
-
NA
5.4 System Timer Calibration value register (STCALIB - 0xE000 E01C)
The STCALIB register contains a value that is initialized by the Boot Code to a factory programmed value that is appropriate for generating an interrupt every 10 milliseconds if the System Tick Timer is clocked at a frequency of 100 MHz. This is the intended use of the System Tick Timer by ARM. It can be used to generate interrupts at other frequencies by selecting the correct reload value.
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Chapter 23: LPC17xx System Tick Timer
Table 443. System Timer Calibration value register (STCALIB - 0xE000 E01C) bit description Bit Symbol Value Description Reset value
23:0
TENMS
Reload value to get a 10 millisecond System Tick underflow rate when running 0x0F 423F at 100 MHz. This value initialized at reset with a factory supplied value selected for the LPC17xx. The provided values of TENMS, SKEW, and NOREF are applicable only when using a CPU clock or external STCLK source of 100 MHz. Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. Indicates whether the TENMS value will generate a precise 10 millisecond time, 0 or an approximation. This bit is initialized at reset with a factory supplied value selected for the LPC17xx. See the description of TENMS above. When 0, the value of TENMS is considered to be precise. When 1, the value of TENMS is not considered to be precise.
29:24 30
SKEW
31
NOREF
Indicates whether an external reference clock is available. This bit is initialized at reset with a factory supplied value selected for the LPC17xx. See the description of TENMS above. When 0, a separate reference clock is available. When 1, a separate reference clock is not available.
0
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Chapter 23: LPC17xx System Tick Timer
6. Example timer calculations
The following examples illustrate selecting System Tick Timer values for different system configurations. All of the examples calculate an interrupt interval of 10 milliseconds, as the System Tick Timer is intended to be used. Example 1) This example is for the System Tick Timer running from the CPU clock (cclk), which is 100 MHz. STCTRL = 7. This enables the timer and its interrupt, and selects cclk as the clock source. RELOAD = (cclk / 100) - 1 = 1,000,000 - 1 = 999,999 = 0xF423F In this case, there is no rounding error, so the result is as accurate as cclk. Example 2) This example is for the System Tick Timer running from the CPU clock (cclk), which is 80 MHz. STCTRL = 7. This enables the timer and its interrupt, and selects cclk as the clock source. RELOAD = (cclk / 100) - 1 = 800,000 - 1 = 799,999 = 0xC34FF In this case, there is no rounding error, so the result is as accurate as cclk. Example 3) This example is for the CPU clock (cclk) is taken from the Internal RC Oscillator (IRC), factory trimmed to 4 MHz. STCTRL = 7. This enables the timer and its interrupt, and selects cclk as the clock source. RELOAD = (FIRC / 100) - 1 = 40,000 - 1 = 39,999 = 0x9C3F In this case, there is no rounding error, so the result is as accurate as the IRC. Example 4) This example is for the System Tick Timer running from an external clock source (the STCLK pin), which in this case happens to be 32.768 kHz. STCTRL = 3. This enables the timer and its interrupt, and selects the STCLK pin as the clock source. STCLK must be selected as the function of the relevant pin. See Section 8-5.6. RELOAD = (cclk / 100) - 1 = 327.6 - 1 = 327 (rounded up) = 0x0147 In this case, there is rounding error, so the interrupt rate will drift slightly relative to the input frequency.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The PWM is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCPWM1. Remark: On reset, the PWM is enabled (PCPWM1 = 1). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_PWM1. 3. Pins: Select PWM pins through the PINSEL registers. Select pin modes for port pins with PWM1 functions through the PINMODE registers (Section 8-5). 4. Interrupts: See registers PWM1MCR (Table 24-450) and PWM1CCR (Table 24-451) for match and capture events. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register.
2. Features
* Counter or Timer operation (may use the peripheral clock or one of the capture inputs
as the clock source).
* Seven match registers allow up to 6 single edge controlled or 3 double edge
controlled PWM outputs, or a mix of both types. The match registers also allow: - Continuous operation with optional interrupt generation on match. - Stop timer on match with optional interrupt generation. - Reset timer on match with optional interrupt generation.
* Supports single edge controlled and/or double edge controlled PWM outputs. Single
edge controlled PWM outputs all go high at the beginning of each cycle unless the output is a constant low. Double edge controlled PWM outputs can have either edge occur at any position within a cycle. This allows for both positive going and negative going pulses.
* Pulse period and width can be any number of timer counts. This allows complete
flexibility in the trade-off between resolution and repetition rate. All PWM outputs will occur at the same repetition rate.
* Double edge controlled PWM outputs can be programmed to be either positive going
or negative going pulses.
* Match register updates are synchronized with pulse outputs to prevent generation of
erroneous pulses. Software must "release" new match values before they can become effective.
* May be used as a standard timer if the PWM mode is not enabled. * A 32-bit Timer/Counter with a programmable 32-bit prescaler. * Two 32-bit capture channels take a snapshot of the timer value when an input signal
transitions. A capture event may also optionally generate an interrupt.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
3. Description
The PWM is based on the standard Timer block and inherits all of its features, although only the PWM function is pinned out on the LPC17xx. The Timer is designed to count cycles of the peripheral clock (PCLK) and optionally generate interrupts or perform other actions when specified timer values occur, based on seven match registers. The PWM function is in addition to these features, and is based on match register events. The ability to separately control rising and falling edge locations allows the PWM to be used for more applications. For instance, multi-phase motor control typically requires three non-overlapping PWM outputs with individual control of all three pulse widths and positions. Two match registers can be used to provide a single edge controlled PWM output. One match register (PWMMR0) controls the PWM cycle rate, by resetting the count upon match. The other match register controls the PWM edge position. Additional single edge controlled PWM outputs require only one match register each, since the repetition rate is the same for all PWM outputs. Multiple single edge controlled PWM outputs will all have a rising edge at the beginning of each PWM cycle, when an PWMMR0 match occurs. Three match registers can be used to provide a PWM output with both edges controlled. Again, the PWMMR0 match register controls the PWM cycle rate. The other match registers control the two PWM edge positions. Additional double edge controlled PWM outputs require only two match registers each, since the repetition rate is the same for all PWM outputs. With double edge controlled PWM outputs, specific match registers control the rising and falling edge of the output. This allows both positive going PWM pulses (when the rising edge occurs prior to the falling edge), and negative going PWM pulses (when the falling edge occurs prior to the rising edge). Figure 24-118 shows the block diagram of the PWM. The portions that have been added to the standard timer block are on the right hand side and at the top of the diagram.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
MATCH REGISTER 0 MATCH REGISTER 1 MATCH REGISTER 2 MATCH REGISTER 3 MATCH REGISTER 4 MATCH REGISTER 5 MATCH REGISTER 6
SHADOW REGISTER 0 LOAD ENABLE SHADOW REGISTER 1 LOAD ENABLE SHADOW REGISTER 2 LOAD ENABLE SHADOW REGISTER 3 LOAD ENABLE SHADOW REGISTER 4 LOAD ENABLE SHADOW REGISTER 5 LOAD ENABLE SHADOW REGISTER 6 LOAD ENABLE
Match 0
S Q
PWM1
Match 1
R EN
PWMENA1
PWMSEL2
PWM2
Match0
LOAD ENABLE REGISTER CLEAR
MUX
S
Q PWMENA2
Match 2
R EN
PWMSEL3
MATCH CONTROL REGISTER MUX S Q PWMENA3 R EN PWM3
Match 3
INTERRUPT REGISTER
PWMSEL4
PWM4 MUX = S Q PWMENA4 R EN
CONTROL M[6:0] INTERRUPT CAPTURE[1:0] STOP ON MATCH RESET ON MATCH LOAD[1:0]
= = = = = =
Match 4
PWMSEL5
PWM5 MUX S Q PWMENA5 R EN
Match 5
PWMSEL6
CAPTURE CONTROL REGISTER MUX CAPTURE REGISTER 0 CAPTURE REGISTER 1 RESERVED RESERVED S Q PWMENA6 R EN PWM6
CSN
TIMER COUNTER
Match 6
CE
TCI
PRESCALE COUNTER
PWMENA1..6
PWMSEL2..6
reset
TIMER CONTROL REGISTER
enable
MAXVAL
PRESCALE REGISTER PWM CONTROL REGISTER
Fig 118. PWM block diagram
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
4. Sample waveform with rules for single and double edge control
A sample of how PWM values relate to waveform outputs is shown in Figure 24-119. PWM output logic is shown in Figure 24-118 that allows selection of either single or double edge controlled PWM outputs via the muxes controlled by the PWMSELn bits. The match register selections for various PWM outputs is shown in Table 24-444. This implementation supports up to N-1 single edge PWM outputs or (N-1)/2 double edge PWM outputs, where N is the number of match registers that are implemented. PWM types can be mixed if desired.
PWM2 PWM4
PWM5
1
27
41
53
65
78
100 (counter is reset)
The waveforms below show a single PWM cycle and demonstrate PWM outputs under the following conditions: The timer is configured for PWM mode (counter resets to 1). Match 0 is configured to reset the timer/counter when a match event occurs. All PWM related Match registers are configured for toggle on match. Control bits PWMSEL2 and PWMSEL4 are set. The Match register values are as follows: MR0 = 100 (PWM rate) MR1 = 41, MR2 = 78 (PWM2 output) MR3 = 53, MR4 = 27 (PWM4 output) MR5 = 65 (PWM5 output)
Fig 119. Sample PWM waveforms Table 444. Set and reset inputs for PWM Flip-Flops PWM Channel Single Edge PWM (PWMSELn = 0) Set by Reset by Double Edge PWM (PWMSELn = 1) Set by Reset by
1 2 3 4 5 6
[1] [2]
Match 0 Match 0 Match 0 Match 0 Match 0 Match 0
Match 1 Match 2 Match 3 Match 4 Match 5 Match 6
Match
0[1]
Match 1[1] Match 2 Match 3[2] Match 4 Match 5[2] Match 6
Match 1 Match 2[2] Match 3 Match 4[2] Match 5
Identical to single edge mode in this case since Match 0 is the neighboring match register. Essentially, PWM1 cannot be a double edged output. It is generally not advantageous to use PWM channels 3 and 5 for double edge PWM outputs because it would reduce the number of double edge PWM outputs that are possible. Using PWM 2, PWM4, and PWM6 for double edge PWM outputs provides the most pairings.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
4.1 Rules for Single Edge Controlled PWM Outputs
1. All single edge controlled PWM outputs go high at the beginning of a PWM cycle unless their match value is equal to 0. 2. Each PWM output will go low when its match value is reached. If no match occurs (i.e. the match value is greater than the PWM rate), the PWM output remains continuously high.
4.2 Rules for Double Edge Controlled PWM Outputs
Five rules are used to determine the next value of a PWM output when a new cycle is about to begin: 1. The match values for the next PWM cycle are used at the end of a PWM cycle (a time point which is coincident with the beginning of the next PWM cycle), except as noted in rule 3. 2. A match value equal to 0 or the current PWM rate (the same as the Match channel 0 value) have the same effect, except as noted in rule 3. For example, a request for a falling edge at the beginning of the PWM cycle has the same effect as a request for a falling edge at the end of a PWM cycle. 3. When match values are changing, if one of the "old" match values is equal to the PWM rate, it is used again once if the neither of the new match values are equal to 0 or the PWM rate, and there was no old match value equal to 0. 4. If both a set and a clear of a PWM output are requested at the same time, clear takes precedence. This can occur when the set and clear match values are the same as in, or when the set or clear value equals 0 and the other value equals the PWM rate. 5. If a match value is out of range (i.e. greater than the PWM rate value), no match event occurs and that match channel has no effect on the output. This means that the PWM output will remain always in one state, allowing always low, always high, or "no change" outputs.
5. Pin description
Table 24-445 gives a brief summary of each of PWM related pins.
Table 445. Pin summary Pin Type Description
PWM1[1] PWM1[2] PWM1[3] PWM1[4] PWM1[5] PWM1[6] PCAP1[1:0]
Output Output Output Output Output Output Input
Output from PWM channel 1. Output from PWM channel 2. Output from PWM channel 3. Output from PWM channel 4. Output from PWM channel 5. Output from PWM channel 6. Capture Inputs. A transition on a capture pin can be configured to load the corresponding Capture Register with the value of the Timer Counter and optionally generate an interrupt. The PWM brings out 2 capture inputs.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
6. Register description
The PWM1 function includes registers as shown in Table 24-446 below.
Table 446. PWM1 register map Generic Description Name Access Reset PWMn Register Value[1] Name & Address
IR TCR TC PR PC
Interrupt Register. The IR can be written to clear interrupts. The IR can be R/W read to identify which of eight possible interrupt sources are pending. Timer Control Register. The TCR is used to control the Timer Counter functions. The Timer Counter can be disabled or reset through the TCR. R/W
0 0 0 0 0
PWM1IR 0x4001 8000 PWM1TCR 0x4001 8004 PWM1TC 0x4001 8008 PWM1PR 0x4001 800C PWM1PC 0x4001 8010
Timer Counter. The 32-bit TC is incremented every PR+1 cycles of PCLK. R/W The TC is controlled through the TCR. Prescale Register. The TC is incremented every PR+1 cycles of PCLK. Prescale Counter. The 32-bit PC is a counter which is incremented to the value stored in PR. When the value in PR is reached, the TC is incremented. The PC is observable and controllable through the bus interface. Match Control Register. The MCR is used to control if an interrupt is generated and if the TC is reset when a Match occurs. R/W R/W
MCR MR0
R/W
0 0
PWM1MCR 0x4001 8014 PWM1MR0 0x4001 8018
Match Register 0. MR0 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC sets any PWM output that is in single-edge mode, and sets PWM1 if it's in double-edge mode. Match Register 1. MR1 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM1 in either edge mode, and sets PWM2 if it's in double-edge mode. Match Register 2. MR2 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM2 in either edge mode, and sets PWM3 if it's in double-edge mode. Match Register 3. MR3 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM3 in either edge mode, and sets PWM4 if it's in double-edge mode. Capture Control Register. The CCR controls which edges of the capture inputs are used to load the Capture Registers and whether or not an interrupt is generated when a capture takes place. Capture Register 0. CR0 is loaded with the value of the TC when there is an event on the CAPn.0 input. Capture Register 1. See CR0 description. Capture Register 2. See CR0 description. Capture Register 3. See CR0 description. R/W
MR1
0
PWM1MR1 0x4001 801C
MR2
0
PWM1MR2 0x4001 8020
MR3
0
PWM1MR3 0x4001 8024
CCR
0
PWM1CCR 0x4001 8028
CR0 CR1 CR2 CR3
RO RO RO RO
0 0 0 0
PWM1CR0 0x4001 802C PWM1CR1 0x4001 8030 PWM1CR2 0x4001 8034 PWM1CR3 0x4001 8038
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
Table 446. PWM1 register map Generic Description Name Access Reset PWMn Register Value[1] Name & Address
MR4
Match Register 4. MR4 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM4 in either edge mode, and sets PWM5 if it's in double-edge mode. Match Register 5. MR5 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM5 in either edge mode, and sets PWM6 if it's in double-edge mode. Match Register 6. MR6 can be enabled in the MCR to reset the TC, stop R/W both the TC and PC, and/or generate an interrupt when it matches the TC. In addition, a match between this value and the TC clears PWM6 in either edge mode. PWM Control Register. Enables PWM outputs and selects PWM channel types as either single edge or double edge controlled. Load Enable Register. Enables use of new PWM match values. Count Control Register. The CTCR selects between Timer and Counter mode, and in Counter mode selects the signal and edge(s) for counting.
[1]
0
PWM1MR4 0x4001 8040
MR5
0
PWM1MR5 0x4001 8044
MR6
0
PWM1MR6 0x4001 8048
PCR LER CTCR
R/W R/W R/W
0 0 0
PWM1PCR 0x4001 804C PWM1LER 0x4001 8050 PWM1CTCR 0x4001 8070
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
6.1 PWM Interrupt Register (PWM1IR - 0x4001 8000)
The PWM Interrupt Register consists of 11 bits (Table 24-447), 7 for the match interrupts and 4 reserved for the future use. If an interrupt is generated then the corresponding bit in the PWMIR will be high. Otherwise, the bit will be low. Writing a logic 1 to the corresponding IR bit will reset the interrupt. Writing a 0 has no effect.
Table 447: PWM Interrupt Register (PWM1IR - address 0x4001 8000) bit description Bit Symbol Description Reset Value
0 1 2 3 4 5 7:6 8 9 10
PWMMR0 Interrupt Interrupt flag for PWM match channel 0. PWMMR1 Interrupt Interrupt flag for PWM match channel 1. PWMMR2 Interrupt Interrupt flag for PWM match channel 2. PWMMR3 Interrupt Interrupt flag for PWM match channel 3. PWMCAP0 Interrupt PWMCAP1 Interrupt Interrupt flag for capture input 0 Interrupt flag for capture input 1.
0 0 0 0 0 0
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. 0 0 0
PWMMR4 Interrupt Interrupt flag for PWM match channel 4. PWMMR5 Interrupt Interrupt flag for PWM match channel 5. PWMMR6 Interrupt Interrupt flag for PWM match channel 6.
31:11 -
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
6.2 PWM Timer Control Register (PWM1TCR 0x4001 8004)
The PWM Timer Control Register (PWMTCR) is used to control the operation of the PWM Timer Counter. The function of each of the bits is shown in Table 24-448.
Table 448: PWM Timer Control Register (PWM1TCR address 0x4001 8004) bit description Bit Symbol Value Description Reset Value
0 1
Counter Enable Counter Reset
1 0 1
The PWM Timer Counter and PWM Prescale Counter are enabled for counting. The counters are disabled.
0
The PWM Timer Counter and the PWM Prescale Counter are synchronously reset 0 on the next positive edge of PCLK. The counters remain reset until this bit is returned to zero. Clear reset. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
0 2 3 PWM Enable 1
PWM mode is enabled (counter resets to 1). PWM mode causes the shadow 0 registers to operate in connection with the Match registers. A program write to a Match register will not have an effect on the Match result until the corresponding bit in PWMLER has been set, followed by the occurrence of a PWM Match 0 event. Note that the PWM Match register that determines the PWM rate (PWM Match Register 0 - MR0) must be set up prior to the PWM being enabled. Otherwise a Match event will not occur to cause shadow register contents to become effective. Timer mode is enabled (counter resets to 0). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
0 31:4 -
6.3 PWM Count Control Register (PWM1CTCR - 0x4001 8070)
The Count Control Register (CTCR) is used to select between Timer and Counter mode, and in Counter mode to select the pin and edge(s) for counting. The function of each of the bits is shown in Table 24-449.
Table 449: PWM Count control Register (PWM1CTCR - address 0x4001 8004) bit description Bit Symbol Value Description Reset Value
1:0
Counter/ Timer Mode
00 01 10 11
Timer Mode: the TC is incremented when the Prescale Counter matches the Prescale 00 Register. Counter Mode: the TC is incremented on rising edges of the PCAP input selected by bits 3:2. Counter Mode: the TC is incremented on falling edges of the PCAP input selected by bits 3:2. Counter Mode: the TC is incremented on both edges of the PCAP input selected by bits 3:2. When bits 1:0 of this register are not 00, these bits select which PCAP pin which carries the signal used to increment the TC. 00
3:2
Count Input Select 00 01
PCAP1.0 PCAP1.1 (Other combinations are reserved) Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
31:4
-
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
6.4 PWM Match Control Register (PWM1MCR - 0x4001 8014)
The PWM Match Control Registers are used to control what operations are performed when one of the PWM Match Registers matches the PWM Timer Counter. The function of each of the bits is shown in Table 24-450.
Table 450: Match Control Register (PWM1MCR - address 0x4000 4014) bit description Bit Symbol Value Description Reset Value
0
PWMMR0I
1 0
Interrupt on PWMMR0: an interrupt is generated when PWMMR0 matches the value in 0 the PWMTC. This interrupt is disabled. Reset on PWMMR0: the PWMTC will be reset if PWMMR0 matches it. This feature is disabled. Stop on PWMMR0: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR0 matches the PWMTC. This feature is disabled Interrupt on PWMMR1: an interrupt is generated when PWMMR1 matches the value in 0 the PWMTC. This interrupt is disabled. Reset on PWMMR1: the PWMTC will be reset if PWMMR1 matches it. This feature is disabled. Stop on PWMMR1: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR1 matches the PWMTC. This feature is disabled. Interrupt on PWMMR2: an interrupt is generated when PWMMR2 matches the value in 0 the PWMTC. This interrupt is disabled. Reset on PWMMR2: the PWMTC will be reset if PWMMR2 matches it. This feature is disabled. Stop on PWMMR2: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR2 matches the PWMTC. This feature is disabled Interrupt on PWMMR3: an interrupt is generated when PWMMR3 matches the value in 0 the PWMTC. This interrupt is disabled. Reset on PWMMR3: the PWMTC will be reset if PWMMR3 matches it. This feature is disabled Stop on PWMMR3: The PWMTC and PWMPC will be stopped and PWMTCR[0] will be set to 0 if PWMMR3 matches the PWMTC. This feature is disabled Interrupt on PWMMR4: An interrupt is generated when PWMMR4 matches the value in the PWMTC. This interrupt is disabled. Reset on PWMMR4: the PWMTC will be reset if PWMMR4 matches it. This feature is disabled. 0 0 0 0 0 0 0
1 2
PWMMR0R PWMMR0S
1 0 1 0
3
PWMMR1I
1 0
4 5
PWMMR1R PWMMR1S
1 0 1 0
6
PWMMR2I
1 0
7 8
PWMMR2R PWMMR2S
1 0 1 0
9
PWMMR3I
1 0
10 11
PWMMR3R PWMMR3S
1 0 1 0
12
PWMMR4I
1 0
13
PWMMR4R
1 0
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
Table 450: Match Control Register (PWM1MCR - address 0x4000 4014) bit description Bit Symbol Value Description Reset Value
14
PWMMR4S
1 0
Stop on PWMMR4: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR4 matches the PWMTC. This feature is disabled Interrupt on PWMMR5: An interrupt is generated when PWMMR5 matches the value in the PWMTC. This interrupt is disabled. Reset on PWMMR5: the PWMTC will be reset if PWMMR5 matches it. This feature is disabled. Stop on PWMMR5: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR5 matches the PWMTC. This feature is disabled Interrupt on PWMMR6: an interrupt is generated when PWMMR6 matches the value in 0 the PWMTC. This interrupt is disabled. Reset on PWMMR6: the PWMTC will be reset if PWMMR6 matches it. This feature is disabled. Stop on PWMMR6: the PWMTC and PWMPC will be stopped and PWMTCR[0] will be 0 set to 0 if PWMMR6 matches the PWMTC. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. 0 0 0
15
PWMMR5I
1 0
16 17
PWMMR5R PWMMR5S
1 0 1 0
18
PWMMR6I
1 0
19 20
PWMMR6R PWMMR6S
1 0 1
31:21 -
6.5 PWM Capture Control Register (PWM1CCR - 0x4001 8028)
The Capture Control Register is used to control whether one of the four Capture Registers is loaded with the value in the Timer Counter when a capture event occurs, and whether an interrupt is generated by the capture event. Setting both the rising and falling bits at the same time is a valid configuration, resulting in a capture event for both edges. In the descriptions below, "n" represents the Timer number, 0 or 1. Note: If Counter mode is selected for a particular CAP input in the CTCR, the 3 bits for that input in this register should be programmed as 000, but capture and/or interrupt can be selected for the other 3 CAP inputs.
Table 451: PWM Capture Control Register (PWM1CCR - address 0x4001 8028) bit description Bit Symbol Value Description Reset Value
0
Capture on CAPn.0 rising edge Capture on CAPn.0 falling edge Interrupt on CAPn.0 event
0 1 0 1 0 1
This feature is disabled. A synchronously sampled rising edge on the CAPn.0 input will cause CR0 to be loaded with the contents of the TC. This feature is disabled. A synchronously sampled falling edge on CAPn.0 will cause CR0 to be loaded with the contents of TC. This feature is disabled. A CR0 load due to a CAPn.0 event will generate an interrupt.
0
1
0
2
0
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Chapter 24: LPC17xx Pulse Width Modulator (PWM)
Table 451: PWM Capture Control Register (PWM1CCR - address 0x4001 8028) bit description Bit Symbol Value Description Reset Value
3
Capture on CAPn.1rising edge Capture on CAPn.1falling edge Interrupt on CAPn.1 event -
0 1 0 1 0 1
This feature is disabled. A synchronously sampled rising edge on the CAPn.1 input will cause CR1 to be loaded with the contents of the TC. This feature is disabled. A synchronously sampled falling edge on CAPn.1 will cause CR1 to be loaded with the contents of TC. This feature is disabled. A CR1 load due to a CAPn.1 event will generate an interrupt.
0
4
0
5 31:6
0
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined.
6.6 PWM Control Register (PWM1PCR - 0x4001 804C)
The PWM Control Register is used to enable and select the type of each PWM channel. The function of each of the bits are shown in Table 24-452.
Table 452: PWM Control Register (PWM1PCR - address 0x4001 804C) bit description Bit Symbol Value Description Reset Value
1:0 2 3 4 5 6 8:7 9 10 11 12 13
Unused PWMSEL2 PWMSEL3 PWMSEL4 PWMSEL5 PWMSEL6 PWMENA1 PWMENA2 PWMENA3 PWMENA4 PWMENA5 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
Unused, always zero. Selects double edge controlled mode for the PWM2 output. Selects single edge controlled mode for PWM2. Selects double edge controlled mode for the PWM3 output. Selects single edge controlled mode for PWM3. Selects double edge controlled mode for the PWM4 output. Selects single edge controlled mode for PWM4. Selects double edge controlled mode for the PWM5 output. Selects single edge controlled mode for PWM5. Selects double edge controlled mode for the PWM6 output. Selects single edge controlled mode for PWM6.
NA 0 0 0 0 0
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. The PWM1 output enabled. The PWM1 output disabled. The PWM2 output enabled. The PWM2 output disabled. The PWM3 output enabled. The PWM3 output disabled. The PWM4 output enabled. The PWM4 output disabled. The PWM5 output enabled. The PWM5 output disabled. 0 0 0 0 0
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Table 452: PWM Control Register (PWM1PCR - address 0x4001 804C) bit description Bit Symbol Value Description Reset Value
14
PWMENA6
1 0
The PWM6 output enabled. The PWM6 output disabled. Unused, always zero.
0 NA
31:15 Unused
6.7 PWM Latch Enable Register (PWM1LER - 0x4001 8050)
The PWM Latch Enable Registers are used to control the update of the PWM Match registers when they are used for PWM generation. When software writes to the location of a PWM Match register while the Timer is in PWM mode, the value is captured, but not used immediately. When a PWM Match 0 event occurs (normally also resetting the timer in PWM mode), the contents of shadow registers will be transferred to the shadow registers if the corresponding bit in the Latch Enable Register has been set. At that point, the new values will take effect and determine the course of the next PWM cycle. Once the transfer of new values has taken place, all bits of the LER are automatically cleared. Until the corresponding bit in the PWMLER is set and a PWM Match 0 event occurs, any value written to the PWM Match registers has no effect on PWM operation. For example, if PWM2 is configured for double edge operation and is currently running, a typical sequence of events for changing the timing would be:
* * * *
Write a new value to the PWM Match1 register. Write a new value to the PWM Match2 register. Write to the PWMLER, setting bits 1 and 2 at the same time. The altered values will become effective at the next reset of the timer (when a PWM Match 0 event occurs).
The order of writing the two PWM Match registers is not important, since neither value will be used until after the write to LER. This insures that both values go into effect at the same time, if that is required. A single value may be altered in the same way if needed. The function of each of the bits in the LER is shown in Table 24-453.
Table 453: PWM Latch Enable Register (PWM1LER - address 0x4001 8050) bit description Bit Symbol Description Reset Value
0
Enable PWM Match 0 Latch Enable PWM Match 1 Latch Enable PWM Match 2 Latch Enable PWM Match 3 Latch
Writing a one to this bit allows the last value written to the PWM Match 0 register to be 0 become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". 0 Writing a one to this bit allows the last value written to the PWM Match 1 register to be become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". 0 Writing a one to this bit allows the last value written to the PWM Match 2 register to be become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". 0 Writing a one to this bit allows the last value written to the PWM Match 3 register to be become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)".
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Table 453: PWM Latch Enable Register (PWM1LER - address 0x4001 8050) bit description Bit Symbol Description Reset Value
4
Enable PWM Match 4 Latch Enable PWM Match 5 Latch Enable PWM Match 6 Latch -
Writing a one to this bit allows the last value written to the PWM Match 4 register to be 0 become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". 0 Writing a one to this bit allows the last value written to the PWM Match 5 register to be become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". 0 Writing a one to this bit allows the last value written to the PWM Match 6 register to be become effective when the timer is next reset by a PWM Match event. See Section 24-6.4 "PWM Match Control Register (PWM1MCR - 0x4001 8014)". Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
5
6
31:7
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1. Introduction
The Motor Control PWM (MCPWM) is optimized for three-phase AC and DC motor control applications, but can be used in many other applications that need timing, counting, capture, and comparison.
2. Description
The MCPWM contains three independent channels, each including:
* * * * * * *
a 32-bit Timer/Counter (TC) a 32-bit Limit register (LIM) a 32-bit Match register (MAT) a 10-bit dead-time register (DT) and an associated 10-bit dead-time counter a 32-bit capture register (CAP) two modulated outputs (MCOA and MCOB) with opposite polarities a period interrupt, a pulse-width interrupt, and a capture interrupt
Input pins MCI0-2 can trigger TC capture or increment a channel's TC. A global Abort input can force all of the channels into "A passive" state and cause an interrupt.
3. Pin description
Table 25-454 lists the MCPWM pins.
Table 454. Pin summary Pin Type Description
MCOA0, MCOA1, MCOA2 MCOB0, MCOB1, MCOB2 MCABORT MCI0, MCI1, MCI2
O O I I
Output A for channels 0, 1, 2 Output B for channels 0, 1, 2 Low-active Fast Abort Input for channels 0, 1, 2
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4. Block Diagram
PCLK MCI0-2
Clock selection
TC0
Event selection
Clock selection
TC1
Event selection
Clock selection
TC2
Event selection
MCCNTCON MCCAPCON RT0 cntl RT1 cntl RT2 cntl
MAT0 (write) MAT0 (oper) LIM0 (write) LIM0 (oper) = CAP0 =
MAT1 (write) MAT1 (oper) LIM1 (write) LIM1 (oper) = =
mux
ACMODE
MAT2 (write) MAT2 (oper) LIM2 (write) LIM2 (oper) = =
mux
ACMODE
CAP1
CAP2
interrupt logic MCABORT MCINTEN MCINTF
ACMODE DT0 dead-time counter channel output control A0 MCCON MCCP MCABORT B0 MCCON DT1 dead-time counter
mux
ACMODE DT2
mux
channel output control A1 B1
MCCON
dead-time counter
channel output control A2 B2
MCCON
global output control
MCOA0
MCOB0
MCOA1
MCOB1
MCOA2
MCOB2
Fig 120. MCPWM Block Diagram
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5. Configuring other modules for MCPWM use
Configure the following registers in other modules before using the Motor Control PWM: 1. Power: in the PCONP register (Table 4-46), set bit PCMCPWM. Remark: On reset the MCPWM is disabled (PCMCPWM = 0). 2. Peripheral clock: in the PCLKSEL1 register (Table 4-40) select PCLK_MCPWM. 3. Pins: select MCPWM functions through the PINSEL registers. Select modes for these pins through the PINMODE registers (Section 8-5). 4. Interrupts: See Section 25-7.3 for motor control PWM related interrupts. Interrupts can be enabled in the NVIC using the appropriate Interrupt Set Enable register.
6. General Operation
Section 25-8 includes detailed descriptions of the various modes of MCPWM operation, but a quick preview here will provide background for the register descriptions below. The MCPWM includes 3 channels, each of which controls a pair of outputs that in turn can control something off-chip, like one set of coils in a motor. Each channel includes a Timer/Counter (TC) register that is incremented by a processor clock (timer mode) or by an input pin (counter mode). Each channel has a Limit register that is compared to the TC value, and when a match occurs the TC is "recycled" in one of two ways. In "edge-aligned mode" the TC is reset to 0, while in "centered mode" a match switches the TC into a state in which it decrements on each processor clock or input pin transition until it reaches 0, at which time it starts counting up again. Each channel also includes a Match register that holds a smaller value than the Limit register. In edge-aligned mode the channel's outputs are switched whenever the TC matches either the Match or Limit register, while in center-aligned mode they are switched only when it matches the Match register. So the Limit register controls the period of the outputs, while the Match register controls how much of each period the outputs spend in each state. Having a small value in the Limit register minimizes "ripple" if the output is integrated into a voltage, and allows the MCPWM to control devices that operate at high speed. The "downside" of small values in the Limit register is that they reduce the resolution of the duty cycle controlled by the Match register. If you have 8 in the Limit register, the Match register can only select the duty cycle among 0%, 12.5%, 25%, ..., 87.5%, or 100%. In general, the resolution of each step in the Match value is 1 divided by the Limit value. This trade-off between resolution and period/frequency is inherent in the design of pulse width modulators.
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7. Register description
"Control" registers and "interrupt" registers have separate read, set, and clear addresses. Reading such a register's read address(e.g. MCCON) yields the state of the register bits. Writing ones to the set address (e.g. MCCON_SET) sets register bit(s), and writing ones to the clear address (e.g. MCCON_CLR) clears register bit(s). The Capture registers (MCCAP) are read-only, and the write-only MCCAP_CLR address can be used to clear one or more of them. All the other MCPWM registers (MCTIM, MCPER, MCPW, MCDEADTIME, and MCCP) are normal read-write registers.
Table 455. Motor Control Pulse Width Modulator (MCPWM) register map Name Description Access Reset value Address
MCCON MCCON_SET MCCON_CLR MCCAPCON MCCAPCON_SET MCCAPCON_CLR MCTC0 MCTC1 MCTC2 MCLIM0 MCLIM1 MCLIM2 MCMAT0 MCMAT1 MCMAT2 MCDT MCCP MCCAP0 MCCAP1 MCCAP2 MCINTEN MCINTEN_SET MCINTEN_CLR MCCNTCON MCCNTCON_SET MCCNTCON_CLR MCINTF MCINTF_SET MCINTF_CLR MCCAP_CLR
PWM Control read address PWM Control set address PWM Control clear address Capture Control read address Capture Control set address Event Control clear address Timer Counter register, channel 0 Timer Counter register, channel 1 Timer Counter register, channel 2 Limit register, channel 0 Limit register, channel 1 Limit register, channel 2 Match register, channel 0 Match register, channel 1 Match register, channel 2 Dead time register Commutation Pattern register Capture register, channel 0 Capture register, channel 1 Capture register, channel 2 Interrupt Enable read address Interrupt Enable set address Interrupt Enable clear address Count Control read address Count Control set address Count Control clear address Interrupt flags read address Interrupt flags set address Interrupt flags clear address Capture clear address
RO WO WO RO WO WO R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W RO RO RO RO WO WO RO WO WO RO WO WO WO
0 0 0 0 0
0x400B 8000 0x400B 8004 0x400B 8008 0x400B 800C 0x400B 8010 0x400B 8014 0x400B 8018 0x400B 801C 0x400B 8020
0xFFFF FFFF 0x400B 8024 0xFFFF FFFF 0x400B 8028 0xFFFF FFFF 0x400B 802C 0xFFFF FFFF 0x400B 8030 0xFFFF FFFF 0x400B 8034 0xFFFF FFFF 0x400B 8038 0x3FFF FFFF 0x400B 803C 0 0 0 0 0 0 0 0x400B 8040 0x400B 8044 0x400B 8048 0x400B 804C 0x400B 8050 0x400B 8054 0x400B 8058 0x400B 805C 0x400B 8060 0x400B 8064 0x400B 8068 0x400B 806C 0x400B 8070 0x400B 8074
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7.1 MCPWM Control register
7.1.1 MCPWM Control read address (MCCON - 0x400B 8000)
The MCCON register controls the operation of all channels of the PWM. This address is read-only, but the underlying register can be modified by writing to addresses MCCON_SET and MCCON_CLR.
Table 456. MCPWM Control read address (MCCON - 0x400B 8000) bit description Bit Symbol Value Description Reset value
0
RUN0 0 1
Stops/starts timer channel 0. Stop. Run. Edge/center aligned operation for channel 0. 0 1 Edge-aligned. Center-aligned. Selects polarity of the MCOA0 and MCOB0 pins. 0 1 Passive state is LOW, active state is HIGH. Passive state is HIGH, active state is LOW. Controls the dead-time feature for channel 0. 0 1 Dead-time disabled. Dead-time enabled. Enable/disable updates of functional registers for channel 0 (see Section 25-8.2). 0 1 Functional registers are updated from the write registers at the end of each PWM cycle. Functional registers remain the same as long as the timer is running. Reserved. Stops/starts timer channel 1. 0 1 Stop. Run. Edge/center aligned operation for channel 1. 0 1 Edge-aligned. Center-aligned. Selects polarity of the MCOA1 and MCOB1 pins. 0 1 Passive state is LOW, active state is HIGH. Passive state is HIGH, active state is LOW. Controls the dead-time feature for channel 1. 0 1 Dead-time disabled. Dead-time enabled. Enable/disable updates of functional registers for channel 1 (see Section 25-8.2). 0 1 Functional registers are updated from the write registers at the end of each PWM cycle. Functional registers remain the same as long as the timer is running. Reserved.
0
1
CENTER0
0
2
POLA0
0
3
DTE0
0
4
DISUP0
0
7:5 8
RUN1
-
0
9
CENTER1
0
10
POLA1
0
11
DTE1
0
12
DISUP1
0
15:13
-
-
0
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Table 456. MCPWM Control read address (MCCON - 0x400B 8000) bit description Bit Symbol Value Description Reset value
16
RUN2 0 1
Stops/starts timer channel 2. Stop. Run. Edge/center aligned operation for channel 2. 0 1 Edge-aligned. Center-aligned. Selects polarity of the MCOA2 and MCOB2 pins. 0 1 Passive state is LOW, active state is HIGH. Passive state is HIGH, active state is LOW. Controls the dead-time feature for channel 1. 0 1 Dead-time disabled. Dead-time enabled. Enable/disable updates of functional registers for channel 2 (see Section 25-8.2). 0 1 Functional registers are updated from the write registers at the end of each PWM cycle. Functional registers remain the same as long as the timer is running. Reserved. Controls the polarity of the MCOB outputs for all 3 channels. This bit is typically set to 1 only in 3-phase DC mode. 0 1 The MCOB outputs have opposite polarity from the MCOA outputs (aside from dead time). The MCOB outputs have the same basic polarity as the MCOA outputs. (see Section 25-8.6) 3-phase AC mode select (see Section 25-8.7). 0 1 3-phase AC-mode off: Each PWM channel uses its own timer-counter and period register. 3-phase AC-mode on: All PWM channels use the timer-counter and period register of channel 0. 3-phase DC mode select (see Section 25-8.6). 0 1 3-phase DC mode off: PWM channels are independent (unless bit ACMODE = 1) 3-phase DC mode on: The internal MCOA0 output is routed through the MCCP (i.e. a mask) register to all six PWM outputs.
0
17
CENTER2
0
18
POLA2
0
19
DTE2
0
20
DISUP2
0
28:21 29
INVBDC
-
30
ACMODE
0
31
DCMODE
0
7.1.2 MCPWM Control set address (MCCON_SET - 0x400B 8004)
Writing ones to this write-only address sets the corresponding bits in MCCON.
Table 457. MCPWM Control set address (MCCON_SET - 0x400B 8004) bit description Bit Description
31:0
Writing ones to this address sets the corresponding bits in the MCCON register. See Table 25-456.
7.1.3 MCPWM Control clear address (MCCON_CLR - 0x400B 8008)
Writing ones to this write-only address clears the corresponding bits in MCCON.
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Table 458. MCPWM Control clear address (MCCON_CLR - 0x400B 8008) bit description Bit Description
31:0
Writing ones to this address clears the corresponding bits in the MCCON register. See Table 25-456.
7.2 MCPWM Capture Control register
7.2.1 MCPWM Capture Control read address (MCCAPCON - 0x400B 800C)
The MCCAPCON register controls detection of events on the MCI0-2 inputs for all MCPWM channels. Any of the three MCI inputs can be used to trigger a capture event on any or all of the three channels. This address is read-only, but the underlying register can be modified by writing to addresses MCCAPCON_SET and MCCAPCON_CLR.
Table 459. MCPWM Capture Control read address (MCCAPCON - 0x400B 800C) bit description Bit Symbol Description Reset Value
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
CAP0MCI0_RE CAP0MCI0_FE CAP0MCI1_RE CAP0MCI1_FE CAP0MCI2_RE CAP0MCI2_FE CAP1MCI0_RE CAP1MCI0_FE CAP1MCI1_RE CAP1MCI1_FE CAP1MCI2_RE CAP1MCI2_FE CAP2MCI0_RE CAP2MCI0_FE CAP2MCI1_RE CAP2MCI1_FE CAP2MCI2_RE CAP2MCI2_FE RT0 RT1 RT2 HNFCAP0 HNFCAP1 HNFCAP2
A 1 in this bit enables a channel 0 capture event on a rising edge on MCI0. A 1 in this bit enables a channel 0 capture event on a falling edge on MCI0. A 1 in this bit enables a channel 0 capture event on a rising edge on MCI1. A 1 in this bit enables a channel 0 capture event on a falling edge on MCI1. A 1 in this bit enables a channel 0 capture event on a rising edge on MCI2. A 1 in this bit enables a channel 0 capture event on a falling edge on MCI2. A 1 in this bit enables a channel 1 capture event on a rising edge on MCI0. A 1 in this bit enables a channel 1 capture event on a falling edge on MCI0. A 1 in this bit enables a channel 1 capture event on a rising edge on MCI1. A 1 in this bit enables a channel 1 capture event on a falling edge on MCI1. A 1 in this bit enables a channel 1 capture event on a rising edge on MCI2. A 1 in this bit enables a channel 1 capture event on a falling edge on MCI2. A 1 in this bit enables a channel 2 capture event on a rising edge on MCI0. A 1 in this bit enables a channel 2 capture event on a falling edge on MCI0. A 1 in this bit enables a channel 2 capture event on a rising edge on MCI1. A 1 in this bit enables a channel 2 capture event on a falling edge on MCI1. A 1 in this bit enables a channel 2 capture event on a rising edge on MCI2. A 1 in this bit enables a channel 2 capture event on a falling edge on MCI2. If this bit is 1, TC0 is reset by a channel 0 capture event. If this bit is 1, TC1 is reset by a channel 1 capture event. If this bit is 1, TC2 is reset by a channel 2 capture event.
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Hardware noise filter: if this bit is 1, channel 0 capture events are delayed as described in 0 Section 25-8.4. Hardware noise filter: if this bit is 1, channel 1 capture events are delayed as described in 0 Section 25-8.4. Hardware noise filter: if this bit is 1, channel 2 capture events are delayed as described in 0 Section 25-8.4. Reserved. -
31:24 -
7.2.2 MCPWM Capture Control set address (MCCAPCON_SET - 0x400B 8010)
Writing ones to this write-only address sets the corresponding bits in MCCAPCON.
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Table 460. MCPWM Capture Control set address (MCCAPCON_SET - 0x400B 8010) bit description Bit Description
31:0
Writing ones to this address sets the corresponding bits in the MCCAPCON register. See Table 25-459.
7.2.3 MCPWM Capture control clear address (MCCAPCON_CLR - 0x400B 8014)
Writing ones to this write-only address clears the corresponding bits in MCCAPCON.
Table 461. MCPWM Capture control clear register (MCCAPCON_CLR - address 0x400B 8014) bit description Bit Description
31:0
Writing ones to this address clears the corresponding bits in the MCCAPCON register. See Table 25-459.
7.3 MCPWM Interrupt registers
The Motor Control PWM module includes the following interrupt sources:
Table 462. Motor Control PWM interrupts Symbol Description
ILIM0/1/2 IMAT0/1/2 ICAP0/1/2 ABORT
Limit interrupts for channels 0, 1, 2. Match interrupts for channels 0, 1, 2. Capture interrupts for channels 0, 1, 2. Fast abort interrupt
All MCPWM interrupt registers contain one bit for each source as shown in Table 25-463.
Table 463. Interrupt sources bit allocation table Bit Symbol Bit Symbol Bit Symbol Bit Symbol 31 30 29 28 27 26 25 24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
ABORT
7
6
5
4
3
ICAP2
2
IMAT2
1
ILIM2
0
-
ICAP1
IMAT1
ILIM1
-
ICAP0
IMAT0
ILIM0
7.3.1 MCPWM Interrupt Enable read address (MCINTEN - 0x400B 8050)
The MCINTEN register controls which of the MCPWM interrupts are enabled. This address is read-only, but the underlying register can be modified by writing to addresses MCINTEN_SET and MCINTEN_CLR.
Table 464. MCPWM Interrupt Enable read address (MCINTEN - 0x400B 8050) bit description Bit Value Description Reset value
31:0 1 0
See Table 25-463 for the bit allocation. Interrupt enabled. Interrupt disabled.
0
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7.3.2 MCPWM Interrupt Enable set address (MCINTEN_SET - 0x400B 8054)
Writing ones to this write-only address sets the corresponding bits in MCINTEN, thus enabling interrupts.
Table 465. PWM interrupt enable set register (MCINTEN_SET - address 0x400B 8054) bit description Bit Description
31:0
Writing ones to this address sets the corresponding bits in MCINTEN, thus enabling interrupts. See Table 25-463.
7.3.3 MCPWM Interrupt Enable clear address (MCINTEN_CLR - 0x400B 8058)
Writing ones to this write-only address clears the corresponding bits in MCINTEN, thus disabling interrupts.
Table 466. PWM interrupt enable clear register (MCINTEN_CLR - address 0x400B 8058) bit description Bit Description
31:0
Writing ones to this address clears the corresponding bits in MCINTEN, thus disabling interrupts. See Table 25-463.
7.3.4 MCPWM Interrupt Flags read address (MCINTF - 0x400B 8068)
The MCINTF register includes all MCPWM interrupt flags, which are set when the corresponding hardware event occurs, or when ones are written to the MCINTF_SET address. When corresponding bits in this register and MCINTEN are both 1, the MCPWM asserts its interrupt request to the Interrupt Controller module. This address is read-only, but the bits in the underlying register can be modified by writing ones to addresses MCINTF_SET and MCINTF_CLR.
Table 467. MCPWM Interrupt Flags read address (MCINTF - 0x400B 8068) bit description Bit Value Description Reset value
31:0 1 0
See Table 25-463 for the bit allocation. If the corresponding bit in MCINTEN is 1, the MCPWM module is asserting its interrupt request to the Interrupt Controller. This interrupt source is not contributing to the MCPWM interrupt request.
0
7.3.5 MCPWM Interrupt Flags set address (MCINTF_SET - 0x400B 806C)
Writing one(s) to this write-only address sets the corresponding bit(s) in MCINTF, thus possibly simulating hardware interrupt(s).
Table 468. MCPWM Interrupt Flags set address (PWMINTF_SET - 0x400B 806C) bit description Bit Description
31:0
Writing one(s) to this write-only address sets the corresponding bit(s) in the MCINTF register, thus possibly simulating hardware interrupt(s). See Table 25-463.
7.3.6 MCPWM Interrupt Flags clear address (MCINTF_CLR - 0x400B 8070)
Writing one(s) to this write-only address sets the corresponding bit(s) in MCINTF, thus clearing the corresponding interrupt request(s). This is typically done in interrupt service routines.
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Table 469. MCPWM Interrupt Flags clear address (PWMINTF_CLR - 0x400B 8070) bit description Bit Description
31:0
Writing one(s) to this write-only address sets the corresponding bit(s) in the MCINTF register, thus clearing the corresponding interrupt request(s). See Table 25-463.
7.4 MCPWM Count Control register
7.4.1 MCPWM Count Control read address (MCCNTCON - 0x400B 805C)
The MCCNTCON register controls whether the MCPWM channels are in timer or counter mode, and in counter mode whether the counter advances on rising and/or falling edges on any or all of the three MCI inputs. If timer mode is selected, the counter advances based on the PCLK clock. This address is read-only. To set or clear the register bits, write ones to the MCCNTCON_SET or MCCNTCON_CLR address.
Table 470. MCPWM Count Control read address (MCCNTCON - 0x400B 805C) bit description Bit Symbol Value Description Reset Value
0 1 2 3 4 5 6 7 8 9 10 11 12
TC0MCI0_RE TC0MCI0_FE TC0MCI1_RE TC0MCI1_FE TC0MCI2_RE TC0MCI2_FE TC1MCI0_RE TC1MCI0_FE TC1MCI1_RE TC1MCI1_FE TC1MCI2_RE TC1MCI2_FE TC2MCI0_RE
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
If MODE0 is 1, counter 0 advances on a rising edge on MCI0. A rising edge on MCI0 does not affect counter 0. If MODE0 is 1, counter 0 advances on a falling edge on MCI0. A falling edge on MCI0 does not affect counter 0. If MODE0 is 1, counter 0 advances on a rising edge on MCI1. A rising edge on MCI1 does not affect counter 0. If MODE0 is 1, counter 0 advances on a falling edge on MCI1. A falling edge on MCI1 does not affect counter 0. If MODE0 is 1, counter 0 advances on a rising edge on MCI2. A rising edge on MCI0 does not affect counter 0. If MODE0 is 1, counter 0 advances on a falling edge on MCI2. A falling edge on MCI0 does not affect counter 0. If MODE1 is 1, counter 1 advances on a rising edge on MCI0. A rising edge on MCI0 does not affect counter 1. If MODE1 is 1, counter 1 advances on a falling edge on MCI0. A falling edge on MCI0 does not affect counter 1. If MODE1 is 1, counter 1 advances on a rising edge on MCI1. A rising edge on MCI1 does not affect counter 1. If MODE1 is 1, counter 1 advances on a falling edge on MCI1. A falling edge on MCI0 does not affect counter 1. If MODE1 is 1, counter 1 advances on a rising edge on MCI2. A rising edge on MCI2 does not affect counter 1. If MODE1 is 1, counter 1 advances on a falling edge on MCI2. A falling edge on MCI2 does not affect counter 1. If MODE2 is 1, counter 2 advances on a rising edge on MCI0. A rising edge on MCI0 does not affect counter 2.
0 0 0 0 0 0 0 0 0 0 0 0 0
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Table 470. MCPWM Count Control read address (MCCNTCON - 0x400B 805C) bit description Bit Symbol Value Description Reset Value
13 14 15 16 17
TC2MCI0_FE TC2MCI1_RE TC2MCI1_FE TC2MCI2_RE TC2MCI2_FE
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
If MODE2 is 1, counter 2 advances on a falling edge on MCI0. A falling edge on MCI0 does not affect counter 2. If MODE2 is 1, counter 2 advances on a rising edge on MCI1. A rising edge on MCI1 does not affect counter 2. If MODE2 is 1, counter 2 advances on a falling edge on MCI1. A falling edge on MCI1 does not affect counter 2. If MODE2 is 1, counter 2 advances on a rising edge on MCI2. A rising edge on MCI2 does not affect counter 2. If MODE2 is 1, counter 2 advances on a falling edge on MCI2. A falling edge on MCI2 does not affect counter 2. Reserved. Channel 0 is in counter mode. Channel 0 is in timer mode. Channel 1 is in counter mode. Channel 1 is in timer mode. Channel 2 is in counter mode. Channel 2 is in timer mode.
0 0 0 0 0 0 0 0
28:18 29 30 31 CNTR0 CNTR1 CNTR2
7.4.2 MCPWM Count Control set address (MCCNTCON_SET - 0x400B 8060)
Writing one(s) to this write-only address sets the corresponding bit(s) in MCCNTCON.
Table 471. MCPWM Count Control set address (MCCNTCON_SET - 0x400B 8060) bit description Bit Description
31:0
Writing one(s) to this write-only address sets the corresponding bit(s) in the MCCNTCON register. See Table 25-470.
7.4.3 MCPWM Count Control clear address (MCCNTCON_CLR - 0x400B 8064)
Writing one(s) to this write-only address clears the corresponding bit(s) in MCCNTCON.
Table 472. MCPWM Count Control clear address (MCCAPCON_CLR - 0x400B 8064) bit description Bit Description
31:0
Writing one(s) to this write-only address clears the corresponding bit(s) in the MCCNTCON register. See Table 25-470.
7.5 MCPWM Timer/Counter 0-2 registers (MCTC0-2 - 0x400B 8018, 0x400B 801C, 0x400B 8020)
These registers hold the current values of the 32-bit counter/timers for channels 0-2. Each value is incremented on every PCLK, or by edges on the MCI0-2 pins, as selected by MCCNTCON. The timer/counter counts up from 0 until it reaches the value in its corresponding MCPER register (or is stopped by writing to MCCON_CLR). A TC register can be read at any time. In order to write to the TC register, its channel must be stopped. If not, the write will not take place, no exception is generated.
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Table 473. MCPWM Timer/Counter 0-2 registers (MCTC0-2 - 0x400B 8018, 0x400B 801C, 0x400B 8020) bit description Bit Symbol Description Reset value
31:0
MCTC0/1/2
Timer/Counter values for channels 0, 1, 2.
0
7.6 MCPWM Limit 0-2 registers (MCLIM0-2 - 0x400B 8024, 0x400B 8028, 0x400B 802C)
These registers hold the limiting values for timer/counters 0-2. When a timer/counter reaches its corresponding limiting value: 1) in edge-aligned mode, it is reset and starts over at 0; 2) in center-aligned mode, it begins counting down until it reaches 0, at which time it begins counting up again. If the channel's CENTER bit in MCCON is 0 selecting edge-aligned mode, the match between TC and LIM switches the channel's A output from "active" to "passive" state. If the channel's CENTER and DTE bits in MCCON are both 0, the match simultaneously switches the channel's B output from "passive" to "active" state. If the channel's CENTER bit is 0 but the DTE bit is 1, the match triggers the channel's deadtime counter to begin counting -- when the deadtime counter expires, the channel's B output switches from "passive" to "active" state. In center-aligned mode, matches between a channel's TC and LIM registers have no effect on its A and B outputs. Writing to either a Limit or a Match (7.7) register loads a "write" register, and if the channel is stopped it also loads an "operating" register that is compared to the TC. If the channel is running and its "disable update" bit in MCCON is 0, the operating registers are loaded from the write registers: 1) in edge-aligned mode, when the TC matches the operating Limit register; 2) in center-aligned mode, when the TC counts back down to 0. If the channel is running and the "disable update" bit is 1, the operating registers are not loaded from the write registers until software stops the channel. Reading an MCLIM address always returns the operating value.
Table 474. MCPWM Limit 0-2 registers (MCLIM0-2 - 0x400B 8024, 0x400B 8028, 0x400B 802C) bit description Bit Symbol Description Reset value
31:0
MCLIM0/1/2
Limit values for TC0, 1, 2.
0xFFFF FFFF
Note: In timer mode, the period of a channel's modulated MCO outputs is determined by its Limit register, and the pulse width at the start of the period is determined by its Match register. If it suits your way of thinking, consider the Limit register to be the "Period register" and the Match register to be the "Pulse Width register".
7.7 MCPWM Match 0-2 registers (MCMAT0-2 - 0x400B 8030, 0x400B 8034, 0x400B 8038)
These registers also have "write" and "operating" versions as described above for the Limit registers, and the operating registers are also compared to the channels' TCs. See 7.6 above for details of reading and writing both Limit and Match registers. The Match and Limit registers control the MCO0-2 outputs. If a Match register is to have any effect on its channel's operation, it must contain a smaller value than the corresponding Limit register.
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Table 475. MCPWM Match 0-2 registers (MCMAT0-2 - addresses 0x400B 8030, 0x400B 8034, 0x400B 8038) bit description Bit Symbol Description Reset value
31:0
MCMAT0/1/2
Match values for TC0, 1, 2.
0xFFFF FFFF
7.7.1 Match register in Edge-Aligned mode
If the channel's CENTER bit in MCCON is 0 selecting edge-aligned mode, a match between TC and MAT switches the channel's B output from "active" to "passive" state. If the channel's CENTER and DTE bits in MCCON are both 0, the match simultaneously switches the channel's A output from "passive" to "active" state. If the channel's CENTER bit is 0 but the DTE bit is 1, the match triggers the channel's deadtime counter to begin counting -- when the deadtime counter expires, the channel's A output switches from "passive" to "active" state.
7.7.2 Match register in Center-Aligned mode
If the channel's CENTER bit in MCCON is 1 selecting center-aligned mode, a match between TC and MAT while the TC is incrementing switches the channel's B output from "active" to "passive" state, and a match while the TC is decrementing switches the A output from "active" to "passive". If the channel's CENTER bit in MCCON is 1 but the DTE bit is 0, a match simultaneously switches the channel's other output in the opposite direction. If the channel's CENTER and DTE bits are both 1, a match between TC and MAT triggers the channel's deadtime counter to begin counting -- when the deadtime counter expires, the channel's B output switches from "passive" to "active" if the TC was counting up at the time of the match, and the channel's A output switches from "passive" to "active" if the TC was counting down at the time of the match.
7.7.3 0 and 100% duty cycle
To lock a channel's MCO outputs at the state "B active, A passive", write its Match register with a higher value than you write to its Limit register. The match never occurs. To lock a channel's MCO outputs at the opposite state, "A active, B passive", simply write 0 to its Match register.
7.8 MCPWM Dead-time register (MCDT - 0x400B 803C)
This register holds the dead-time values for the three channels. If a channel's DTE bit in MCCON is 1 to enable its dead-time counter, the counter counts down from this value whenever one its channel's outputs changes from "active" to "passive" state. When the dead-time counter reaches 0, the channel changes its other output from "passive" to "active" state. The motivation for the dead-time feature is that power transistors, like those driven by the A and B outputs in a motor-control application, take longer to fully turn off than they take to start to turn on. If the A and B transistors are ever turned on at the same time, a wasteful and damaging current will flow between the power rails through the transistors. In such applications, the dead-time register should be programmed with the number of PCLK periods that is greater than or equal to the transistors' maximum turn-off time minus their minimum turn-on time.
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Table 476. MCPWM Dead-time register (MCDT - address 0x400B 803C) bit description Bit Symbol Description Reset value
9:0 19:10 29:20 31:30
DT0 DT1 DT2 [1] [2]
Dead time for channel Dead time for channel reserved
0.[1] 1.[2]
0x3FF 0x3FF 0x3FF
Dead time for channel 2.[2]
If ACMODE is 1 selecting AC-mode, this field controls the dead time for all three channels. If ACMODE is 0.
7.9 MCPWM Commutation Pattern register (MCCP - 0x400B 8040)
This register is used in DC mode only. The internal MCOA0 signal is routed to any or all of the six output pins under the control of the bits in this register. Like the Match and Limit registers, this register has "write" and "operational" versions. See 7.6 and 8.2 for more about this subject.
Table 477. MCPWM Commutation Pattern register (MCCP - address 0x400B 8040) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 31:6
CCPA0 CCPB0 CCPA1 CCPB1 CCPA2 CCPB2 -
0 = MCOA0 passive, 1 = internal MCOA0. 0 = MCOB0 passive, 1 = MCOB0 tracks internal MCOA0. 0 = MCOA1 passive, 1 = MCOA1 tracks internal MCOA0. 0 = MCOB1 passive, 1 = MCOB1 tracks internal MCOA0. 0 = MCOA2 passive, 1 = MCOA2 tracks internal MCOA0. 0 = MCOB2 passive, 1 = MCOB2 tracks internal MCOA0. Reserved.
0 0 0 0 0 0
7.10 MCPWM Capture Registers
7.10.1 MCPWM Capture read addresses (MCCAP0-2 - 0x400B 8044, 0x400B 8048, 0x400B 804C)
The MCCAPCON register (Table 25-459) allows software to select any edge(s) on any of the MCI0-2 inputs as a capture event for each channel. When a channel's capture event occurs, the current TC value for that channel is stored in its read-only Capture register. These addresses are read-only, but the underlying registers can be cleared by writing to the CAP_CLR address
Table 478. MCPWM Capture read addresses (MCCAP0/1/2 - 0x400B 8044, 0x400B 8048, 0x400B 804C) bit description Bit Symbol Description Reset value
31:0
CAP0/1/2
TC value at a capture event for channels 0, 1, 2.
0x0000 0000
7.10.2 MCPWM Capture clear address (MCCAP_CLR - 0x400B 8074)
Writing ones to this write-only address clears the selected CAP register(s).
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Table 479. MCPWM Capture clear address (CAP_CLR - 0x400B 8074) bit description Bit Symbol Description
0 1 2 31:3
CAP_CLR0 CAP_CLR1 CAP_CLR2 -
Writing a 1 to this bit clears the MCCAP0 register. Writing a 1 to this bit clears the MCCAP1 register. Writing a 1 to this bit clears the MCCAP2 register. Reserved
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8. PWM operation
8.1 Pulse-width modulation
Each channel of the MCPWM has two outputs, A and B, that can drive a pair of transistors to switch a controlled point between two power rails. Most of the time the two outputs have opposite polarity, but a dead-time feature can be enabled (on a per-channel basis) to delay both signals' transitions from "passive" to "active" state so that the transistors are never both turned on simultaneously. In a more general view, the states of each output pair can be thought of "high", "low", and "floating" or "up", "down", and "center-off". Each channel's mapping from "active" and "passive" to "high" and "low" is programmable. After Reset, the three A outputs are passive/low, and the B outputs are active/high. The MCPWM can perform edge-aligned and center-aligned pulse-width modulation. Note: In timer mode, the period of a channel's modulated MCO outputs is determined by its Limit register, and the pulse width at the start of the period is determined by its Match register. If it suits your way of thinking, consider the Limit register to be the "Period register" and the Match register to be the "Pulse Width register". Edge-aligned PWM without dead-time In this mode the timer TC counts up from 0 to the value in the LIM register. As shown in Figure 25-121, the MCO state is "A passive" until the TC matches the Match register, at which point it changes to "A active". When the TC matches the Limit register, the MCO state changes back to "A passive", and the TC is reset and starts counting up again.
active
passive
active
passive
MCOB
passive
active
passive
active
MCOA
POLA = 0
0
MAT
LIM timer reset
MAT
LIM timer reset
Fig 121. Edge-aligned PWM waveform without dead time, POLA = 0
Center-aligned PWM without dead-time In this mode the timer TC counts up from 0 to the value in the LIM register, then counts back down to 0 and repeats. As shown in Figure 25-122, while the timer counts up, the MCO state is "A passive" until the TC matches the Match register, at which point it changes to "A active". When the TC matches the Limit register it starts counting down. When the TC matches the Match register on the way down, the MCO state changes back to "A passive".
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active
passive
active
passive
MCOB
passive
active
passive
active
MCOA
POLA = 0
0
MAT
LIM
MAT
0
LIM
Fig 122. Center-aligned PWM waveform without dead time, POLA = 0
Dead-time counter When the a channel's DTE bit is set in MCCON, the dead-time counter delays the passive-to-active transitions of both MCO outputs. The dead-time counter starts counting down, from the channel's DT value (in the MCDT register) to 0, whenever the channel's A or B output changes from active to passive. The transition of the other output from passive to active is delayed until the dead-time counter reaches 0. During the dead time, the MCOA and MCOB output levels are both passive. Figure 25-123 shows operation in edge aligned mode with dead time, and Figure 25-124 shows center-aligned operation with dead time.
active passive MCOB
active passive
DT
DT
active passive MCOA passive
active
POLA = 0 DT 0 MAT LIM timer reset MAT DT LIM timer reset
Fig 123. Edge-aligned PWM waveform with dead time, POLA = 0
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active
passive
active
passive
MCOB DT
active passive MCOA DT 0 MAT LIM MAT 0 LIM passive
active
POLA = 0 DT
Fig 124. Center-aligned waveform with dead time, POLA = 0
8.2 Shadow registers and simultaneous updates
The Limit, Match, and Commutation Pattern registers (MCLIM, MCMAT, and MCCP) are implemented as register pairs, each consisting of a write register and an operational register. Software writes into the write registers. The operational registers control the actual operation of each channel and are loaded with the current value in the write registers when the TC starts counting up from 0. Updating of the functional registers can be disabled by setting a channel's DISUP bit in the MCCON register. If the DISUP bits are set, the functional registers are not updated until software stops the channel. If a channel is not running when software writes to its LIM or MAT register, the functional register is updated immediately. Software can write to a TC register only when its channel is stopped.
8.3 Fast Abort (ABORT)
The MCPWM has an external input MCABORT. When this input goes low, all six MCO outputs assume their "A passive" states, and the Abort interrupt is generated if enabled. The outputs remain locked in "A passive" state until the ABORT interrupt flag is cleared or the Abort interrupt is disabled. The ABORT flag may not be cleared before the MCABORT input goes high. In order to clear an ABORT flag, a 1 must be written to bit 15 of the MCINTF_CLR register. This will remove the interrupt request. The interrupt can also be disabled by writing a 1 to bit 15 of the MCINTEN_CLR register.
8.4 Capture events
Each PWM channel can take a snapshot of its TC when an input signal transitions. Any channel may use any combination of rising and/or falling edges on any or all of the MCI0-2 inputs as a capture event, under control of the MCCAPCON register. Rising or falling edges on the inputs are detected synchronously with respect to PCLK.
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If a channel's HNF bit in the MCCAPCON register is set to enable "noise filtering", a selected edge on an MCI pin starts the dead-time counter for that channel, and the capture event actions described below are delayed until the dead-time counter reaches 0. This function is targeted specifically for performing three-phase brushless DC motor control with Hall sensors. A capture event on a channel (possibly delayed by HNF) causes the following:
* The current value of the TC is stored in the Capture register (CAP). * If the channel's capture event interrupt is enabled (see Table 25-464), the capture
event interrupt flag is set.
* If the channel's RT bit is set in the MCCAPCON register, enabling reset on a capture
event, the input event has the same effect as matching the channel's TC to its LIM register. This includes resetting the TC and switching the MCO pin(s) in edge-aligned mode as described in 7.6 and 8.1.
8.5 External event counting (Counter mode)
If a channel's MODE bit is 1 in MCCNTCON, its TC is incremented by rising and/or falling edge(s) (synchronously detected) on the MCI0-2 input(s), rather than by PCLK. The PWM functions and capture functions are unaffected.
8.6 Three-phase DC mode
The three-phase DC mode is selected by setting the DCMODE bit in the MCCON register. In this mode, the internal MCOA0 signal can be routed to any or all of the MCO outputs. Each MCO output is masked by a bit in the current Commutation Pattern register MCCP. If a bit in the MCCP register is 0, its output pin has the logic level for the passive state of output MCOA0. The polarity of the off state is determined by the POLA0 bit. All MCO outputs that have 1 bits in the MCCP register are controlled by the internal MCOA0 signal. The three MCOB output pins are inverted when the INVBDC bit is 1 in the MCCON register. This feature accommodates bridge-drivers that have active-low inputs for the low-side switches. The MCCP register is implemented as a shadow register pair, so that changes to the active commutation pattern occur at the beginning of a new PWM cycle. See 7.6 and 8.2 for more about writing and reading such registers. Figure 25-125 shows sample waveforms of the MCO outputs in three-phase DC mode. Bits 1 and 3 in the MCCP register (corresponding to outputs MCOB1 and MCOB0) are set to 0 so that these outputs are masked and in the off state. Their logic level is determined by the POLA0 bit (here, POLA0 = 0 so the passive state is logic LOW). The INVBDC bit is set to 0 (logic level not inverted) so that the B output have the same polarity as the A outputs. Note that this mode differs from other modes in that the MCOB outputs are not the opposite of the MCOA outputs. In the situation shown in Figure 25-125, bits 0, 2, 4, and 5 in the MCCP register are set to 1. That means that MCOA1 and both MCO outputs for channel 2 follow the MCOA0 signal.
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MCOB2
CCPB2 = 1, on-state
MCOA2
CCPA2 = 1, on-state
MCOB1
CCPB1 = 0, off-state
MCOA1
CCPA1 = 1, on-state
MCOB0
CCPB0 = 0, off-state
CCPA0 = 1, on-state MCOA0 POLA0 = 0, INVBDC = 0
Fig 125. Three-phase DC mode sample waveforms
8.7 Three phase AC mode
The three-phase AC-mode is selected by setting the ACMODE bit in the MCCON register. In this mode, the value of channel 0's TC is routed to all channels for comparison with their MAT registers. (The LIM1-2 registers are not used.) Each channel controls its MCO output by comparing its MAT value to TC0. Figure 25-126 shows sample waveforms for the six MCO outputs in three-phase AC mode. The POLA bits are set to 0 for all three channels, so that for all MCO outputs the active levels are high and the passive levels are low. Each channel has a different MAT value which is compared to the MCTC0 value. In this mode the period value is identical for all three channels and is determined by MCLIM0. The dead-time mode is disabled.
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MCOB2
POLA2 = 0 MCOA2 MAT2 MAT2
MCOB1
MCOA1 MAT1 MAT1
POLA1 = 0
MCOB0
MCOA0
POLA0 = 0
0
MAT0
LIM0 timer reset
LIM0 timer reset
Fig 126. Three-phase AC mode sample waveforms, edge aligned PWM mode
8.8 Interrupts
The MCPWM includes 10 possible interrupt sources:
* When any channel's TC matches its Match register. * When any channel's TC matches its Limit register. * When any channel captures the value of its TC into its Capture register, because a
selected edge occurs on any of MCI0-2.
* When all three channels' outputs are forced to "A passive" state because the
MCABORT pin goes low. Section 25-7.3 "MCPWM Interrupt registers" explains how to enable these interrupts, and Section 25-7.2 "MCPWM Capture Control register" describes how to map edges on the MCI0-2 inputs to "capture events" on the three channels.
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The QEI is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCQEI. Remark: On reset, the QEI is disabled (PCQEI = 0). 2. Peripheral clock: In the PCLKSEL0 register (Table 4-40), select PCLK_QEI. 3. Pins: Select QEI pins through the PINSEL registers. Select pin modes for port pins with QEI functions through the PINMODE registers (Section 8-5). 4. Interrupts: See Section 26-6.4. The QEI interrupt is enabled in the NVIC using the appropriate Interrupt Set Enable register.
2. Features
This Quadrature Encoder Interface (QEI) has the following features:
* * * * * * * * * *
tracks encoder position. increments/ decrements depending on direction. programmable for 2X or 4X position counting. velocity capture using built-in timer. velocity compare function with less than interrupt. uses 32-bit registers for position and velocity. three position compare registers with interrupts. index counter for revolution counting. index compare register with interrupts. can combine index and position interrupts to produce an interrupt for whole and partial revolution displacement.
* digital filter with programmable delays for encoder input signals. * can accept decoded signal inputs (clock and direction).
3. Introduction
A quadrature encoder, also known as a 2-channel incremental encoder, converts angular displacement into two pulse signals. By monitoring both the number of pulses and the relative phase of the two signals, you can track the position, direction of rotation, and velocity. In addition, a third channel, or index signal, can be used to reset the position counter. This quadrature encoder interface module decodes the digital pulses from a quadrature encoder wheel to integrate position over time and determine direction of rotation. In addition, it can capture the velocity of the encoder wheel.
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VELOCITY TIMER
velocity interrupt (TIM_Int)
VELOCITY RELOAD
VELOCITY COMPARE
low velocity interrupt (LVEL_Int)
RST
VELOCITY CAPTURE
index Ph A Ph B PCLK
RST DIGITAL FILTER QUAD DECODER CLK VELOCITY COUNTER encoder clock interrupt (ENCLK_Int) POSITION COMPARE 0 position 0 interrupt (POS0_Int)
CLK DIR INX
POSITION COUNTER
POSITION COMPARE 1
position 1 interrupt (POS1_Int) direction interrupt (DIR_Int)
INDEX COUNTER
INDEX COMPARE
revolution interrupt (REV_Int) index interrupt (INX_Int) phase error interrupt (ERR_Int)
002aad520
ERR
Fig 127.Encoder interface block diagram
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
4. Functional description
The QEI module interprets the two-bit gray code produced by a quadrature encoder wheel to integrate position over time and determine direction of rotation. In addition, it can capture the velocity of the encoder wheel.
4.1 Input signals
The QEI module supports two modes of signal operation: quadrature phase mode and clock/direction mode. In quadrature phase mode, the encoder produces two clocks that are 90 degrees out of phase; the edge relationship is used to determine the direction of rotation. In clock/direction mode, the encoder produces a clock signal to indicate steps and a direction signal to indicate the direction of rotation.). This mode is determined by the SigMode bit of the QEI Control (QEICON) register (See Table 26-485). When the SigMode bit = 1, the quadrature decoder is bypassed and the PhA pin functions as the direction signal and PhB pin functions as the clock signal for the counters, etc. When the SigMode bit = 0, the PhA pin and PhB pins are decoded by the quadrature decoder. In this mode the quadrature decoder produces the direction and clock signals for the counters, etc. In both modes the direction signal is subject to the effects of the direction invert (DIRINV) bit.
4.1.1 Quadrature input signals
When edges on PhA lead edges on PhB, the position counter is incremented. When edges on PhB lead edges on PhA, the position counter is decremented. When a rising and falling edge pair is seen on one of the phases without any edges on the other, the direction of rotation has changed.
Table 480. Encoder states Phase A Phase B state
1 1 0 0
0 1 1 0
1 2 3 4
Table 481. Encoder state transitions[1] from state to state Direction
1 2 3 4 4 3 2 1
[1]
2 3 4 1 3 2 1 4
positive
negative
All other state transitions are illegal and should set the ERR bit.
Interchanging of the PhA and PhB input signals are compensated by complementing the DIR bit. When set = 1, the direction inversion bit (DIRINV) complements the DIR bit.
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Table 482. Encoder direction DIR bit DIRINV bit direction
0 1 0 1
0 0 1 1
forward reverse reverse forward
Figure 26-128 shows how quadrature encoder signals equate to direction and count.
PhA PhB direction position
-1 -1 -1 -1 -1 -1 -1 -1 -1 +1 +1 +1 +1 +1 +1 +1 +1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
Fig 128.Quadrature Encoder Basic Operation
4.1.2 Digital input filtering
All three encoder inputs (PhA, PhB, and index) require digital filtering. The number of sample clocks is user programmable from 1 to 4,294,967,295 (0xFFFF FFFF). In order for a transition to be accepted, the input signal must remain in new state for the programmed number of sample clocks.
4.2 Position capture
The capture mode for the position integrator can be set to update the position counter on every edge of the PhA signal or to update on every edge of both PhA and PhB. Updating the position counter on every PhA and PhB provides more positional resolution at the cost of less range in the positional counter. The position integrator and velocity capture can be independently enabled. Alternatively, the phase signals can be interpreted as a clock and direction signal as output by some encoders. The position counter is automatically reset on one of two conditions. Incrementing past the maximum position value (QEIMAXPOS) will reset the position counter to zero. If the reset on index bit (RESPI) is set, sensing the index pulse will reset the position counter to zero.
4.3 Velocity capture
The velocity capture has a programmable timer and a capture register. It counts the number of phase edges (using the same configuration as for the position integrator) in a given time period. When the velocity timer (QEITIME) overflows the contents of the velocity counter (QEIVEL) are transferred to the capture (QEICAP) register. The velocity counter is then cleared. The velocity timer is loaded with the contents of the velocity reload register (QEILOAD). Finally, the velocity interrupt (TIM_Int) is asserted. The
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number of edges counted in a given time period is directly proportional to the velocity of the encoder. Setting the reset velocity bit (RESV) has the same effect as an overflow of the velocity timer, except that the setting the RESV bit will not generate a velocity interrupt. The following equation converts the velocity counter value into an RPM value: RPM = (PCLK * QEICAP * 60) / (QEILOAD * PPR * Edges) where:
* PCLK is the peripheral clock rate for the QEI block. See Section 4-7.3 for more on
the possibilities for PCLK).
* QEICAP is the captured velocity counter value for the last velocity timer period. * QEILOAD is the velocity timer reload value. * PPR is the number of pulses per revolution of the physical encoder used in the
application
* Edges is 2 or 4, based on the capture mode set in the QEICON register (2 for
CapMode set to 0 and 4 for CapMode set to 1) For example, consider a motor running at 600 RPM. A 2048 pulse per revolution quadrature encoder is attached to the motor, producing 8192 phase edges per revolution (PPR * Edges). This results in 81,920 pulses per second (the motor turns 10 times per second at 600 RPM and there are 8092 edges per revolution). If the timer were clocked at 10,000 Hz, and the QEILOAD was 2,500 (corresponding to 1/4 of a second), it would count 20,480 pulses per update. Using the above equation: RPM = (10000 * 1 * 20480 * 60) / (2500 * 2048 * 4) = 600 RPM Now, consider that the motor is sped up to 3000 RPM. This results in 409,600 pulses per second, or 102,400 every 1/4 of a second. Again, the above equation gives: RPM = (10000 * 1 * 102400 * 60) / (2500 * 2048 * 4) = 3000 RPM These are simple examples, real-world values will have a higher rate for PCLK, and probably a larger value for QEILOAD as well.
4.4 Velocity compare
In addition to velocity capture, the velocity measurement system includes a programmable velocity compare register. After every velocity capture event the contents of the velocity capture register (QEICAP) is compared with the contents of the velocity compare register (VELCOMP). If the captured velocity is less than the compare value an interrupt is asserted provided that the velocity compare interrupt enable bit is set. This can be used to determine if a motor shaft is either stalled or moving too slow.
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
5. Pin description
Table 483. QEI pin description Pin name I/O Description
MCI0 MCI1 MCI2
[1]
[1] [1] [1]
I I I
Used as the Phase A (PhA) input to the Quadrature Encoder Interface. Used as the Phase B (PhB) input to the Quadrature Encoder Interface. Used as the Index (IDX) input to the Quadrature Encoder Interface.
The Quadrature Encoder Interface uses the same pin functions as the Motor Control PWM feedback inputs and are connected when the Motor Control PWM function is selected on these pins. If used as part of motor control, the QEI is an alternative to feedback directly to the MCPWM.
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6. Register description
6.1 Register summary
Table 484. QEI Register summary Name Control registers Description Access Reset value Address
QEICON QEICONF QEISTAT QEIPOS QEIMAXPOS CMPOS0 CMPOS1 CMPOS2 INXCNT INXCMP QEILOAD QEITIME QEIVEL QEICAP VELCOMP FILTER
Interrupt registers
Control register Configuration register Encoder status register Position register Maximum position register position compare register 0 position compare register 1 position compare register 2 Index count register Index compare register Velocity timer reload register Velocity timer register Velocity counter register Velocity capture register Velocity compare register Digital filter register Interrupt status register Interrupt status set register Interrupt status clear register Interrupt enable register Interrupt enable set register Interrupt enable clear register
WO R/W RO RO R/W R/W R/W R/W RO R/W R/W RO RO RO R/W R/W RO WO WO RO WO WO
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0x400B C000 0x400B C008 0x400B C004 0x400B C00C 0x400B C010 0x400B C014 0x400B C018 0x400B C01C 0x400B C020 0x400B C024 0x400B C028 0x400B C02C 0x400B C030 0x400B C034 0x400B C038 0x400B C03C 0x400B CFE0 0x400B CFEC 0x400B CFE8 0x400B CFE4 0x400B CFDC 0x400B CFD8
Position, index, and timer registers
QEIINTSTAT QEISET QEICLR QEIIE QEIIES QEIIEC
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6.2 Control registers
6.2.1 QEI Control register (QEICON - 0x400B C000)
This register contains bits which control the operation of the position and velocity counters of the QEI module.
Table 485: QEI Control register (QEICON - address 0x400B C000) bit description Bit Symbol Description Reset value
0 1 2 3 31:4
RESP RESPI RESV RESI -
Reset position counter. When set = 1, resets the position counter to all zeros. Autoclears when 0 the position counter is cleared. Reset position counter on index. When set = 1, resets the position counter to all zeros when an 0 index pulse occurs. Autoclears when the position counter is cleared. Reset velocity. When set = 1, resets the velocity counter to all zeros and reloads the velocity timer. Autoclears when the velocity counter is cleared. 0
Reset index counter. When set = 1, resets the index counter to all zeros. Autoclears when the 0 index counter is cleared. reserved 0
6.2.2 QEI Configuration register (QEICONF - 0x400B C008)
This register contains the configuration of the QEI module.
Table 486: QEI Configuration register (QEICONF - address 0x400B C008) bit description Bit Symbol Description Reset value
0 1 2 3 31:4
DIRINV SIGMODE
Direction invert. When = 1, complements the DIR bit.
0
Signal Mode. When = 0, PhA and PhB function as quadrature encoder inputs. When = 1, PhA 0 functions as the direction signal and PhB functions as the clock signal.
CAPMODE Capture Mode. When = 0, only PhA edges are counted (2X). When = 1, BOTH PhA and PhB 0 edges are counted (4X), increasing resolution but decreasing range. INVINX Invert Index. When set, inverts the sense of the index input. reserved 0 0
6.2.3 QEI Status register (QEISTAT - 0x400B C004)
This register provides the status of the encoder interface.
Table 487: QEI Interrupt Status register (QEISTAT - address 0x400B C004) bit description Bit Symbol Description Reset value
0 31:1
DIR -
Direction bit. In combination with DIRINV bit indicates forward or reverse direction. See Table 26-482. reserved 0
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
6.3 Position, index and timer registers
6.3.1 QEI Position register (QEIPOS - 0x400B C00C)
This register contains the current value of the encoder position. Increments or decrements when encoder counts occur, depending on the direction of rotation.
Table 488: QEI Position register (QEIPOS - address 0x400B C00C) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
6.3.2 QEI Maximum Position register (QEIMAXPOS - 0x400B C010)
This register contains the maximum value of the encoder position. In forward rotation the position register resets to zero when the position register exceeds this value. In reverse rotation the position register resets to this value when the position register decrements from zero.
Table 489: QEI Maximum Position register (QEIMAXPOS - address 0x400B C010) bit description Bit Symbol Description Reset value
31:0
-
Current maximum position value.
0
6.3.3 QEI Position Compare register 0 (CMPOS0 - 0x400B C014)
This register contains a position compare value. This value is compared against the current value of the position register. Interrupts can be enabled to interrupt when the compare value is equal to the current value of the position register.
Table 490: QEI Position Compare register 0 (CMPOS0 - address 0x400B C014) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
6.3.4 QEI Position Compare register 1 (CMPOS1 - 0x400B C018)
This register contains a position compare value. This value is compared against the current value of the position register. Interrupts can be enabled to interrupt when the compare value is equal to the current value of the position register.
Table 491: QEI Position Compare register 1 (CMPOS1 - address 0x400B C018) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
6.3.5 QEI Position Compare register 2 (CMPOS2 - 0x400B C01C)
This register contains a position compare value. This value is compared against the current value of the position register. Interrupts can be enabled to interrupt when the compare value is equal to the current value of the position register.
Table 492: QEI Position Compare register 2 (CMPOS2 - address 0x400B C01C) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
6.3.6 QEI Index Count register (INXCNT - 0x400B C020)
This register contains the current value of the encoder position. Increments or decrements when encoder counts occur, depending on the direction of rotation.
Table 493: QEI Index Count register (CMPOS - address 0x400B C020) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
6.3.7 QEI Index Compare register (INXCMP - 0x400B C024)
This register contains an index compare value. This value is compared against the current value of the index count register. Interrupts can be enabled to interrupt when the compare value is equal to the current value of the index count register.
Table 494: QEI Index Compare register (CMPOS - address 0x400B C024) bit description Bit Symbol Description Reset value
31:0
-
Current position value.
0
6.3.8 QEI Timer Reload register (QEILOAD - 0x400B C028)
This register contains the reload value of the velocity timer. When the timer (QEITIME) overflows or the RESV bit is asserted, this value is loaded into the timer (QEITIME).
Table 495: QEI Timer Load register (QEILOAD - address 0x400B C028) bit description Bit Symbol Description Reset value
31:0
-
Current velocity timer load value.
0
6.3.9 QEI Timer register (QEITIME - 0x400B C02C)
This register contains the current value of the velocity timer. When this timer overflows the value of velocity counter (QEIVEL) is stored in the velocity capture register (QEICAP), the velocity counter is reset to zero, the timer is reloaded with the value stored in the velocity reload register (QEILOAD), and the velocity interrupt (TIM_Int) is asserted.
Table 496: QEI Timer register (QEITIME - address 0x400B C02C) bit description Bit Symbol Description Reset value
31:0
-
Current velocity timer value.
0
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6.3.10 QEI Velocity register (QEIVEL - 0x400B C030)
This register contains the running count of velocity pulses for the current time period. When the velocity timer (QEITIME) overflows the contents of this register is captured in the velocity capture register (QEICAP). After capture, this register is set to zero. This register is also reset when the velocity reset bit (RESV) is asserted.
Table 497: QEI Velocity register (QEIVEL - address 0x400B C030) bit description Bit Symbol Description Reset value
31:0
-
Current velocity pulse count.
0
6.3.11 QEI Velocity Capture register (QEICAP - 0x400B C034)
This register contains the most recently measured velocity of the encoder. This corresponds to the number of velocity pulses counted in the previous velocity timer period.The current velocity count is latched into this register when the velocity timer overflows.
Table 498: QEI Velocity Capture register (QEICAP - address 0x400B C034) bit description Bit Symbol Description Reset value
31:0
-
Current velocity pulse count.
0
6.3.12 QEI Velocity Compare register (VELCOMP - 0x400B C038)
This register contains a velocity compare value. This value is compared against the captured velocity in the velocity capture register. If the capture velocity is less than the value in this compare register, a velocity compare interrupt (VELC_Int) will be asserted, if enabled.
Table 499: QEI Velocity Compare register (VELCOMP - address 0x400B C038) bit description Bit Symbol Description Reset value
31:0
-
Current velocity pulse count.
0
6.3.13 QEI Digital Filter register (FILTER - 0x400B C03C)
This register contains the sampling count for the digital filter. A sampling count of zero bypasses the filter.
Table 500: QEI Digital Filter register (FILTER - address 0x400B C03C) bit description Bit Symbol Description Reset value
31:0
-
Digital filter sampling delay
0x0
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6.4 Interrupt registers
6.4.1 QEI Interrupt Status register (QEIINTSTAT)
This register provides the status of the encoder interface and the current set of interrupt sources that are asserted to the controller. Bits set to 1 indicate the latched events that have occurred; a zero bit indicates that the event in question has not occurred. Writing a 0 to a bit position clears the corresponding interrupt.
Table 501: QEI Interrupt Status register (QEIINTSTAT - address 0x400B CFE0) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7 8 9 10 11 12 31:13
INX_Int TIM_Int VELC_Int DIR_Int ERR_Int ENCLK_Int POS0_Int POS1_Int POS2_Int REV_Int POS0REV_Int POS1REV_Int POS2REV_Int -
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected. Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0 0 0 0
Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set 0 and the REV_Int is set. Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set 0 and the REV_Int is set. Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set 0 and the REV_Int is set. reserved 0
6.4.2 QEI Interrupt Set register (QEISET - 0x400B CFEC)
Writing a one to a bit in this register sets the corresponding bit in the QEI Interrupt Status register (QEISTAT).
Table 502: QEI Interrupt Set register (QEISET - address 0x400B CFEC) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7 8 9
INX_Int TIM_Int VELC_Int DIR_Int ERR_Int ENCLK_Int POS0_Int POS1_Int POS2_Int REV_Int
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected. Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0 0 0 0
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Table 502: QEI Interrupt Set register (QEISET - address 0x400B CFEC) bit description Bit Symbol Description Reset value
10 11 12 31:13
POS0REV_Int POS1REV_Int POS2REV_Int -
Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set 0 and the REV_Int is set. Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set 0 and the REV_Int is set. Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set 0 and the REV_Int is set. reserved 0
6.4.3 QEI Interrupt Clear register (QEICLR - 0x400B CFE8)
Writing a 1 to a bit in this register clears the corresponding bit in the QEI Interrupt Status register (QEISTAT).
Table 503: QEI Interrupt Clear register (QEICLR - 0x400B CFE8) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7 8 9 10 11 12 31:13
INX_Int TIM_Int VELC_Int DIR_Int ERR_Int ENCLK_Int POS0_Int POS1_Int POS2_Int REV_Int
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected. Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0 0 0 0 0 0 0 0
POS0REV_Int Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set and the REV_Int is set. POS1REV_Int Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set and the REV_Int is set. POS2REV_Int Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set and the REV_Int is set. reserved
6.4.4 QEI Interrupt Enable register (QEIIE - 0x400B CFE4)
This register enables interrupt sources. Bits set to 1 enable the corresponding interrupt; a 0 bit disables the corresponding interrupt.
Table 504: QEI Interrupt Enable register (QEIIE - address 0x400B CFE4) bit description Bit Symbol Description Reset value
0 1 2 3
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INX_Int TIM_Int VELC_Int DIR_Int
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected.
0 0 0 0
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
Table 504: QEI Interrupt Enable register (QEIIE - address 0x400B CFE4) bit description Bit Symbol Description Reset value
4 5 6 7 8 9 10 11 12 31:13
ERR_Int ENCLK_Int POS0_Int POS1_Int POS2_Int REV_Int
Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0
POS0REV_Int Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set 0 and the REV_Int is set. POS1REV_Int Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set 0 and the REV_Int is set. POS2REV_Int Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set 0 and the REV_Int is set. reserved 0
6.4.5 QEI Interrupt Enable Set register (QEIIES - 0x400B CFDC)
Writing a 1 to a bit in this register sets the corresponding bit in the QEI Interrupt Enable register (QEIIE).
Table 505: QEI Interrupt Enable Set register (QEIIES - address 0x400B CFDC) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7 8 9 10 11 12 31:13
INX_EN TIM_EN VELC_EN DIR_EN ERR_EN ENCLK_EN POS0_Int POS1_Int POS2_Int REV_Int
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected. Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0 0 0 0 0
POS0REV_Int Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set 0 and the REV_Int is set. POS1REV_Int Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set 0 and the REV_Int is set. POS2REV_Int Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set 0 and the REV_Int is set. reserved 0
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Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
6.4.6 QEI Interrupt Enable Clear register (QEIIEC - 0x400B CFD8)
Writing a 1 to a bit in this register clears the corresponding bit in the QEI Interrupt Enable register (QEIIE).
Table 506: QEI Interrupt Enable Clear register (QEIIEC - address 0x400B CFD8) bit description Bit Symbol Description Reset value
0 1 2 3 4 5 6 7 8 9 10 11 12 31:13
INX_EN TIM_EN VELC_EN DIR_EN ERR_EN ENCLK_EN POS0_Int POS1_Int POS2_Int REV_Int
Indicates that an index pulse was detected. Indicates that a velocity timer overflow occurred Indicates that captured velocity is less than compare velocity. Indicates that a change of direction was detected. Indicates that an encoder phase error was detected. Indicates that and encoder clock pulse was detected. Indicates that the position 0 compare value is equal to the current position. Indicates that the position 1compare value is equal to the current position. Indicates that the position 2 compare value is equal to the current position. Indicates that the index compare value is equal to the current index count.
0 0 0 0 0 0 0 0 0 0 0 0 0 0
POS0REV_Int Combined position 0 and revolution count interrupt. Set when both the POS0_Int bit is set and the REV_Int is set. POS1REV_Int Combined position 1 and revolution count interrupt. Set when both the POS1_Int bit is set and the REV_Int is set. POS2REV_Int Combined position 2 and revolution count interrupt. Set when both the POS2_Int bit is set and the REV_Int is set. reserved
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Chapter 27: LPC17xx Real-Time Clock (RTC) and backup registers
Rev. 01 -- 4 January 2010 User manual
1. Basic configuration
The RTC is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bits PCRTC. Remark: On reset, the RTC is enabled. See Section 27-7 for power saving options. 2. Clock: The RTC uses the 1 Hz clock output from the RTC oscillator as the only clock source. The peripheral clock rate for accessing registers is CCLK/8. 3. Interrupts: See Section 27-6.1 for RTC interrupt handling. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register.
2. Features
* Measures the passage of time to maintain a calendar and clock. Provides seconds,
minutes, hours, day of month, month, year, day of week, and day of year.
* Ultra-low power design to support battery powered systems. Less than 1 microamp
required for battery operation. Uses power from the CPU power supply when it is present.
* 20 bytes of Battery-backed storage and RTC operation when power is removed from
the CPU.
* * * * *
Dedicated 32 kHz ultra low power oscillator. Dedicated battery power supply pin. RTC power supply is isolated from the rest of the chip. Calibration counter allows adjustment to better than 1 sec/day with 1 sec resolution. Periodic interrupts can be generated from increments of any field of the time registers and selected fractional second values.
* Alarm interrupt can be generated for a specific date/time.
3. Description
The Real Time Clock (RTC) is a set of counters for measuring time when system power is on, and optionally when it is off. It uses very little power when its registers are not being accessed by the CPU, especially reduced power modes. On the LPC17xx, the RTC is clocked by a separate 32 kHz oscillator that produces a 1 Hz internal time reference. The RTC is powered by its own power supply pin, VBAT, which can be connected to a battery, externally tied to a 3V supply, or left floating. The RTC power domain is shown in conceptual form in Figure 27-129. A detailed view of the time keeping portion of the RTC is shown in Figure 27-130.
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4. Architecture
VDD(REG)(3v3) pin
to main regulator RTC power domain Power selector Ultra-low power regulator Backup Registers
VBAT pin
RTC power RTCX1 Ultra-low power oscillator RTCX2 1 Hz clock Real Time Clock Functional Block RTC Alarm & Interrupt
Fig 129. RTC domain conceptual diagram
second
Alarm Registers minute hour
day
month
year
alarm compare 1 Hz Clock second LSB out LSB set minute hour day day of week day of year sign bit match calibration control logic Calibration calibration compare register calibration compare counter reset calibration counter month year Time Registers
Alarm out and Alarm Interrupts Counter Increment Interrupts
Fig 130. RTC functional block diagram
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5. Pin description
Table 507. RTC pin description Name RTCX1 RTCX2 VBAT Type I O I Description Input to the RTC oscillator circuit. Output from the RTC oscillator circuit. Remark: If the RTC is not used, the RTCX1/2 pins can be left floating. RTC power supply: Typically connected to an external 3V battery. If this pin is not powered, the RTC is still powered internally if VDD(REG)(3V3) is present.
6. Register description
The RTC includes a number of registers, shown in Table 27-508. Detailed descriptions of the registers follow. In these descriptions, for most of the registers the Reset Value column shows "NC", meaning that these registers are Not Changed by a Reset. Software must initialize these registers between power-on and setting the RTC into operation. The registers are split into five sections by functionality.
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Table 508. Real-Time Clock register map Name Description Access Reset Value[1] 0 NC 0 0 0x8 0 NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC NC Address
Miscellaneous registers (see Section 27-6.2) ILR CCR CIIR AMR RTC_AUX RTC_AUXEN CTIME0 CTIME1 CTIME2 SEC MIN HOUR DOM DOW DOY MONTH YEAR CALIBRATION GPREG0 GPREG1 GPREG2 GPREG3 GPREG4 ALSEC ALMIN ALHOUR ALDOM ALDOW ALDOY ALMON ALYEAR
[1]
Interrupt Location Register Clock Control Register Counter Increment Interrupt Register Alarm Mask Register RTC Auxiliary control register RTC Auxiliary Enable register Consolidated Time Register 0 Consolidated Time Register 1 Consolidated Time Register 2 Seconds Counter Minutes Register Hours Register Day of Month Register Day of Week Register Day of Year Register Months Register Years Register Calibration Value Register General Purpose Register 0 General Purpose Register 1 General Purpose Register 2 General Purpose Register 3 General Purpose Register 4 Alarm value for Seconds Alarm value for Minutes Alarm value for Hours Alarm value for Day of Month Alarm value for Day of Week Alarm value for Day of Year Alarm value for Months Alarm value for Year
R/W R/W R/W R/W R/W R/W RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
0x4002 4000 0x4002 4008 0x4002 400C 0x4002 4010 0x4002 405C 0x4002 4058 0x4002 4014 0x4002 4018 0x4002 401C 0x4002 4020 0x4002 4024 0x4002 4028 0x4002 402C 0x4002 4030 0x4002 4034 0x4002 4038 0x4002 403C 0x4002 4040 0x4002 4044 0x4002 4048 0x4002 404C 0x4002 4050 0x4002 4054 0x4002 4060 0x4002 4064 0x4002 4068 0x4002 406C 0x4002 4070 0x4002 4074 0x4002 4078 0x4002 407C
Consolidated time registers (see Section 27-6.3)
Time counter registers (see Section 27-6.4)
General purpose registers (see Section 27-6.6)
Alarm register group (see Section 27-6.7)
Reset values apply only to a power-up of the RTC block, other types of reset have no effect on this block. Since the RTC is powered whenever either of the VDD(REG)(3V3), or VBAT supplies are present, power-up reset occurs only when both supplies were absent and then one is turned on. Most registers are not affected by power-up of the RTC and must be initialized by software if the RTC is enabled. The Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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6.1 RTC interrupts
Interrupt generation is controlled through the Interrupt Location Register (ILR), Counter Increment Interrupt Register (CIIR), the alarm registers, and the Alarm Mask Register (AMR). Interrupts are generated only by the transition into the interrupt state. The ILR separately enables CIIR and AMR interrupts. Each bit in CIIR corresponds to one of the time counters. If CIIR is enabled for a particular counter, then every time the counter is incremented an interrupt is generated. The alarm registers allow the user to specify a date and time for an interrupt to be generated. The AMR provides a mechanism to mask alarm compares. If all non-masked alarm registers match the value in their corresponding time counter, then an interrupt is generated. The RTC interrupt can bring the microcontroller out of Power-down mode when the RTC is operating from its own oscillator on the RTCX1-2 pins. When the RTC interrupt is enabled for wake-up and its selected event occurs, the oscillator wake-up cycle associated with the XTAL1/2 pins is started. For details on the RTC based wake-up process see Section 4-8.8 "Wake-up from Reduced Power Modes" on page 63 and Section 4-9 "Wake-up timer" on page 66.
6.2 Miscellaneous register group
6.2.1 Interrupt Location Register (ILR - 0x4002 4000)
The Interrupt Location Register is a 2-bit register that specifies which blocks are generating an interrupt (see Table 27-509). Writing a one to the appropriate bit clears the corresponding interrupt. Writing a zero has no effect. This allows the programmer to read this register and write back the same value to clear only the interrupt that is detected by the read.
Table 509. Interrupt Location Register (ILR - address 0x4002 4000) bit description Bit 0 1 Symbol RTCCIF RTCALF Description Reset value
When one, the Counter Increment Interrupt block generated an interrupt. Writing a one to this bit 0 location clears the counter increment interrupt. When one, the alarm registers generated an interrupt. Writing a one to this bit location clears the 0 alarm interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved NA bit is not defined.
31:21 -
6.2.2 Clock Control Register (CCR - 0x4002 4008)
The clock register is a 4-bit register that controls the operation of the clock divide circuit. Each bit of the clock register is described in Table 27-510. All NC bits in this register should be initialized when the RTC is first turned on.
Table 510. Clock Control Register (CCR - address 0x4002 4008) bit description Bit 0 Symbol CLKEN 1 0 Value Description Clock Enable. The time counters are enabled. The time counters are disabled so that they may be initialized. Reset value NC
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Table 510. Clock Control Register (CCR - address 0x4002 4008) bit description Bit 1 Symbol CTCRST 1 Value Description CTC Reset. When one, the elements in the internal oscillator divider are reset, and remain reset until CCR[1] is changed to zero. This is the divider that generates the 1 Hz clock from the 32.768 kHz crystal. The state of the divider is not visible to software. No effect. Internal test mode controls. These bits must be 0 for normal RTC operation. Calibration counter enable. 1 0 The calibration counter is disabled and reset to zero. The calibration counter is enabled and counting, using the 1 Hz clock. When the calibration counter is equal to the value of the CALIBRATION register, the counter resets and repeats counting up to the value of the CALIBRATION register. See Section 27-6.4.2 and Section 27-6.5. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA NC NC Reset value 0
0 3:2 4 CCALEN
31:5
-
6.2.3 Counter Increment Interrupt Register (CIIR - 0x4002 400C)
The Counter Increment Interrupt Register (CIIR) gives the ability to generate an interrupt every time a counter is incremented. This interrupt remains valid until cleared by writing a 1 to bit 0 of the Interrupt Location Register (ILR[0]).
Table 511. Counter Increment Interrupt Register (CIIR - address 0x4002 400C) bit description Bit 0 1 2 3 4 5 6 7 31:8 Symbol IMSEC IMMIN IMHOUR IMDOM IMDOW IMDOY IMMON IMYEAR Description When 1, an increment of the Second value generates an interrupt. When 1, an increment of the Minute value generates an interrupt. When 1, an increment of the Hour value generates an interrupt. When 1, an increment of the Day of Month value generates an interrupt. When 1, an increment of the Day of Week value generates an interrupt. When 1, an increment of the Day of Year value generates an interrupt. When 1, an increment of the Month value generates an interrupt. When 1, an increment of the Year value generates an interrupt. Reset value 0 0 0 0 0 0 0 0
Reserved, user software should not write ones to reserved bits. The value read from a reserved NA bit is not defined.
6.2.4 Alarm Mask Register (AMR - 0x4002 4010)
The Alarm Mask Register (AMR) allows the user to mask any of the alarm registers. Table 27-512 shows the relationship between the bits in the AMR and the alarms. For the alarm function, every non-masked alarm register must match the corresponding time counter for an interrupt to be generated. The interrupt is generated only when the counter comparison first changes from no match to match. The interrupt is removed when a one is written to the appropriate bit of the Interrupt Location Register (ILR). If all mask bits are set, then the alarm is disabled.
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Table 512. Alarm Mask Register (AMR - address 0x4002 4010) bit description Bit 0 1 2 3 4 5 6 7 31:8 Symbol AMRSEC AMRMIN AMRDOM AMRDOW AMRDOY AMRMON AMRYEAR Description When 1, the Second value is not compared for the alarm. When 1, the Minutes value is not compared for the alarm. When 1, the Day of Month value is not compared for the alarm. When 1, the Day of Week value is not compared for the alarm. When 1, the Day of Year value is not compared for the alarm. When 1, the Month value is not compared for the alarm. When 1, the Year value is not compared for the alarm. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset value 0 0 0 0 0 0 0 0 NA
AMRHOUR When 1, the Hour value is not compared for the alarm.
6.2.5 RTC Auxiliary control register (RTC_AUX - 0x4002 405C)
The RTC Auxiliary Control register contains added interrupt flags for functions that are not part of the Real Time Clock itself (the part recording the passage of time and generating other time related functions). On the LPC17xx, the only added interrupt flag is for failure of the RTC oscillator.
Table 513. RTC Auxiliary control register (RTC_AUX - address 0x4002 405C) bit description Bit 3:0 4 Symbol Description Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Read: this bit is set if the RTC oscillator stops, and when RTC power is first turned on. An interrupt will occur when this bit is set, the RTC_OSCFEN bit in RTC_AUXEN is a 1, and the RTC interrupt is enabled in the NVIC. Write: writing a 1 to this bit clears the flag. 31:5 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA Reset value NA 1
RTC_OSCF RTC Oscillator Fail detect flag.
6.2.6 RTC Auxiliary Enable register (RTC_AUXEN - 0x4002 4058)
The RTC Auxiliary Enable Register controls whether additional interrupt sources represented in the RTC Auxiliary control register are enabled.
Table 514. RTC Auxiliary Enable register (RTC_AUXEN - address 0x4002 4058) bit description Bit 3:0 4 Symbol Description Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When 0: the RTC Oscillator Fail detect interrupt is disabled. When 1: the RTC Oscillator Fail detect interrupt is enabled. See Section 27-6.2.5. 31:5 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA Reset value NA 0
RTC_OSCFEN Oscillator Fail Detect interrupt enable.
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6.3 Consolidated time registers
The values of the Time Counters can optionally be read in a consolidated format which allows the programmer to read all time counters with only three read operations. The various registers are packed into 32-bit values as shown in Table 27-515, Table 27-516, and Table 27-517. The least significant bit of each register is read back at bit 0, 8, 16, or 24. The Consolidated Time Registers are read-only. To write new values to the Time Counters, the Time Counter addresses should be used.
6.3.1 Consolidated Time Register 0 (CTIME0 - 0x4002 4014)
The Consolidated Time Register 0 contains the low order time values: Seconds, Minutes, Hours, and Day of Week.
Table 515. Consolidated Time register 0 (CTIME0 - address 0x4002 4014) bit description Bit 5:0 7:6 13:8 15:14 20:16 23:21 26:24 31:27 Symbol Seconds Minutes Hours Description Seconds value in the range of 0 to 59 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Minutes value in the range of 0 to 59 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Hours value in the range of 0 to 23 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset value NC NA NC NA NC NC NA NC
Day Of Week Day of week value in the range of 0 to 6 -
6.3.2 Consolidated Time Register 1 (CTIME1 - 0x4002 4018)
The Consolidate Time Register 1 contains the Day of Month, Month, and Year values.
Table 516. Consolidated Time register 1 (CTIME1 - address 0x4002 4018) bit description Bit 4:0 7:5 11:8 15:12 27:16 31:28 Symbol Description Reset value NC NA NC NA NC NA
Day of Month Day of month value in the range of 1 to 28, 29, 30, or 31 (depending on the month and whether it is a leap year). Month Year Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Month value in the range of 1 to 12. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Year value in the range of 0 to 4095. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
6.3.3 Consolidated Time Register 2 (CTIME2 - 0x4002 401C)
The Consolidate Time Register 2 contains just the Day of Year value.
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Table 517. Consolidated Time register 2 (CTIME2 - address 0x4002 401C) bit description Bit 11:0 31:12 Symbol Day of Year Description Day of year value in the range of 1 to 365 (366 for leap years). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset value NC NA
6.4 Time Counter Group
The time value consists of the eight counters shown in Table 27-518 and Table 27-519. These counters can be read or written at the locations shown in Table 27-519.
Table 518. Time Counter relationships and values Counter Second Minute Hour Day of Month Day of Week Day of Year Month Year Table 519. Time Counter registers Name SEC MIN HOUR DOM DOW DOY MONTH YEAR Size 6 6 5 5 3 9 4 12 Description Seconds value in the range of 0 to 59 Minutes value in the range of 0 to 59 Hours value in the range of 0 to 23 Day of month value in the range of 1 to 28, 29, 30, or 31 (depending on the month and whether it is a leap year).[1] Day of week value in the range of 0 to 6[1] Day of year value in the range of 1 to 365 (366 for leap years)[1] Month value in the range of 1 to 12 Year value in the range of 0 to 4095
[1]
Size 6 6 5 5 3 9 4 12
Enabled by 1 Hz Clock Second Minute Hour Hour Hour Day of Month Month or day of Year
Minimum value 0 0 0 1 0 1 1 0
Maximum value 59 59 23 28, 29, 30 or 31 6 365 or 366 (for leap year) 12 4095
Access R/W R/W R/W R/W R/W R/W R/W R/W
Address 0x4002 4020 0x4002 4024 0x4002 4028 0x4002 402C 0x4002 4030 0x4002 4034 0x4002 4038 0x4002 403C
These values are simply incremented at the appropriate intervals and reset at the defined overflow point. They are not calculated and must be correctly initialized in order to be meaningful.
6.4.1 Leap year calculation
The RTC does a simple bit comparison to see if the two lowest order bits of the year counter are zero. If true, then the RTC considers that year a leap year. The RTC considers all years evenly divisible by 4 as leap years. This algorithm is accurate from the year 1901 through the year 2099, but fails for the year 2100, which is not a leap year. The only effect of leap year on the RTC is to alter the length of the month of February for the month, day of month, and year counters.
6.4.2 Calibration register (CALIBRATION - address 0x4002 4040)
The following register is used to calibrate the time counter.
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Table 520. Calibration register (CALIBRATION - address 0x4002 4040) bit description Bit 16:0 17 Symbol CALVAL CALDIR 1 0 31:12 Value Description Reset value
If enabled, the calibration counter counts up to this value. The maximum value is 131, NC 072 corresponding to about 36.4 hours. Calibration is disabled if CALVAL = 0. Calibration direction Backward calibration. When CALVAL is equal to the calibration counter, the RTC timers will stop incrementing for 1 second. Forward calibration. When CALVAL is equal to the calibration counter, the RTC timers will jump by 2 seconds. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. NC
6.5 Calibration procedure
The calibration logic can periodically adjust the time counter either by not incrementing the counter, or by incrementing the counter by 2 instead of 1. This allows calibrating the RTC oscillator under some typical voltage and temperature conditions without the need to externally trim the RTC oscillator. A recommended method for determining the calibration value is to use the CLKOUT feature to unintrusively observe the RTC oscillator frequency under the conditions it is to be trimmed for, and calculating the number of clocks that will be seen before the time is off by one second. That value is used to determine CALVAL. If the RTC oscillator is trimmed externally, the same method of unintrusively observing the RTC oscillator frequency may be helpful in that process. Backward calibration Enable the RTC timer and calibration in the CCR register (set bits CLKEN = 1 and CCALEN = 0). In the CALIBRATION register, set the calibration value CALVAL 1 and select CALDIR = 1.
* The SEC timer and the calibration counter count up for every 1 Hz clock cycle. * When the calibration counter reaches CALVAL, a calibration match occurs and all
RTC timers will be stopped for one clock cycle so that the timers will not increment in the next cycle.
* If an alarm match event occurs in the same cycle as the calibration match, the alarm
interrupt will be delayed by one cycle to avoid a double alarm interrupt. Forward calibration Enable the RTC timer and calibration in the CCR register (set bits CLKEN = 1 and CCALEN = 0). In the CALIBRATION register, set the calibration value CALVAL 1 and select CALDIR = 0.
* The SEC timer and the calibration counter count up for every 1 Hz clock cycle. * When the calibration counter reaches CALVAL, a calibration match occurs and the
RTC timers are incremented by 2.
* When the calibration event occurs, the LSB of the ALSEC register is forced to be one
so that the alarm interrupt will not be missed when skipping a second.
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6.6 General purpose registers
6.6.1 General purpose registers 0 to 4 (GPREG0 to GPREG4 - addresses 0x4002 4044 to 0x4002 4054)
These registers can be used to store important information when the main power supply is off. The value in these registers is not affected by chip reset.
Table 521. General purpose registers 0 to 4 (GPREG0 to GPREG4 - addresses 0x4002 4044 to 0x4002 4054) bit description Bit 31:0 Symbol GP0 to GP4 Description General purpose storage. Reset value N/A
6.7 Alarm register group
The alarm registers are shown in Table 27-522. The values in these registers are compared with the time counters. If all the unmasked (See Section 27-6.2.4 "Alarm Mask Register (AMR - 0x4002 4010)" on page 560) alarm registers match their corresponding time counters then an interrupt is generated. The interrupt is cleared when a 1 is written to bit 1 of the Interrupt Location Register (ILR[1]).
Table 522. Alarm registers Name ALSEC ALMIN ALHOUR ALDOM ALDOW ALDOY ALMON ALYEAR Size 6 6 5 5 3 9 4 12 Description Alarm value for Seconds Alarm value for Minutes Alarm value for Hours Alarm value for Day of Month Alarm value for Day of Week Alarm value for Day of Year Alarm value for Months Alarm value for Years Access R/W R/W R/W R/W R/W R/W R/W R/W Address 0x4002 4060 0x4002 4064 0x4002 4068 0x4002 406C 0x4002 4070 0x4002 4074 0x4002 4078 0x4002 407C
7. RTC usage notes
If the RTC is used, VBAT may be connected to an independent power supply (typically an external battery), or left floating. The RTC domain will always be internally powered if VDD(REG)(3V3) is present, even if there is no power applied to VBAT. As long as power is available on either VDD(REG)(3V3) or VBAT, the RTC will lose its time value and backup register contents. If both VDD(REG)(3V3) and VBAT are not present, all RTC information will be lost. RTC incrementation will stop or be unpredictable if the clock source is lost, interrupted, or altered.
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1. Features
* Internally resets chip if not periodically reloaded. * Debug mode. * Enabled by software but requires a hardware reset or a Watchdog reset/interrupt to be
disabled.
* * * *
Incorrect/Incomplete feed sequence causes reset/interrupt if enabled. Flag to indicate Watchdog reset. Programmable 32-bit timer with internal pre-scaler. Selectable time period from (TWDCLK x 256 x 4) to (TWDCLK x 232 x 4) in multiples of TWDCLK x 4. (IRC), the APB peripheral clock (PCLK, see Table 4-40), or the RTC oscillator. This gives a wide range of potential timing choices for Watchdog operation under different power reduction conditions. For increased reliability, it also provides the ability to run the Watchdog timer from an entirely internal source that is not dependent on an external crystal and its associated components and wiring.
* The Watchdog clock (WDCLK) source can be selected from the Internal RC oscillator
* The Watchdog timer can be configured to run in Deep Sleep mode when using the
IRC as the clock source.
2. Applications
The purpose of the Watchdog is to reset the microcontroller within a reasonable amount of time if it enters an erroneous state. When enabled, the Watchdog will generate a system reset if the user program fails to "feed" (or reload) the Watchdog within a predetermined amount of time. For interaction of the on-chip watchdog and other peripherals, especially the reset and boot-up procedures, please read Section 3-4 "Reset" on page 18 of this document.
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Chapter 28: LPC17xx Watchdog Timer (WDT)
3. Description
The Watchdog consists of a divide by 4 fixed pre-scaler and a 32-bit counter. The clock is fed to the timer via a pre-scaler. The timer decrements when clocked. The minimum value from which the counter decrements is 0xFF. Setting a value lower than 0xFF causes 0xFF to be loaded in the counter. Hence the minimum Watchdog interval is (TWDCLK x 256 x 4) and the maximum Watchdog interval is (TWDCLK x 232 x 4) in multiples of (TWDCLK x 4). The Watchdog should be used in the following manner:
* * * *
Set the Watchdog timer constant reload value in WDTC register. Setup the Watchdog timer operating mode in WDMOD register. Enable the Watchdog by writing 0xAA followed by 0x55 to the WDFEED register. The Watchdog should be fed again before the Watchdog counter underflows to prevent reset/interrupt.
When the Watchdog is in the reset mode and the counter underflows, the CPU will be reset, loading the stack pointer and program counter from the vector table as in the case of external reset. The Watchdog time-out flag (WDTOF) can be examined to determine if the Watchdog has caused the reset condition. The WDTOF flag must be cleared by software. The watchdog timer block uses two clocks: PCLK and WDCLK. PCLK is used for the APB accesses to the watchdog registers. The WDCLK is used for the watchdog timer counting. There is some synchronization logic between these two clock domains. When the WDMOD and WDTC registers are updated by APB operations, the new value will take effect in 3 WDCLK cycles on the logic in the WDCLK clock domain. When the watchdog timer is counting on WDCLK, the synchronization logic will first lock the value of the counter on WDCLK and then synchronize it with the PCLK for reading as the WDTV register by the CPU.
4. Register description
The Watchdog contains 4 registers as shown in Table 28-523 below.
Table 523. Watchdog register map Name WDMOD WDTC WDFEED WDTV Description Watchdog mode register. This register contains the basic mode and status of the Watchdog Timer. Watchdog timer constant register. This register determines the time-out value. Watchdog feed sequence register. Writing 0xAA followed by 0x55 to this register reloads the Watchdog timer with the value contained in WDTC. Access Reset Address Value[1] R/W R/W WO 0 0xFF NA 0xFF 0 0x4000 0000 0x4000 0004 0x4000 0008 0x4000 000C 0x4000 0010
Watchdog timer value register. This register reads out the current value of RO the Watchdog timer. R/W
WDCLKSEL Watchdog clock source selection register.
[1]
Reset Value reflects the data stored in used bits only. It does not include reserved bits content.
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Chapter 28: LPC17xx Watchdog Timer (WDT)
4.1 Watchdog Mode register (WDMOD - 0x4000 0000)
The WDMOD register controls the operation of the Watchdog as per the combination of WDEN and RESET bits. Note that a watchdog feed must be performed before any changes to the WDMOD register take effect.
Table 524: Watchdog Mode register (WDMOD - address 0x4000 0000) bit description Bit 0 1 2 3 31:4 Symbol WDEN WDRESET WDTOF WDINT Description WDEN Watchdog enable bit (set-only). When 1, the watchdog timer is running. WDRESET Watchdog reset enable bit (set -only). When 1, a watchdog timeout will cause a chip reset. WDTOF Watchdog time-out flag. Set when the watchdog timer times out, cleared by software. WDINT Watchdog interrupt flag (read-only, not clearable by software). Reset Value 0 0 0 (Only after external reset) 0
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined.
Once the WDEN and/or WDRESET bits are set they can not be cleared by software. Both flags are cleared by an external reset or a Watchdog timer underflow. WDTOF The Watchdog time-out flag is set when the Watchdog times out. This flag is cleared by software. WDINT The Watchdog interrupt flag is set when the Watchdog times out. This flag is cleared when any reset occurs. Once the watchdog interrupt is serviced, it can be disabled in the NVIC or the watchdog interrupt request will be generated indefinitely. the intent of the watchdog interrupt is to allow debugging watchdog activity without resetting the device when the watchdog overflows. Watchdog reset or interrupt will occur any time the watchdog is running and has an operating clock source. Any clock source works in Sleep mode, and the IRC works in Deep Sleep mode. If a watchdog interrupt occurs in Sleep or Deep Sleep mode, it will wake up the device.
Table 525. Watchdog operating modes selection WDEN 0 1 WDRESET X (0 or 1) 0 Mode of Operation Debug/Operate without the Watchdog running. Watchdog interrupt mode: debug with the Watchdog interrupt but no WDRESET enabled. When this mode is selected, a watchdog counter underflow will set the WDINT flag and the Watchdog interrupt request will be generated. 1 1 Watchdog reset mode: operate with the Watchdog interrupt and WDRESET enabled. When this mode is selected, a watchdog counter underflow will reset the microcontroller. Although the Watchdog interrupt is also enabled in this case (WDEN = 1) it will not be recognized since the watchdog reset will clear the WDINT flag.
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Chapter 28: LPC17xx Watchdog Timer (WDT)
4.2 Watchdog Timer Constant register (WDTC - 0x4000 0004)
The WDTC register determines the time-out value. Every time a feed sequence occurs the WDTC content is reloaded in to the Watchdog timer. It's a 32-bit register with 8 LSB set to 1 on reset. Writing values below 0xFF will cause 0x0000 00FF to be loaded to the WDTC. Thus the minimum time-out interval is TWDCLK x 256 x 4.
Table 526: Watchdog Constant register (WDTC - address 0x4000 0004) bit description Bit 31:0 Symbol Count Description Watchdog time-out interval. Reset Value 0x0000 00FF
4.3 Watchdog Feed register (WDFEED - 0x4000 0008)
Writing 0xAA followed by 0x55 to this register will reload the Watchdog timer with the WDTC value. This operation will also start the Watchdog if it is enabled via the WDMOD register. Setting the WDEN bit in the WDMOD register is not sufficient to enable the Watchdog. A valid feed sequence must be completed after setting WDEN before the Watchdog is capable of generating a reset. Until then, the Watchdog will ignore feed errors. After writing 0xAA to WDFEED, access to any Watchdog register other than writing 0x55 to WDFEED causes an immediate reset/interrupt when the Watchdog is enabled. The reset will be generated during the second PCLK following an incorrect access to a Watchdog register during a feed sequence. Interrupts should be disabled during the feed sequence. An abort condition will occur if an interrupt happens during the feed sequence.
Table 527: Watchdog Feed register (WDFEED - address 0x4000 0008) bit description Bit 7:0 31:8 Symbol Feed Description Feed value should be 0xAA followed by 0x55. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset Value NA NA
4.4 Watchdog Timer Value register (WDTV - 0x4000 000C)
The WDTV register is used to read the current value of Watchdog timer. When reading the value of the 32-bit timer, the lock and synchronization procedure takes up to 6 WDCLK cycles plus 6 PCLK cycles, so the value of WDTV is older than the actual value of the timer when it's being read by the CPU.
Table 528: Watchdog Timer Value register (WDTV - address 0x4000 000C) bit description Bit 31:0 Symbol Count Description Counter timer value. Reset Value 0x0000 00FF
4.5 Watchdog Timer Clock Source Selection register (WDCLKSEL 0x4000 0010)
This register allows selecting the clock source for the Watchdog timer. The possibilities are the Internal RC oscillator (IRC) or the APB peripheral clock (pclk). The function of bits in WDCLKSEL are shown in Table 28-529. The clock source selection can be locked by software, so that it cannot be modified. On reset, the clock source selection bits are always unlocked.
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Chapter 28: LPC17xx Watchdog Timer (WDT)
When the IRC is chosen as the watchdog clock source, the watchdog timer can remain running in deep sleep mode, and can reset or wake up the device from that mode.
Table 529: Watchdog Timer Clock Source Selection register (WDCLKSEL - address 0x4000 0010) bit description Bit 1:0 Symbol WDSEL Value Description These bits select the clock source for the Watchdog timer as described below. Warning: Improper setting of this value may result in incorrect operation of the Watchdog timer, which could adversely affect system operation. If the WDLOCK bit in this register is set, the WDSEL bit cannot be modified. 00 01 10 11 30:2 31 WDLOCK 0 1 Selects the Internal RC oscillator (irc_clk) as the Watchdog clock source (default). Selects the APB peripheral clock (watchdog pclk) as the Watchdog clock source. Selects the RTC oscillator (rtc_clk) as the Watchdog clock source. Reserved, this setting should not be used. Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. This bit is set to 0 on any reset. It cannot be cleared by software. Software can set this bit to 1 at any time. Once WDLOCK is set, the bits of this register cannot be modified. 0 Reset Value 0
5. Block diagram
The block diagram of the Watchdog is shown below in the Figure 28-131. The synchronization logic (PCLK - WDCLK) is not shown in the block diagram.
feed sequence feed ok WDFEED feed error RTC oscillator pclk internal RC oscillator WDCLKSEL wdclk /4
WDTC
32-BIT DOWN COUNTER underflow WDTV enable count
SHADOW BIT
WMOD register WDINT WDTOF WDRESET WDEN
reset interrupt
Fig 131. Watchdog block diagram
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
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1. Basic configuration
The ADC is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set the PCADC bit. Remark: On reset, the ADC is disabled. To enable the ADC, first set the PCADC bit, and then enable the ADC in the AD0CR register (bit PDN Table 29-532). To disable the ADC, first clear the PDN bit, and then clear the PCADC bit. 2. Clock: In the PCLKSEL0 register (Table 4-40), select PCLK_ADC. To scale the clock for the ADC, see bits CLKDIV in Table 29-532. 3. Pins: Enable ADC0 pins through PINSEL registers. Select the pin modes for the port pins with ADC0 functions through the PINMODE registers (Section 8-5). 4. Interrupts: To enable interrupts in the ADC, see Table 29-536. Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. Disable the ADC interrupt in the NVIC using the appropriate Interrupt Set Enable register. 5. DMA: See Section 29-6.4. For GPDMA system connections, see Table 31-544.
2. Features
* * * * * * *
12-bit successive approximation analog to digital converter. Input multiplexing among 8 pins. Power-down mode. Measurement range VREFN to VREFP (typically 3 V; not to exceed VDDA voltage level). 12-bit conversion rate of 200 kHz. Burst conversion mode for single or multiple inputs. Optional conversion on transition on input pin or Timer Match signal.
3. Description
Basic clocking for the A/D converters is provided by the APB clock. A programmable divider is included in each converter to scale this clock to the clock (maximum 13 MHz) needed by the successive approximation process. A fully accurate conversion requires 65 of these clocks.
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
4. Pin description
Table 29-530 gives a brief summary of each of ADC related pins.
Table 530. ADC pin description Pin AD0.7 to AD0.0 Type Input Description Analog Inputs. The ADC cell can measure the voltage on any of these input signals. Digital signals are disconnected from the ADC input pins when the ADC function is selected on that pin in the Pin Select register. Warning: if the ADC is used, signal levels on analog input pins must not be above the level of VDDA at any time. Otherwise, A/D converter readings will be invalid. If the A/D converter is not used in an application then the pins associated with A/D inputs can be used as 5 V tolerant digital IO pins. VREFP, VREFN Reference Voltage References. These pins provide a voltage reference level for the ADC and DAC. Note: VREFP should be tied to VDD(3V3) and VREFN should be tied to VSS if the ADC and DAC are not used. Analog Power and Ground. These should typically be the same voltages as VDD and VSS, but should be isolated to minimize noise and error. Note: VDDA should be tied to VDD(3V3) and VSSA should be tied to VSS if the ADC and DAC are not used.
VDDA, VSSA
Power
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
5. Register description
The A/D Converter registers are shown in Table 29-531.
Table 531. ADC registers Generic Name ADCR ADGDR ADINTEN Description A/D Control Register. The ADCR register must be written to select the operating mode before A/D conversion can occur. Access R/W Reset AD0 Name & value[1] Address 1 NA 0x100 AD0CR 0x4003 4000 AD0GDR 0x4003 4004 AD0INTEN 0x4003 400C AD0DR0 0x4003 4010 AD0DR1 0x4003 4014 AD0DR2 0x4003 4018 AD0DR3 0x4003 401C AD0DR4 0x4003 4020 AD0DR5 0x4003 4024 AD0DR6 0x4003 4028 AD0DR7 0x4003 402C AD0STAT 0x4003 4030 AD0TRM 0x4003 4034
A/D Global Data Register. This register contains the ADC's DONE bit and R/W the result of the most recent A/D conversion. A/D Interrupt Enable Register. This register contains enable bits that allow R/W the DONE flag of each A/D channel to be included or excluded from contributing to the generation of an A/D interrupt. A/D Channel 0 Data Register. This register contains the result of the most RO recent conversion completed on channel 0. A/D Channel 1 Data Register. This register contains the result of the most RO recent conversion completed on channel 1. A/D Channel 2 Data Register. This register contains the result of the most RO recent conversion completed on channel 2. A/D Channel 3 Data Register. This register contains the result of the most RO recent conversion completed on channel 3. A/D Channel 4 Data Register. This register contains the result of the most RO recent conversion completed on channel 4. A/D Channel 5 Data Register. This register contains the result of the most RO recent conversion completed on channel 5. A/D Channel 6 Data Register. This register contains the result of the most RO recent conversion completed on channel 6. A/D Channel 7 Data Register. This register contains the result of the most RO recent conversion completed on channel 7. A/D Status Register. This register contains DONE and OVERRUN flags for all of the A/D channels, as well as the A/D interrupt/DMA flag. ADC trim register. RO R/W
ADDR0 ADDR1 ADDR2 ADDR3 ADDR4 ADDR5 ADDR6 ADDR7 ADSTAT ADTRM
NA NA NA NA NA NA NA NA 0 0
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
5.1 A/D Control Register (AD0CR - 0x4003 4000)
Table 532: A/D Control Register (AD0CR - address 0x4003 4000) bit description Bit 7:0 Symbol Value Description SEL Selects which of the AD0.7:0 pins is (are) to be sampled and converted. For AD0, bit 0 selects Pin AD0.0, and bit 7 selects pin AD0.7. In software-controlled mode, only one of these bits should be 1. In hardware scan mode, any value containing 1 to 8 ones is allowed. All zeroes is equivalent to 0x01. The APB clock (PCLK_ADC0) is divided by (this value plus one) to produce the clock for the A/D converter, which should be less than or equal to 13 MHz. Typically, software should program the smallest value in this field that yields a clock of 13 MHz or slightly less, but in certain cases (such as a high-impedance analog source) a slower clock may be desirable. 1 Reset value 0x01
15:8
CLKDIV
0
16
BURST
The AD converter does repeated conversions at up to 200 kHz, scanning (if necessary) 0 through the pins selected by bits set to ones in the SEL field. The first conversion after the start corresponds to the least-significant 1 in the SEL field, then higher numbered 1-bits (pins) if applicable. Repeated conversions can be terminated by clearing this bit, but the conversion that's in progress when this bit is cleared will be completed. Remark: START bits must be 000 when BURST = 1 or conversions will not start. Conversions are software controlled and require 65 clocks. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA 0 NA 0
0 20:17 21 PDN 1 0 23:22 26:24 START 000 001 010 011 100 101 110 111 27 EDGE 1 0 31:28 -
The A/D converter is operational. The A/D converter is in power-down mode. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. When the BURST bit is 0, these bits control whether and when an A/D conversion is started: No start (this value should be used when clearing PDN to 0). Start conversion now. Start conversion when the edge selected by bit 27 occurs on the P2.10 / EINT0 / NMI pin. Start conversion when the edge selected by bit 27 occurs on the P1.27 / CLKOUT / USB_OVRCRn / CAP0.1 pin. Start conversion when the edge selected by bit 27 occurs on MAT0.1. Note that this does not require that the MAT0.1 function appear on a device pin. Start conversion when the edge selected by bit 27 occurs on MAT0.3. Note that it is not possible to cause the MAT0.3 function to appear on a device pin. Start conversion when the edge selected by bit 27 occurs on MAT1.0. Note that this does not require that the MAT1.0 function appear on a device pin. Start conversion when the edge selected by bit 27 occurs on MAT1.1. Note that this does not require that the MAT1.1 function appear on a device pin. This bit is significant only when the START field contains 010-111. In these cases: Start conversion on a falling edge on the selected CAP/MAT signal. Start conversion on a rising edge on the selected CAP/MAT signal. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
0
NA
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
5.2 A/D Global Data Register (AD0GDR - 0x4003 4004)
The A/D Global Data Register holds the result of the most recent A/D conversion that has completed, and also includes copies of the status flags that go with that conversion. Results of ADC conversion can be read in one of two ways. One is to use the A/D Global Data Register to read all data from the ADC. Another is to use the A/D Channel Data Registers. It is important to use one method consistently because the DONE and OVERRUN flags can otherwise get out of synch between the AD0GDR and the A/D Channel Data Registers, potentially causing erroneous interrupts or DMA activity.
Table 533: A/D Global Data Register (AD0GDR - address 0x4003 4004) bit description Bit 3:0 15:4 Symbol RESULT Description Reset value
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined. When DONE is 1, this field contains a binary fraction representing the voltage on the AD0[n] pin selected by the SEL field, as it falls within the range of VREFP to VREFN. Zero in the field indicates that the voltage on the input pin was less than, equal to, or close to that on VREFN, while 0x3FF indicates that the voltage on the input was close to, equal to, or greater than that on VREFP. NA
23:16 26:24 29:27 30
CHN OVERRUN
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined. These bits contain the channel from which the RESULT bits were converted (e.g. 000 identifies channel 0, 001 channel 1...). NA
Reserved, user software should not write ones to reserved bits. The value read from NA a reserved bit is not defined. This bit is 1 in burst mode if the results of one or more conversions was (were) lost and overwritten before the conversion that produced the result in the RESULT bits. This bit is cleared by reading this register. This bit is set to 1 when an A/D conversion completes. It is cleared when this register is read and when the ADCR is written. If the ADCR is written while a conversion is still in progress, this bit is set and a new conversion is started. 0
31
DONE
0
5.3 A/D Interrupt Enable register (AD0INTEN - 0x4003 400C)
This register allows control over which A/D channels generate an interrupt when a conversion is complete. For example, it may be desirable to use some A/D channels to monitor sensors by continuously performing conversions on them. The most recent results are read by the application program whenever they are needed. In this case, an interrupt is not desirable at the end of each conversion for some A/D channels.
Table 534: A/D Status register (AD0INTEN - address 0x4003 400C) bit description Bit 0 1 2 Symbol ADINTEN0 ADINTEN1 ADINTEN2 Value 0 1 0 1 0 1 Description Completion of a conversion on ADC channel 0 will not generate an interrupt. Completion of a conversion on ADC channel 0 will generate an interrupt. Completion of a conversion on ADC channel 1 will not generate an interrupt. Completion of a conversion on ADC channel 1 will generate an interrupt. Completion of a conversion on ADC channel 2 will not generate an interrupt. Completion of a conversion on ADC channel 2 will generate an interrupt. 0 0 Reset value 0
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
Table 534: A/D Status register (AD0INTEN - address 0x4003 400C) bit description Bit 3 4 5 6 7 8 Symbol ADINTEN3 ADINTEN4 ADINTEN5 ADINTEN6 ADINTEN7 ADGINTEN Value 0 1 0 1 0 1 0 1 0 1 0 1 31:17 Description Completion of a conversion on ADC channel 3 will not generate an interrupt. Completion of a conversion on ADC channel 3 will generate an interrupt. Completion of a conversion on ADC channel 4 will not generate an interrupt. Completion of a conversion on ADC channel 4 will generate an interrupt. Completion of a conversion on ADC channel 5 will not generate an interrupt. Completion of a conversion on ADC channel 5 will generate an interrupt. Completion of a conversion on ADC channel 6 will not generate an interrupt. Completion of a conversion on ADC channel 6 will generate an interrupt. Completion of a conversion on ADC channel 7 will not generate an interrupt. Completion of a conversion on ADC channel 7 will generate an interrupt. Only the individual ADC channels enabled by ADINTEN7:0 will generate interrupts. Only the global DONE flag in ADDR is enabled to generate an interrupt. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA 1 0 0 0 0 Reset value 0
5.4 A/D Data Registers (AD0DR0 to AD0DR7 - 0x4003 4010 to 0x4003 402C)
The A/D Data Registers hold the result of the last conversion for each A/D channel, when an A/D conversion is complete. They also include the flags that indicate when a conversion has been completed and when a conversion overrun has occurred. Results of ADC conversion can be read in one of two ways. One is to use the A/D Global Data Register to read all data from the ADC. Another is to use the A/D Channel Data Registers. It is important to use one method consistently because the DONE and OVERRUN flags can otherwise get out of synch between the AD0GDR and the A/D Channel Data Registers, potentially causing erroneous interrupts or DMA activity.
Table 535: A/D Data Registers (AD0DR0 to AD0DR7 - 0x4003 4010 to 0x4003 402C) bit description Bit 3:0 15:4 Symbol RESULT Description Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset value NA
When DONE is 1, this field contains a binary fraction representing the voltage on the AD0[n] NA pin, as it falls within the range of VREFP to VREFN. Zero in the field indicates that the voltage on the input pin was less than, equal to, or close to that on VREFN, while 0x3FF indicates that the voltage on the input was close to, equal to, or greater than that on VREFP. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
29:16 30
-
OVERRUN This bit is 1 in burst mode if the results of one or more conversions was (were) lost and overwritten before the conversion that produced the result in the RESULT bits.This bit is cleared by reading this register. DONE This bit is set to 1 when an A/D conversion completes. It is cleared when this register is read. NA
31
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
5.5 A/D Status register (ADSTAT - 0x4003 4030)
The A/D Status register allows checking the status of all A/D channels simultaneously. The DONE and OVERRUN flags appearing in the ADDRn register for each A/D channel are mirrored in ADSTAT. The interrupt flag (the logical OR of all DONE flags) is also found in ADSTAT.
Table 536: A/D Status register (AD0STAT - address 0x4003 4030) bit description Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 31:17 Symbol DONE0 DONE1 DONE2 DONE3 DONE4 DONE5 DONE6 DONE7 OVERRUN0 OVERRUN1 OVERRUN2 OVERRUN3 OVERRUN4 OVERRUN5 OVERRUN6 OVERRUN7 ADINT Description This bit mirrors the DONE status flag from the result register for A/D channel 0. This bit mirrors the DONE status flag from the result register for A/D channel 1. This bit mirrors the DONE status flag from the result register for A/D channel 2. This bit mirrors the DONE status flag from the result register for A/D channel 3. This bit mirrors the DONE status flag from the result register for A/D channel 4. This bit mirrors the DONE status flag from the result register for A/D channel 5. This bit mirrors the DONE status flag from the result register for A/D channel 6. This bit mirrors the DONE status flag from the result register for A/D channel 7. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 0. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 1. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 2. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 3. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 4. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 5. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 6. This bit mirrors the OVERRRUN status flag from the result register for A/D channel 7. Reset value 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
This bit is the A/D interrupt flag. It is one when any of the individual A/D channel Done 0 flags is asserted and enabled to contribute to the A/D interrupt via the ADINTEN register. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA
5.6 A/D Trim register (ADTRIM - 0x4003 4034)
This register will be set by the bootcode on start-up. It contains the trim values for the DAC and the ADC. The offset trim values for the ADC can be overwritten by the user. All 12 bits are visible when this register is read.
Table 537: A/D Trim register (ADTRM - address 0x4003 4034) bit description Bit 3:0 7:4 11:8 Symbol ADCOFFS TRIM Description reserved. written-to by boot code. Can not be overwritten by the user. These bits are locked after boot code write. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset value NA 0 NA
Offset trim bits for ADC operation. Initialized by the boot code. Can be overwritten by the user. 0
31:12 -
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Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
6. Operation
Once an ADC conversion is started, it cannot be interrupted. A new software write to launch a new conversion or a new edge-trigger event will be ignored while the previous conversion is in progress.
6.1 Hardware-triggered conversion
If the BURST bit in the ADCR is 0 and the START field contains 010-111, the ADC will start a conversion when a transition occurs on a selected pin or Timer Match signal. The choices include conversion on a specified edge of any of 4 Match signals, or conversion on a specified edge of either of 2 Capture/Match pins. The pin state from the selected pad or the selected Match signal, XORed with ADCR bit 27, is used in the edge detection logic.
6.2 Interrupts
An interrupt request is asserted to the NVIC when the DONE bit is 1. Software can use the Interrupt Enable bit for the A/D Converter in the NVIC to control whether this assertion results in an interrupt. DONE is negated when the ADDR is read.
6.3 Accuracy vs. digital receiver
The ADC function must be selected via the PINSEL registers in order to get accurate voltage readings on the monitored pin. The PINMODE should also be set to the mode for which neither pull-up nor pull-down resistor is enabled. For a pin hosting an ADC input, it is not possible to have a have a digital function selected and yet get valid ADC readings. An inside circuit disconnects ADC hardware from the associated pin whenever a digital function is selected on that pin.
6.4 DMA control
A DMA transfer request is generated from the ADC interrupt request line. To generate a DMA transfer the same conditions must be met as the conditions for generating an interrupt (see Section 29-6.2 and Section 29-5.3). Remark: If the DMA is used, the ADC interrupt must be disabled in the NVIC. For DMA transfers, only burst requests are supported. The burst size can be set to one in the DMA channel control register (see Section 31-5.20). If the number of ADC channels is not equal to one of the other DMA-supported burst sizes (applicable DMA burst sizes are 1, 4, 8 - see Section 31-5.20), set the burst size to one. The DMA transfer size determines when a DMA interrupt is generated. The transfer size can be set to the number of ADC channels being converted (see Section 31-5.20). Non-contiguous channels can be transferred by the DMA using the scatter/gather linked lists (see Section 31-5.19).
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Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
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1. Basic configuration
The DAC is configured using the following registers: 1. Power: The DAC is always connected to VDDA. Register access is determined by PINSEL and PINMODE settings (see below). 2. Clock: In the PCLKSEL0 register (Table 4-40), select PCLK_DAC. 3. Pins: Enable the DAC pin through the PINSEL registers. Select pin mode for port pin with DAC through the PINMODE registers (Section 8-5). This must be done before accessing any DAC registers. 4. DMA: The DAC can be connected to the GPDMA controller (see Section 30-4.2). For GPDMA connections, see Table 31-544.
2. Features
* * * * * *
10-bit digital to analog converter Resistor string architecture Buffered output Power-down mode Selectable speed vs. power Maximum update rate of 1 MHz.
3. Pin description
Table 30-538 gives a brief summary of each of DAC related pins.
Table 538. D/A Pin Description Pin AOUT VREFP, VREFN Type Output Reference Description Analog Output. After the selected settling time after the DACR is written with a new value, the voltage on this pin (with respect to VSSA) is VALUE x ((VREFP - VREFN)/1024) + VREFN. Voltage References. These pins provide a voltage reference level for the ADC and DAC. Note: VREFP should be tied to VDD(3V3) and VREFN should be tied to VSS if the ADC and DAC are not used. Analog Power and Ground. These should typically be the same voltages as VDD and VSS, but should be isolated to minimize noise and error. Note: VDDA should be tied to VDD(3V3) and VSSA should be tied to VSS if the ADC and DAC are not used.
VDDA, VSSA
Power
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Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
4. Register description
The DAC registers are shown in Table 30-539. Note that the DAC does not have a control bit in the PCONP register. To enable the DAC, its output must be selected to appear on the related pin, P0.26, by configuring the PINSEL1 register. See Section 8-5.2 "Pin Function Select Register 1 (PINSEL1 - 0x4002 C004)". the DAC must be enabled in this manner prior to accessing any DAC registers.
Table 539. DAC registers Name DACR DACCTRL DACCNTVAL Description D/A Converter Register. This register contains the digital value to be converted to analog and a power control bit. Access R/W Reset Address value[1] 0 0 0 0x4008 C000 0x4008 C004 0x4008 C008
DAC Control register. This register controls DMA and timer operation. R/W DAC Counter Value register. This register contains the reload value for R/W the DAC DMA/Interrupt timer.
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
4.1 D/A Converter Register (DACR - 0x4008 C000)
This read/write register includes the digital value to be converted to analog, and a bit that trades off performance vs. power. Bits 5:0 are reserved for future, higher-resolution D/A converters.
Table 540: D/A Converter Register (DACR - address 0x4008 C000) bit description Bit 5:0 15:6 16 Symbol Value VALUE BIAS[1] 0 1 31:17 Description Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Reset Value NA
After the selected settling time after this field is written with a new VALUE, the voltage on 0 the AOUT pin (with respect to VSSA) is VALUE x ((VREFP - VREFN)/1024) + VREFN. The settling time of the DAC is 1 s max, and the maximum current is 700 A. This allows 0 a maximum update rate of 1 MHz. The settling time of the DAC is 2.5 s and the maximum current is 350 A. This allows a maximum update rate of 400 kHz. Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
[1]
NA
The settling times noted in the description of the BIAS bit are valid for a capacitance load on the AOUT pin not exceeding 100 pF. A load impedance value greater than that value will cause settling time longer than the specified time. One or more graph(s) of load impedance vs. settling time will be included in the final data sheet.
4.2 D/A Converter Control register (DACCTRL - 0x4008 C004)
This read/write register enables the DMA operation and controls the DMA timer.
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Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
Table 541. D/A Control register (DACCTRL - address 0x4008 C004) bit description Bit 0 1 Symbol Value Description This bit is cleared on any write to the DACR register. This bit is set by hardware when the timer times out. DACR double-buffering is disabled. When this bit and the CNT_ENA bit are both set, the double-buffering feature in the DACR register will be enabled. Writes to the DACR register are written to a pre-buffer and then transferred to the DACR on the next time-out of the counter. Time-out counter operation is disabled. Time-out counter operation is enabled. DMA access is disabled. DMA Burst Request Input 7 is enabled for the DAC (see Table 31-544). Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. NA 0 0 0 Reset Value 0
INT_DMA_REQ 0 1 DBLBUF_ENA 0 1
2 3 31:4
CNT_ENA DMA_ENA -
0 1 0 1
4.3 D/A Converter Counter Value register (DACCNTVAL - 0x4008 C008)
This read/write register contains the reload value for the Interrupt/DMA counter.
Table 542: D/A Converter register (DACR - address 0x4008 C000) bit description Bit 15:0 Symbol VALUE Description 16-bit reload value for the DAC interrupt/DMA timer. Reset Value 0
5. Operation
5.1 DMA counter
When the counter enable bit CNT_ENA in DACCTRL is set, a 16-bit counter will begin counting down, at the rate selected by PCLK_DAC (see Table 4-40), from the value programmed into the DACCNTVAL register. The counter is decremented Each time the counter reaches zero, the counter will be reloaded by the value of DACCNTVAL and the DMA request bit INT_DMA_REQ will be set in hardware. Note that the contents of the DACCTRL and DACCNTVAL registers are read and write accessible, but the timer itself is not accessible for either read or write. If the DMA_ENA bit is set in the DACCTRL register, the DAC DMA request will be routed to the GPDMA. When the DMA_ENA bit is cleared, the default state after a reset, DAC DMA requests are blocked.
5.2 Double buffering
Double-buffering is enabled only if both, the CNT_ENA and the DBLBUF_ENA bits are set in DACCTRL. In this case, any write to the DACR register will only load the pre-buffer, which shares its register address with the DACR register. The DACR itself will be loaded from the pre-buffer whenever the counter reaches zero and the DMA request is set. At the same time the counter is reloaded with the COUNTVAL register value. Reading the DACR register will only return the contents of the DACR register itself, not the contents of the pre-buffer register.
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If either the CNT_ENA or the DBLBUF_ENA bits are 0, any writes to the DACR address will go directly to the DACR register.
pbus
CNTVAL pbus pbus_wr_toDACR pbus
16
LD PRE-BUFFER
3
DMA_ena cnt_ena dblbuf_ena intrptDMA_req
EN LD COUNTER
16
pbus set_intrpt pbus_wr_to_DACR
S C
2 1 0
zero
set_intrpt ena_cnt_and_dblbuf
1 0
MUX
pbus_wr_to_DACR
LD DACR pbus DAC value
Fig 132. DAC control with DMA interrupt and timer
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Chapter 31: LPC17xx General Purpose DMA (GPDMA) controller
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1. Basic configuration
The GPDMA is configured using the following registers: 1. Power: In the PCONP register (Table 4-46), set bit PCGPDMA. Remark: On reset, the GPDMA is disabled (PCGPDMA = 0). 2. Clock: see Table 4-38. 3. Interrupts: Interrupts are enabled in the NVIC using the appropriate Interrupt Set Enable register. 4. Programming: see Section 31-6.
2. Introduction
The DMA controller allows peripheral-to memory, memory-to-peripheral, and memory-to-memory transactions. Each DMA stream provides unidirectional serial DMA transfers for a single source and destination. For example, a bi-directional port requires one stream for transmit and one for receives. The source and destination areas can each be either a memory region or a peripheral.
3. Features
* Eight DMA channels. Each channel can support an unidirectional transfer. * 16 DMA request lines. * Memory-to-memory, memory-to-peripheral, and peripheral-to-memory transfers are
supported.
* GPDMA supports the SSP, I2S, UART, A/D Converter, and D/A Converter peripherals.
DMA can also be triggered by a timer match condition. Memory-to-memory transfers and transfers to or from GPIO are also supported.
* Scatter or gather DMA is supported through the use of linked lists. This means that
the source and destination areas do not have to occupy contiguous areas of memory.
* Hardware DMA channel priority. * AHB slave DMA programming interface. The DMA Controller is programmed by
writing to the DMA control registers over the AHB slave interface.
* One AHB bus master for transferring data. The interface transfers data when a DMA
request goes active.
* 32-bit AHB master bus width. * Incrementing or non-incrementing addressing for source and destination. * Programmable DMA burst size. The DMA burst size can be programmed to more
efficiently transfer data.
* Internal four-word FIFO per channel.
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* Supports 8-bit, 16-bit, and 32-bit wide transactions. * Big-endian and little-endian support. The DMA Controller defaults to little-endian
mode on reset.
* An interrupt to the processor can be generated on a DMA completion or when a DMA
error has occurred.
* Raw interrupt status. The DMA error and DMA count raw interrupt status can be read
prior to masking.
* DMA can operate in Sleep mode. (Note that in Sleep mode the GPDMA cannot
access the flash memory).
4. Functional description
This section describes the major functional blocks of the DMA Controller.
4.1 DMA controller functional description
The DMA Controller enables peripheral-to-memory, memory-to-peripheral, peripheral-to-peripheral, and memory-to-memory transactions. Each DMA stream provides unidirectional serial DMA transfers for a single source and destination. For example, a bidirectional port requires one stream for transmit and one for receive. The source and destination areas can each be either a memory region or a peripheral, and can be accessed through the AHB master. Figure 31-133 shows a block diagram of the DMA Controller.
GPDMA
AHB BUS
AHB SLAVE INTERFACE
CONTROL LOGIC AND REGISTERS
DMA requests DMA responses
DMA REQUEST AND RESPONSE INTERFACE
CHANNEL LOGIC AND REGISTERS
AHB MASTER INTERFACE
AHB BUS
DMA Interrupts
INTERRUPT REQUEST
Fig 133. DMA controller block diagram
The functions of the DMA Controller are described in the following sections.
4.1.1 AHB slave interface
All transactions to DMA Controller registers on the AHB slave interface are 32 bits wide. 8-bit and 16-bit accesses are not supported and will result in an exception.
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4.1.2 Control logic and register bank
The register block stores data written or to be read across the AHB interface.
4.1.3 DMA request and response interface
See Section 31-4.2 for information on the DMA request and response interface.
4.1.4 Channel logic and channel register bank
The channel logic and channel register bank contains registers and logic required for each DMA channel.
4.1.5 Interrupt request
The interrupt request generates the interrupt to the ARM processor.
4.1.6 AHB master interface
The DMA Controller contains one AHB master interface. The AHB master is capable of dealing with all types of AHB transactions, including:
* Split, retry, and error responses from slaves. If a peripheral performs a split or retry,
the DMA Controller stalls and waits until the transaction can complete.
* Locked transfers for source and destination of each stream. * Setting of protection bits for transfers on each stream.
4.1.6.1 Bus and transfer widths The physical width of the AHB bus is 32 bits. Source and destination transfers can be of differing widths and can be the same width or narrower than the physical bus width. The DMA Controller packs or unpacks data as appropriate. 4.1.6.2 Endian behavior The DMA Controller can cope with both little-endian and big-endian addressing. Internally the DMA Controller treats all data as a stream of bytes instead of 16-bit or 32-bit quantities. This means that when performing mixed-endian activity, where the endianness of the source and destination are different, byte swapping of the data within the 32-bit data bus is observed. Note: If byte swapping is not required, then use of different endianness between the source and destination addresses must be avoided. Table 31-543 shows endian behavior for different source and destination combinations.
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Table 543. Endian behavior Source endian Little Destination endian Little Source width 8 Destination width 8 Source Source data Destination Destination data transfer transfer no/byte lane no/byte lane 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] Little Little 8 16 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] Little Little 8 32 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] Little Little 16 8 1/[7:0] 1/[15:8] 2/[23:16] 2/[31:24] Little Little 16 16 1/[7:0] 1/[15:8] 2/[23:16] 2/[31:24] Little Little 16 32 1/[7:0] 1/[15:8] 2/[23:16] 2/[31:24] Little Little 32 8 1/[7:0] 1/[15:8] 1/[23:16] 1/[31:24] Little Little 32 16 1/[7:0] 1/[15:8] 1/[23:16] 1/[31:24] Little Little 32 32 1/[7:0] 1/[15:8] 1/[23:16] 1/[31:24] Big Big 8 8 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 21 43 65 87 12 34 56 78 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] 12121212 34343434 56565656 78787878 1/[31:0] 87654321 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] 1/[15:0] 2/[31:16] 21212121 43434343 65656565 87878787 43214321 87658765 1/[31:0] 87654321 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] 1/[15:0] 2/[31:16] 21212121 43434343 65656565 87878787 43214321 87658765 1/[31:0] 87654321 1/[7:0] 2/[15:8] 3/[23:16] 4/[31:24] 1/[15:0] 2/[31:16] 21212121 43434343 65656565 87878787 43214321 87658765
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Table 543. Endian behavior ...continued Source endian Big Destination endian Big Source width 8 Destination width 16 Source Source data Destination Destination data transfer transfer no/byte lane no/byte lane 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] Big Big 8 32 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] Big Big 16 8 1/[31:24] 1/[23:16] 2/[15:8] 2/[7:0] Big Big 16 16 1/[31:24] 1/[23:16] 2/[15:8] 2/[7:0] Big Big 16 32 1/[31:24] 1/[23:16] 2/[15:8] 2/[7:0] Big Big 32 8 1/[31:24] 1/[23:16] 1/[15:8] 1/[7:0] Big Big 32 16 1/[31:24] 1/[23:16] 1/[15:8] 1/[7:0] Big Big 32 32 1/[31:24] 1/[23:16] 1/[15:8] 1/[7:0] 12 34 56 78 12 34 56 78 12 34 56 78 12 34 56 78 12 34 56 78 12 34 56 78 12 34 56 78 12 34 56 78 1/[31:0] 12345678 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] 1/[15:0] 2/[31:16] 12121212 34343434 56565656 78787878 12341234 56785678 1/[31:0] 12345678 1/[31:24] 2/[23:16] 3/[15:8] 4/[7:0] 1/[15:0] 2/[31:16] 12121212 34343434 56565656 78787878 12341234 56785678 1/[31:0] 12345678 1/[15:0] 2/[31:16] 12341234 56785678
4.1.6.3
Error conditions An error during a DMA transfer is flagged directly by the peripheral by asserting an Error response on the AHB bus during the transfer. The DMA Controller automatically disables the DMA stream after the current transfer has completed, and can optionally generate an error interrupt to the CPU. This error interrupt can be masked.
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4.1.7 Channel hardware
Each stream is supported by a dedicated hardware channel, including source and destination controllers, as well as a FIFO. This enables better latency than a DMA controller with only a single hardware channel shared between several DMA streams and simplifies the control logic.
4.1.8 DMA request priority
DMA channel priority is fixed. DMA channel 0 has the highest priority and DMA channel 7 has the lowest priority. If the DMA Controller is transferring data for the lower priority channel and then the higher priority channel goes active, it completes the number of transfers delegated to the master interface by the lower priority channel before switching over to transfer data for the higher priority channel. Transfers delegated to the master interface are staged in the DMA channel FIFO, so the amount of data that needs to transfer could be as large as a 4 words. It is recommended that memory-to-memory transactions use the lowest priority channel.
4.1.9 Interrupt generation
A combined interrupt output is generated as an OR function of the individual interrupt requests of the DMA Controller and is connected to the interrupt controller.
4.2 DMA system connections
4.2.1 DMA request signals
The DMA request signals are used by peripherals to request a data transfer. The DMA request signals indicate whether a single or burst transfer of data is required. The DMA available request signals are: DMACBREQ[15:0] -- Burst request signals. These cause a programmed burst number of data to be transferred. DMACSREQ[15:0] -- Single transfer request signals. These cause a single data to be transferred. The DMA controller transfers a single transfer to or from the peripheral. DMACLBREQ[15:0] -- Last burst request signals. DMACLSREQ[15:0] -- Last single transfer request signals. Note that peripherals on this device do not support "last" request types, and many do not support both single and burst request types. See Section 31-4.2.3.
4.2.2 DMA response signals
The DMA response signals indicate whether the transfer initiated by the DMA request signal has completed. The response signals can also be used to indicate whether a complete packet has been transferred. The DMA response signals from the DMA controller are: DMACCLR[15:0] -- DMA clear or acknowledge signals. The DMACCLR signal is used by the DMA controller to acknowledge a DMA request from the peripheral.
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DMACTC[15:0] -- DMA terminal count signals. The DMACTC signal can be used by the DMA controller to indicate to the peripheral that the DMA transfer is complete.
4.2.3 DMA request connections
The connection of the GPDMA to the supported peripheral devices depends on the DMA functions implemented in those peripherals. Table 31-544 shows the DMA Request numbers used by the supported peripherals. UART and timer DMA requests on channels 8 through 15 are chosen via the DMAREQSEL register, see Section 31-5.15.
Table 544. DMA Connections Peripheral Function SSP0 Tx SSP0 Rx SSP1 Tx SSP1 Rx ADC I2S channel 0 I2S channel 1 DAC UART0 Tx / MAT0.0 UART0 Rx / MAT0.1 UART1 Tx / MAT1.0 UART1 Rx / MAT1.1 UART2 Tx / MAT2.0 UART2 Rx / MAT2.1 UART3 Tx / MAT3.0 UART3 Rx / MAT3.1
[1]
DMA Single Request DMA Burst Request Input (DMACSREQ) Input (DMACBREQ) 0 1 2 3 4 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
DMA Request Signal Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests ADC interrupt request [1] Dedicated DMA request Dedicated DMA request Dedicated DMA request Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests Dedicated DMA requests
Generates an interrupt and/or DMA request depending on software setup.
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5. Register description
The DMA Controller supports 8 channels. Each channel has registers specific to the operation of that channel. Other registers controls aspects of how source peripherals relate to the DMA Controller. There are also global DMA control and status registers. The DMA Controller registers are shown in Table 31-545.
Table 545. GPDMA register map Name General registers DMACIntStat DMACIntTCStat DMACIntTCClear DMACIntErrStat DMACIntErrClr DMACRawIntTCStat DMACRawIntErrStat DMACEnbldChns DMACSoftBReq DMACSoftSReq DMACSoftLBReq DMACSoftLSReq DMACConfig DMACSync DMAREQSEL Channel 0 registers DMACC0SrcAddr DMACC0DestAddr DMACC0LLI DMACC0Control DMACC0Config Channel 1 registers DMACC1SrcAddr DMACC1DestAddr DMACC1LLI DMACC1Control DMACC1Config Channel 2 registers DMACC2SrcAddr DMACC2DestAddr DMACC2LLI DMACC2Control
UM10360_1
Description
Access Reset state RO RO WO RO WO RO RO RO R/W R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 0 0 0 0 0 0 0
Address
DMA Interrupt Status Register DMA Interrupt Terminal Count Request Status Register DMA Interrupt Terminal Count Request Clear Register DMA Interrupt Error Status Register DMA Interrupt Error Clear Register DMA Raw Interrupt Terminal Count Status Register DMA Raw Error Interrupt Status Register DMA Enabled Channel Register DMA Software Burst Request Register DMA Software Single Request Register DMA Software Last Burst Request Register DMA Software Last Single Request Register DMA Configuration Register DMA Synchronization Register Selects between UART and timer DMA requests on channels 8 through 15 DMA Channel 0 Source Address Register DMA Channel 0 Destination Address Register DMA Channel 0 Linked List Item Register DMA Channel 0 Control Register DMA Channel 0 Configuration Register DMA Channel 1 Source Address Register DMA Channel 1 Destination Address Register DMA Channel 1 Linked List Item Register DMA Channel 1 Control Register DMA Channel 1 Configuration Register DMA Channel 2 Source Address Register DMA Channel 2 Destination Address Register DMA Channel 2 Linked List Item Register DMA Channel 2 Control Register
0x5000 4000 0x5000 4004 0x5000 4008 0x5000 400C 0x5000 4010 0x5000 4014 0x5000 4018 0x5000 401C 0x5000 4020 0x5000 4024 0x5000 4028 0x5000 402C 0x5000 4030 0x5000 4034 0x400F C1C4
R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
0 0 0 0 0 0 0 0 0 0 [1] 0 0 0 0
[1]
0x5000 4100 0x5000 4104 0x5000 4108 0x5000 410C 0x5000 4110 0x5000 4120 0x5000 4124 0x5000 4128 0x5000 412C 0x5000 4130 0x5000 4140 0x5000 4144 0x5000 4148 0x5000 414C
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Table 545. GPDMA register map Name DMACC2Config Channel 3 registers DMACC3SrcAddr DMACC3DestAddr DMACC3LLI DMACC3Control DMACC3Config Channel 4 registers DMACC4SrcAddr DMACC4DestAddr DMACC4LLI DMACC4Control DMACC4Config Channel 5 registers DMACC5SrcAddr DMACC5DestAddr DMACC5LLI DMACC5Control DMACC5Config Channel 6 registers DMACC6SrcAddr DMACC6DestAddr DMACC6LLI DMACC6Control DMACC6Config Channel 7 registers DMACC7SrcAddr DMACC7DestAddr DMACC7LLI DMACC7Control DMACC7Config
[1]
Description DMA Channel 2 Configuration Register DMA Channel 3 Source Address Register DMA Channel 3 Destination Address Register DMA Channel 3 Linked List Item Register DMA Channel 3 Control Register DMA Channel 3 Configuration Register DMA Channel 4 Source Address Register DMA Channel 4 Destination Address Register DMA Channel 4 Linked List Item Register DMA Channel 4 Control Register DMA Channel 4 Configuration Register DMA Channel 5 Source Address Register DMA Channel 5 Destination Address Register DMA Channel 5 Linked List Item Register DMA Channel 5 Control Register DMA Channel 5 Configuration Register DMA Channel 6 Source Address Register DMA Channel 6 Destination Address Register DMA Channel 6 Linked List Item Register DMA Channel 6 Control Register DMA Channel 6 Configuration Register DMA Channel 7 Source Address Register DMA Channel 7 Destination Address Register DMA Channel 7 Linked List Item Register DMA Channel 7 Control Register DMA Channel 7 Configuration Register
Access Reset state R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W 0 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 [1] 0 0 0 0 0
[1] [1] [1] [1]
Address 0x5000 4150 0x5000 4160 0x5000 4164 0x5000 4168 0x5000 416C 0x5000 4170 0x5000 4180 0x5000 4184 0x5000 4188 0x5000 418C 0x5000 4190 0x5000 41A0 0x5000 41A4 0x5000 41A8 0x5000 41AC 0x5000 41B0 0x5000 41C0 0x5000 41C4 0x5000 41C8 0x5000 41CC 0x5000 41D0 0x5000 41E0 0x5000 41E4 0x5000 41E8 0x5000 41EC 0x5000 41F0
Bit 17 of this register is a read-only status flag.
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5.1 DMA Interrupt Status register (DMACIntStat - 0x5000 4000)
The DMACIntStat Register is read-only and shows the status of the interrupts after masking. A 1 bit indicates that a specific DMA channel interrupt request is active. The request can be generated from either the error or terminal count interrupt requests. Table 31-546 shows the bit assignments of the DMACIntStat Register.
Table 546. DMA Interrupt Status register (DMACIntStat - 0x5000 4000) Bit 7:0 Name IntStat Function Status of DMA channel interrupts after masking. Each bit represents one channel: 0 - the corresponding channel has no active interrupt request. 1 - the corresponding channel does have an active interrupt request. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.2 DMA Interrupt Terminal Count Request Status register (DMACIntTCStat - 0x5000 4004)
The DMACIntTCStat Register is read-only and indicates the status of the terminal count after masking. Table 31-547 shows the bit assignments of the DMACIntTCStat Register.
Table 547. DMA Interrupt Terminal Count Request Status register (DMACIntTCStat - 0x5000 4004) Bit 7:0 Name IntTCStat Function Terminal count interrupt request status for DMA channels. Each bit represents one channel: 0 - the corresponding channel has no active terminal count interrupt request. 1 - the corresponding channel does have an active terminal count interrupt request. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.3 DMA Interrupt Terminal Count Request Clear register (DMACIntTCClear - 0x5000 4008)
The DMACIntTCClear Register is write-only and clears one or more terminal count interrupt requests. When writing to this register, each data bit that contains a 1 causes the corresponding bit in the status register (DMACIntTCStat) to be cleared. Data bits that are 0 have no effect. Table 31-548 shows the bit assignments of the DMACIntTCClear Register.
Table 548. DMA Interrupt Terminal Count Request Clear register (DMACIntTCClear - 0x5000 4008) Bit 7:0 Name IntTCClear Function Allows clearing the Terminal count interrupt request (IntTCStat) for DMA channels. Each bit represents one channel: 0 - writing 0 has no effect. 1 - clears the corresponding channel terminal count interrupt. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.4 DMA Interrupt Error Status register (DMACIntErrStat - 0x5000 400C)
The DMACIntErrStat Register is read-only and indicates the status of the error request after masking. Table 31-549 shows the bit assignments of the DMACIntErrStat Register.
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Table 549. DMA Interrupt Error Status register (DMACIntErrStat - 0x5000 400C) Bit 7:0 Name IntErrStat Function Interrupt error status for DMA channels. Each bit represents one channel: 0 - the corresponding channel has no active error interrupt request. 1 - the corresponding channel does have an active error interrupt request. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.5 DMA Interrupt Error Clear register (DMACIntErrClr - 0x5000 4010)
The DMACIntErrClr Register is write-only and clears the error interrupt requests. When writing to this register, each data bit that is 1 causes the corresponding bit in the status register to be cleared. Data bits that are 0 have no effect on the corresponding bit in the register. Table 31-550 shows the bit assignments of the DMACIntErrClr Register.
Table 550. DMA Interrupt Error Clear register (DMACIntErrClr - 0x5000 4010) Bit 7:0 Name IntErrClr Function Writing a 1 clears the error interrupt request (IntErrStat) for DMA channels. Each bit represents one channel: 0 - writing 0 has no effect. 1 - clears the corresponding channel error interrupt. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.6 DMA Raw Interrupt Terminal Count Status register (DMACRawIntTCStat - 0x5000 4014)
The DMACRawIntTCStat Register is read-only and indicates which DMA channel is requesting a transfer complete (terminal count interrupt) prior to masking. (Note: the DMACIntTCStat Register contains the same information after masking.) A 1 bit indicates that the terminal count interrupt request is active prior to masking. Table 31-551 shows the bit assignments of the DMACRawIntTCStat Register.
Table 551. DMA Raw Interrupt Terminal Count Status register (DMACRawIntTCStat - 0x5000 4014) Bit 7:0 Name RawIntTCStat Function Status of the terminal count interrupt for DMA channels prior to masking. Each bit represents one channel: 0 - the corresponding channel has no active terminal count interrupt request. 1 - the corresponding channel does have an active terminal count interrupt request. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.7 DMA Raw Error Interrupt Status register (DMACRawIntErrStat 0x5000 4018)
The DMACRawIntErrStat Register is read-only and indicates which DMA channel is requesting an error interrupt prior to masking. (Note: the DMACIntErrStat Register contains the same information after masking.) A 1 bit indicates that the error interrupt request is active prior to masking. Table 31-552 shows the bit assignments of register of the DMACRawIntErrStat Register.
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Chapter 31: LPC17xx General Purpose DMA (GPDMA) controller
Table 552. DMA Raw Error Interrupt Status register (DMACRawIntErrStat - 0x5000 4018) Bit 7:0 Name RawIntErrStat Function Status of the error interrupt for DMA channels prior to masking. Each bit represents one channel: 0 - the corresponding channel has no active error interrupt request. 1 - the corresponding channel does have an active error interrupt request. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.8 DMA Enabled Channel register (DMACEnbldChns - 0x5000 401C)
The DMACEnbldChns Register is read-only and indicates which DMA channels are enabled, as indicated by the Enable bit in the DMACCxConfig Register. A 1 bit indicates that a DMA channel is enabled. A bit is cleared on completion of the DMA transfer. Table 31-553 shows the bit assignments of the DMACEnbldChns Register.
Table 553. DMA Enabled Channel register (DMACEnbldChns - 0x5000 401C) Bit 7:0 Name EnabledChannels Function Enable status for DMA channels. Each bit represents one channel: 0 - DMA channel is disabled. 1 - DMA channel is enabled. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.9 DMA Software Burst Request register (DMACSoftBReq - 0x5000 4020)
The DMACSoftBReq Register is read/write and enables DMA burst requests to be generated by software. A DMA request can be generated for each source by writing a 1 to the corresponding register bit. A register bit is cleared when the transaction has completed. Reading the register indicates which sources are requesting DMA burst transfers. A request can be generated from either a peripheral or the software request register. Each bit is cleared when the related transaction has completed. Table 31-554 shows the bit assignments of the DMACSoftBReq Register.
Table 554. DMA Software Burst Request register (DMACSoftBReq - 0x5000 4020) Bit 15:0 Name SoftBReq Function Software burst request flags for each of 16 possible sources. Each bit represents one DMA request line or peripheral function (refer to Table 31-544 for peripheral hardware connections to the DMA controller): 0 - writing 0 has no effect. 1 - writing 1 generates a DMA burst request for the corresponding request line. 31:16 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
Note: It is recommended that software and hardware peripheral requests are not used at the same time.
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5.10 DMA Software Single Request register (DMACSoftSReq - 0x5000 4024)
The DMACSoftSReq Register is read/write and enables DMA single transfer requests to be generated by software. A DMA request can be generated for each source by writing a 1 to the corresponding register bit. A register bit is cleared when the transaction has completed. Reading the register indicates which sources are requesting single DMA transfers. A request can be generated from either a peripheral or the software request register. Table 31-555 shows the bit assignments of the DMACSoftSReq Register.
Table 555. DMA Software Single Request register (DMACSoftSReq - 0x5000 4024) Bit 15:0 Name SoftSReq Function Software single transfer request flags for each of 16 possible sources. Each bit represents one DMA request line or peripheral function: 0 - writing 0 has no effect. 1 - writing 1 generates a DMA single transfer request for the corresponding request line. 31:16 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.11 DMA Software Last Burst Request register (DMACSoftLBReq - 0x5000 4028)
The DMACSoftLBReq Register is read/write and enables DMA last burst requests to be generated by software. A DMA request can be generated for each source by writing a 1 to the corresponding register bit. A register bit is cleared when the transaction has completed. Reading the register indicates which sources are requesting last burst DMA transfers. A request can be generated from either a peripheral or the software request register. Table 31-556 shows the bit assignments of the DMACSoftLBReq Register.
Table 556. DMA Software Last Burst Request register (DMACSoftLBReq - 0x5000 4028) Bit 15:0 Name SoftLBReq Function Software last burst request flags for each of 16 possible sources. Each bit represents one DMA request line or peripheral function: 0 - writing 0 has no effect. 1 - writing 1 generates a DMA last burst request for the corresponding request line. 31:16 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.12 DMA Software Last Single Request register (DMACSoftLSReq 0x5000 402C)
The DMACSoftLSReq Register is read/write and enables DMA last single requests to be generated by software. A DMA request can be generated for each source by writing a 1 to the corresponding register bit. A register bit is cleared when the transaction has completed. Reading the register indicates which sources are requesting last single DMA transfers. A request can be generated from either a peripheral or the software request register. Table 31-557 shows the bit assignments of the DMACSoftLSReq Register.
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Table 557. DMA Software Last Single Request register (DMACSoftLSReq - 0x5000 402C) Bit 15:0 Name SoftLSReq Function Software last single transfer request flags for each of 16 possible sources. Each bit represents one DMA request line or peripheral function: 0 - writing 0 has no effect. 1 - writing 1 generates a DMA last single transfer request for the corresponding request line. 31:16 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.13 DMA Configuration register (DMACConfig - 0x5000 4030)
The DMACConfig Register is read/write and configures the operation of the DMA Controller. The endianness of the AHB master interface can be altered by writing to the M bit of this register. The AHB master interface is set to little-endian mode on reset. Table 31-558 shows the bit assignments of the DMACConfig Register.
Table 558. DMA Configuration register (DMACConfig - 0x5000 4030) Bit 0 Name E Function DMA Controller enable: 0 = disabled (default). Disabling the DMA Controller reduces power consumption. 1 = enabled. 1 M AHB Master endianness configuration: 0 = little-endian mode (default). 1 = big-endian mode. 31:2 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.14 DMA Synchronization register (DMACSync - 0x5000 4034)
The DMACSync Register is read/write and enables or disables synchronization logic for the DMA request signals. The DMA request signals consist of the DMACBREQ[15:0], DMACSREQ[15:0], DMACLBREQ[15:0], and DMACLSREQ[15:0]. A bit set to 0 enables the synchronization logic for a particular group of DMA requests. A bit set to 1 disables the synchronization logic for a particular group of DMA requests. This register is reset to 0, synchronization logic enabled. Table 31-559 shows the bit assignments of the DMACSync Register.
Table 559. DMA Synchronization register (DMACSync - 0x5000 4034) Bit 15:0 Name DMACSync Function Controls the synchronization logic for DMA request signals. Each bit represents one set of DMA request lines as described in the preceding text: 0 - synchronization logic for the corresponding DMA request signals are disabled. 1 - synchronization logic for the corresponding request line signals are enabled. 31:16 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
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5.15 DMA Request Select register (DMAReqSel - 0x400F C1C4)
DMAReqSel is a read/write register that allows selecting between UART or Timer DMA requests for DMA inputs 8 through 15. Table 31-560 shows the bit assignments of the DMAReqSel Register.
Table 560. DMA Request Select register (DMAReqSel - 0x400F C1C4) Bit 0 Name DMASEL08 Function Selects the DMA request for GPDMA input 8: 0 - UART0 TX is selected. 1 - Timer 0 match 0 is selected. 1 DMASEL09 Selects the DMA request for GPDMA input 9: 0 - UART0 RX is selected. 1 - Timer 0 match 1 is selected. 2 DMASEL10 Selects the DMA request for GPDMA input 10: 0 - UART1 TX is selected. 1 - Timer 1match 0 is selected. 3 DMASEL11 Selects the DMA request for GPDMA input 11: 0 - UART1 RX is selected. 1 - Timer 1match 1 is selected. 4 DMASEL12 Selects the DMA request for GPDMA input 12: 0 - UART2 TX is selected. 1 - Timer 2 match 0 is selected. 5 DMASEL13 Selects the DMA request for GPDMA input 13: 0 - UART2 RX is selected. 1 - Timer 2 match 1 is selected. 6 DMASEL14 Selects the DMA request for GPDMA input 14: 0 - UART3 TX is selected. 1 - Timer 3 match 0 is selected. 7 DMASEL15 Selects the DMA request for GPDMA input 15: 0 - UART3 RX is selected. 1 - Timer 3 match 1 is selected. 31:8 Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
5.16 DMA Channel registers
The channel registers are used to program the eight DMA channels. These registers consist of:
* * * * *
Eight DMACCxSrcAddr Registers. Eight DMACCxDestAddr Registers. Eight DMACCxLLI Registers. Eight DMACCxControl Registers. Eight DMACCxConfig Registers.
When performing scatter/gather DMA, the first four of these are automatically updated.
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5.17 DMA Channel Source Address registers (DMACCxSrcAddr 0x5000 41x0)
The eight read/write DMACCxSrcAddr Registers (DMACC0SrcAddr to DMACC7SrcAddr) contain the current source address (byte-aligned) of the data to be transferred. Each register is programmed directly by software before the appropriate channel is enabled. When the DMA channel is enabled this register is updated:
* As the source address is incremented. * By following the linked list when a complete packet of data has been transferred.
Reading the register when the channel is active does not provide useful information. This is because by the time software has processed the value read, the address may have progressed. It is intended to be read-only when the channel has stopped, in which case it shows the source address of the last item read. Note: The source and destination addresses must be aligned to the source and destination widths. Table 31-561 shows the bit assignments of the DMACCxSrcAddr Registers.
Table 561. DMA Channel Source Address registers (DMACCxSrcAddr - 0x5000 41x0) Bit 31:0 Name SrcAddr Function DMA source address. Reading this register will return the current source address.
5.18 DMA Channel Destination Address registers (DMACCxDestAddr 0x5000 41x4)
The eight read/write DMACCxDestAddr Registers (DMACC0DestAddr to DMACC7DestAddr) contain the current destination address (byte-aligned) of the data to be transferred. Each register is programmed directly by software before the channel is enabled. When the DMA channel is enabled the register is updated as the destination address is incremented and by following the linked list when a complete packet of data has been transferred. Reading the register when the channel is active does not provide useful information. This is because by the time that software has processed the value read, the address may have progressed. It is intended to be read-only when a channel has stopped, in which case it shows the destination address of the last item read. Table 31-562 shows the bit assignments of the DMACCxDestAddr Register.
Table 562. DMA Channel Destination Address registers (DMACCxDestAddr - 0x5000 41x4) Bit 31:0 Name DestAddr Function DMA Destination address. Reading this register will return the current destination address.
5.19 DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8)
The eight read/write DMACCxLLI Registers (DMACC0LLI to DMACC7LLI) contain a word-aligned address of the next Linked List Item (LLI). If the LLI is 0, then the current LLI is the last in the chain, and the DMA channel is disabled when all DMA transfers associated with it are completed. Programming this register when the DMA channel is enabled may have unpredictable side effects. Table 31-563 shows the bit assignments of the DMACCxLLI Register.
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Table 563. DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8) Bit 1:0 31:2 Name LLI Function Reserved, and must be written as 0. Linked list item. Bits [31:2] of the address for the next LLI. Address bits [1:0] are 0.
5.20 DMA channel control registers (DMACCxControl - 0x5000 41xC)
The eight read/write DMACCxControl Registers (DMACC0Control to DMACC7Control) contain DMA channel control information such as the transfer size, burst size, and transfer width. Each register is programmed directly by software before the DMA channel is enabled. When the channel is enabled the register is updated by following the linked list when a complete packet of data has been transferred. Reading the register while the channel is active does not give useful information. This is because by the time software has processed the value read, the channel may have advanced. It is intended to be read-only when a channel has stopped. Table 31-564 shows the bit assignments of the DMACCxControl Register.
5.20.1 Protection and access information
AHB access information is provided to the source and/or destination peripherals when a transfer occurs, although on the LPC17xx this has no effect. The transfer information is provided by programming the DMA channel (the Prot bits of the DMACCxControl Register, and the Lock bit of the DMACCxConfig Register). These bits are programmed by software, and can be used by peripherals. Three bits of information are provided, and are used as shown in Table 31-564.
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Table 564. DMA channel control registers (DMACCxControl - 0x5000 41xC) Bit 11:0 Name TransferSize Function Transfer size. This field sets the size of the transfer. The transfer size value must be set before the channel is enabled. Transfer size is updated as data transfers are completed. A read from this field indicates the number of transfers completed on the destination bus. Reading the register when the channel is active does not give useful information because by the time that the software has processed the value read, the channel might have progressed. It is intended to be used only when a channel is enabled and then disabled. 14:12 SBSize Source burst size. Indicates the number of transfers that make up a source burst. This value must be set to the burst size of the source peripheral, or if the source is memory, to the memory boundary size. The burst size is the amount of data that is transferred when the DMACBREQ signal goes active in the source peripheral. 000 - 1 001 - 4 010 - 8 011 - 16 100 - 32 101 - 64 110 - 128 111 - 256 17:15 DBSize Destination burst size. Indicates the number of transfers that make up a destination burst transfer request. This value must be set to the burst size of the destination peripheral or, if the destination is memory, to the memory boundary size. The burst size is the amount of data that is transferred when the DMACBREQ signal goes active in the destination peripheral. 000 - 1 001 - 4 010 - 8 011 - 16 100 - 32 101 - 64 110 - 128 111 - 256 20:18 SWidth Source transfer width. Transfers wider than the AHB master bus width are illegal. The source and destination widths can be different from each other. The hardware automatically packs and unpacks the data as required. 000 - Byte (8-bit) 001 - Halfword (16-bit) 010 - Word (32-bit) 011 to 111 - Reserved 23:21 DWidth Destination transfer width. Transfers wider than the AHB master bus width are not supported. The source and destination widths can be different from each other. The hardware automatically packs and unpacks the data as required. 000 - Byte (8-bit) 001 - Halfword (16-bit) 010 - Word (32-bit) 011 to 111 - Reserved 25:24 Reserved, and must be written as 0.
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Table 564. DMA channel control registers (DMACCxControl - 0x5000 41xC) ...continued Bit 26 Name SI Function Source increment: 0 - the source address is not incremented after each transfer. 1 - the source address is incremented after each transfer. 27 DI Destination increment: 0 - the destination address is not incremented after each transfer. 1 - the destination address is incremented after each transfer. 28 Prot1 This is provided to the peripheral during a DMA bus access and indicates that the access is in user mode or privileged mode. This information is not used in the LPC17xx. 0 - access is in user mode. 1 - access is in privileged mode. 29 Prot2 This is provided to the peripheral during a DMA bus access and indicates to the peripheral that the access is bufferable or not bufferable. This information is not used in the LPC17xx. 0 - access is not bufferable. 1 - access is bufferable. 30 Prot3 This is provided to the peripheral during a DMA bus access and indicates to the peripheral that the access is cacheable or not cacheable. This information is not used in the LPC17xx. 0 - access is not cacheable. 1 - access is cacheable. 31 I Terminal count interrupt enable bit. 0 - the terminal count interrupt is disabled. 1 - the terminal count interrupt is enabled.
5.21 DMA Channel Configuration registers (DMACCxConfig - 0x5000 41x0)
The eight DMACCxConfig Registers (DMACC0Config to DMACC7Config) are read/write with the exception of bit[17] which is read-only. Used these to configure the DMA channel. The registers are not updated when a new LLI is requested. Table 31-565 shows the bit assignments of the DMACCxConfig Register.
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Table 565. DMA Channel Configuration registers (DMACCxConfig - 0x5000 41x0) Bit 0 Name E Function Channel enable. Reading this bit indicates whether a channel is currently enabled or disabled: 0 = channel disabled. 1 = channel enabled. The Channel Enable bit status can also be found by reading the DMACEnbldChns Register. A channel is enabled by setting this bit. A channel can be disabled by clearing the Enable bit. This causes the current AHB transfer (if one is in progress) to complete and the channel is then disabled. Any data in the FIFO of the relevant channel is lost. Restarting the channel by setting the Channel Enable bit has unpredictable effects, the channel must be fully re-initialized. The channel is also disabled, and Channel Enable bit cleared, when the last LLI is reached, the DMA transfer is completed, or if a channel error is encountered. If a channel must be disabled without losing data in the FIFO, the Halt bit must be set so that further DMA requests are ignored. The Active bit must then be polled until it reaches 0, indicating that there is no data left in the FIFO. Finally, the Channel Enable bit can be cleared. 5:1 SrcPeripheral Source peripheral. This value selects the DMA source request peripheral. This field is ignored if the source of the transfer is from memory. See Table 31-544 for peripheral identification. Destination peripheral. This value selects the DMA destination request peripheral. This field is ignored if the destination of the transfer is to memory. See Table 31-544 for peripheral identification. This value indicates the type of transfer. The transfer type can be memory-to-memory, memory-to-peripheral, peripheral-to-memory, or peripheral-to-peripheral. Refer to Table 31-566 for the encoding of this field. 14 15 16 17 IE ITC L A Interrupt error mask. When cleared, this bit masks out the error interrupt of the relevant channel. Terminal count interrupt mask. When cleared, this bit masks out the terminal count interrupt of the relevant channel. Lock. When set, this bit enables locked transfers. This information is not used in the LPC17xx. Active: 0 = there is no data in the FIFO of the channel. 1 = the channel FIFO has data. This value can be used with the Halt and Channel Enable bits to cleanly disable a DMA channel. This is a read-only bit. 18 H Halt: 0 = enable DMA requests. 1 = ignore further source DMA requests. The contents of the channel FIFO are drained. This value can be used with the Active and Channel Enable bits to cleanly disable a DMA channel. 31:19 Reserved Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined.
10:6
DestPeripheral
13:11
TransferType
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5.21.1 Lock control
The lock control may set the lock bit by writing a 1 to bit 16 of the DMACCxConfig Register. When a burst occurs, the AHB arbiter will not de-grant the master during the burst until the lock is de-asserted. The DMA Controller can be locked for a a single burst such as a long source fetch burst or a long destination drain burst. The DMA Controller does not usually assert the lock continuously for a source fetch burst followed by a destination drain burst. There are situations when the DMA Controller asserts the lock for source transfers followed by destination transfers. This is possible when internal conditions in the DMA Controller permit it to perform a source fetch followed by a destination drain back-to-back.
5.21.2 Transfer type
Table 31-566 lists the bit values of the transfer type bits identified in Table 31-565.
Table 566. Transfer type bits Bit value 000 001 010 011 100 to 111 Transfer type Memory to memory Memory to peripheral Peripheral to memory Source peripheral to destination peripheral Reserved, do not use these combinations Controller DMA DMA DMA DMA -
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6. Using the DMA controller
6.1 Programming the DMA controller
All accesses to the DMA Controller internal register must be word (32-bit) reads and writes.
6.1.1 Enabling the DMA controller
To enable the DMA controller set the Enable bit in the DMACConfig register.
6.1.2 Disabling the DMA controller
To disable the DMA controller:
* Read the DMACEnbldChns register and ensure that all the DMA channels have been
disabled. If any channels are active, see Disabling a DMA channel.
* Disable the DMA controller by writing 0 to the DMA Enable bit in the DMACConfig
register.
6.1.3 Enabling a DMA channel
To enable the DMA channel set the channel enable bit in the relevant DMA channel configuration register. Note that the channel must be fully initialized before it is enabled.
6.1.4 Disabling a DMA channel
A DMA channel can be disabled in three ways:
* By writing directly to the channel enable bit. Any outstanding data in the FIFO's is lost
if this method is used.
* By using the active and halt bits in conjunction with the channel enable bit. * By waiting until the transfer completes. This automatically clears the channel.
Disabling a DMA channel and losing data in the FIFO Clear the relevant channel enable bit in the relevant channel configuration register. The current AHB transfer (if one is in progress) completes and the channel is disabled. Any data in the FIFO is lost. Disabling the DMA channel without losing data in the FIFO
* Set the halt bit in the relevant channel configuration register. This causes any future
DMA request to be ignored.
* Poll the active bit in the relevant channel configuration register until it reaches 0. This
bit indicates whether there is any data in the channel that has to be transferred.
* Clear the channel enable bit in the relevant channel configuration register
6.1.5 Setting up a new DMA transfer
To set up a new DMA transfer: If the channel is not set aside for the DMA transaction:
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1. Read the DMACEnbldChns controller register and find out which channels are inactive. 2. Choose an inactive channel that has the required priority. 3. Program the DMA controller
6.1.6 Halting a DMA channel
Set the halt bit in the relevant DMA channel configuration register. The current source request is serviced. Any further source DMA request is ignored until the halt bit is cleared.
6.1.7 Programming a DMA channel
1. Choose a free DMA channel with the priority needed. DMA channel 0 has the highest priority and DMA channel 7 the lowest priority. 2. Clear any pending interrupts on the channel to be used by writing to the DMACIntTCClear and DMACIntErrClear register. The previous channel operation might have left interrupt active. 3. Write the source address into the DMACCxSrcAddr register. 4. Write the destination address into the DMACCxDestAddr register. 5. Write the address of the next LLI into the DMACCxLLI register. If the transfer comprises of a single packet of data then 0 must be written into this register. 6. Write the control information into the DMACCxControl register. 7. Write the channel configuration information into the DMACCxConfig register. If the enable bit is set then the DMA channel is automatically enabled.
6.2 Flow control
The device that controls the length of the packet is known as the flow controller. On the LPC17xx, the flow controller is always the DMA Controller, and the packet length is programmed by software before the DMA channel is enabled. When the DMA transfer is completed: 1. The DMA Controller issues an acknowledge to the peripheral in order to indicate that the transfer has finished. 2. A TC interrupt is generated, if enabled. 3. The DMA Controller moves on to the next LLI. The following sections describe the DMA Controller data flow sequences for the four allowed transfer types:
* * * *
Memory-to-peripheral. Peripheral-to-memory. Memory-to-memory. Peripheral-to-peripheral.
Table 31-567 indicates the request signals used for each type of transfer.
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Table 567. DMA request signal usage Transfer direction Memory-to-peripheral Peripheral-to-memory Memory-to-memory Source peripheral to destination peripheral Request generator Peripheral Peripheral DMA Controller Source peripheral and destination peripheral Flow controller DMA Controller DMA Controller DMA Controller DMA Controller
6.2.1 Peripheral-to-memory or memory-to-peripheral DMA flow
For a peripheral-to-memory or memory-to-peripheral DMA flow, the following sequence occurs: 1. Program and enable the DMA channel. 2. Wait for a DMA request. 3. The DMA Controller starts transferring data when: - The DMA request goes active. - The DMA stream has the highest pending priority. - The DMA Controller is the bus master of the AHB bus. 4. If an error occurs while transferring the data, an error interrupt is generated and disables the DMA stream, and the flow sequence ends. 5. Decrement the transfer count. 6. If the transfer has completed (indicated by the transfer count reaching 0): - The DMA Controller responds with a DMA acknowledge. - The terminal count interrupt is generated (this interrupt can be masked). - If the DMACCxLLI Register is not 0, then reload the DMACCxSrcAddr, DMACCxDestAddr, DMACCxLLI, and DMACCxControl registers and go to back to step 2. However, if DMACCxLLI is 0, the DMA stream is disabled and the flow sequence ends.
6.2.2 Peripheral-to-peripheral DMA flow
For a peripheral-to-peripheral DMA flow, the following sequence occurs: 1. Program and enable the DMA channel. 2. Wait for a source DMA request. 3. The DMA Controller starts transferring data when: - The DMA request goes active. - The DMA stream has the highest pending priority. - The DMA Controller is the bus master of the AHB bus. 4. If an error occurs while transferring the data an error interrupt is generated, the DMA stream is disabled, and the flow sequence ends. 5. Decrement the transfer count. 6. If the transfer has completed (indicated by the transfer count reaching 0): - The DMA Controller responds with a DMA acknowledge to the source peripheral. - Further source DMA requests are ignored.
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7. When the destination DMA request goes active and there is data in the DMA Controller FIFO, transfer data into the destination peripheral. 8. If an error occurs while transferring the data, an error interrupt is generated, the DMA stream is disabled, and the flow sequence ends. 9. If the transfer has completed it is indicated by the transfer count reaching 0. The following happens: - The DMA Controller responds with a DMA acknowledge to the destination peripheral. - The terminal count interrupt is generated (this interrupt can be masked). - If the DMACCxLLI Register is not 0, then reload the DMACCxSrcAddr, DMACCxDestAddr, DMACCxLLI, and DMACCxControl Registers and go to back to step 2. However, if DMACCxLLI is 0, the DMA stream is disabled and the flow sequence ends.
6.2.3 Memory-to-memory DMA flow
For a memory-to-memory DMA flow the following sequence occurs: 1. Program and enable the DMA channel. 2. Transfer data whenever the DMA channel has the highest pending priority and the DMA Controller gains mastership of the AHB bus. 3. If an error occurs while transferring the data, generate an error interrupt and disable the DMA stream. 4. Decrement the transfer count. 5. If the count has reached zero: - Generate a terminal count interrupt (the interrupt can be masked). - If the DMACCxLLI Register is not 0, then reload the DMACCxSrcAddr, DMACCxDestAddr, DMACCxLLI, and DMACCxControl Registers and go to back to step 2. However, if DMACCxLLI is 0, the DMA stream is disabled and the flow sequence ends. Note: Memory-to-memory transfers should be programmed with a low channel priority, otherwise other DMA channels cannot access the bus until the memory-to-memory transfer has finished, or other AHB masters cannot perform any transaction.
6.3 Interrupt requests
Interrupt requests can be generated when an AHB error is encountered or at the end of a transfer (terminal count), after all the data corresponding to the current LLI has been transferred to the destination. The interrupts can be masked by programming bits in the relevant DMACCxControl and DMACCxConfig Channel Registers. The interrupt requests from all DMA channels can be found in the DMACRawIntTCStat and DMACRawIntErrStat registers. The masked versions of the DMA interrupt data is contained in the DMACIntTCStat and DMACIntErrStat registers. The DMACIntStat register then combines the DMACIntTCStat and DMACIntErrStat requests into a single register to enable the source of an interrupt to be found quickly. Writing to the DMACIntTCClear or the DMACIntErrClr Registers with a bit set to 1 enables selective clearing of interrupts.
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6.3.1 Hardware interrupt sequence flow
When a DMA interrupt request occurs, the Interrupt Service Routine needs to: 1. Read the DMACIntTCStat Register to determine whether the interrupt was generated due to the end of the transfer (terminal count). A 1 bit indicates that the transfer completed. If more than one request is active, it is recommended that the highest priority channels be checked first. 2. Read the DMACIntErrStat Register to determine whether the interrupt was generated due to an error occurring. A 1 bit indicates that an error occurred. 3. Service the interrupt request. 4. For a terminal count interrupt, write a 1 to the relevant bit of the DMACIntTCClr Register. For an error interrupt write a 1 to the relevant bit of the DMACIntErrClr Register to clear the interrupt request.
6.4 Address generation
Address generation can be either incrementing or non-incrementing (address wrapping is not supported). Some devices, especially memories, disallow burst accesses across certain address boundaries. The DMA controller assumes that this is the case with any source or destination area, which is configured for incrementing addressing. This boundary is assumed to be aligned with the specified burst size. For example, if the channel is set for 16-transfer burst to a 32-bit wide device then the boundary is 64-bytes aligned (that is address bits [5:0] equal 0). If a DMA burst is to cross one of these boundaries, then, instead of a burst, that transfer is split into separate AHB transactions.
6.4.1 Word-aligned transfers across a boundary
The channel is configured for 16-transfer bursts, each transfer 32-bits wide, to a destination for which address incrementing is enabled. The start address for the current burst is 0x0C000024, the next boundary (calculated from the burst size and transfer width) is 0x0C000040. The transfer will be split into two AHB transactions:
* a 7-transfer burst starting at address 0x0C000024 * a 9-transfer burst starting at address 0x0C000040. 6.5 Scatter/gather
Scatter/gather is supported through the use of linked lists. This means that the source and destination areas do not have to occupy contiguous areas in memory. Where scatter/gather is not required, the DMACCxLLI Register must be set to 0. The source and destination data areas are defined by a series of linked lists. Each Linked List Item (LLI) controls the transfer of one block of data, and then optionally loads another LLI to continue the DMA operation, or stops the DMA stream. The first LLI is programmed into the DMA Controller. The data to be transferred described by an LLI (referred to as the packet of data) usually requires one or more DMA bursts (to each of the source and destination).
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6.5.1 Linked list items
A Linked List Item (LLI) consists of four words. These words are organized in the following order: 1. DMACCxSrcAddr. 2. DMACCxDestAddr. 3. DMACCxLLI. 4. DMACCxControl. Note: The DMACCxConfig DMA channel Configuration Register is not part of the linked list item. 6.5.1.1 Programming the DMA controller for scatter/gather DMA To program the DMA Controller for scatter/gather DMA: 1. Write the LLIs for the complete DMA transfer to memory. Each linked list item contains four words: - Source address. - Destination address. - Pointer to next LLI. - Control word. The last LLI has its linked list word pointer set to 0. 2. Choose a free DMA channel with the priority required. DMA channel 0 has the highest priority and DMA channel 7 the lowest priority. 3. Write the first linked list item, previously written to memory, to the relevant channel in the DMA Controller. 4. Write the channel configuration information to the channel Configuration Register and set the Channel Enable bit. The DMA Controller then transfers the first and then subsequent packets of data as each linked list item is loaded. 5. An interrupt can be generated at the end of each LLI depending on the Terminal Count bit in the DMACCxControl Register. If this bit is set an interrupt is generated at the end of the relevant LLI. The interrupt request must then be serviced and the relevant bit in the DMACIntTCClear Register must be set to clear the interrupt. 6.5.1.2 Example of scatter/gather DMA See Figure 31-134 for an example of an LLI. A section of memory is to be transferred to a peripheral. The addresses of each LLI entry are given, in hexadecimal, at the left-hand side of the figure. In this example, the LLIs describing the transfer are to be stored contiguously from address 0x2002 0000, but they could be located anywhere. The right side of the figure shows the memory containing the data to be transferred.
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Linked List Array LLI1 Source address 0x2002 0000 Destination address Next LLI address Control information LLI2 Source address 0x2002 0010 Destination address Next LLI address Control information LLI3 Source address 0x2002 0020 Destination address Next LLI address Control information = 0x 2002 A200 = peripheral = 0x2002 0010 = length 3072 = 0x 2002 B200 = peripheral = 0x2002 0020 = length 3072 = 0x 2002 C200 = peripheral = 0x2002 0030 = length 3072
0x2002 A200 3072 bytes of data 0x2002 ADFF 0x2002 B200 3072 bytes of data 0x2002 BDFF 0x2002 C200 3072 bytes of data 0x2002 CDFF
LLI8 Source address 0x2002 0070 Destination address Next LLI address Control information
= 0x 2003 1200 = peripheral = 0 (end of list) = length 3072
0x2003 1200 3072 bytes of data 0x2003 1DFF
Fig 134. LLI example
The first LLI, stored at 0x2002 0000, defines the first block of data to be transferred, which is the data stored from address 0x2002 A200 to 0x2002 ADFF:
* * * * * *
Source start address 0x2002 A200. Destination address set to the destination peripheral address. Transfer width, word (32-bit). Transfer size, 3072 bytes (0XC00). Source and destination burst sizes, 16 transfers. Next LLI address, 0x2002 0010.
The second LLI, stored at 0x2002 0010, describes the next block of data to be transferred:
* * * * * *
Source start address 0x2002 B200. Destination address set to the destination peripheral address. Transfer width, word (32-bit). Transfer size, 3072 bytes (0xC00). Source and destination burst sizes, 16 transfers. Next LLI address, 0x2002 0020.
A chain of descriptors is built up, each one pointing to the next in the series. To initialize the DMA stream, the first LLI, 0x2002 0000, is programmed into the DMA Controller. When the first packet of data has been transferred the next LLI is automatically loaded. The final LLI is stored at 0x2002 0070 and contains:
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* * * * * *
Source start address 0x2003 1200. Destination address set to the destination peripheral address. Transfer width, word (32-bit). Transfer size, 3072 bytes (0xC00). Source and destination burst sizes, 16 transfers. Next LLI address, 0x0.
Because the next LLI address is set to zero, this is the last descriptor, and the DMA channel is disabled after transferring the last item of data. The channel is probably set to generate an interrupt at this point to indicate to the ARM processor that the channel can be reprogrammed.
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Rev. 01 -- 4 January 2010 User manual
1. Introduction
The boot loader controls initial operation after reset and also provides the tools for programming the flash memory. This could be initial programming of a blank device, erasure and re-programming of a previously programmed device, or programming of the flash memory by the application program in a running system.
2. Features
* In-System Programming: In-System programming (ISP) is programming or
reprogramming the on-chip flash memory, using the boot loader software and UART0 serial port. This can be done when the part resides in the end-user board.
* In Application Programming: In-Application (IAP) programming is performing erase
and write operation on the on-chip flash memory, as directed by the end-user application code.
* Flash signature generation: built-in hardware can generate a signature for a range of
flash addresses, or for the entire flash memory.
3. Description
The flash boot loader code is executed every time the part is powered on or reset. The loader can execute the ISP command handler or the user application code. A LOW level after reset at pin P2.10 is considered an external hardware request to start the ISP command handler. Assuming that power supply pins are on their nominal levels when the rising edge on RESET pin is generated, it may take up to 3 ms before P2.10 is sampled and the decision on whether to continue with user code or ISP handler is made. If P2.10 is sampled low and the watchdog overflow flag is set, the external hardware request to start the ISP command handler is ignored. If there is no request for the ISP command handler execution (P2.10 is sampled HIGH after reset), a search is made for a valid user program. If a valid user program is found then the execution control is transferred to it. If a valid user program is not found, the auto-baud routine is invoked. Pin P2.10 is used as a hardware request signal for ISP and therefore requires special attention. Since P2.10 is in high impedance mode after reset, it is important that the user provides external hardware (a pull-up resistor or other device) to put the pin in a defined state. Otherwise unintended entry into ISP mode may occur. When ISP mode is entered after a power on reset, the IRC and PLL are used to generate the CCLK of 14.748 MHz. The baud rates that can easily be obtained in this case are: 9600 baud, 19200 baud, 38400 baud, 57600 baud, 115200 baud, and 230400 baud. This may not be the case when ISP is invoked by the user application (see Section 32-8.9 "Re-invoke ISP" on page 633).
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A hardware flash signature generation capability is built into the flash memory. this feature can be used to create a signature that can then be used to verify flash contents. Details of flash signature generation are in Section 32-10.
3.1 Memory map after any reset
When a user program begins execution after reset, the interrupt vectors are set to point to the beginning of flash memory.
Fig 135. Map of lower memory
3.1.1 Criterion for Valid User Code
The reserved Cortex-M3 exception vector location 7 (offset 0x 001C in the vector table) should contain the 2's complement of the check-sum of table entries 0 through 6. This causes the checksum of the first 8 table entries to be 0. The boot loader code checksums the first 8 locations in sector 0 of the flash. If the result is 0, then execution control is transferred to the user code. If the signature is not valid, the auto-baud routine synchronizes with the host via serial port 0. The host should send a "?" (0x3F) as a synchronization character and wait for a response. The host side serial port settings should be 8 data bits, 1 stop bit and no parity. The auto-baud routine measures the bit time of the received synchronization character in terms of its own frequency and programs the baud rate generator of the serial port. It also
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sends an ASCII string ("Synchronized") to the host. In response to this the host should send the same string ("Synchronized"). The auto-baud routine looks at the received characters to verify synchronization. If synchronization is verified then "OK" string is sent to the host. The host should respond by sending the crystal frequency (in kHz) at which the part is running. For example, if the part is running at 10 MHz, the response from the host should be "10000". "OK" string is sent to the host after receiving the crystal frequency. If synchronization is not verified then the auto-baud routine waits again for a synchronization character. For auto-baud to work correctly in case of user invoked ISP, the CCLK frequency should be greater than or equal to 10 MHz. For more details on Reset, PLL and startup/boot code interaction see Section 4-5.1.1 "PLL0 and startup/boot code interaction". Once the crystal frequency is received the part is initialized and the ISP command handler is invoked. For safety reasons an "Unlock" command is required before executing the commands resulting in flash erase/write operations and the "Go" command. The rest of the commands can be executed without the unlock command. The Unlock command is required to be executed once per ISP session. The Unlock command is explained in Section 32-7 "ISP commands" on page 620.
3.2 Communication protocol
All ISP commands should be sent as single ASCII strings. Strings should be terminated with Carriage Return (CR) and/or Line Feed (LF) control characters. Extra and characters are ignored. All ISP responses are sent as terminated ASCII strings. Data is sent and received in UU-encoded format.
3.2.1 ISP command format
"Command Parameter_0 Parameter_1 ... Parameter_n" "Data" (Data only for Write commands).
3.2.2 ISP response format
"Return_CodeResponse_0Response_1 ... Response_n" "Data" (Data only for Read commands).
3.2.3 ISP data format
The data stream is in UU-encoded format. The UU-encode algorithm converts 3 bytes of binary data in to 4 bytes of printable ASCII character set. It is more efficient than Hex format which converts 1 byte of binary data in to 2 bytes of ASCII hex. The sender should send the check-sum after transmitting 20 UU-encoded lines. The length of any UU-encoded line should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes. The receiver should compare it with the check-sum of the received bytes. If the check-sum matches then the receiver should respond with "OK" to continue further transmission. If the check-sum does not match the receiver should respond with "RESEND". In response the sender should retransmit the bytes.
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3.2.4 ISP flow control
A software XON/XOFF flow control scheme is used to prevent data loss due to buffer overrun. When the data arrives rapidly, the ASCII control character DC3 (0x13) is sent to stop the flow of data. Data flow is resumed by sending the ASCII control character DC1 (0x11). The host should also support the same flow control scheme.
3.2.5 ISP command abort
Commands can be aborted by sending the ASCII control character "ESC" (0x1B). This feature is not documented as a command under "ISP Commands" section. Once the escape code is received the ISP command handler waits for a new command.
3.2.6 Interrupts during IAP
The on-chip flash memory is not accessible during erase/write operations. When the user application code starts executing the interrupt vectors from the user flash area are active. The user should either disable interrupts, or ensure that user interrupt vectors are active in RAM and that the interrupt handlers reside in RAM, before making a flash erase/write IAP call. The IAP code does not use or disable interrupts.
3.2.7 RAM used by ISP command handler
ISP commands use on-chip RAM from 0x1000 0118 to 0x1000 01FF. The user could use this area, but the contents may be lost upon reset. Flash programming commands use the top 32 bytes of on-chip RAM. The stack is located at RAM top - 32. The maximum stack usage is 256 bytes and it grows downwards.
3.2.8 RAM used by IAP command handler
Flash programming commands use the top 32 bytes of on-chip RAM. The maximum stack usage in the user allocated stack space is 128 bytes and it grows downwards.
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4. Boot process flowchart
RESET
INITIALIZE
CRP1/2/3 ENABLED?
no
yes
ENABLE DEBUG
WATCHDOG FLAG SET?
yes A
no USER CODE VALID? yes
no CRP3 ENABLED?
yes
EXECUTE INTERNAL USER CODE Enter ISP MODE? (P2.10=LOW) yes
USER CODE VALID? no yes
no
A
RUN AUTO-BAUD
no
AUTO-BAUD SUCCESSFUL?
yes RECEIVE CRYSTAL FREQUENCY 1 RUN ISP COMMAND HANDLER 2
(1) For details on handling the crystal frequency, see Section 32-8.9 "Re-invoke ISP" on page 633 (2) For details on available ISP commands based on the CRP settings see Section 32-6 "Code Read Protection (CRP)"
Fig 136. Boot process flowchart
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5. Sector numbers
Some IAP and ISP commands operate on "sectors" and specify sector numbers. The following table indicate the correspondence between sector numbers and memory addresses for LPC17xx devices containing 32, 64, 128, 256 and 512 kB of flash respectively. IAP and ISP routines are located in the Boot ROM.
Table 568. Sectors in a LPC17xx device Sector Number Sector Size [kB] Start Address End Address 32 kB Part 64 kB Part 128 kB Part 256 kB Part 512 kB Part
0 1 2 3 4 5 6 7 8 9 10 (0x0A) 11 (0x0B) 12 (0x0C) 13 (0x0D) 14 (0X0E) 15 (0x0F) 16 (0x10) 17 (0x11) 18 (0x12) 19 (0x13) 20 (0x14) 21 (0x15) 22 (0x16) 23 (0x17) 24 (0x18) 25 (0x19) 26 (0x1A) 27 (0x1B) 28 (0x1C) 29 (0x1D)
4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 32 32 32 32 32 32 32 32 32 32 32 32 32 32
0X0000 0000 0X0000 1000 0X0000 2000 0X0000 3000 0X0000 4000 0X0000 5000 0X0000 6000 0X0000 7000 0x0000 8000 0x0000 9000 0x0000 A000 0x0000 B000 0x0000 C000 0x0000 D000 0x0000 E000 0x0000 F000 0x0001 0000 0x0001 8000 0x0002 0000 0x0002 8000 0x0003 0000 0x0003 8000 0x0004 0000 0x0004 8000 0x0005 0000 0x0005 8000 0x0006 0000 0x0006 8000 0x0007 0000 0x0007 8000
0X0000 0FFF 0X0000 1FFF 0X0000 2FFF 0X0000 3FFF 0X0000 4FFF 0X0000 5FFF 0X0000 6FFF 0X0000 7FFF 0X0000 8FFF 0X0000 9FFF 0X0000 AFFF 0X0000 BFFF 0X0000 CFFF 0X0000 DFFF 0X0000 EFFF 0X0000 FFFF 0x0001 7FFF 0x0001 FFFF 0x0002 7FFF 0x0002 FFFF 0x0003 7FFF 0x0003 FFFF 0x0004 7FFF 0x0004 FFFF 0x0005 7FFF 0x0005 FFFF 0x0006 7FFF 0x0006 FFFF 0x0007 7FFF 0x0007 FFFF
x x x x x x x x
x x x x x x x x x x x x x x x x
x x x x x x x x x x x x x x x x x x
x x x x x x x x x x x x x x x x x x x x x x
x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x
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6. Code Read Protection (CRP)
Code Read Protection is a mechanism that allows user to enable different levels of security in the system so that access to the on-chip flash and use of the ISP can be restricted. When needed, CRP is invoked by programming a specific pattern in flash location at 0x000002FC. IAP commands are not affected by the code read protection. Important: Any CRP change becomes effective only after the device has gone through a power cycle.
Table 569. Code Read Protection options Name Pattern programmed in 0x000002FC Description
CRP1 0x12345678
Access to chip via the JTAG pins is disabled. This mode allows partial flash update using the following ISP commands and restrictions:
* * * * * *
Write to RAM command can not access RAM below 0x10000200. This is due to use of the RAM by the ISP code, see Section 32-3.2.7. Read Memory command: disabled. Copy RAM to Flash command: cannot write to Sector 0. Go command: disabled. Erase sector(s) command: can erase any individual sector except sector 0 only, or can erase all sectors at once. Compare command: disabled
This mode is useful when CRP is required and flash field updates are needed but all sectors can not be erased. The compare command is disabled, so in the case of partial flash updates the secondary loader should implement a checksum mechanism to verify the integrity of the flash. CRP2 0x87654321 This is similar to CRP1 with the following additions:
* * *
CRP3 0x43218765
Write to RAM command: disabled. Copy RAM to Flash: disabled. Erase command: only allows erase of all sectors.
This is similar to CRP2, but ISP entry by pulling P2.10 LOW is disabled if a valid user code is present in flash sector 0. This mode effectively disables ISP override using the P2.10 pin. It is up to the user's application to provide for flash updates by using IAP calls or by invoking ISP with UART0.
Caution: If CRP3 is selected, no future factory testing can be performed on the device.
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Table 570. Code Read Protection hardware/software interaction CRP option User Code Valid P2.10 pin at reset JTAG enabled LPC17xx enters ISP mode partial flash update in ISP mode
None
No Yes Yes
X High Low x High Low x High Low x x
Yes Yes Yes No No No No No No No No
Yes No Yes Yes No Yes Yes No Yes Yes No
Yes NA Yes Yes NA Yes No NA No No NA
CRP1
No Yes Yes
CRP2
No Yes Yes
CRP3
No Yes
If any CRP mode is enabled and access to the chip is allowed via the ISP, an unsupported or restricted ISP command will be terminated with return code CODE_READ_PROTECTION_ENABLED.
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7. ISP commands
The following commands are accepted by the ISP command handler. Detailed status codes are supported for each command. The command handler sends the return code INVALID_COMMAND when an undefined command is received. Commands and return codes are in ASCII format. CMD_SUCCESS is sent by ISP command handler only when received ISP command has been completely executed and the new ISP command can be given by the host. Exceptions from this rule are "Set Baud Rate", "Write to RAM", "Read Memory", and "Go" commands.
Table 571. ISP command summary ISP Command Usage Described in
Unlock Set Baud Rate Echo Write to RAM Read Memory Prepare sector(s) for write operation Copy RAM to Flash Go Erase sector(s) Blank check sector(s) Read Part ID Read serial number Compare
U B A W R

P C G

E I J N M
Table 32-572 Table 32-573 Table 32-575 Table 32-576 Table 32-577 Table 32-578 Table 32-579 Table 32-580 Table 32-581 Table 32-582 Table 32-583 Table 32-585 Table 32-586 Table 32-587
Read Boot Code version K
7.1 Unlock
Table 572. ISP Unlock command Command U
Input Return Code
Unlock code: 2313010 CMD_SUCCESS | INVALID_CODE | PARAM_ERROR
Description Example
This command is used to unlock Flash Write, Erase, and Go commands. "U 23130" unlocks the Flash Write/Erase & Go commands.
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7.2 Set Baud Rate
Table 573. ISP Set Baud Rate command Command B
Input Return Code
Baud Rate: 9600 | 19200 | 38400 | 57600 | 115200 | 230400 Stop bit: 1 | 2 CMD_SUCCESS | INVALID_BAUD_RATE | INVALID_STOP_BIT | PARAM_ERROR
Description Example
This command is used to change the baud rate. The new baud rate is effective after the command handler sends the CMD_SUCCESS return code. "B 57600 1" sets the serial port to baud rate 57600 bps and 1 stop bit.
Table 574. Correlation between possible ISP baudrates and CCLK frequency (in MHz) ISP Baudrate .vs. CCLK Frequency 9600 19200 38400 57600 115200 230400
10.0000 11.0592 12.2880 14.7456[1] 15.3600 18.4320 19.6608 24.5760 25.0000
[1]
+ + + + + + + + +
+ + + + + + + +
+ + + + + + + + + + +
ISP entry after reset uses the on chip IRC and PLL to run the device at CCLK = 14.748 MHz
7.3 Echo
Table 575. ISP Echo command Command A
Input Return Code Description Example
Setting: ON = 1 | OFF = 0 CMD_SUCCESS | PARAM_ERROR The default setting for echo command is ON. When ON the ISP command handler sends the received serial data back to the host. "A 0" turns echo off.
7.4 Write to RAM
The host should send the data only after receiving the CMD_SUCCESS return code. The host should send the check-sum after transmitting 20 UU-encoded lines. The checksum is generated by adding raw data (before UU-encoding) bytes and is reset after transmitting 20 UU-encoded lines. The length of any UU-encoded line should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes. When the data fits in less then 20 UU-encoded lines then the check-sum should be of the actual number of bytes sent.
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The ISP command handler compares it with the check-sum of the received bytes. If the check-sum matches, the ISP command handler responds with "OK" to continue further transmission. If the check-sum does not match, the ISP command handler responds with "RESEND". In response the host should retransmit the bytes.
Table 576. ISP Write to RAM command Command W Start Address: RAM address where data bytes are to be written. This address should be a word boundary. Number of Bytes: Number of bytes to be written. Count should be a multiple of 4
Input
Return Code
CMD_SUCCESS | ADDR_ERROR (Address not on word boundary) | ADDR_NOT_MAPPED | COUNT_ERROR (Byte count is not multiple of 4) | PARAM_ERROR | CODE_READ_PROTECTION_ENABLED
Description
This command is used to download data to RAM. Data should be in UU-encoded format. This command is blocked when code read protection levels CRP2 or CRP3 are enabled. "W 268435968 4" writes 4 bytes of data to address 0x1000 0200.
Example
7.5 Read Memory

The data stream is followed by the command success return code. The check-sum is sent after transmitting 20 UU-encoded lines. The checksum is generated by adding raw data (before UU-encoding) bytes and is reset after transmitting 20 UU-encoded lines. The length of any UU-encoded line should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes. When the data fits in less then 20 UU-encoded lines then the check-sum is of actual number of bytes sent. The host should compare it with the checksum of the received bytes. If the check-sum matches then the host should respond with "OK" to continue further transmission. If the check-sum does not match then the host should respond with "RESEND". In response the ISP command handler sends the data again.
Table 577. ISP Read Memory command Command R Start Address: Address from where data bytes are to be read. This address should be a word boundary. Number of Bytes: Number of bytes to be read. Count should be a multiple of 4.
Input
Return Code
CMD_SUCCESS followed by | ADDR_ERROR (Address not on word boundary) | ADDR_NOT_MAPPED | COUNT_ERROR (Byte count is not a multiple of 4) | PARAM_ERROR | CODE_READ_PROTECTION_ENABLED
Description Example
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This command is used to read data from RAM or flash memory. This command is blocked when any level of code read protection is enabled. "R 268435968 4" reads 4 bytes of data from address 0x1000 0200.
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7.6 Prepare sector(s) for write operation
This command makes flash write/erase operation a two step process.
Table 578. ISP Prepare sector(s) for write operation command Command P Start Sector Number End Sector Number: Should be greater than or equal to start sector number.
Input Return Code
CMD_SUCCESS | BUSY | INVALID_SECTOR | PARAM_ERROR
Description
This command must be executed before executing "Copy RAM to Flash" or "Erase Sector(s)" command. Successful execution of the "Copy RAM to Flash" or "Erase Sector(s)" command causes relevant sectors to be protected again. To prepare a single sector use the same "Start" and "End" sector numbers. "P 0 0" prepares the flash sector 0.
Example
7.7 Copy RAM to Flash
Table 579. ISP Copy command Command C Flash Address(DST): Destination flash address where data bytes are to be written. The destination address should be a 256 byte boundary. RAM Address(SRC): Source RAM address from where data bytes are to be read. Number of Bytes: Number of bytes to be written. Should be 256 | 512 | 1024 | 4096.
Input
Return Code CMD_SUCCESS | SRC_ADDR_ERROR (Address not on word boundary) | DST_ADDR_ERROR (Address not on correct boundary) | SRC_ADDR_NOT_MAPPED | DST_ADDR_NOT_MAPPED | COUNT_ERROR (Byte count is not 256 | 512 | 1024 | 4096) | SECTOR_NOT_PREPARED_FOR WRITE_OPERATION | BUSY | CMD_LOCKED | PARAM_ERROR | CODE_READ_PROTECTION_ENABLED Description This command is used to program the flash memory. The "Prepare Sector(s) for Write Operation" command should precede this command. The affected sectors are automatically protected again once the copy command is successfully executed. This command is blocked when code read protection levels CRP2 or CRP3 are enabled. When code read protection level CRP1 is enabled, individual sectors other than sector 0 can be written. "C 0 268468224 512" copies 512 bytes from the RAM address 0x1000 8000 to the flash address 0.
Example
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Chapter 32: LPC17xx Flash memory interface and programming
7.8 Go

Table 580. ISP Go command Command G Address: Flash or RAM address from which the code execution is to be started. This address should be on a word boundary. Mode (retained for backward compatibility): T (Execute program in Thumb Mode) | A (not allowed).
Input
Return Code CMD_SUCCESS | ADDR_ERROR | ADDR_NOT_MAPPED | CMD_LOCKED | PARAM_ERROR | CODE_READ_PROTECTION_ENABLED Description This command is used to execute a program residing in RAM or flash memory. It may not be possible to return to the ISP command handler once this command is successfully executed. This command is blocked when any level of code read protection is enabled. "G 0 T" branches to address 0x0000 0000.
Example
When the GO command is used, execution begins at the specified address (assuming it is an executable address) with the device left as it was configured for the ISP code. This means that some things are different than they would be for entering user code directly following a chip reset. Most importantly, the main PLL will be running and connected, configured to generate a CPU clock with a frequency of approximately 14.7456 MHz.
7.9 Erase sector(s)
Table 581. ISP Erase sector command Command E Start Sector Number End Sector Number: Should be greater than or equal to start sector number.
Input
Return Code CMD_SUCCESS | BUSY | INVALID_SECTOR | SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION | CMD_LOCKED | PARAM_ERROR | CODE_READ_PROTECTION_ENABLED Description This command is used to erase one or more sector(s) of on-chip flash memory. This command is blocked when code read protection level CRP3 is enabled. When code read protection level CRP1 is enabled, individual sectors other than sector 0 can be erased. All sectors can be erased at once in CRP1 and CRP2. "E 2 3" erases the flash sectors 2 and 3.
Example
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7.10 Blank check sector(s)
Table 582. ISP Blank check sector command Command I Start Sector Number: End Sector Number: Should be greater than or equal to start sector number.
Input
Return Code CMD_SUCCESS | SECTOR_NOT_BLANK (followed by ) | INVALID_SECTOR | PARAM_ERROR | Description Example This command is used to blank check one or more sectors of on-chip flash memory. "I 2 3" blank checks the flash sectors 2 and 3.
7.11 Read Part Identification number
Table 583. ISP Read Part Identification command Command J
Input
None.
Return Code CMD_SUCCESS followed by part identification number in ASCII (see Table 32-584 "LPC17xx part identification numbers"). Description This command is used to read the part identification number. The part identification number maps to a feature subset within a device family. This number will not normally change as a result of technical revisions.
Table 584. LPC17xx part identification numbers Device ASCII/dec coding Hex coding
LPC1769 LPC1768 LPC1767 LPC1766 LPC1765 LPC1764 LPC1759 LPC1758 LPC1756 LPC1754 LPC1752 LPC1751
638664503 637615927 637610039 637615923 637613875 637606178 621885239 620838711 620828451 620828450 620761377 620761368
0x2611 3F37 0x2601 3F37 0x2601 2837 0x2601 3F33 0x2601 3733 0x2601 1922 0x2511 3737 0x2501 3F37 0x2501 1723 0x2501 1722 0x2500 1121 0x2500 1118
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7.12 Read Boot Code version number
Table 585. ISP Read Boot Code version number command Command K
Input
None
Return Code CMD_SUCCESS followed by 2 bytes of boot code version number in ASCII format. It is to be interpreted as .. Description This command is used to read the boot code version number.
7.13 Read device serial number
Table 586. ISP Read device serial number command Command N
Input
None.
Return Code CMD_SUCCESS followed by the device serial number in 4 decimal ASCII groups, each representing a 32-bit value. Description This command is used to read the device serial number. The serial number may be used to uniquely identify a single unit among all LPC17xx devices.
7.14 Compare
Table 587. ISP Compare command Command M Address1 (DST): Starting flash or RAM address of data bytes to be compared. This address should be a word boundary. Address2 (SRC): Starting flash or RAM address of data bytes to be compared. This address should be a word boundary. Number of Bytes: Number of bytes to be compared; should be a multiple of 4.
Input
Return Code CMD_SUCCESS | (Source and destination data are equal) COMPARE_ERROR | (Followed by the offset of first mismatch) COUNT_ERROR (Byte count is not a multiple of 4) | ADDR_ERROR | ADDR_NOT_MAPPED | PARAM_ERROR | Description Example This command is used to compare the memory contents at two locations. This command is blocked when any level of code read protection is enabled. "M 8192 268435968 4" compares 4 bytes from the RAM address 0x1000 0200 to the 4 bytes from the flash address 0x2000.
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7.15 ISP Return Codes
Table 588. ISP Return Codes Summary Return Mnemonic Code Description
0
CMD_SUCCESS
Command is executed successfully. Sent by ISP handler only when command given by the host has been completely and successfully executed. Invalid command. Source address is not on word boundary. Destination address is not on a correct boundary. Source address is not mapped in the memory map. Count value is taken into consideration where applicable. Destination address is not mapped in the memory map. Count value is taken into consideration where applicable. Byte count is not multiple of 4 or is not a permitted value. Sector number is invalid or end sector number is greater than start sector number. Sector is not blank.
1 2 3 4
INVALID_COMMAND SRC_ADDR_ERROR DST_ADDR_ERROR SRC_ADDR_NOT_MAPPED
5
DST_ADDR_NOT_MAPPED
6 7 8 9 10 11 12 13 14 15 16 17 18 19
COUNT_ERROR INVALID_SECTOR SECTOR_NOT_BLANK
SECTOR_NOT_PREPARED_FOR_ Command to prepare sector for write operation WRITE_OPERATION was not executed. COMPARE_ERROR BUSY PARAM_ERROR ADDR_ERROR ADDR_NOT_MAPPED CMD_LOCKED INVALID_CODE INVALID_BAUD_RATE INVALID_STOP_BIT CODE_READ_PROTECTION_ ENABLED Source and destination data not equal. Flash programming hardware interface is busy. Insufficient number of parameters or invalid parameter. Address is not on word boundary. Address is not mapped in the memory map. Count value is taken in to consideration where applicable. Command is locked. Unlock code is invalid. Invalid baud rate setting. Invalid stop bit setting. Code read protection enabled.
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8. IAP commands
For in application programming the IAP routine should be called with a word pointer in register r0 pointing to memory (RAM) containing command code and parameters. Result of the IAP command is returned in the result table pointed to by register r1. The user can reuse the command table for result by passing the same pointer in registers r0 and r1. The parameter table should be big enough to hold all the results in case if number of results are more than number of parameters. Parameter passing is illustrated in the Figure 32-137. The number of parameters and results vary according to the IAP command. The maximum number of parameters is 5, passed to the "Copy RAM to Flash" command. The maximum number of results is 4, returned by the "Read device serial number" command. The command handler sends the status code INVALID_COMMAND when an undefined command is received. The IAP routine resides at location 0x1FFF 1FF0. The IAP function could be called in the following way using C. Define the IAP location entry point. Bit 0 of the IAP location is set since the Cortex-M3 uses only Thumb mode. #define IAP_LOCATION 0x1FFF1FF1 Define data structure or pointers to pass IAP command table and result table to the IAP function: unsigned long command[5]; unsigned long result[5]; or unsigned long * command; unsigned long * result; command=(unsigned long *) 0x...... result= (unsigned long *) 0x...... Define pointer to function type, which takes two parameters and returns void. Note the IAP returns the result with the base address of the table residing in R1. typedef void (*IAP)(unsigned int [],unsigned int[]); IAP iap_entry; Setting function pointer: iap_entry=(IAP) IAP_LOCATION; Whenever you wish to call IAP you could use the following statement. iap_entry (command, result); The IAP call could be simplified further by using the symbol definition file feature supported by ARM Linker in ADS (ARM Developer Suite). You could also call the IAP routine using assembly code.
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As per the ARM specification (The ARM Thumb Procedure Call Standard SWS ESPC 0002 A-05) up to 4 parameters can be passed in the r0, r1, r2 and r3 registers respectively. Additional parameters are passed on the stack. Up to 4 parameters can be returned in the r0, r1, r2 and r3 registers respectively. Additional parameters are returned indirectly via memory. Some of the IAP calls require more than 4 parameters. If the ARM suggested scheme is used for the parameter passing/returning then it might create problems due to difference in the C compiler implementation from different vendors. The suggested parameter passing scheme reduces such risk. The flash memory is not accessible during a write or erase operation. IAP commands, which results in a flash write/erase operation, use 32 bytes of space in the top portion of the on-chip RAM for execution. The user program should not be use this space if IAP flash programming is permitted in the application.
Table 589. IAP Command Summary IAP Command Command Code Described in
Prepare sector(s) for write operation Copy RAM to Flash Erase sector(s) Blank check sector(s) Read part ID Read Boot Code version Read device serial number Compare Reinvoke ISP
5010 5110 5210 5310 5410 5510 5810 5610 5710
Table 32-590 Table 32-591 Table 32-592 Table 32-593 Table 32-594 Table 32-595 Table 32-596 Table 32-597 Table 32-598
COMMAND CODE PARAMETER 1 PARAMETER 2 ARM REGISTER r0 command parameter table
PARAMETER n ARM REGISTER r1
STATUS CODE RESULT 1 RESULT 2 command result table
RESULT n
Fig 137. IAP parameter passing
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8.1 Prepare sector(s) for write operation
This command makes flash write/erase operation a two step process.
Table 590. IAP Prepare sector(s) for write operation command Command Prepare sector(s) for write operation Command code: 5010 Param0: Start Sector Number Param1: End Sector Number (should be greater than or equal to start sector number).
Input
Return Code
CMD_SUCCESS | BUSY | INVALID_SECTOR
Result Description
None This command must be executed before executing "Copy RAM to Flash" or "Erase Sector(s)" command. Successful execution of the "Copy RAM to Flash" or "Erase Sector(s)" command causes relevant sectors to be protected again. To prepare a single sector use the same "Start" and "End" sector numbers.
8.2 Copy RAM to Flash
Table 591. IAP Copy RAM to Flash command Command Copy RAM to Flash Command code: 5110 Param0(DST): Destination flash address where data bytes are to be written. This address should be a 256 byte boundary. Param1(SRC): Source RAM address from which data bytes are to be read. This address should be a word boundary. Param2: Number of bytes to be written. Should be 256 | 512 | 1024 | 4096. Param3: CPU Clock Frequency (CCLK) in kHz.
Input
Return Code
CMD_SUCCESS | SRC_ADDR_ERROR (Address not a word boundary) | DST_ADDR_ERROR (Address not on correct boundary) | SRC_ADDR_NOT_MAPPED | DST_ADDR_NOT_MAPPED | COUNT_ERROR (Byte count is not 256 | 512 | 1024 | 4096) | SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION | BUSY |
Result Description
None This command is used to program the flash memory. The affected sectors should be prepared first by calling "Prepare Sector for Write Operation" command. The affected sectors are automatically protected again once the copy command is successfully executed.
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8.3 Erase Sector(s)
Table 592. IAP Erase Sector(s) command Command Erase Sector(s) Command code: 5210 Param0: Start Sector Number Param1: End Sector Number (should be greater than or equal to start sector number). Param2: CPU Clock Frequency (CCLK) in kHz.
Input
Return Code
CMD_SUCCESS | BUSY | SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION | INVALID_SECTOR
Result Description
None This command is used to erase a sector or multiple sectors of on-chip flash memory. To erase a single sector use the same "Start" and "End" sector numbers.
8.4 Blank check sector(s)
Table 593. IAP Blank check sector(s) command Command Blank check sector(s) Command code: 5310 Param0: Start Sector Number Param1: End Sector Number (should be greater than or equal to start sector number).
Input
Return Code
CMD_SUCCESS | BUSY | SECTOR_NOT_BLANK | INVALID_SECTOR
Result
Result0: Offset of the first non blank word location if the Status Code is SECTOR_NOT_BLANK. Result1: Contents of non blank word location.
Description
This command is used to blank check a sector or multiple sectors of on-chip flash memory. To blank check a single sector use the same "Start" and "End" sector numbers.
8.5 Read part identification number
Table 594. IAP Read part identification number command Command Read part identification number Command code: 5410 Parameters: None
Input Return Code Result Description
CMD_SUCCESS |
Result0: Part Identification Number.
This command is used to read the part identification number. The value returned is the hexadecimal version of the part ID. See Table 32-584 "LPC17xx part identification numbers".
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8.6 Read Boot Code version number
Table 595. IAP Read Boot Code version number command Command Read boot code version number Command code: 5510 Parameters: None
Input Return Code Result Description
CMD_SUCCESS |
Result0: 2 bytes of boot code version number in ASCII format. It is to be interpreted as .
This command is used to read the boot code version number.
8.7 Read device serial number
Table 596. IAP Read device serial number command Command Read device serial number Command code: 5810 Parameters: None
Input Return Code Result
CMD_SUCCESS |
Result0: First 32-bit word of Device Identification Number (at the lowest address) Result1: Second 32-bit word of Device Identification Number Result2: Third 32-bit word of Device Identification Number Result3: Fourth 32-bit word of Device Identification Number
Description
This command is used to read the device identification number. The serial number may be used to uniquely identify a single unit among all LPC17xx devices.
8.8 Compare
Table 597. IAP Compare command Command Compare Command code: 5610 Param0(DST): Starting flash or RAM address of data bytes to be compared. This address should be a word boundary. Param1(SRC): Starting flash or RAM address of data bytes to be compared. This address should be a word boundary. Param2: Number of bytes to be compared; should be a multiple of 4.
Input
Return Code
CMD_SUCCESS | COMPARE_ERROR | COUNT_ERROR (Byte count is not a multiple of 4) | ADDR_ERROR | ADDR_NOT_MAPPED
Result Description
Result0: Offset of the first mismatch if the Status Code is COMPARE_ERROR.
This command is used to compare the memory contents at two locations.
The result may not be correct when the source or destination includes any of the first 64 bytes starting from address zero. The first 64 bytes can be re-mapped to RAM.
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8.9 Re-invoke ISP
Table 598. Re-invoke ISP Command Compare Command code: 5710
Input Return Code Result Description
None
None.
This command is used to invoke the boot loader in ISP mode. It maps boot vectors, sets PCLK = CCLK / 4, configures UART0 pins Rx and Tx, resets TIMER1 and resets the U0FDR (see Section 14-4.12). This command may be used when a valid user program is present in the internal flash memory and the P2.10 pin is not accessible to force the ISP mode. The command does not disable the PLL hence it is possible to invoke the boot loader when the part is running off the PLL. In such case the ISP utility should pass the CCLK (crystal or PLL output depending on the clock source selection Section 4-4.1) frequency after auto-baud handshake. Another option is to disable the PLL and select the IRC as the clock source before making this IAP call. In this case frequency sent by ISP is ignored and IRC and PLL are used to generate CCLK = 14.748 MHz.
8.10 IAP Status Codes
Table 599. IAP Status Codes Summary Status Mnemonic Code Description
0 1 2 3 4
CMD_SUCCESS INVALID_COMMAND SRC_ADDR_ERROR DST_ADDR_ERROR SRC_ADDR_NOT_MAPPED
Command is executed successfully. Invalid command. Source address is not on a word boundary. Destination address is not on a correct boundary. Source address is not mapped in the memory map. Count value is taken in to consideration where applicable. Destination address is not mapped in the memory map. Count value is taken in to consideration where applicable. Byte count is not multiple of 4 or is not a permitted value. Sector number is invalid. Sector is not blank. Command to prepare sector for write operation was not executed. Source and destination data is not same. Flash programming hardware interface is busy.
5
DST_ADDR_NOT_MAPPED
6 7 8 9 10 11
COUNT_ERROR INVALID_SECTOR SECTOR_NOT_BLANK SECTOR_NOT_PREPARED_ FOR_WRITE_OPERATION COMPARE_ERROR BUSY
9. JTAG flash programming interface
Debug tools can write parts of the flash image to the RAM and then execute the IAP call "Copy RAM to Flash" repeatedly with proper offset.
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Chapter 32: LPC17xx Flash memory interface and programming
10. Flash signature generation
The flash module contains a built-in signature generator. This generator can produce a 128-bit signature from a range of flash memory. A typical usage is to verify the flashed contents against a calculated signature (e.g. during programming). The address range for generating a signature must be aligned on flash-word boundaries, i.e. 128-bit boundaries. Once started, signature generation completes independently. While signature generation is in progress, the flash memory cannot be accessed for other purposes, and an attempted read will cause a wait state to be asserted until signature generation is complete. Code outside of the flash (e.g. internal RAM) can be executed during signature generation. This can include interrupt services, if the interrupt vector table is re-mapped to memory other than the flash memory. The code that initiates signature generation should also be placed outside of the flash memory.
10.1 Register description for signature generation
Table 600. Register overview: FMC (base address 0x2020 0000) Name Description Access Reset Value Address Reference
FMSSTART FMSSTOP FMSW0 FMSW1 FMSW2 FMSW3 FMSTAT FMSTATCLR
Signature start address register Signature stop-address register 128-bit signature Word 0 128-bit signature Word 1 128-bit signature Word 2 128-bit signature Word 3 Signature generation status register Signature generation status clear register
R/W R/W R R R R R W
0 0 0 -
0x4008 4020 0x4008 4024 0x4008 402C 0x4008 4030 0x4008 4034 0x4008 4038 0x4008 4FE0
Table 32-601 Table 32-602 Table 32-603 Table 32-604 Table 32-605 Table 32-606 Section 32-10.1.3
0x4008 4FE8 Section 32-10.1.4
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10.1.1 Signature generation address and control registers
These registers control automatic signature generation. A signature can be generated for any part of the flash memory contents. The address range to be used for generation is defined by writing the start address to the signature start address register (FMSSTART) and the stop address to the signature stop address register (FMSSTOP. The start and stop addresses must be aligned to 128-bit boundaries and can be derived by dividing the byte address by 16. Signature generation is started by setting the SIG_START bit in the FMSSTOP register. Setting the SIG_START bit is typically combined with the signature stop address in a single write. Table 32-601 and Table 32-602 show the bit assignments in the FMSSTART and FMSSTOP registers respectively.
Table 601. Flash Module Signature Start register (FMSSTART - 0x4008 4020) bit description Bit Symbol Description Reset Value
31:17 16:0
START
Reserved, user software should not write ones to reserved bits. The value read from a NA reserved bit is not defined. Signature generation start address (corresponds to AHB byte address bits[20:4]). 0
Table 602. Flash Module Signature Stop register (FMSSTOP - 0x4008 4024) bit description Bit Symbol Value Description Reset Value
31:18 17
SIG_START 0 1
Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. Start control bit for signature generation. Signature generation is stopped Initiate signature generation BIST stop address divided by 16 (corresponds to AHB byte address [20:4]).
NA 0
16:0
STOP
0
10.1.2 Signature generation result registers
The signature generation result registers return the flash signature produced by the embedded signature generator. The 128-bit signature is reflected by the four registers FMSW0, FMSW1, FMSW2 and FMSW3. The generated flash signature can be used to verify the flash memory contents. The generated signature can be compared with an expected signature and thus makes saves time and code space. The method for generating the signature is described in Section 32-10.2. Table 32-606 show bit assignment of the FMSW0 and FMSW1, FMSW2, FMSW3 registers respectively.
Table 603. FMSW0 register bit description (FMSW0, address: 0x2020 002C) Bit Symbol Description Reset Value
31:0
SW0[31:0]
Word 0 of 128-bit signature (bits 31 to 0).
-
Table 604. FMSW1 register bit description (FMSW1, address: 0x2020 0030) Bit Symbol Description Reset Value
31:0
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SW1[63:32]
Word 1 of 128-bit signature (bits 63 to 32).
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Table 605. FMSW2 register bit description (FMSW2, address: 0x2020 0034) Bit Symbol Description Reset Value
31:0
SW2[95:64]
Word 2 of 128-bit signature (bits 95 to 64).
-
Table 606. FMSW3 register bit description (FMSW3, address: 0x2020 0038) Bit Symbol Description Reset Value
31:0
SW3[127:96]
Word 3 of 128-bit signature (bits 127 to 96).
-
10.1.3 Flash Module Status register (FMSTAT - 0x0x4008 4FE0)
The read-only FMSTAT register provides a means of determining when signature generation has completed. Completion of signature generation can be checked by polling the SIG_DONE bit in FMSTAT. SIG_DONE should be cleared via the FMSTATCLR register before starting a signature generation operation, otherwise the status might indicate completion of a previous operation.
Table 607. Flash module Status register (FMSTAT - 0x4008 4FE0) bit description Bit Symbol Description Reset Value
31:2 2 1:0
SIG_DONE -
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. When 1, a previously started signature generation has completed. See FMSTATCLR register description for clearing this flag. 0
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined.
10.1.4 Flash Module Status Clear register (FMSTATCLR - 0x0x4008 4FE8)
The FMSTATCLR register is used to clear the signature generation completion flag.
Table 608. Flash Module Status Clear register (FMSTATCLR - 0x0x4008 4FE8) bit description Bit Symbol Description Reset Value
31:2 2 1:0
SIG_DONE_CLR -
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined. Writing a 1 to this bits clears the signature generation completion flag (SIG_DONE) in the FMSTAT register. 0
Reserved, user software should not write ones to reserved bits. The value read NA from a reserved bit is not defined.
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10.2 Algorithm and procedure for signature generation
Signature generation A signature can be generated for any part of the flash contents. The address range to be used for signature generation is defined by writing the start address to the FMSSTART register, and the stop address to the FMSSTOP register. The signature generation is started by writing a `1' to FMSSTOP.MISR_START. Starting the signature generation is typically combined with defining the stop address, which is done in another field FMSSTOP.FMSSTOP of the same register. The time that the signature generation takes is proportional to the address range for which the signature is generated. Reading of the flash memory for signature generation uses a self-timed read mechanism and does not depend on any configurable timing settings for the flash. A safe estimation for the duration of the signature generation is: Duration = int( (60 / tcy) + 3 ) x (FMSSTOP - FMSSTART + 1) When signature generation is triggered via software, the duration is in AHB clock cycles, and tcy is the time in ns for one AHB clock. The SIG_DONE bit in FMSTAT can be polled by software to determine when signature generation is complete. If signature generation is triggered via JTAG, the duration is in JTAG tck cycles, and tcy is the time in ns for one JTAG clock. Polling the SIG_DONE bit in FMSTAT is not possible in this case. After signature generation, a 128-bit signature can be read from the FMSW0 to FMSW3 registers. The 128-bit signature reflects the corrected data read from the flash. The 128-bit signature reflects flash parity bits and check bit values. Content verification The signature as it is read from the FMSW0 to FMSW3 registers must be equal to the reference signature. The algorithms to derive the reference signature is given in Figure 32-138.
sign = 0 FOR address = FMSTART.FMSTART TO FMSTOP.FMSTOP { FOR i = 0 TO 126 nextSign[i] = f_Q[address][i] XOR sign[i+1] nextSign[127] = f_Q[address][127] XOR sign[0] XOR sign[2] XOR sign[27] XOR sign[29] sign = nextSign } signature128 = sign
Fig 138. Algorithm for generating a 128 bit signature
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Chapter 33: LPC17xx JTAG, Serial Wire Debug, and Trace
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1. Features
* * * *
Supports both standard JTAG and ARM Serial Wire Debug modes. Direct debug access to all memories, registers, and peripherals. No target resources are required for the debugging session. Trace port provides CPU instruction trace capability. Output can be via a 4-bit trace data port, or Serial Wire Viewer. instruction addresses for code patches. Two data comparators that can be used to remap addresses for patches to literal values.
* Eight Breakpoints. Six instruction breakpoints that can also be used to remap
* Four data Watchpoints that can also be used as trace triggers. * Instrumentation Trace Macrocell allows additional software controlled trace.
2. Introduction
Debug and trace functions are integrated into the ARM Cortex-M3. Serial wire debug and trace functions are supported in addition to a standard JTAG debug and parallel trace functions. The ARM Cortex-M3 is configured to support up to eight breakpoints and four watchpoints.
3. Description
Debugging with the LPC17xx defaults to JTAG. Once in the JTAG debug mode, the debug tool can switch to Serial Wire Debug mode. Trace can be done using either a 4-bit parallel interface or the Serial Wire Output. When the Serial Wire Output is used, less data can be traced, but it uses no application related pins. Parallel trace has a greater bandwidth, but uses 5 functional pins that may be needed in the application. Note that the trace function available for the Cortex-M3 is functionally very different than the trace that was available for previous ARM7 based devices, using only 5 pins instead of 10.
4. Pin Description
The tables below indicate the various pin functions related to debug and trace. Some of these functions share pins with other functions which therefore may not be used at the same time. Use of the JTAG port excludes use of Serial Wire Debug and Serial Wire Output. Use of the parallel trace requires 5 pins that may be part of the user application, limiting debug possibilities for those features. Trace using the Serial Wire Output does not have this limitation, but has a limited bandwidth.
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Table 609. JTAG pin description Pin Name Type Description JTAG Test Clock. This pin is the clock for debug logic when in the JTAG debug mode. JTAG Test Mode Select. The TMS pin selects the next state in the TAP state machine. JTAG Test Data In. This is the serial data input for the shift register. JTAG Test Data Output. This is the serial data output from the shift register. Data is shifted out of the device on the negative edge of the TCK signal. JTAG Test Reset. The TRST pin can be used to reset the test logic within the debug logic. JTAG Returned Test Clock. This is an extra signal added to the JTAG port, and is included for backward pin compatibility with LPC23xx series devices that share the same pinout as this device. RTCK is not normally used with the Cortex-M3.
TCK TMS TDI TDO
Input Input Input Output
TRST RTCK
Input Output
For designs based on ARM7TDMI-S processor core, this signal could be used by external JTAG host interface logic to maintain synchronization with targets having a slow or varying clock frequency. For details refer to "Multi-ICE System Design considerations Application Note 72 (ARM DAI 0072A)".
Table 610. Serial Wire Debug pin description Pin Name Type Description Serial Wire Clock. This pin is the clock for debug logic when in the Serial Wire Debug mode. Serial wire debug data input/output. The SWDIO pin is used by an external debug tool to communicate with and control the Cortex-M3 CPU. Serial Wire Output. The SWO pin optionally provides data from the ITM and/or the ETM for an external debug tool to evaluate.
SWDCLK SWDIO
Input Input / Output Output
SWO
Table 611. Parallel Trace pin description Pin Name Type Description Trace Clock. This pin provides the sample clock for trace data on the TRACEDATA pins when tracing is enabled by an external debug tool. Trace Data bits 3 to 0. These pins provide ETM trace data when tracing is enabled by an external debug tool. The debug tool can then interpret the compressed information and make it available to the user.
TRACECLK
Input
TRACEDATA[3:0]
Output
5. Debug Notes
Important: The user should be aware of certain limitations during debugging. The most important is that, due to limitations of the Cortex-M3 integration, the LPC17xx cannot wake up in the usual manner from Deep Sleep and Power-down modes. It is recommended not to use these modes during debug.
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Another issue is that debug mode changes the way in which reduced power modes are handled by the Cortex-M3 CPU. This causes power modes at the device level to be different from normal modes operation. These differences mean that power measurements should not be made while debugging, the results will be higher than during normal operation in an application. During a debugging session, the System Tick Timer and the Repetitive Interrupt Timers are automatically stopped whenever the CPU is stopped. Other peripherals are not affected. If the Repetitive Interrupt Timer is configured such that its PCLK rate is lower than the CPU clock rate, the RIT may not increment predictably during some debug operations, such as single stepping. Debugging is disabled if code read protection is enabled.
6. Debug memory re-mapping
Following chip reset, a portion of the Boot ROM is mapped to address 0 so that it will be automatically executed. The Boot ROM switches the map to point to Flash memory prior to user code being executed. In this way a user normally does not need to know that this re-mapping occurs. However, when a debugger halts CPU execution immediately following reset, the Boot ROM is still mapped to address 0 and can cause confusion. Ideally, the debugger should correct the mapping automatically in this case, so that a user does not need to deal with it.
6.1 Memory Mapping Control register (MEMMAP - 0x400F C040)
The MEMMAP register allows switch the mapping of the bottom of memory, including default reset and interrupt vectors, between the Boot ROM and the bottom of on-chip Flash memory.
Table 612. Memory Mapping Control register (MEMMAP - 0x400F C040) bit description Bit Symbol Value Description Reset value
0
MAP 0 1
Memory map control. Boot mode. A portion of the Boot ROM is mapped to address 0. User mode. The on-chip Flash memory is mapped to address 0. Reserved. The value read from a reserved bit is not defined.
0
31:1
-
NA
7. JTAG TAP Identification
The JTAG TAP controller contains device ID that can be used by debugging software to identify the general type of device. More detailed device information is available through ISP/IAP commands (see Section 32-7 and Section 32-8). For the LPC17xx family, this ID value is 0x4BA0 0477.
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1. ARM Cortex-M3 User Guide: Introduction
The material in this appendix is provided by ARM Limited for inclusion in the User Manuals of devices containing the Cortex-M3 CPU. Minimal changes have been made to reflect implementation options and other distinctions that apply specifically to LPC17xx devices.
1.1 About the processor and core peripherals
The Cortex-M3 processor is a high performance 32-bit processor designed for the microcontroller market. It offers significant benefits to developers, including:
* * * * *
outstanding processing performance combined with fast interrupt handling enhanced system debug with extensive breakpoint and trace capabilities efficient processor core, system and memories ultra-low power consumption with integrated sleep modes platform security, with optional integrated memory protection unit (MPU).
Fig 139. Typical Cortex-M3 implementation
The Cortex-M3 processor is built on a high-performance processor core, with a 3-stage pipeline Harvard architecture, making it ideal for demanding embedded applications. The processor delivers exceptional power efficiency through an efficient instruction set and extensively optimized design, providing high-end processing hardware including single-cycle 32x32 multiplication and dedicated hardware division.
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To facilitate the design of cost-sensitive devices, the Cortex-M3 processor implements tightly-coupled system components that reduce processor area while significantly improving interrupt handling and system debug capabilities. The Cortex-M3 processor implements a version of the Thumb instruction set, ensuring high code density and reduced program memory requirements. The Cortex-M3 instruction set provides the exceptional performance expected of a modern 32-bit architecture, with the high code density of 8-bit and 16-bit microcontrollers. The Cortex-M3 processor closely integrates a configurable nested interrupt controller (NVIC), to deliver industry-leading interrupt performance. The NVIC includes a non-maskable interrupt (NMI), and provides up to 256 interrupt priority levels. The tight integration of the processor core and NVIC provides fast execution of interrupt service routines (ISRs), dramatically reducing the interrupt latency. This is achieved through the hardware stacking of registers, and the ability to suspend load-multiple and store-multiple operations. Interrupt handlers do not require any assembler stubs, removing any code overhead from the ISRs. Tail-chaining optimization also significantly reduces the overhead when switching from one ISR to another. To optimize low-power designs, the NVIC integrates with the sleep modes, that include a deep sleep function that enables the entire device to be rapidly powered down. LPC17xx devices support additional reduced power modes, see Section 4-8 "Power control" for details.
1.1.1 System level interface
The Cortex-M3 processor provides multiple interfaces using AMBA technology to provide high speed, low latency memory accesses. It supports unaligned data accesses and implements atomic bit manipulation that enables faster peripheral controls, system spinlocks and thread-safe Boolean data handling. The Cortex-M3 processor has an optional memory protection unit (MPU) that provides fine grain memory control, enabling applications to implement security privilege levels, separating code, data and stack on a task-by-task basis. Such requirements are becoming critical in many embedded applications such as automotive. The MPU is included in LPC17xx devices.
1.1.2 Integrated configurable debug
The Cortex-M3 processor implements a complete hardware debug solution. This provides high system visibility of the processor and memory through either a traditional JTAG port or a 2-pin Serial Wire Debug (SWD) port that is ideal for microcontrollers and other small package devices. The MCU vendor determines the debug feature configuration and therefore this can differ across different devices and families. For system trace the processor integrates an Instrumentation Trace Macrocell (ITM) alongside data watchpoints and a profiling unit. To enable simple and cost-effective profiling of the system events these generate, a Serial Wire Viewer (SWV) can export a stream of software-generated messages, data trace, and profiling information through a single pin. The optional Embedded Trace Macrocell (ETM) delivers unrivalled instruction trace capture in an area far smaller than traditional trace units, enabling many low cost MCUs to implement full instruction trace for the first time.
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LPC17xx devices support JTAG and Serial Wire Debug, Serial Wire Viewer, and include the Embedded Trace Macrocell. See Section 33-1 for additional information.
1.1.3 Cortex-M3 processor features and benefits summary
* * * * * * * * * *
tight integration of system peripherals reduces area and development costs Thumb instruction set combines high code density with 32-bit performance code-patch ability for ROM system updates power control optimization of system components integrated sleep modes for low power consumption fast code execution permits slower processor clock or increases sleep mode time hardware division and fast multiplier deterministic, high-performance interrupt handling for time-critical applications optional memory protection unit (MPU) for safety-critical applications extensive debug and trace capabilities: - Serial Wire Debug and Serial Wire Trace reduce the number of pins required for debugging and tracing.
1.1.4 Cortex-M3 core peripherals
These are:
* Nested Vectored Interrupt Controller
The Nested Vectored Interrupt Controller (NVIC) is an embedded interrupt controller that supports low latency interrupt processing.
* System control block
The System control block (SCB) is the programmers model interface to the processor. It provides system implementation information and system control, including configuration, control, and reporting of system exceptions.
* System timer
The system timer, SysTick, is a 24-bit count-down timer. Use this as a Real Time Operating System (RTOS) tick timer or as a simple counter.
* Memory protection unit
The Memory protection unit (MPU) improves system reliability by defining the memory attributes for different memory regions. It provides up to eight different regions, and an optional predefined background region.
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2. ARM Cortex-M3 User Guide: Instruction Set
2.1 Instruction set summary
The processor implements a version of the Thumb instruction set. Table 34-613 lists the supported instructions. Note In Table 34-613:
* * * * *
angle brackets, <>, enclose alternative forms of the operand braces, {}, enclose optional operands the Operands column is not exhaustive Op2 is a flexible second operand that can be either a register or a constant most instructions can use an optional condition code suffix.
For more information on the instructions and operands, see the instruction descriptions.
Table 613. Cortex-M3 instructions Mnemonic
ADC, ADCS ADD, ADDS ADD, ADDW ADR AND, ANDS ASR, ASRS B BFC BFI BIC, BICS BKPT BL BLX BX CBNZ CBZ CLREX CLZ CMN, CMNS CMP, CMPS CPSID CPSIE DMB DSB EOR, EORS
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Operands
{Rd,} Rn, Op2 {Rd,} Rn, Op2 {Rd,} Rn, #imm12 Rd, label {Rd,} Rn, Op2 Rd, Rm, label Rd, #lsb, #width Rd, Rn, #lsb, #width {Rd,} Rn, Op2 #imm label Rm Rm Rn, label Rn, label
Brief description
Flags
Page
Add with Carry Add Add Load PC-relative address Logical AND Arithmetic Shift Right Branch Bit Field Clear Bit Field Insert Bit Clear Breakpoint Branch with Link Branch indirect with Link Branch indirect Compare and Branch if Non Zero Compare and Branch if Zero Clear Exclusive Count leading zeros Compare Negative Compare Change Processor State, Disable Interrupts Change Processor State, Enable Interrupts Data Memory Barrier Data Synchronization Barrier Exclusive OR
N,Z,C,V N,Z,C,V N,Z,C,V N,Z,C N,Z,C N,Z,C N,Z,C,V N,Z,C,V N,Z,C
Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.4.1 Section 34-2.5.2 Section 34-2.5.3 Section 34-2.9.1 Section 34-2.8.1 Section 34-2.8.1 Section 34-2.5.2 Section 34-2.10.1 Section 34-2.9.1 Section 34-2.9.1 Section 34-2.9.1 Section 34-2.9.2 Section 34-2.9.2 Section 34-2.4.9 Section 34-2.5.4 Section 34-2.5.5 Section 34-2.5.5 Section 34-2.10.2 Section 34-2.10.2 Section 34-2.10.3 Section 34-2.10.4 Section 34-2.5.2
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Rd, Rm Rn, Op2 Rn, Op2 iflags iflags {Rd,} Rn, Op2
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Table 613. Cortex-M3 instructions ...continued Mnemonic
ISB IT LDM LDMDB, LDMEA LDMFD, LDMIA LDR LDRB, LDRBT LDRD LDREX LDREXB LDREXH LDRH, LDRHT LDRSB, LDRSBT LDRSH, LDRSHT LDRT LSL, LSLS LSR, LSRS MLA MLS MOV, MOVS MOVT MOVW, MOV MRS MSR MUL, MULS MVN, MVNS NOP ORN, ORNS ORR, ORRS POP PUSH RBIT REV REV16 REVSH ROR, RORS RRX, RRXS RSB, RSBS SBC, SBCS SBFX
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Operands
-
Brief description
Flags
Page
Instruction Synchronization Barrier If-Then condition block Load Multiple registers, increment after Load Multiple registers, decrement before Load Multiple registers, increment after Load Register with word Load Register with byte Load Register Exclusive Load Register Exclusive with byte Load Register Exclusive with halfword Load Register with halfword Load Register with signed byte Load Register with signed halfword Load Register with word Logical Shift Left Logical Shift Right Multiply with Accumulate, 32-bit result Multiply and Subtract, 32-bit result Move Move Top Move 16-bit constant Move from special register to general register Move from general register to special register Multiply, 32-bit result Move NOT No Operation Logical OR NOT Logical OR Pop registers from stack Push registers onto stack Reverse Bits Reverse byte order in a word Reverse byte order in each halfword Reverse byte order in bottom halfword and sign extend Rotate Right Rotate Right with Extend Reverse Subtract Subtract with Carry Signed Bit Field Extract
N,Z,C N,Z,C N,Z,C N,Z,C N,Z,C,V N,Z N,Z,C N,Z,C N,Z,C N,Z,C N,Z,C N,Z,C,V N,Z,C,V -
Section 34-2.10.5 Section 34-2.9.3 Section 34-2.4.6 Section 34-2.4.6 Section 34-2.4.6 Section 34-2.4 Section 34-2.4 Section 34-2.4.2 Section 34-2.4.8 Section 34-2.4.8 Section 34-2.4.8 Section 34-2.4 Section 34-2.4 Section 34-2.4 Section 34-2.4 Section 34-2.5.3 Section 34-2.5.3 Section 34-2.6.1 Section 34-2.6.1 Section 34-2.5.6 Section 34-2.5.7 Section 34-2.5.6 Section 34-2.10.6 Section 34-2.10.7 Section 34-2.6.1 Section 34-2.5.6 Section 34-2.10.8 Section 34-2.5.2 Section 34-2.5.2 Section 34-2.4.7 Section 34-2.4.7 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.3 Section 34-2.5.3 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.8.2
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Rn{!}, reglist Rn{!}, reglist Rn{!}, reglist Rt, [Rn, #offset] Rt, [Rn, #offset]
Rt, Rt2, [Rn, #offset] Load Register with two bytes Rt, [Rn, #offset] Rt, [Rn] Rt, [Rn] Rt, [Rn, #offset] Rt, [Rn, #offset] Rt, [Rn, #offset] Rt, [Rn, #offset] Rd, Rm, Rd, Rm, Rd, Rn, Rm, Ra Rd, Rn, Rm, Ra Rd, Op2 Rd, #imm16 Rd, #imm16 Rd, spec_reg spec_reg, Rm {Rd,} Rn, Rm Rd, Op2
{Rd,} Rn, Op2 {Rd,} Rn, Op2 reglist reglist Rd, Rn Rd, Rn Rd, Rn Rd, Rn Rd, Rm, Rd, Rm {Rd,} Rn, Op2 {Rd,} Rn, Op2 Rd, Rn, #lsb, #width
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Table 613. Cortex-M3 instructions ...continued Mnemonic
SDIV SEV SMLAL SMULL SSAT STM STMDB, STMEA STMFD, STMIA STR STRB, STRBT STRD STREX STREXB STREXH STRH, STRHT STRT SUB, SUBS SUB, SUBW SVC SXTB SXTH TBB TBH TEQ TST UBFX UDIV UMLAL UMULL USAT UXTB UXTH WFE WFI
Operands
{Rd,} Rn, Rm
Brief description
Flags
Page
Signed Divide Send Event Signed Multiply with Accumulate (32 x 32 + 64), 64-bit result Signed Multiply (32 x 32), 64-bit result Store Multiple registers, increment after Store Multiple registers, decrement before Store Multiple registers, increment after Store Register word Store Register byte Store Register Exclusive Store Register Exclusive byte Store Register Exclusive halfword Store Register halfword Store Register word Subtract Subtract Supervisor Call Sign extend a byte Sign extend a halfword Table Branch Byte Table Branch Halfword Test Equivalence Test Unsigned Bit Field Extract Unsigned Divide Unsigned Multiply with Accumulate (32 x 32 + 64), 64-bit result Unsigned Multiply (32 x 32), 64-bit result Zero extend a byte Zero extend a halfword Wait For Event Wait For Interrupt
Q N,Z,C,V N,Z,C,V N,Z,C N,Z,C Q -
Section 34-2.6.3 Section 34-2.10.9 Section 34-2.6.2 Section 34-2.6.2 Section 34-2.7.1 Section 34-2.4.6 Section 34-2.4.6 Section 34-2.4.6 Section 34-2.4 Section 34-2.4 Section 34-2.4.2 Section 34-2.4.8 Section 34-2.4.8 Section 34-2.4.8 Section 34-2.4 Section 34-2.4 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.10.1 0 Section 34-2.8.3 Section 34-2.8.3 Section 34-2.9.4 Section 34-2.9.4 Section 34-2.5.9 Section 34-2.5.9 Section 34-2.8.2 Section 34-2.6.3 Section 34-2.6.2 Section 34-2.6.2 Section 34-2.7.1 Section 34-2.8.3 Section 34-2.8.3 Section 34-2.10.1 1 Section 34-2.10.1 2
RdLo, RdHi, Rn, Rm RdLo, RdHi, Rn, Rm
Rd, #n, Rm {,shift #s} Signed Saturate Rn{!}, reglist Rn{!}, reglist Rn{!}, reglist Rt, [Rn, #offset] Rt, [Rn, #offset]
Rt, Rt2, [Rn, #offset] Store Register two words Rd, Rt, [Rn, #offset] Rd, Rt, [Rn] Rd, Rt, [Rn] Rt, [Rn, #offset] Rt, [Rn, #offset] {Rd,} Rn, Op2 {Rd,} Rn, #imm12 #imm {Rd,} Rm {,ROR #n} {Rd,} Rm {,ROR #n} [Rn, Rm] [Rn, Rm, LSL #1] Rn, Op2 Rn, Op2 Rd, Rn, #lsb, #width {Rd,} Rn, Rm RdLo, RdHi, Rn, Rm RdLo, RdHi, Rn, Rm
Rd, #n, Rm {,shift #s} Unsigned Saturate {Rd,} Rm {,ROR #n} {Rd,} Rm {,ROR #n}
-
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2.2 Intrinsic functions
ANSI cannot directly access some Cortex-M3 instructions. This section describes intrinsic functions that can generate these instructions, provided by the CMIS and that might be provided by a C compiler. If a C compiler does not support an appropriate intrinsic function, you might have to use inline assembler to access some instructions. The CMSIS provides the following intrinsic functions to generate instructions that ANSI cannot directly access:
Table 614. CMSIS intrinsic functions to generate some Cortex-M3 instructions Instruction
CPSIE I CPSID I CPSIE F CPSID F ISB DSB DMB REV REV16 REVSH RBIT SEV WFE WFI
CMSIS intrinsic function
void __enable_irq(void) void __disable_irq(void) void __enable_fault_irq(void) void __disable_fault_irq(void) void __ISB(void) void __DSB(void) void __DMB(void) uint32_t __REV(uint32_t int value) uint32_t __REV16(uint32_t int value) uint32_t __REVSH(uint32_t int value) uint32_t __RBIT(uint32_t int value) void __SEV(void) void __WFE(void) void __WFI(void)
The CMSIS also provides a number of functions for accessing the special registers using MRS and MSR instructions:
Table 615. CMSIS intrinsic functions to access the special registers Special register Access CMSIS function
uint32_t __get_PRIMASK (void) void __set_PRIMASK (uint32_t value) uint32_t __get_FAULTMASK (void) void __set_FAULTMASK (uint32_t value) uint32_t __get_BASEPRI (void) void __set_BASEPRI (uint32_t value) uint32_t __get_CONTROL (void) void __set_CONTROL (uint32_t value) uint32_t __get_MSP (void) void __set_MSP (uint32_t TopOfMainStack) uint32_t __get_PSP (void) void __set_PSP (uint32_t TopOfProcStack)
PRIMASK FAULTMASK BASEPRI CONTROL MSP PSP
Read Write Read Write Read Write Read Write Read Write Read Write
2.3 About the instruction descriptions
The following sections give more information about using the instructions:
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* * * * * * * *
Section 34-2.3.1 "Operands" Section 34-2.3.2 "Restrictions when using PC or SP" Section 34-2.3.3 "Flexible second operand" Section 34-2.3.4 "Shift Operations" Section 34-2.3.5 "Address alignment" Section 34-2.3.6 "PC-relative expressions" Section 34-2.3.7 "Conditional execution" Section 34-2.3.8 "Instruction width selection".
2.3.1 Operands
An instruction operand can be an ARM register, a constant, or another instruction-specific parameter. Instructions act on the operands and often store the result in a destination register. When there is a destination register in the instruction, it is usually specified before the operands. Operands in some instructions are flexible in that they can either be a register or a constant. See Section 34-2.3.3.
2.3.2 Restrictions when using PC or SP
Many instructions have restrictions on whether you can use the Program Counter (PC) or Stack Pointer (SP) for the operands or destination register. See instruction descriptions for more information. Remark: Bit[0] of any address you write to the PC with a BX, BLX, LDM, LDR, or POP instruction must be 1 for correct execution, because this bit indicates the required instruction set, and the Cortex-M3 processor only supports Thumb instructions.
2.3.3 Flexible second operand
Many general data processing instructions have a flexible second operand. This is shown as Operand2 in the descriptions of the syntax of each instruction. Operand2 can be a:
* Section 34-2.3.3.1 "Constant" * Section 34-2.3.3.2 "Register with optional shift"
2.3.3.1 Constant You specify an Operand2 constant in the form: #constant where constant can be:
* any constant that can be produced by shifting an 8-bit value left by any number of bits
within a 32-bit word
* any constant of the form 0x00XY00XY * any constant of the form 0xXY00XY00 * any constant of the form 0xXYXYXYXY.
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Remark: In the constants shown above, X and Y are hexadecimal digits. In addition, in a small number of instructions, constant can take a wider range of values. These are described in the individual instruction descriptions. When an Operand2 constant is used with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to bit[31] of the constant, if the constant is greater than 255 and can be produced by shifting an 8-bit value. These instructions do not affect the carry flag if Operand2 is any other constant. Instruction substitution: Your assembler might be able to produce an equivalent instruction in cases where you specify a constant that is not permitted. For example, an assembler might assemble the instruction CMP Rd, #0xFFFFFFFE as the equivalent instruction CMN Rd, #0x2. 2.3.3.2 Register with optional shift You specify an Operand2 register in the form: Rm {, shift} where: Rm is the register holding the data for the second operand. shift is an optional shift to be applied to Rm. It can be one of: ASR#n: arithmetic shift right n bits, 1 n 32. LSL#n: logical shift left n bits, 1 n 31. LSR#n: logical shift right n bits, 1 n 32. ROR#n: rotate right n bits, 1 n 31. RRX: rotate right one bit, with extend. --: if omitted, no shift occurs, equivalent to LSL#0. If you omit the shift, or specify LSL #0, the instruction uses the value in Rm. If you specify a shift, the shift is applied to the value in Rm, and the resulting 32-bit value is used by the instruction. However, the contents in the register Rm remains unchanged. Specifying a register with shift also updates the carry flag when used with certain instructions. For information on the shift operations and how they affect the carry flag, see Section 34-2.3.4 "Shift Operations"
2.3.4 Shift Operations
Register shift operations move the bits in a register left or right by a specified number of bits, the shift length. Register shift can be performed:
* directly by the instructions ASR, LSR, LSL, ROR, and RRX, and the result is written to a
destination register
* during the calculation of Operand2 by the instructions that specify the second
operand as a register with shift, see Section 34-2.3.3. The result is used by the instruction.
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The permitted shift lengths depend on the shift type and the instruction, see the individual instruction description or Section 34-2.3.3. If the shift length is 0, no shift occurs. Register shift operations update the carry flag except when the specified shift length is 0. The following sub-sections describe the various shift operations and how they affect the carry flag. In these descriptions, Rm is the register containing the value to be shifted, and n is the shift length. 2.3.4.1 ASR Arithmetic shift right by n bits moves the left-hand 32-n bits of the register Rm, to the right by n places, into the right-hand 32-n bits of the result. And it copies the original bit[31] of the register into the left-hand n bits of the result. See Figure 34-140. You can use the ASR #n operation to divide the value in the register Rm by 2n, with the result being rounded towards negative-infinity. When the instruction is ASRS or when ASR #n is used in Operand2 with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit shifted out, bit[n-1], of the register Rm.
Note
* If n is 32 or more, then all the bits in the result are set to the value of bit[31] of Rm. * If n is 32 or more and the carry flag is updated, it is updated to the value of bit[31] of
Rm.
Fig 140. ASR #3
2.3.4.2
LSR Logical shift right by n bits moves the left-hand 32-n bits of the register Rm, to the right by n places, into the right-hand 32-n bits of the result. And it sets the left-hand n bits of the result to 0. See Figure 34-141. You can use the LSR #n operation to divide the value in the register Rm by 2n, if the value is regarded as an unsigned integer. When the instruction is LSRS or when LSR #n is used in Operand2 with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit shifted out, bit[n-1], of the register Rm. Note
* If n is 32 or more, then all the bits in the result are cleared to 0.
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* If n is 33 or more and the carry flag is updated, it is updated to 0.
Fig 141. LSR#3
2.3.4.3
LSL Logical shift left by n bits moves the right-hand 32-n bits of the register Rm, to the left by n places, into the left-hand 32-n bits of the result. And it sets the right-hand n bits of the result to 0. See Figure 34-142. You can use he LSL #n operation to multiply the value in the register Rm by 2n, if the value is regarded as an unsigned integer or a two's complement signed integer. Overflow can occur without warning. When the instruction is LSLS or when LSL #n, with non-zero n, is used in Operand2 with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit shifted out, bit[32-n], of the register Rm. These instructions do not affect the carry flag when used with LSL #0. Note
* If n is 32 or more, then all the bits in the result are cleared to 0. * If n is 33 or more and the carry flag is updated, it is updated to 0.
Fig 142. LSL#3
2.3.4.4
ROR Rotate right by n bits moves the left-hand 32-n bits of the register Rm, to the right by n places, into the right-hand 32-n bits of the result. And it moves the right-hand n bits of the register into the left-hand n bits of the result. See Figure 34-143. When the instruction is RORS or when ROR #n is used in Operand2 with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit rotation, bit[n-1], of the register Rm. Note
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* If n is 32, then the value of the result is same as the value in Rm, and if the carry flag
is updated, it is updated to bit[31] of Rm.
* ROR with shift length, n, more than 32 is the same as ROR with shift length n-32.
Fig 143. ROR#3
2.3.4.5
RRX Rotate right with extend moves the bits of the register Rm to the right by one bit. And it copies the carry flag into bit[31] of the result. See Figure 34-144. When the instruction is RRXS or when RRX is used in Operand2 with the instructions MOVS, MVNS, ANDS, ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to bit[0] of the register Rm.
Fig 144. RRX
2.3.5 Address alignment
An aligned access is an operation where a word-aligned address is used for a word, dual word, or multiple word access, or where a halfword-aligned address is used for a halfword access. Byte accesses are always aligned. The Cortex-M3 processor supports unaligned access only for the following instructions:
* * * * *
LDR, LDRT LDRH, LDRHT LDRSH, LDRSHT STR, STRT STRH, STRHT
All other load and store instructions generate a usage fault exception if they perform an unaligned access, and therefore their accesses must be address aligned. For more information about usage faults see Section 34-3.4 "Fault handling".
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Unaligned accesses are usually slower than aligned accesses. In addition, some memory regions might not support unaligned accesses. Therefore, ARM recommends that programmers ensure that accesses are aligned. To avoid accidental generation of unaligned accesses, use the UNALIGN_TRP bit in the Configuration and Control Register to trap all unaligned accesses, see Section 34-4.3.8 "Configuration and Control Register".
2.3.6 PC-relative expressions
A PC-relative expression or label is a symbol that represents the address of an instruction or literal data. It is represented in the instruction as the PC value plus or minus a numeric offset. The assembler calculates the required offset from the label and the address of the current instruction. If the offset is too big, the assembler produces an error. Note
* For B, BL, CBNZ, and CBZ instructions, the value of the PC is the address of the current
instruction plus 4 bytes.
* For all other instructions that use labels, the value of the PC is the address of the
current instruction plus 4 bytes, with bit[1] of the result cleared to 0 to make it word-aligned.
* Your assembler might permit other syntaxes for PC-relative expressions, such as a
label plus or minus a number, or an expression of the form [PC, #number].
2.3.7 Conditional execution
Most data processing instructions can optionally update the condition flags in the Application Program Status Register (APSR) according to the result of the operation, see Section 34-3.1.3.5 "Program Status Register". Some instructions update all flags, and some only update a subset. If a flag is not updated, the original value is preserved. See the instruction descriptions for the flags they affect. You can execute an instruction conditionally, based on the condition flags set in another instruction, either:
* immediately after the instruction that updated the flags * after any number of intervening instructions that have not updated the flags.
Conditional execution is available by using conditional branches or by adding condition code suffixes to instructions. See Table 34-616 for a list of the suffixes to add to instructions to make them conditional instructions. The condition code suffix enables the processor to test a condition based on the flags. If the condition test of a conditional instruction fails, the instruction:
* * * *
does not execute does not write any value to its destination register does not affect any of the flags does not generate any exception.
Conditional instructions, except for conditional branches, must be inside an If-Then instruction block. See Section 34-2.9.3 for more information and restrictions when using the IT instruction. Depending on the vendor, the assembler might automatically insert an IT instruction if you have conditional instructions outside the IT block.
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Use the CBZ and CBNZ instructions to compare the value of a register against zero and branch on the result. This section describes:
* Section 34-2.3.7.1 "The condition flags" * Section 34-2.3.7.2 "Condition code suffixes".
2.3.7.1 The condition flags The APSR contains the following condition flags: N -- Set to 1 when the result of the operation was negative, cleared to 0 otherwise. Z -- Set to 1 when the result of the operation was zero, cleared to 0 otherwise. C -- Set to 1 when the operation resulted in a carry, cleared to 0 otherwise. V -- Set to 1 when the operation caused overflow, cleared to 0 otherwise. For more information about the APSR see Section 34-3.1.3.5 "Program Status Register". A carry occurs:
* if the result of an addition is greater than or equal to 232 * if the result of a subtraction is positive or zero * as the result of an inline barrel shifter operation in a move or logical instruction.
Overflow occurs if the result of an add, subtract, or compare is greater than or equal to 231, or less than -231. Remark: Most instructions update the status flags only if the S suffix is specified. See the instruction descriptions for more information. 2.3.7.2 Condition code suffixes The instructions that can be conditional have an optional condition code, shown in syntax descriptions as {cond}. Conditional execution requires a preceding IT instruction. An instruction with a condition code is only executed if the condition code flags in the APSR meet the specified condition. Table 34-616 shows the condition codes to use. You can use conditional execution with the IT instruction to reduce the number of branch instructions in code. Table 34-616 also shows the relationship between condition code suffixes and the N, Z, C, and V flags.
Table 616. Condition code suffixes Suffix
EQ NE CS or HS CC or LO MI
Flags
Meaning
Z=1 Z=0 C=1 C=0 N=1
Equal Not equal Higher or same, unsigned Lower, unsigned < Negative
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Table 616. Condition code suffixes Suffix
PL VS VC HI LS GE LT GT LE AL
Flags
Meaning
N=0 V=1 V=0 C = 1 and Z = 0 C = 0 or Z = 1 N=V N != V Z = 0 and N = V Z = 1 and N != V Can have any value
Positive or zero Overflow No overflow Higher, unsigned > Lower or same, unsigned Greater than or equal, signed Less than, signed < Greater than, signed > Less than or equal, signed Always. This is the default when no suffix is specified.
Section 34- shows the use of a conditional instruction to find the absolute value of a number. R0 = ABS(R1). Section 34- shows the use of conditional instructions to update the value of R4 if the signed values R0 is greater than R1 and R2 is greater than R3. Example: Absolute value: IT MI RSBMI R0, R1, #0 MOVS R0, R1 ; R0 = R1, setting flags ; IT instruction for the negative condition ; If negative, R0 = -R1
Example: Compare and update value: CMP R0, R1 ; Compare R0 and R1, setting flags ITT GT ; IT instruction for the two GT conditions CMPGT R2, R3 ; If 'greater than', compare R2 and R3, setting flags MOVGT R4, R5 ; If still 'greater than', do R4 = R5
2.3.8 Instruction width selection
There are many instructions that can generate either a 16-bit encoding or a 32-bit encoding depending on the operands and destination register specified. For some of these instructions, you can force a specific instruction size by using an instruction width suffix. The .W suffix forces a 32-bit instruction encoding. The .N suffix forces a 16-bit instruction encoding. If you specify an instruction width suffix and the assembler cannot generate an instruction encoding of the requested width, it generates an error. Remark: In some cases it might be necessary to specify the .W suffix, for example if the operand is the label of an instruction or literal data, as in the case of branch instructions. This is because the assembler might not automatically generate the right size encoding. To use an instruction width suffix, place it immediately after the instruction mnemonic and condition code, if any. Section 34-2.3.8.1 shows instructions with the instruction width suffix.
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2.3.8.1
Example: Instruction width selection BCS.W label ; creates a 32-bit instruction even for a short branch
ADDS.W R0, R0, R1 ; creates a 32-bit instruction even though the same ; operation can be done by a 16-bit instruction
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2.4 Memory access instructions
Table 34-617 shows the memory access instructions:
Table 617. Memory access instructions Mnemonic
ADR CLREX LDM{mode} LDR{type} LDR{type} LDR{type}T LDR LDREX{type} POP PUSH STM{mode} STR{type} STR{type} STR{type}T STREX{type}
Brief description
See
Load PC-relative address Clear Exclusive Load Multiple registers Load Register using immediate offset Load Register using register offset Load Register with unprivileged access Load Register Exclusive Pop registers from stack Push registers onto stack Store Multiple registers Store Register using immediate offset Store Register using register offset Store Register with unprivileged access Store Register Exclusive
Section 34-2.4.1 Section 34-2.4.9 Section 34-2.4.6 Section 34-2.4.2 Section 34-2.4.3 Section 34-2.4.4 Section 34-2.4.8 Section 34-2.4.7 Section 34-2.4.7 Section 34-2.4.6 Section 34-2.4.2 Section 34-2.4.3 Section 34-2.4.4 Section 34-2.4.8
Load Register using PC-relative address Section 34-2.4.5
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2.4.1 ADR
Load PC-relative address. 2.4.1.1 Syntax ADR{cond} Rd, label where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. label is a PC-relative expression. See Section 34-2.3.6 "PC-relative expressions".
2.4.1.2
Operation ADR determines the address by adding an immediate value to the PC, and writes the result to the destination register. ADR produces position-independent code, because the address is PC-relative. If you use ADR to generate a target address for a BX or BLX instruction, you must ensure that bit[0] of the address you generate is set to1 for correct execution. Values of label must be within the range of -4095 to +4095 from the address in the PC. Remark: You might have to use the .W suffix to get the maximum offset range or to generate addresses that are not word-aligned. See Section 34-2.3.8 "Instruction width selection".
2.4.1.3
Restrictions Rd must not be SP and must not be PC.
2.4.1.4
Condition flags This instruction does not change the flags.
2.4.1.5
Examples ADR R1, TextMessage ; Write address value of a location labelled as ; TextMessage to R1
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2.4.2 LDR and STR, immediate offset
Load and Store with immediate offset, pre-indexed immediate offset, or post-indexed immediate offset. 2.4.2.1 Syntax op{type}{cond} Rt, [Rn {, #offset}] op{type}{cond} Rt, [Rn, #offset]! op{type}{cond} Rt, [Rn], #offset opD{cond} Rt, Rt2, [Rn {, #offset}] opD{cond} Rt, Rt2, [Rn, #offset]! opD{cond} Rt, Rt2, [Rn], #offset where: op is one of: LDR: Load register. STR: Store register. type is one of: B: unsigned byte, zero extend to 32 bits on loads. SB: signed byte, sign extend to 32 bits (LDR only). H: unsigned halfword, zero extend to 32 bits on loads. SH: signed halfword, sign extend to 32 bits (LDR only). --: omit, for word. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rt is the register to load or store. Rn is the register on which the memory address is based. offset is an offset from Rn. If offset is omitted, the address is the contents of Rn. Rt2 is the additional register to load or store for two-word operations. 2.4.2.2 Operation LDR instructions load one or two registers with a value from memory. STR instructions store one or two register values to memory. Load and store instructions with immediate offset can use the following addressing modes: ; immediate offset ; pre-indexed ; post-indexed ; immediate offset, two words ; pre-indexed, two words ; post-indexed, two words
* Offset addressing
The offset value is added to or subtracted from the address obtained from the register Rn. The result is used as the address for the memory access. The register Rn is unaltered. The assembly language syntax for this mode is:
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[Rn, #offset]
* Pre-indexed addressing
The offset value is added to or subtracted from the address obtained from the register Rn. The result is used as the address for the memory access and written back into the register Rn. The assembly language syntax for this mode is: [Rn, #offset]!
* Post-indexed addressing
The address obtained from the register Rn is used as the address for the memory access. The offset value is added to or subtracted from the address, and written back into the register Rn. The assembly language syntax for this mode is: [Rn], #offset The value to load or store can be a byte, halfword, word, or two words. Bytes and halfwords can either be signed or unsigned. See Section 34-2.3.5 "Address alignment". Table 34-618 shows the ranges of offset for immediate, pre-indexed and post-indexed forms.
Table 618. Offset ranges Instruction type Immediate offset Pre-indexed
-255 to 255
Post-indexed
-255 to 255
Word, halfword, signed -255 to 4095 halfword, byte, or signed byte Two words multiple of 4 in the range -1020 to 1020
multiple of 4 in the range -1020 to 1020
multiple of 4 in the range -1020 to 1020
2.4.2.3
Restrictions For load instructions:
* Rt can be SP or PC for word loads only * Rt must be different from Rt2 for two-word loads * Rn must be different from Rt and Rt2 in the pre-indexed or post-indexed forms.
When Rt is PC in a word load instruction:
* bit[0] of the loaded value must be 1 for correct execution * a branch occurs to the address created by changing bit[0] of the loaded value to 0 * if the instruction is conditional, it must be the last instruction in the IT block.
For store instructions:
* * * *
2.4.2.4
Rt can be SP for word stores only Rt must not be PC Rn must not be PC Rn must be different from Rt and Rt2 in the pre-indexed or post-indexed forms.
Condition flags These instructions do not change the flags.
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2.4.2.5
Examples LDR LDRNE ; ; ; ; R2, [R9,#const-struc] ; ; R3, [R4], #4 ; ; R8, R9, [R3, #0x20] ; ; ; R0, R1, [R8], #-16 ; ; ; R8, [R10] R2, [R5, #960]! Loads R8 from the address in R10. Loads (conditionally) R2 from a word 960 bytes above the address in R5, and increments R5 by 960. const-struc is an expression evaluating to a constant in the range 0-4095. Store R3 as halfword data into address in R4, then increment R4 by 4 Load R8 from a word 32 bytes above the address in R3, and load R9 from a word 36 bytes above the address in R3 Store R0 to address in R8, and store R1 to a word 4 bytes above the address in R8, and then decrement R8 by 16.
STR STRH LDRD
STRD
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2.4.3 LDR and STR, register offset
Load and Store with register offset. 2.4.3.1 Syntax op{type}{cond} Rt, [Rn, Rm {, LSL #n}] where: op is one of: LDR: Load Register. STR: Store Register. type is one of: B: unsigned byte, zero extend to 32 bits on loads. SB: signed byte, sign extend to 32 bits (LDR only). H: unsigned halfword, zero extend to 32 bits on loads. SH: signed halfword, sign extend to 32 bits (LDR only). --: omit, for word. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rt is the register to load or store. Rn is the register on which the memory address is based. Rm is a register containing a value to be used as the offset. LSL #n is an optional shift, with n in the range 0 to 3. 2.4.3.2 Operation LDR instructions load a register with a value from memory. STR instructions store a register value into memory. The memory address to load from or store to is at an offset from the register Rn. The offset is specified by the register Rm and can be shifted left by up to 3 bits using LSL. The value to load or store can be a byte, halfword, or word. For load instructions, bytes and halfwords can either be signed or unsigned. See Section 34-2.3.5 "Address alignment". 2.4.3.3 Restrictions In these instructions:
* * * *
Rn must not be PC Rm must not be SP and must not be PC Rt can be SP only for word loads and word stores Rt can be PC only for word loads.
When Rt is PC in a word load instruction:
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* bit[0] of the loaded value must be 1 for correct execution, and a branch occurs to this
halfword-aligned address
* if the instruction is conditional, it must be the last instruction in the IT block.
2.4.3.4 Condition flags These instructions do not change the flags. 2.4.3.5 Examples ; ; LDRSB R0, [R5, R1, LSL #1] ; ; ; STR R0, [R1, R2, LSL #2] ; ; STR R0, [R5, R1] Store value of R0 into an address equal to sum of R5 and R1 Read byte value from an address equal to sum of R5 and two times R1, sign extended it to a word value and put it in R0 Stores R0 to an address equal to sum of R1 and four times R2
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2.4.4 LDR and STR, unprivileged
Load and Store with unprivileged access. 2.4.4.1 Syntax op{type}T{cond} Rt, [Rn {, #offset}] where: op is one of: LDR: Load Register. STR: Store Register. type is one of: B: unsigned byte, zero extend to 32 bits on loads. SB: signed byte, sign extend to 32 bits (LDR only). H: unsigned halfword, zero extend to 32 bits on loads. SH: signed halfword, sign extend to 32 bits (LDR only). --: omit, for word. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rt is the register to load or store. Rn is the register on which the memory address is based. offset is an offset from Rn and can be 0 to 255. If offset is omitted, the address is the value in Rn. 2.4.4.2 Operation These load and store instructions perform the same function as the memory access instructions with immediate offset, see Section 34-2.4.2. The difference is that these instructions have only unprivileged access even when used in privileged software. When used in unprivileged software, these instructions behave in exactly the same way as normal memory access instructions with immediate offset. 2.4.4.3 Restrictions In these instructions: ; immediate offset
* Rn must not be PC * Rt must not be SP and must not be PC.
2.4.4.4 Condition flags These instructions do not change the flags.
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2.4.4.5
Examples STRBTEQ R4, [R7] LDRHT R2, [R2, #8] ; ; ; ; Conditionally store least significant byte in R4 to an address in R7, with unprivileged access Load halfword value from an address equal to sum of R2 and 8 into R2, with unprivileged access
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2.4.5 LDR, PC-relative
Load register from memory. 2.4.5.1 Syntax LDR{type}{cond} Rt, label LDRD{cond} Rt, Rt2, label type is one of: B: unsigned byte, zero extend to 32 bits on loads. SB: signed byte, sign extend to 32 bits (LDR only). H: unsigned halfword, zero extend to 32 bits on loads. SH: signed halfword, sign extend to 32 bits (LDR only). --: omit, for word. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rt is the register to load or store. Rt2 is the second register to load or store. label is a PC-relative expression. See Section 34-2.3.6 "PC-relative expressions". 2.4.5.2 Operation LDR loads a register with a value from a PC-relative memory address. The memory address is specified by a label or by an offset from the PC. The value to load or store can be a byte, halfword, or word. For load instructions, bytes and halfwords can either be signed or unsigned. See Section 34-2.3.5 "Address alignment". label must be within a limited range of the current instruction. Table 34-619 shows the possible offsets between label and the PC.
Table 619. Offset ranges Instruction type Offset range
-4095 to 4095 -1020 to 1020
; Load two words
Word, halfword, signed halfword, byte, signed byte Two words
Remark: You might have to use the .W suffix to get the maximum offset range. See Section 34-2.3.8 "Instruction width selection". 2.4.5.3 Restrictions In these instructions:
* Rt can be SP or PC only for word loads * Rt2 must not be SP and must not be PC * Rt must be different from Rt2.
When Rt is PC in a word load instruction:
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* bit[0] of the loaded value must be 1 for correct execution, and a branch occurs to this
halfword-aligned address
* if the instruction is conditional, it must be the last instruction in the IT block.
2.4.5.4 Condition flags These instructions do not change the flags. 2.4.5.5 Examples LDR LDRSB R0, LookUpTable R7, localdata ; ; ; ; ; Load R0 with a word of data from an address labelled as LookUpTable Load a byte value from an address labelled as localdata, sign extend it to a word value, and put it in R7
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2.4.6 LDM and STM
Load and Store Multiple registers. 2.4.6.1 Syntax op{addr_mode}{cond} Rn{!}, reglist where: op is one of: LDM: Load Multiple registers. STM: Store Multiple registers. addr_mode is any one of the following: IA: Increment address After each access. This is the default. DB: Decrement address Before each access. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rn is the register on which the memory addresses are based. ! is an optional writeback suffix. If ! is present the final address, that is loaded from or stored to, is written back into Rn. reglist is a list of one or more registers to be loaded or stored, enclosed in braces. It can contain register ranges. It must be comma separated if it contains more than one register or register range, see Section 34-2.4.6.5. LDM and LDMFD are synonyms for LDMIA. LDMFD refers to its use for popping data from Full Descending stacks. LDMEA is a synonym for LDMDB, and refers to its use for popping data from Empty Ascending stacks. STM and STMEA are synonyms for STMIA. STMEA refers to its use for pushing data onto Empty Ascending stacks. STMFD is s synonym for STMDB, and refers to its use for pushing data onto Full Descending stacks 2.4.6.2 Operation LDM instructions load the registers in reglist with word values from memory addresses based on Rn. STM instructions store the word values in the registers in reglist to memory addresses based on Rn. For LDM, LDMIA, LDMFD, STM, STMIA, and STMEA the memory addresses used for the accesses are at 4-byte intervals ranging from Rn to Rn + 4 * (n-1), where n is the number of registers in reglist. The accesses happens in order of increasing register numbers, with the lowest numbered register using the lowest memory address and the highest number register using the highest memory address. If the writeback suffix is specified, the value of Rn + 4 * (n-1) is written back to Rn.
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For LDMDB, LDMEA, STMDB, and STMFD the memory addresses used for the accesses are at 4-byte intervals ranging from Rn to Rn - 4 * (n-1), where n is the number of registers in reglist. The accesses happen in order of decreasing register numbers, with the highest numbered register using the highest memory address and the lowest number register using the lowest memory address. If the writeback suffix is specified, the value of Rn - 4 * (n-1) is written back to Rn. The PUSH and POP instructions can be expressed in this form. See Section 34-2.4.7 for details. 2.4.6.3 Restrictions In these instructions:
* * * * *
Rn must not be PC reglist must not contain SP in any STM instruction, reglist must not contain PC in any LDM instruction, reglist must not contain PC if it contains LR reglist must not contain Rn if you specify the writeback suffix.
When PC is in reglist in an LDM instruction:
* bit[0] of the value loaded to the PC must be 1 for correct execution, and a branch
occurs to this halfword-aligned address
* if the instruction is conditional, it must be the last instruction in the IT block.
2.4.6.4 Condition flags These instructions do not change the flags. 2.4.6.5 Examples LDM STMDB 2.4.6.6 R8,{R0,R2,R9} ; LDMIA is a synonym for LDM R1!,{R3-R6,R11,R12}
Incorrect examples STM LDM R5!,{R5,R4,R9} ; Value stored for R5 is unpredictable R2, {} ; There must be at least one register in the list
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2.4.7 PUSH and POP
Push registers onto, and pop registers off a full-descending stack. 2.4.7.1 Syntax PUSH{cond} reglist POP{cond} reglist where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". reglist is a non-empty list of registers, enclosed in braces. It can contain register ranges. It must be comma separated if it contains more than one register or register range. PUSH and POP are synonyms for STMDB and LDM (or LDMIA) with the memory addresses for the access based on SP, and with the final address for the access written back to the SP. PUSH and POP are the preferred mnemonics in these cases. 2.4.7.2 Operation PUSH stores registers on the stack in order of decreasing the register numbers, with the highest numbered register using the highest memory address and the lowest numbered register using the lowest memory address. POP loads registers from the stack in order of increasing register numbers, with the lowest numbered register using the lowest memory address and the highest numbered register using the highest memory address. See Section 34-2.4.6 for more information. 2.4.7.3 Restrictions In these instructions:
* reglist must not contain SP * for the PUSH instruction, reglist must not contain PC * for the POP instruction, reglist must not contain PC if it contains LR.
When PC is in reglist in a POP instruction:
* bit[0] of the value loaded to the PC must be 1 for correct execution, and a branch
occurs to this halfword-aligned address
* if the instruction is conditional, it must be the last instruction in the IT block.
2.4.7.4 Condition flags These instructions do not change the flags. 2.4.7.5 Examples PUSH PUSH POP
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2.4.8 LDREX and STREX
Load and Store Register Exclusive. 2.4.8.1 Syntax LDREX{cond} Rt, [Rn {, #offset}] STREX{cond} Rd, Rt, [Rn {, #offset}] LDREXB{cond} Rt, [Rn] STREXB{cond} Rd, Rt, [Rn] LDREXH{cond} Rt, [Rn] STREXH{cond} Rd, Rt, [Rn] where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register for the returned status. Rt is the register to load or store. Rn is the register on which the memory address is based. offset is an optional offset applied to the value in Rn. If offset is omitted, the address is the value in Rn. 2.4.8.2 Operation LDREX, LDREXB, and LDREXH load a word, byte, and halfword respectively from a memory address. STREX, STREXB, and STREXH attempt to store a word, byte, and halfword respectively to a memory address. The address used in any Store-Exclusive instruction must be the same as the address in the most recently executed Load-exclusive instruction. The value stored by the Store-Exclusive instruction must also have the same data size as the value loaded by the preceding Load-exclusive instruction. This means software must always use a Load-exclusive instruction and a matching Store-Exclusive instruction to perform a synchronization operation, see Section 34-3.2.7 "Synchronization primitives" If an Store-Exclusive instruction performs the store, it writes 0 to its destination register. If it does not perform the store, it writes 1 to its destination register. If the Store-Exclusive instruction writes 0 to the destination register, it is guaranteed that no other process in the system has accessed the memory location between the Load-exclusive and Store-Exclusive instructions. For reasons of performance, keep the number of instructions between corresponding Load-Exclusive and Store-Exclusive instruction to a minimum. Remark: The result of executing a Store-Exclusive instruction to an address that is different from that used in the preceding Load-Exclusive instruction is unpredictable. 2.4.8.3 Restrictions In these instructions:
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* * * *
2.4.8.4
do not use PC do not use SP for Rd and Rt for STREX, Rd must be different from both Rt and Rn the value of offset must be a multiple of four in the range 0-1020.
Condition flags These instructions do not change the flags.
2.4.8.5
Examples MOV try LDREX CMP ITT STREXEQ CMPEQ BNE .... R0, R0, EQ R0, R0, try [LockAddr] #0 ; ; ; R1, [LockAddr] ; #0 ; ; ; Load the lock value Is the lock free? IT instruction for STREXEQ and CMPEQ Try and claim the lock Did this succeed? No - try again Yes - we have the lock R1, #0x1 ; Initialize the `lock taken' value
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2.4.9 CLREX
Clear Exclusive. 2.4.9.1 Syntax CLREX{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.4.9.2 Operation Use CLREX to make the next STREX, STREXB, or STREXH instruction write 1 to its destination register and fail to perform the store. It is useful in exception handler code to force the failure of the store exclusive if the exception occurs between a load exclusive instruction and the matching store exclusive instruction in a synchronization operation. See Section 34-3.2.7 "Synchronization primitives" for more information. 2.4.9.3 Condition flags These instructions do not change the flags. 2.4.9.4 Examples CLREX
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2.5 General data processing instructions
Table 34-620 shows the data processing instructions:
Table 620. Data processing instructions Mnemonic
ADC ADD ADDW AND ASR BIC CLZ CMN CMP EOR LSL LSR MOV MOVT MOVW MVN ORN ORR RBIT REV REV16 REVSH ROR RRX RSB SBC SUB SUBW TEQ TST
Brief description
See
Add with Carry Add Add Logical AND Arithmetic Shift Right Bit Clear Count leading zeros Compare Negative Compare Exclusive OR Logical Shift Left Logical Shift Right Move Move Top Move 16-bit constant Move NOT Logical OR NOT Logical OR Reverse Bits Reverse byte order in a word Reverse byte order in each halfword Reverse byte order in bottom halfword and sign extend Rotate Right Rotate Right with Extend Reverse Subtract Subtract with Carry Subtract Subtract Test Equivalence Test
Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.2 Section 34-2.5.3 Section 34-2.5.2 Section 34-2.5.4 Section 34-2.5.5 Section 34-2.5.5 Section 34-2.5.2 Section 34-2.5.3 Section 34-2.5.3 Section 34-2.5.6 Section 34-2.5.7 Section 34-2.5.6 Section 34-2.5.6 Section 34-2.5.2 Section 34-2.5.2 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.8 Section 34-2.5.3 Section 34-2.5.3 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.1 Section 34-2.5.9 Section 34-2.5.9
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2.5.1 ADD, ADC, SUB, SBC, and RSB
Add, Add with carry, Subtract, Subtract with carry, and Reverse Subtract. 2.5.1.1 Syntax op{S}{cond} {Rd,} Rn, Operand2 op{cond} {Rd,} Rn, #imm12 where: op is one of: ADD: Add. ADC: Add with Carry. SUB: Subtract. RSB: Reverse Subtract. S: is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see Section 34-2.3.7 "Conditional execution". cond: is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. If Rd is omitted, the destination register is Rn. Rn is the register holding the first operand. Operand2 is a flexible second operand. See Section 34-2.3.3 for details of the options. imm12 is any value in the range 0-4095. 2.5.1.2 Operation The ADD instruction adds the value of Operand2 or imm12 to the value in Rn. The ADC instruction adds the values in Rn and Operand2, together with the carry flag. The SUB instruction subtracts the value of Operand2 or imm12 from the value in Rn. The SBC instruction subtracts the value of Operand2 from the value in Rn. If the carry flag is clear, the result is reduced by one. The RSB instruction subtracts the value in Rn from the value of Operand2. This is useful because of the wide range of options for Operand2. Use ADC and SBC to synthesize multiword arithmetic, see Section 34-2.5.1.6. See also Section 34-2.4.1. Remark: ADDW is equivalent to the ADD syntax that uses the imm12 operand. SUBW is equivalent to the SUB syntax that uses the imm12 operand. 2.5.1.3 Restrictions ; ADD and SUB only
* Operand2 must not be SP and must not be PC * Rd can be SP only in ADD and SUB, and only with the additional restrictions:
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- Rn must also be SP - any shift in Operand2 must be limited to a maximum of 3 bits using LSL
* Rn can be SP only in ADD and SUB * Rd can be PC only in the cond instruction where:
- you must not specify the S suffix - Rm must not be PC and must not be SP - if the instruction is conditional, it must be the last instruction in the IT block
* with the exception of the cond instruction, Rn can be PC only in ADD and SUB, and only
with the additional restrictions: - you must not specify the S suffix - the second operand must be a constant in the range 0 to 4095. Note
* When using the PC for an addition or a subtraction, bits[1:0] of the PC are rounded to
b00 before performing the calculation, making the base address for the calculation word-aligned.
* If you want to generate the address of an instruction, you have to adjust the constant
based on the value of the PC. ARM recommends that you use the ADR instruction instead of ADD or SUB with Rn equal to the PC, because your assembler automatically calculates the correct constant for the ADR instruction. When Rd is PC in the cond instruction:
* bit[0] of the value written to the PC is ignored * a branch occurs to the address created by forcing bit[0] of that value to 0.
2.5.1.4 Condition flags If S is specified, these instructions update the N, Z, C and V flags according to the result. 2.5.1.5 Examples ADD SUBS RSB ADCHI R2, R1, R3 R8, R6, #240 R4, R4, #1280 R11, R0, R3
; ; ; ;
Sets the flags on the result Subtracts contents of R4 from 1280 Only executed if C flag set and Z flag clear
2.5.1.6
Multiword arithmetic examples Section 34- shows two instructions that add a 64-bit integer contained in R2 and R3 to another 64-bit integer contained in R0 and R1, and place the result in R4 and R5. Multiword values do not have to use consecutive registers. Section 34- shows instructions that subtract a 96-bit integer contained in R9, R1, and R11 from another contained in R6, R2, and R8. The example stores the result in R6, R9, and R2. 64-bit addition: ADDS R4, R0, R2 ADC R5, R1, R3
; add the least significant words ; add the most significant words with carry
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96-bit subtraction: SUBS R6, R6, R9 SBCS R9, R2, R1 SBC R2, R8, R11
; subtract the least significant words ; subtract the middle words with carry ; subtract the most significant words with carry
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2.5.2 AND, ORR, EOR, BIC, and ORN
Logical AND, OR, Exclusive OR, Bit Clear, and OR NOT. 2.5.2.1 Syntax op{S}{cond} {Rd,} Rn, Operand2 where: op is one of: AND: logical AND. ORR: logical OR, or bit set. EOR: logical Exclusive OR. BIC: logical AND NOT, or bit clear. ORN: logical OR NOT. S is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see Section 34-2.3.7 "Conditional execution". cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. Rn is the register holding the first operand. Operand2 is a flexible second operand. See Section 34-2.3.3 for details of the options. 2.5.2.2 Operation The AND, EOR, and ORR instructions perform bitwise AND, Exclusive OR, and OR operations on the values in Rn and Operand2. The BIC instruction performs an AND operation on the bits in Rn with the complements of the corresponding bits in the value of Operand2. The ORN instruction performs an OR operation on the bits in Rn with the complements of the corresponding bits in the value of Operand2. 2.5.2.3 Restrictions Do not use SP and do not use PC. 2.5.2.4 Condition flags If S is specified, these instructions:
* update the N and Z flags according to the result * can update the C flag during the calculation of Operand2, see Section 34-2.3.3 * do not affect the V flag.
2.5.2.5 Examples AND ORREQ ANDS
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Chapter 34: Appendix: Cortex-M3 User Guide EORS BIC ORN ORNS R7, R0, R7, R7, R11, #0x18181818 R1, #0xab R11, R14, ROR #4 R11, R14, ASR #32
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2.5.3 ASR, LSL, LSR, ROR, and RRX
Arithmetic Shift Right, Logical Shift Left, Logical Shift Right, Rotate Right, and Rotate Right with Extend. 2.5.3.1 Syntax op{S}{cond} Rd, Rm, Rs op{S}{cond} Rd, Rm, #n RRX{S}{cond} Rd, Rm where: op is one of: ASR: Arithmetic Shift Right. LSL: Logical Shift Left. LSR: Logical Shift Right. ROR: Rotate Right. S is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. Rm is the register holding the shift length to apply to the value in Rm. Only the least significant byte is used and can be in the range 0 to 255. Rs s the register holding the shift length to apply to the value in Rm. Only the least significant byte is used and can be in the range 0 to 255. n is the shift length. The range of shift length depends on the instruction: ASR: shift length from 1 to 32 LSL: shift length from 0 to 31 LSR: shift length from 1 to 32 ROR: shift length from 1 to 31 Remark: MOV{S}{cond} Rd, Rm is the preferred syntax for LSL{S}{cond} Rd, Rm, #0. 2.5.3.2 Operation ASR, LSL, LSR, and ROR move the bits in the register Rm to the left or right by the number of places specified by constant n or register Rs. RRX moves the bits in register Rm to the right by 1. In all these instructions, the result is written to Rd, but the value in register Rm remains unchanged. For details on what result is generated by the different instructions, see Section 34-2.3.4 "Shift Operations". 2.5.3.3 Restrictions Do not use SP and do not use PC.
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2.5.3.4
Condition flags If S is specified:
* these instructions update the N and Z flags according to the result * the C flag is updated to the last bit shifted out, except when the shift length is 0, see
Section 34-2.3.4 "Shift Operations". 2.5.3.5 Examples ASR LSLS LSR ROR RRX R7, R1, R4, R4, R4, R8, R2, R5, R5, R5 #9 #3 #6 R6 ; ; ; ; ; Arithmetic shift right by 9 bits Logical shift left by 3 bits with flag update Logical shift right by 6 bits Rotate right by the value in the bottom byte of R6 Rotate right with extend
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2.5.4 CLZ
Count Leading Zeros. 2.5.4.1 Syntax CLZ{cond} Rd, Rm where: cond is an optional condition code, see Section 34-2.3.7. Rd is the destination register. Rm is the operand register. 2.5.4.2 Operation The CLZ instruction counts the number of leading zeros in the value in Rm and returns the result in Rd. The result value is 32 if no bits are set in the source register, and zero if bit[31] is set. 2.5.4.3 Restrictions Do not use SP and do not use PC. 2.5.4.4 Condition flags This instruction does not change the flags. 2.5.4.5 Examples CLZ CLZNE R4,R9 R2,R3
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2.5.5 CMP and CMN
Compare and Compare Negative. 2.5.5.1 Syntax CMP{cond} Rn, Operand2 CMN{cond} Rn, Operand2 where: cond is an optional condition code, see Section 34-2.3.7. Rn is the register holding the first operand. Operand2 is a flexible second operand. See Flexible second operand on page 3-10for details of the options. 2.5.5.2 Operation These instructions compare the value in a register with Operand2. They update the condition flags on the result, but do not write the result to a register. The CMP instruction subtracts the value of Operand2 from the value in Rn. This is the same as a SUBS instruction, except that the result is discarded. The CMN instruction adds the value of Operand2 to the value in Rn. This is the same as an ADDS instruction, except that the result is discarded. 2.5.5.3 Restrictions In these instructions:
* do not use PC * Operand2 must not be SP.
2.5.5.4 Condition flags These instructions update the N, Z, C and V flags according to the result. 2.5.5.5 Examples CMP CMN CMPGT R2, R9 R0, #6400 SP, R7, LSL #2
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2.5.6 MOV and MVN
Move and Move NOT. 2.5.6.1 Syntax MOV{S}{cond} Rd, Operand2 MOV{cond} Rd, #imm16 MVN{S}{cond} Rd, Operand2 where: S is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see Section 34-2.3.7. cond is an optional condition code, see Section 34-2.3.7. Rd is the destination register. Operand2 is a flexible second operand. See Flexible second operand on page 3-10for details of the options. imm16 is any value in the range 0-65535. 2.5.6.2 Operation The MOV instruction copies the value of Operand2 into Rd. When Operand2 in a MOV instruction is a register with a shift other than LSL #0, the preferred syntax is the corresponding shift instruction:
* ASR{S}{cond} Rd, Rm, #n is the preferred syntax for MOV{S}{cond} Rd, Rm, ASR #n * LSL{S}{cond} Rd, Rm, #n is the preferred syntax for MOV{S}{cond} Rd, Rm, LSL #nn if !=
0
* LSR{S}{cond} Rd, Rm, #n is the preferred syntax for MOV{S}{cond} Rd, Rm, LSR #n * ROR{S}{cond} Rd, Rm, #n is the preferred syntax for MOV{S}{cond} Rd, Rm, ROR #n * RRX{S}{cond} Rd, Rm is the preferred syntax for MOV{S}{cond} Rd, Rm, RRX.
Also, the MOV instruction permits additional forms of Operand2 as synonyms for shift instructions:
* * * *
MOV{S}{cond} Rd, Rm, ASR Rs is a synonym for ASR{S}{cond} Rd, Rm, Rs MOV{S}{cond} Rd, Rm, LSL Rs is a synonym for LSL{S}{cond} Rd, Rm, Rs MOV{S}{cond} Rd, Rm, LSR Rs is a synonym for LSR{S}{cond} Rd, Rm, Rs MOV{S}{cond} Rd, Rm, ROR Rs is a synonym for ROR{S}{cond} Rd, Rm, Rs
See Section 34-2.5.3. The MVN instruction takes the value of Operand2, performs a bitwise logical NOT operation on the value, and places the result into Rd. Remark: The MOVW instruction provides the same function as MOV, but is restricted to using the imm16 operand.
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2.5.6.3
Restrictions You can use SP and PC only in the MOV instruction, with the following restrictions:
* the second operand must be a register without shift * you must not specify the S suffix.
When Rd is PC in a MOV instruction:
* bit[0] of the value written to the PC is ignored * a branch occurs to the address created by forcing bit[0] of that value to 0.
Remark: Though it is possible to use MOV as a branch instruction, ARM strongly recommends the use of a BX or BLX instruction to branch for software portability to the ARM instruction set. 2.5.6.4 Condition flags If S is specified, these instructions:
* update the N and Z flags according to the result * can update the C flag during the calculation of Operand2, see Section 34-2.3.3 * do not affect the V flag.
2.5.6.5 Example MOVS R11, MOV MOVS MOV MOV MVNS #0x000B ; Write value of 0x000B to R11, flags get updated R1, #0xFA05 ; Write value of 0xFA05 to R1, flags are not updated R10, R12 ; Write value in R12 to R10, flags get updated R3, #23 ; Write value of 23 to R3 R8, SP ; Write value of stack pointer to R8 R2, #0xF ; Write value of 0xFFFFFFF0 (bitwise inverse of 0xF) ; to the R2 and update flags
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2.5.7 MOVT
Move Top. 2.5.7.1 Syntax MOVT{cond} Rd, #imm16 where: cond is an optional condition code, see Section 34-2.3.7. Rd is the destination register. imm16 is a 16-bit immediate constant. 2.5.7.2 Operation MOVT writes a 16-bit immediate value, imm16, to the top halfword, Rd[31:16], of its destination register. The write does not affect Rd[15:0]. The MOV, MOVT instruction pair enables you to generate any 32-bit constant. 2.5.7.3 Restrictions Rd must not be SP and must not be PC. 2.5.7.4 Condition flags This instruction does not change the flags. 2.5.7.5 Examples MOVT R3, #0xF123 ; Write 0xF123 to upper halfword of R3, lower halfword ; and APSR are unchanged
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2.5.8 REV, REV16, REVSH, and RBIT
Reverse bytes and Reverse bits. 2.5.8.1 Syntax op{cond} Rd, Rn where: op is any of: REV Reverse byte order in a word. REV16 Reverse byte order in each halfword independently. REVSH Reverse byte order in the bottom halfword, and sign extend to RBIT Reverse the bit order in a 32-bit word. cond is an optional condition code, see Section 34-2.3.7. Rd is the destination register. Rn is the register holding the operand.
2.5.8.2
Operation Use these instructions to change endianness of data: REV: converts 32-bit big-endian data into little-endian data or 32-bit little-endian data into big-endian data. REV16 converts 16-bit big-endian data into little-endian data or 16-bit little-endian data into big-endian data. REVSH converts either: 16-bit signed big-endian data into 32-bit signed little-endian data 16-bit signed little-endian data into 32-bit signed big-endian data.
2.5.8.3
Restrictions Do not use SP and do not use PC.
2.5.8.4
Condition flags These instructions do not change the flags.
2.5.8.5
Examples REV REV16 REVSH REVHS RBIT R3, R0, R0, R3, R7, R7 R0 R5 R7 R8 ; ; ; ; ; Reverse Reverse Reverse Reverse Reverse byte order of value in R7 and write it to R3 byte order of each 16-bit halfword in R0 Signed Halfword with Higher or Same condition bit order of value in R8 and write the result to R7
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2.5.9 TST and TEQ
Test bits and Test Equivalence. 2.5.9.1 Syntax TST{cond} Rn, Operand2 TEQ{cond} Rn, Operand2 where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rn is the register holding the first operand. Operand2 is a flexible second operand. See Section 34-2.3.3 for details of the options. 2.5.9.2 Operation These instructions test the value in a register against Operand2. They update the condition flags based on the result, but do not write the result to a register. The TST instruction performs a bitwise AND operation on the value in Rn and the value of Operand2. This is the same as the ANDS instruction, except that it discards the result. To test whether a bit of Rn is 0 or 1, use the TST instruction with an Operand2 constant that has that bit set to 1 and all other bits cleared to 0. The TEQ instruction performs a bitwise Exclusive OR operation on the value in Rn and the value of Operand2. This is the same as the EORS instruction, except that it discards the result. Use the TEQ instruction to test if two values are equal without affecting the V or C flags. TEQ is also useful for testing the sign of a value. After the comparison, the N flag is the logical Exclusive OR of the sign bits of the two operands. 2.5.9.3 Restrictions Do not use SP and do not use PC. 2.5.9.4 Condition flags These instructions:
* update the N and Z flags according to the result * can update the C flag during the calculation of Operand2, see Section 34-2.3.3 * do not affect the V flag.
2.5.9.5 Examples TST TEQEQ R0, #0x3F8 ; ; R10, R9 ; ; Perform bitwise AND of R0 value to 0x3F8, APSR is updated but result is discarded Conditionally test if value in R10 is equal to value in R9, APSR is updated but result is discarded
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2.6 Multiply and divide instructions
Table 34-621 shows the multiply and divide instructions:
Table 621. Multiply and divide instructions Mnemonic
MLA MLS MUL SDIV SMLAL SMULL UDIV UMLAL UMULL
Brief description
See
Multiply with Accumulate, 32-bit result Multiply and Subtract, 32-bit result Multiply, 32-bit result Signed Divide Signed Multiply with Accumulate (32x32+64), 64-bit result Signed Multiply (32x32), 64-bit result Unsigned Divide Unsigned Multiply with Accumulate (32x32+64), 64-bit result Unsigned Multiply (32x32), 64-bit result
Section 34-2.6.1 Section 34-2.6.1 Section 34-2.6.1 Section 34-2.6.3 Section 34-2.6.2 Section 34-2.6.2 Section 34-2.6.3 Section 34-2.6.2 Section 34-2.6.2
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2.6.1 MUL, MLA, and MLS
Multiply, Multiply with Accumulate, and Multiply with Subtract, using 32-bit operands, and producing a 32-bit result. 2.6.1.1 Syntax MUL{S}{cond} {Rd,} Rn, Rm ; Multiply MLA{cond} Rd, Rn, Rm, Ra ; Multiply with accumulate MLS{cond} Rd, Rn, Rm, Ra ; Multiply with subtract where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". S is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. If Rd is omitted, the destination register is Rn. Rn, Rm are registers holding the values to be multiplied. Ra is a register holding the value to be added or subtracted from. 2.6.1.2 Operation The MUL instruction multiplies the values from Rn and Rm, and places the least significant 32 bits of the result in Rd. The MLA instruction multiplies the values from Rn and Rm, adds the value from Ra, and places the least significant 32 bits of the result in Rd. The MLS instruction multiplies the values from Rn and Rm, subtracts the product from the value from Ra, and places the least significant 32 bits of the result in Rd. The results of these instructions do not depend on whether the operands are signed or unsigned. 2.6.1.3 Restrictions In these instructions, do not use SP and do not use PC. If you use the S suffix with the MUL instruction:
* Rd, Rn, and Rm must all be in the range R0 to R7 * Rd must be the same as Rm * you must not use the cond suffix.
2.6.1.4 Condition flags If S is specified, the MUL instruction:
* updates the N and Z flags according to the result * does not affect the C and V flags.
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2.6.1.5
Examples MUL MLA MULS MULLT MLS R10, R2, R5 R10, R2, R1, R5 R0, R2, R2 R2, R3, R2 R4, R5, R6, R7 ; ; ; ; ; Multiply, R10 Multiply with Multiply with Conditionally Multiply with = R2 x R5 accumulate, R10 = flag update, R0 = multiply, R2 = R3 subtract, R4 = R7
(R2 x R1) + R5 R2 x R2 x R2 - (R5 x R6)
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2.6.2 UMULL, UMLAL, SMULL, and SMLAL
Signed and Unsigned Long Multiply, with optional Accumulate, using 32-bit operands and producing a 64-bit result. 2.6.2.1 Syntax op{cond} RdLo, RdHi, Rn, Rm where: op is one of: UMULL: Unsigned Long Multiply. UMLAL: Unsigned Long Multiply, with Accumulate. SMULL: Signed Long Multiply. SMLAL: Signed Long Multiply, with Accumulate. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". RdHi, RdLo are the destination registers. For UMLAL and SMLAL they also hold the accumulating value. Rn, Rm are registers holding the operands.
2.6.2.2
Operation The UMULL instruction interprets the values from Rn and Rm as unsigned integers. It multiplies these integers and places the least significant 32 bits of the result in RdLo, and the most significant 32 bits of the result in RdHi. The UMLAL instruction interprets the values from Rn and Rm as unsigned integers. It multiplies these integers, adds the 64-bit result to the 64-bit unsigned integer contained in RdHi and RdLo, and writes the result back to RdHi and RdLo. The SMULL instruction interprets the values from Rn and Rm as two's complement signed integers. It multiplies these integers and places the least significant 32 bits of the result in RdLo, and the most significant 32 bits of the result in RdHi. The SMLAL instruction interprets the values from Rn and Rm as two's complement signed integers. It multiplies these integers, adds the 64-bit result to the 64-bit signed integer contained in RdHi and RdLo, and writes the result back to RdHi and RdLo.
2.6.2.3
Restrictions In these instructions:
* do not use SP and do not use PC * RdHi and RdLo must be different registers.
2.6.2.4 Condition flags These instructions do not affect the condition code flags.
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2.6.2.5
Examples UMULL SMLAL R0, R4, R5, R6 R4, R5, R3, R8 ; Unsigned (R4,R0) = R5 x R6 ; Signed (R5,R4) = (R5,R4) + R3 x R8
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2.6.3 SDIV and UDIV
Signed Divide and Unsigned Divide. 2.6.3.1 Syntax SDIV{cond} {Rd,} Rn, Rm UDIV{cond} {Rd,} Rn, Rm where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. If Rd is omitted, the destination register is Rn. Rn is the register holding the value to be divided. Rm is a register holding the divisor. 2.6.3.2 Operation SDIV performs a signed integer division of the value in Rn by the value in Rm. UDIV performs an unsigned integer division of the value in Rn by the value in Rm. For both instructions, if the value in Rn is not divisible by the value in Rm, the result is rounded towards zero. 2.6.3.3 Restrictions Do not use SP and do not use PC. 2.6.3.4 Condition flags These instructions do not change the flags. 2.6.3.5 Examples SDIV R0, R2, R4 ; Signed divide, R0 = R2/R4 UDIV R8, R8, R1 ; Unsigned divide, R8 = R8/R1
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2.7 Saturating instructions
This section describes the saturating instructions, SSAT and USAT.
2.7.1 SSAT and USAT
Signed Saturate and Unsigned Saturate to any bit position, with optional shift before saturating. 2.7.1.1 Syntax op{cond} Rd, #n, Rm {, shift #s} where: op is one of: SSAT Saturates a signed value to a signed range. USAT Saturates a signed value to an unsigned range. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. n specifies the bit position to saturate to:
* n ranges from 1 to 32 for SSAT. * n ranges from 0 to 31 for USAT.
Rm is the register containing the value to saturate. shift #s is an optional shift applied to Rm before saturating. It must be one of the following: ASR #s: where s is in the range 1 to 31 LSL #s: where s is in the range 0 to 31. 2.7.1.2 Operation These instructions saturate to a signed or unsigned n-bit value. The SSAT instruction applies the specified shift, then saturates to the signed range -2n-1 x 2n-1-1. The USAT instruction applies the specified shift, then saturates to the unsigned range 0 x 2n-1. For signed n-bit saturation using SSAT, this means that:
* if the value to be saturated is less than -2n-1, the result returned is -2n-1 * if the value to be saturated is greater than 2n-1-1, the result returned is 2n-1-1 * otherwise, the result returned is the same as the value to be saturated.
For unsigned n-bit saturation using USAT, this means that:
* if the value to be saturated is less than 0, the result returned is 0 * if the value to be saturated is greater than 2n-1, the result returned is 2n-1
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* otherwise, the result returned is the same as the value to be saturated.
If the returned result is different from the value to be saturated, it is called saturation. If saturation occurs, the instruction sets the Q flag to 1 in the APSR. Otherwise, it leaves the Q flag unchanged. To clear the Q flag to 0, you must use the MSR instruction, see Section 34-2.10.7. To read the state of the Q flag, use the MRS instruction, see Section 34-2.10.6. 2.7.1.3 Restrictions Do not use SP and do not use PC. 2.7.1.4 Condition flags These instructions do not affect the condition code flags. If saturation occurs, these instructions set the Q flag to 1. 2.7.1.5 Examples SSAT R7, #16, R7, LSL #4 ; ; ; USATNE R0, #7, R5 ; ; Logical shift left value in R7 by 4, then saturate it as a signed 16-bit value and write it back to R7 Conditionally saturate value in R5 as an unsigned 7 bit value and write it to R0
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2.8 Bitfield instructions
Table 34-622 shows the instructions that operate on adjacent sets of bits in registers or bitfields:
Table 622. Packing and unpacking instructions Mnemonic
BFC BFI SBFX SXTB SXTH UBFX UXTB UXTH
Brief description
See
Bit Field Clear Bit Field Insert Signed Bit Field Extract Sign extend a byte Sign extend a halfword Unsigned Bit Field Extract Zero extend a byte Zero extend a halfword
Section 34-2.8.1 Section 34-2.8.1 Section 34-2.8.2 Section 34-2.8.3 Section 34-2.8.3 Section 34-2.8.2 Section 34-2.8.3 Section 34-2.8.3
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2.8.1 BFC and BFI
Bit Field Clear and Bit Field Insert. 2.8.1.1 Syntax BFC{cond} Rd, #lsb, #width BFI{cond} Rd, Rn, #lsb, #width where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. Rn is the source register. lsb is the position of the least significant bit of the bitfield. lsb must be in the range 0 to 31. width is the width of the bitfield and must be in the range 1 to 32-lsb. 2.8.1.2 Operation BFC clears a bitfield in a register. It clears width bits in Rd, starting at the low bit position lsb. Other bits in Rd are unchanged. BFI copies a bitfield into one register from another register. It replaces width bits in Rd starting at the low bit position lsb, with width bits from Rn starting at bit[0]. Other bits in Rd are unchanged. 2.8.1.3 Restrictions Do not use SP and do not use PC. 2.8.1.4 Condition flags These instructions do not affect the flags. 2.8.1.5 Examples BFC BFI R4, #8, #12 R9, R2, #8, #12 ; Clear bit 8 to bit 19 (12 bits) of R4 to 0 ; Replace bit 8 to bit 19 (12 bits) of R9 with ; bit 0 to bit 11 from R2
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2.8.2 SBFX and UBFX
Signed Bit Field Extract and Unsigned Bit Field Extract. 2.8.2.1 Syntax SBFX{cond} Rd, Rn, #lsb, #width UBFX{cond} Rd, Rn, #lsb, #width where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. Rn is the source register. lsb is the position of the least significant bit of the bitfield. lsb must be in the range 0 to 31. width is the width of the bitfield and must be in the range 1 to 32-lsb. 2.8.2.2 Operation SBFX extracts a bitfield from one register, sign extends it to 32 bits, and writes the result to the destination register. UBFX extracts a bitfield from one register, zero extends it to 32 bits, and writes the result to the destination register. 2.8.2.3 Restrictions Do not use SP and do not use PC. 2.8.2.4 Condition flags These instructions do not affect the flags. 2.8.2.5 Examples SBFX R0, R1, #20, #4 ; ; UBFX R8, R11, #9, #10 ; ; Extract bit 20 to bit 23 (4 bits) from R1 and sign extend to 32 bits and then write the result to R0. Extract bit 9 to bit 18 (10 bits) from R11 and zero extend to 32 bits and then write the result to R8
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2.8.3 SXT and UXT
Sign extend and Zero extend. 2.8.3.1 Syntax SXTextend{cond} {Rd,} Rm {, ROR #n} UXTextend{cond} {Rd}, Rm {, ROR #n} where: extend is one of: B: Extends an 8-bit value to a 32-bit value. H: Extends a 16-bit value to a 32-bit value. cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. Rm is the register holding the value to extend. ROR #n is one of: ROR #8: Value from Rm is rotated right 8 bits. ROR #16: Value from Rm is rotated right 16 bits. ROR #24:Value from Rm is rotated right 24 bits. If ROR #n is omitted, no rotation is performed. 2.8.3.2 Operation These instructions do the following: 1. Rotate the value from Rm right by 0, 8, 16 or 24 bits. 2. Extract bits from the resulting value: - SXTB extracts bits[7:0] and sign extends to 32 bits. - UXTB extracts bits[7:0] and zero extends to 32 bits. - SXTH extracts bits[15:0] and sign extends to 32 bits. - UXTH extracts bits[15:0] and zero extends to 32 bits. 2.8.3.3 Restrictions Do not use SP and do not use PC. 2.8.3.4 Condition flags These instructions do not affect the flags.
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2.8.3.5
Examples SXTH R4, R6, ROR #16 ; ; ; UXTB R3, R10 ; ; Rotate R6 right by 16 bits, then obtain the lower halfword of the result and then sign extend to 32 bits and write the result to R4. Extract lowest byte of the value in R10 and zero extend it, and write the result to R3
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2.9 Branch and control instructions
Table 34-623 shows the branch and control instructions:
Table 623. Branch and control instructions Mnemonic
B BL BLX BX CBNZ CBZ IT TBB TBH
Brief description
See
Branch Branch with Link Branch indirect with Link Branch indirect Compare and Branch if Non Zero Compare and Branch if Non Zero If-Then Table Branch Byte Table Branch Halfword
Section 34-2.9.1 Section 34-2.9.1 Section 34-2.9.1 Section 34-2.9.1 Section 34-2.9.2 Section 34-2.9.2 Section 34-2.9.3 Section 34-2.9.4 Section 34-2.9.4
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2.9.1 B, BL, BX, and BLX
Branch instructions. 2.9.1.1 Syntax B{cond} label BL{cond} label BX{cond} Rm BLX{cond} Rm where: B is branch (immediate). BL is branch with link (immediate). BX is branch indirect (register). BLX is branch indirect with link (register). cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". label is a PC-relative expression. See Section 34-2.3.6 "PC-relative expressions". Rm is a register that indicates an address to branch to. Bit[0] of the value in Rm must be 1, but the address to branch to is created by changing bit[0] to 0. 2.9.1.2 Operation All these instructions cause a branch to label, or to the address indicated in Rm. In addition:
* The BL and BLX instructions write the address of the next instruction to LR (the link
register, R14).
* The BX and BLX instructions cause a UsageFault exception if bit[0] of Rm is 0.
Bcond label is the only conditional instruction that can be either inside or outside an IT block. All other branch instructions must be conditional inside an IT block, and must be unconditional outside the IT block, see Section 34-2.9.3. Table 34-624 shows the ranges for the various branch instructions.
Table 624. Branch ranges Instruction
B label Bcond label (outside IT block) Bcond label (inside IT block) BL{cond} label BX{cond} Rm BLX{cond} Rm
Branch range
-16 MB to +16 MB -1 MB to +1 MB -16 MB to +16 MB -16 MB to +16 MB
Any value in register Any value in register
Remark: You might have to use the .W suffix to get the maximum branch range. See Section 34-2.3.8 "Instruction width selection".
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2.9.1.3
Restrictions The restrictions are:
* do not use PC in the BLX instruction * for BX and BLX, bit[0] of Rm must be 1 for correct execution but a branch occurs to the
target address created by changing bit[0] to 0
* when any of these instructions is inside an IT block, it must be the last instruction of
the IT block. Bcond is the only conditional instruction that is not required to be inside an IT block. However, it has a longer branch range when it is inside an IT block. 2.9.1.4 Condition flags These instructions do not change the flags. 2.9.1.5 Examples B BLE B.W BEQ BEQ.W BL BX BXNE BLX loopA ng target target target funC LR R0 R0 ; ; ; ; ; ; ; ; ; ; ; Branch to loopA Conditionally branch to label ng Branch to target within 16MB range Conditionally branch to target Conditionally branch to target within 1MB Branch with link (Call) to function funC, return address stored in LR Return from function call Conditionally branch to address stored in R0 Branch with link and exchange (Call) to a address stored in R0
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2.9.2 CBZ and CBNZ
Compare and Branch on Zero, Compare and Branch on Non-Zero. 2.9.2.1 Syntax CBZ Rn, label CBNZ Rn, label where: Rn is the register holding the operand. label is the branch destination. 2.9.2.2 Operation Use the CBZ or CBNZ instructions to avoid changing the condition code flags and to reduce the number of instructions. CBZ Rn, label does not change condition flags but is otherwise equivalent to: CMP Rn, #0 BEQ label
CBNZ Rn, label does not change condition flags but is otherwise equivalent to: CMP Rn, #0 BNE label
2.9.2.3
Restrictions The restrictions are:
* Rn must be in the range of R0 to R7 * the branch destination must be within 4 to 130 bytes after the instruction * these instructions must not be used inside an IT block.
2.9.2.4 Condition flags These instructions do not change the flags. 2.9.2.5 Examples CBZ CBNZ R5, target ; Forward branch if R5 is zero R0, target ; Forward branch if R0 is not zero
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2.9.3 IT
If-Then condition instruction. 2.9.3.1 Syntax IT{x{y{z}}} cond where: x specifies the condition switch for the second instruction in the IT block. y specifies the condition switch for the third instruction in the IT block. z specifies the condition switch for the fourth instruction in the IT block. cond specifies the condition for the first instruction in the IT block. The condition switch for the second, third and fourth instruction in the IT block can be either: T: Then. Applies the condition cond to the instruction. E: Else. Applies the inverse condition of cond to the instruction. Remark: It is possible to use AL (the always condition) for cond in an IT instruction. If this is done, all of the instructions in the IT block must be unconditional, and each of x, y, and z must be T or omitted but not E. 2.9.3.2 Operation The IT instruction makes up to four following instructions conditional. The conditions can be all the same, or some of them can be the logical inverse of the others. The conditional instructions following the IT instruction form the IT block. The instructions in the IT block, including any branches, must specify the condition in the {cond} part of their syntax. Remark: Your assembler might be able to generate the required IT instructions for conditional instructions automatically, so that you do not need to write them yourself. See your assembler documentation for details. A BKPT instruction in an IT block is always executed, even if its condition fails. Exceptions can be taken between an IT instruction and the corresponding IT block, or within an IT block. Such an exception results in entry to the appropriate exception handler, with suitable return information in LR and stacked PSR. Instructions designed for use for exception returns can be used as normal to return from the exception, and execution of the IT block resumes correctly. This is the only way that a PC-modifying instruction is permitted to branch to an instruction in an IT block. 2.9.3.3 Restrictions The following instructions are not permitted in an IT block:
* IT * CBZ and CBNZ
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* CPSID and CPSIE.
Other restrictions when using an IT block are:
* a branch or any instruction that modifies the PC must either be outside an IT block or
must be the last instruction inside the IT block. These are: - ADD PC, PC, Rm - MOV PC, Rm - B, BL, BX, BLX - any LDM, LDR, or POP instruction that writes to the PC - TBB and TBH
* do not branch to any instruction inside an IT block, except when returning from an
exception handler
* all conditional instructions except Bcond must be inside an IT block. Bcond can be
either outside or inside an IT block but has a larger branch range if it is inside one
* each instruction inside the IT block must specify a condition code suffix that is either
the same or logical inverse as for the other instructions in the block. Remark: Your assembler might place extra restrictions on the use of IT blocks, such as prohibiting the use of assembler directives within them. 2.9.3.4 Condition flags This instruction does not change the flags. 2.9.3.5 Example
ITTE ANDNE ADDSNE MOVEQ CMP
NE R0, R0, R1 R2, R2, #1 R2, R3 R0, #9
; ; ; ;
Next 3 instructions are conditional ANDNE does not update condition flags ADDSNE updates condition flags Conditional move Convert R0 hex value (0 to 15) into ASCII ('0'-'9', 'A'-'F') Next 2 instructions are conditional Convert 0xA -> 'A' Convert 0x0 -> '0'
; ; ITE GT ; ADDGT R1, R0, #55 ; ADDLE R1, R0, #48 ;
IT
GT
; IT block with only one conditional instruction ; Increment R1 conditionally
ADDGT R1, R1, #1 ITTEE MOVEQ ADDEQ ANDNE BNE.W
EQ ; Next 4 instructions are conditional R0, R1 ; Conditional move R2, R2, #10 ; Conditional add R3, R3, #1 ; Conditional AND dloop ; Branch instruction can only be used in the last ; instruction of an IT block
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IT ADD
NE R0, R0, R1
; Next instruction is conditional ; Syntax error: no condition code used in IT block
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2.9.4 TBB and TBH
Table Branch Byte and Table Branch Halfword. 2.9.4.1 Syntax TBB [Rn, Rm] TBH [Rn, Rm, LSL #1] where: Rn is the register containing the address of the table of branch lengths. If Rn is PC, then the address of the table is the address of the byte immediately following the TBB or TBH instruction. Rm is the index register. This contains an index into the table. For halfword tables, LSL #1 doubles the value in Rm to form the right offset into the table. 2.9.4.2 Operation These instructions cause a PC-relative forward branch using a table of single byte offsets for TBB, or halfword offsets for TBH. Rn provides a pointer to the table, and Rm supplies an index into the table. For TBB the branch offset is twice the unsigned value of the byte returned from the table. and for TBH the branch offset is twice the unsigned value of the halfword returned from the table. The branch occurs to the address at that offset from the address of the byte immediately after the TBB or TBH instruction. 2.9.4.3 Restrictions The restrictions are:
* Rn must not be SP * Rm must not be SP and must not be PC * when any of these instructions is used inside an IT block, it must be the last
instruction of the IT block. 2.9.4.4 Condition flags These instructions do not change the flags. 2.9.4.5 Examples ADR.W R0, BranchTable_Byte TBB [R0, R1] ; R1 is the index, R0 is the base address of the ; branch table Case1 ; an instruction sequence follows Case2 ; an instruction sequence follows Case3 ; an instruction sequence follows BranchTable_Byte DCB 0 ; Case1 offset calculation DCB ((Case2-Case1)/2) ; Case2 offset calculation DCB ((Case3-Case1)/2) ; Case3 offset calculation
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TBH
[PC, R1, LSL #1]
; R1 is the index, PC is used as base of the ; branch table
BranchTable_H DCI ((CaseA - BranchTable_H)/2) ; CaseA offset calculation DCI ((CaseB - BranchTable_H)/2) ; CaseB offset calculation DCI ((CaseC - BranchTable_H)/2) ; CaseC offset calculation CaseA ; an instruction sequence follows CaseB ; an instruction sequence follows CaseC ; an instruction sequence follows
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2.10 Miscellaneous instructions
Table 34-625 shows the remaining Cortex-M3 instructions:
Table 625. Miscellaneous instructions Mnemonic
BKPT CPSID CPSIE DMB DSB ISB MRS MSR NOP SEV SVC WFE WFI
Brief description
See
Breakpoint Change Processor State, Disable Interrupts Change Processor State, Enable Interrupts Data Memory Barrier Data Synchronization Barrier Instruction Synchronization Barrier Move from special register to register Move from register to special register No Operation Send Event Supervisor Call Wait For Event Wait For Interrupt
Section 34-2.10.1 Section 34-2.10.2 Section 34-2.10.2 Section 34-2.10.3 Section 34-2.10.4 Section 34-2.10.5 Section 34-2.10.6 Section 34-2.10.7 Section 34-2.10.8 Section 34-2.10.9 Section 34-2.10.10 Section 34-2.10.11 Section 34-2.10.12
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2.10.1 BKPT
Breakpoint. 2.10.1.1 Syntax BKPT #imm where: imm is an expression evaluating to an integer in the range 0-255 (8-bit value). 2.10.1.2 Operation The BKPT instruction causes the processor to enter Debug state. Debug tools can use this to investigate system state when the instruction at a particular address is reached. imm is ignored by the processor. If required, a debugger can use it to store additional information about the breakpoint. The BKPT instruction can be placed inside an IT block, but it executes unconditionally, unaffected by the condition specified by the IT instruction. 2.10.1.3 Condition flags This instruction does not change the flags. 2.10.1.4 Examples BKPT 0xAB ; Breakpoint with immediate value set to 0xAB (debugger can ; extract the immediate value by locating it using the PC)
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2.10.2 CPS
Change Processor State. 2.10.2.1 Syntax CPSeffect iflags where: effect is one of: IE Clears the special purpose register. ID Sets the special purpose register iflags is a sequence of one or more flags: i Set or clear PRIMASK. f Set or clear FAULTMASK. 2.10.2.2 Operation CPS changes the PRIMASK and FAULTMASK special register values. See Section 34-3.1.3.6 "Exception mask registers" for more information about these registers. 2.10.2.3 Restrictions The restrictions are:
* use CPS only from privileged software, it has no effect if used in unprivileged software. * CPS cannot be conditional and so must not be used inside an IT block.
2.10.2.4 Condition flags This instruction does not change the condition flags. 2.10.2.5 Examples CPSID CPSID CPSIE CPSIE i f i f ; ; ; ; Disable interrupts and configurable fault handlers (set PRIMASK) Disable interrupts and all fault handlers (set FAULTMASK) Enable interrupts and configurable fault handlers (clear PRIMASK) Enable interrupts and fault handlers (clear FAULTMASK)
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2.10.3 DMB
Data Memory Barrier. 2.10.3.1 Syntax DMB{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.3.2 Operation DMB acts as a data memory barrier. It ensures that all explicit memory accesses that appear, in program order, before the DMB instruction are completed before any explicit memory accesses that appear, in program order, after the DMB instruction. DMB does not affect the ordering or execution of instructions that do not access memory. 2.10.3.3 Condition flags This instruction does not change the flags. 2.10.3.4 Examples DMB ; Data Memory Barrier
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2.10.4 DSB
Data Synchronization Barrier. 2.10.4.1 Syntax DSB{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.4.2 Operation DSB acts as a special data synchronization memory barrier. Instructions that come after the DSB, in program order, do not execute until the DSB instruction completes. The DSB instruction completes when all explicit memory accesses before it complete. 2.10.4.3 Condition flags This instruction does not change the flags. 2.10.4.4 Examples DSB ; Data Synchronisation Barrier
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2.10.5 ISB
Instruction Synchronization Barrier. 2.10.5.1 Syntax ISB{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.5.2 Operation ISB acts as an instruction synchronization barrier. It flushes the pipeline of the processor, so that all instructions following the ISB are fetched from cache or memory again, after the ISB instruction has been completed. 2.10.5.3 Condition flags This instruction does not change the flags. 2.10.5.4 Examples ISB ; Instruction Synchronisation Barrier
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2.10.6 MRS
Move the contents of a special register to a general-purpose register. 2.10.6.1 Syntax MRS{cond} Rd, spec_reg where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rd is the destination register. spec_reg can be any of: APSR, IPSR, EPSR, IEPSR, IAPSR, EAPSR, PSR, MSP, PSP, PRIMASK, BASEPRI, BASEPRI_MAX, FAULTMASK, or CONTROL. 2.10.6.2 Operation Use MRS in combination with MSR as part of a read-modify-write sequence for updating a PSR, for example to clear the Q flag. In process swap code, the programmers model state of the process being swapped out must be saved, including relevant PSR contents. Similarly, the state of the process being swapped in must also be restored. These operations use MRS in the state-saving instruction sequence and MSR in the state-restoring instruction sequence. Remark: BASEPRI_MAX is an alias of BASEPRI when used with the MRS instruction. See Section 34-2.10.7. 2.10.6.3 Restrictions Rd must not be SP and must not be PC. 2.10.6.4 Condition flags This instruction does not change the flags. 2.10.6.5 Examples MRS R0, PRIMASK ; Read PRIMASK value and write it to R0
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2.10.7 MSR
Move the contents of a general-purpose register into the specified special register. 2.10.7.1 Syntax MSR{cond} spec_reg, Rn where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". Rn is the source register. spec_reg can be any of: APSR, IPSR, EPSR, IEPSR, IAPSR, EAPSR, PSR, MSP, PSP, PRIMASK, BASEPRI, BASEPRI_MAX, FAULTMASK, or CONTROL. 2.10.7.2 Operation The register access operation in MSR depends on the privilege level. Unprivileged software can only access the APSR, see Table 34-629 "APSR bit assignments". Privileged software can access all special registers. In unprivileged software writes to unallocated or execution state bits in the PSR are ignored. Note When you write to BASEPRI_MAX, the instruction writes to BASEPRI only if either:
* Rn is non-zero and the current BASEPRI value is 0 * Rn is non-zero and less than the current BASEPRI value.
See Section 34-2.10.6. 2.10.7.3 Restrictions Rn must not be SP and must not be PC. 2.10.7.4 Condition flags This instruction updates the flags explicitly based on the value in Rn. 2.10.7.5 Examples MSR CONTROL, R1 ; Read R1 value and write it to the CONTROL register
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2.10.8 NOP
No Operation. 2.10.8.1 Syntax NOP{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.8.2 Operation NOP does nothing. NOP is not necessarily a time-consuming NOP. The processor might remove it from the pipeline before it reaches the execution stage. Use NOP for padding, for example to place the following instruction on a 64-bit boundary. 2.10.8.3 Condition flags This instruction does not change the flags. 2.10.8.4 Examples NOP ; No operation
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2.10.9 SEV
Send Event. 2.10.9.1 Syntax SEV{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.9.2 Operation SEV is a hint instruction that causes an event to be signaled to all processors within a multiprocessor system. It also sets the local event register to 1, see Section 34-3.5 "Power management". 2.10.9.3 Condition flags This instruction does not change the flags. 2.10.9.4 Examples SEV ; Send Event
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2.10.10 SVC
Supervisor Call. 2.10.10.1 Syntax SVC{cond} #imm where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". imm is an expression evaluating to an integer in the range 0-255 (8-bit value). 2.10.10.2 Operation The SVC instruction causes the SVC exception. imm is ignored by the processor. If required, it can be retrieved by the exception handler to determine what service is being requested. 2.10.10.3 Condition flags This instruction does not change the flags. 2.10.10.4 Examples SVC 0x32 ; Supervisor Call (SVC handler can extract the immediate value ; by locating it via the stacked PC)
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2.10.11 WFE
Wait For Event. 2.10.11.1 Syntax WFE{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution" 2.10.11.2 Operation WFE is a hint instruction. If the event register is 0, WFE suspends execution until one of the following events occurs:
* an exception, unless masked by the exception mask registers or the current priority
level
* an exception enters the Pending state, if SEVONPEND in the System Control Register is
set
* a Debug Entry request, if Debug is enabled * an event signaled by a peripheral or another processor in a multiprocessor system
using the SEV instruction. If the event register is 1, WFE clears it to 0 and returns immediately. For more information see Section 34-3.5 "Power management". 2.10.11.3 Condition flags This instruction does not change the flags. 2.10.11.4 Examples WFE ; Wait for event
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2.10.12 WFI
Wait for Interrupt. 2.10.12.1 Syntax WFI{cond} where: cond is an optional condition code, see Section 34-2.3.7 "Conditional execution". 2.10.12.2 Operation WFI is a hint instruction that suspends execution until one of the following events occurs:
* an exception * a Debug Entry request, regardless of whether Debug is enabled.
2.10.12.3 Condition flags This instruction does not change the flags. 2.10.12.4 Examples WFI ; Wait for interrupt
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3. ARM Cortex-M3 User Guide: Processor
3.1 Programmers model
This section describes the Cortex-M3 programmers model. In addition to the individual core register descriptions, it contains information about the processor modes and privilege levels for software execution and stacks.
3.1.1 Processor mode and privilege levels for software execution
The processor modes are:
* Thread mode
Used to execute application software. The processor enters Thread mode when it comes out of reset.
* Handler mode
Used to handle exceptions. The processor returns to Thread mode when it has finished exception processing. The privilege levels for software execution are:
* Unprivileged
The software: - has limited access to the MSR and MRS instructions, and cannot use the CPS instruction - cannot access the system timer, NVIC, or system control block - might have restricted access to memory or peripherals. Unprivileged software executes at the unprivileged level.
* Privileged
The software can use all the instructions and has access to all resources. Privileged software executes at the privileged level. In Thread mode, the CONTROL register controls whether software execution is privileged or unprivileged, see Table 34-635. In Handler mode, software execution is always privileged. Only privileged software can write to the CONTROL register to change the privilege level for software execution in Thread mode. Unprivileged software can use the SVC instruction to make a supervisor call to transfer control to privileged software.
3.1.2 Stacks
The processor uses a full descending stack. This means the stack pointer indicates the last stacked item on the stack memory. When the processor pushes a new item onto the stack, it decrements the stack pointer and then writes the item to the new memory location. The processor implements two stacks, the main stack and the process stack, with independent copies of the stack pointer, see Section 34-3.1.3.2. In Thread mode, the CONTROL register controls whether the processor uses the main stack or the process stack, see Table 34-635. In Handler mode, the processor always uses the main stack. The options for processor operations are:
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Table 626. Summary of processor mode, execution privilege level, and stack use options Processor mode Used to execute Privilege level for software execution Stack used
Thread Handler
[1] See Table 34-635.
Applications Exception handlers
Privileged or unprivileged [1] Always privileged
Main stack or process stack [1] Main stack
3.1.3 Core registers
The processor core registers are:
Table 627. Core register set summary Name Type [1] Required privilege [2] Reset value Description
R0-R12 MSP PSP LR PC PSR ASPR IPSR
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RW RW RW RW RW RW RW RO
Either Privileged Either Either Either Privileged Either Privileged
Undefined See description Undefined
0xFFFFFFFF
Section 34-3.1.3.1 Section 34-3.1.3.2 Section 34-3.1.3.2 Section 34-3.1.3.3 Section 34-3.1.3.4 Section 34-3.1.3.5 Table 34-629 Table 34-630
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See description
0x01000000 0x00000000 0x00000000
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Table 627. Core register set summary Name Type [1] Required privilege [2] Reset value
0x01000000 0x00000000 0x00000000 0x00000000 0x00000000
Description
EPSR PRIMASK FAULTMASK BASEPRI CONTROL
[1] [2]
RO RW RW RW RW
Privileged Privileged Privileged Privileged Privileged
Table 34-631 Table 34-632 Table 34-633 Table 34-634 Table 34-635
Describes access type during program execution in thread mode and Handler mode. Debug access can differ. An entry of Either means privileged and unprivileged software can access the register.
3.1.3.1
General-purpose registers R0-R12 are 32-bit general-purpose registers for data operations.
3.1.3.2
Stack Pointer The Stack Pointer (SP) is register R13. In Thread mode, bit[1] of the CONTROL register indicates the stack pointer to use: On reset, the processor loads the MSP with the value from address 0x00000000.
* 0 = Main Stack Pointer (MSP). This is the reset value. * 1 = Process Stack Pointer (PSP).
3.1.3.3 Link Register The Link Register (LR) is register R14. It stores the return information for subroutines, function calls, and exceptions. On reset, the processor loads the LR value 0xFFFFFFFF. 3.1.3.4 Program Counter The Program Counter (PC) is register R15. It contains the current program address. Bit[0] is always 0 because instruction fetches must be halfword aligned. On reset, the processor loads the PC with the value of the reset vector, which is at address 0x00000004. 3.1.3.5 Program Status Register The Program Status Register (PSR) combines:
* Application Program Status Register (APSR) * Interrupt Program Status Register (IPSR) * Execution Program Status Register (EPSR).
These registers are mutually exclusive bitfields in the 32-bit PSR. The bit assignments are:
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The PSR bit assignments are:
Access these registers individually or as a combination of any two or all three registers, using the register name as an argument to the MSR or MRS instructions. For example:
* read all of the registers using PSR with the MRS instruction * write to the APSR using APSR with the MSR instruction.
The PSR combinations and attributes are:
Table 628. PSR register combinations Register Type Combination
PSR IEPSR IAPSR EAPSR
[1] [2]
RW[1][2] RO RW[1] RW[2]
APSR, EPSR, and IPSR EPSR and IPSR APSR and IPSR APSR and EPSR
The processor ignores writes to the IPSR bits. Reads of the EPSR bits return zero, and the processor ignores writes to the these bits
See the instruction descriptions Section 34-2.10.6 "MRS" and Section 34-2.10.7 "MSR" for more information about how to access the program status registers. Application Program Status Register: The APSR contains the current state of the condition flags from previous instruction executions. See the register summary in Table 34-627 for its attributes. The bit assignments are:
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Table 629. APSR bit assignments Bits Name Function
[31]
N
Negative or less than flag: 0 = operation result was positive, zero, greater than, or equal 1 = operation result was negative or less than.
[30]
Z
Zero flag: 0 = operation result was not zero 1 = operation result was zero.
[29]
C
Carry or borrow flag: 0 = add operation did not result in a carry bit or subtract operation resulted in a borrow bit 1 = add operation resulted in a carry bit or subtract operation did not result in a borrow bit.
[28]
V
Overflow flag: 0 = operation did not result in an overflow 1 = operation resulted in an overflow.
[27]
Q
Sticky saturation flag: 0 = indicates that saturation has not occurred since reset or since the bit was last cleared to zero 1 = indicates when an SSAT or USAT instruction results in saturation. This bit is cleared to zero by software using an MRS instruction.
[26:0]
-
Reserved.
Interrupt Program Status Register: The IPSR contains the exception type number of the current Interrupt Service Routine (ISR). See the register summary in Table 34-627 for its attributes. The bit assignments are:
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Table 630. IPSR bit assignments Bits Name Function
[31:9] [8:0]
ISR_NUMBER
Reserved This is the number of the current exception: 0 = Thread mode 1 = Reserved 2 = NMI 3 = Hard fault 4 = Memory management fault 5 = Bus fault 6 = Usage fault 7-10 = Reserved 11 = SVCall 12 = Reserved for Debug 13 = Reserved 14 = PendSV 15 = SysTick 16 = IRQ0 17 = IRQ1, first device specific interrupt . . 255 = IRQ243 (last implemented interrupt depends on device) see Section 34-3.3.2 for more information.
Execution Program Status Register: The EPSR contains the Thumb state bit, and the execution state bits for either the:
* If-Then (IT) instruction * Interruptible-Continuable Instruction (ICI) field for an interrupted load multiple or
store multiple instruction. See the register summary in Table 34-627 for the EPSR attributes. The bit assignments are:
Table 631. EPSR bit assignments Bits Name Function
[31:27] [26:25], [15:10] [26:25], [15:10] [24] [23:16] [9:0]
ICI IT T -
Reserved. Interruptible-continuable instruction bits, see Section 34-. Indicates the execution state bits of the IT instruction, see Section 34-2.9.3 "IT". Always set to 1. Reserved. Reserved.
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Attempts to read the EPSR directly through application software using the MSR instruction always return zero. Attempts to write the EPSR using the MSR instruction in application software are ignored. Fault handlers can examine EPSR value in the stacked PSR to indicate the operation that is at fault. See Section 34-3.3.7 Interruptible-continuable instructions: When an interrupt occurs during the execution of an LDM or STM instruction, the processor: After servicing the interrupt, the processor:
* stops the load multiple or store multiple instruction operation temporarily. * stores the next register operand in the multiple operation to EPSR bits[15:12]. * returns to the register pointed to by bits[15:12]. * resumes execution of the multiple load or store instruction.
When the EPSR holds ICI execution state, bits[26:25,11:10] are zero. If-Then block: The If-Then block contains up to four instructions following a 16-bit IT instruction. Each instruction in the block is conditional. The conditions for the instructions are either all the same, or some can be the inverse of others. See Section 34-2.9.3 "IT" for more information. 3.1.3.6 Exception mask registers The exception mask registers disable the handling of exceptions by the processor. Disable exceptions where they might impact on timing critical tasks. To access the exception mask registers use the MSR and MRS instructions, or the CPS instruction to change the value of PRIMASK or FAULTMASK. See Section 34-2.10.6 "MRS", Section 34-2.10.7 "MSR", and Section 34-2.10.2 "CPS" for more information. Priority Mask Register: The PRIMASK register prevents activation of all exceptions with configurable priority. See the register summary in Table 34-627 for its attributes. The bit assignments are shown in Table 34-632.
Table 632. PRIMASK register bit assignments Bits Name Function
[31:1] [0]
PRIMASK
Reserved 0 = no effect 1 = prevents the activation of all exceptions with configurable priority.
Fault Mask Register: The FAULTMASK register prevents activation of all exceptions except for Non-Maskable Interrupt (NMI). See the register summary in Table 34-627 for its attributes. The bit assignments are shown in Table 34-633.
Table 633. FAULTMASK register bit assignments Bits Name Function
[31:1] [0]
FAULTMASK
Reserved 0 = no effect 1 = prevents the activation of all exceptions except for NMI.
The processor clears the FAULTMASK bit to 0 on exit from any exception handler except the NMI handler.
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Base Priority Mask Register: The BASEPRI register defines the minimum priority for exception processing. When BASEPRI is set to a nonzero value, it prevents the activation of all exceptions with same or lower priority level as the BASEPRI value. See the register summary in Table 34-627 for its attributes. The bit assignments are shown in Table 34-634.
Table 634. BASEPRI register bit assignments Bits Name Function
[31:8] [7:0]
BASEPRI [1]
Reserved Priority mask bits:
0x0000 = no effect
Nonzero = defines the base priority for exception processing. The processor does not process any exception with a priority value greater than or equal to BASEPRI.
[1] This field is similar to the priority fields in the interrupt priority registers. The processor implements only bits[7:M] of this field, bits[M-1:0] read as zero and ignore writes. The value of M depends on the specific device. See Section 34-4.2.7 "Interrupt Priority Registers" for more information. Remember that higher priority field values correspond to lower exception priorities.
3.1.3.7
CONTROL register The CONTROL register controls the stack used and the privilege level for software execution when the processor is in Thread mode. See the register summary in Table 34-627 for its attributes. The bit assignments are shown in Table 34-635.
Table 635. CONTROL register bit assignments Bits Name Function
[31:2] [1]
Active stack pointer
Reserved Defines the current stack: 0 = MSP is the current stack pointer 1 = PSP is the current stack pointer. In Handler mode this bit reads as zero and ignores writes.
[0]
Thread mode privilege level
Defines the Thread mode privilege level: 0 = privileged 1 = unprivileged.
Handler mode always uses the MSP, so the processor ignores explicit writes to the active stack pointer bit of the CONTROL register when in Handler mode. The exception entry and return mechanisms update the CONTROL register. In an OS environment, ARM recommends that threads running in Thread mode use the process stack and the kernel and exception handlers use the main stack. By default, Thread mode uses the MSP. To switch the stack pointer used in Thread mode to the PSP, use the MSR instruction to set the Active stack pointer bit to 1, see Section 34-2.10.7 "MSR". Remark: When changing the stack pointer, software must use an ISB instruction immediately after the MSR instruction. This ensures that instructions after the ISB execute using the new stack pointer. See Section 34-2.10.5 "ISB"
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3.1.4 Exceptions and interrupts
The Cortex-M3 processor supports interrupts and system exceptions. The processor and the Nested Vectored Interrupt Controller (NVIC) prioritize and handle all exceptions. An exception changes the normal flow of software control. The processor uses handler mode to handle all exceptions except for reset. See Section 34-3.3.7.1 and Section 34-3.3.7.2 for more information. The NVIC registers control interrupt handling. See Section 34-4.2 "Nested Vectored Interrupt Controller" for more information.
3.1.5 Data types
The processor:
* supports the following data types:
- 32-bit words - 16-bit halfwords - 8-bit bytes
* supports 64-bit data transfer instructions. * manages all data memory accesses as little-endian. See Section 34-3.2.1 for more
information.
3.1.6 The Cortex Microcontroller Software Interface Standard
For a Cortex-M3 microcontroller system, the Cortex Microcontroller Software Interface Standard (CMSIS) defines:
* a common way to:
- access peripheral registers - define exception vectors
* the names of:
- the registers of the core peripherals - the core exception vectors
* a device-independent interface for RTOS kernels, including a debug channel.
The CMSIS includes address definitions and data structures for the core peripherals in the Cortex-M3 processor. It also includes optional interfaces for middleware components comprising a TCP/IP stack and a Flash file system. CMSIS simplifies software development by enabling the reuse of template code and the combination of CMSIS-compliant software components from various middleware vendors. Software vendors can expand the CMSIS to include their peripheral definitions and access functions for those peripherals. This document includes the register names defined by the CMSIS, and gives short descriptions of the CMSIS functions that address the processor core and the core peripherals. Remark: This document uses the register short names defined by the CMSIS. In a few cases these differ from the architectural short names that might be used in other documents.
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The following sections give more information about the CMSIS:
* * * *
Section 34-3.5.4 Section 34-2.2 "Intrinsic functions" Section 34-4.2.1 "The CMSIS mapping of the Cortex-M3 NVIC registers" Section 34-4.2.10.1 "NVIC programming hints".
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3.2 Memory model
This section describes the processor memory map, the behavior of memory accesses, and the bit-banding features. The processor has a fixed memory map that provides up to 4GB of addressable memory. The memory map is:
The regions for SRAM and peripherals include bit-band regions. Bit-banding provides atomic operations to bit data, see Section 34-3.2.5. The processor reserves regions of the Private peripheral bus (PPB) address range for core peripheral registers, see Section 34-4.1 "About the Cortex-M3 peripherals".
3.2.1 Memory regions, types and attributes
The memory map and the programming of the MPU split the memory map into regions. Each region has a defined memory type, and some regions have additional memory attributes. The memory type and attributes determine the behavior of accesses to the region. The memory types are:
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* Normal: The processor can re-order transactions for efficiency, or perform speculative
reads.
* Device: The processor preserves transaction order relative to other transactions to
Device or Strongly-ordered memory.
* Strongly-ordered: The processor preserves transaction order relative to all other
transactions. The different ordering requirements for Device and Strongly-ordered memory mean that the memory system can buffer a write to Device memory, but must not buffer a write to Strongly-ordered memory. The additional memory attributes include.
* Shareable
For a shareable memory region, the memory system provides data synchronization between bus masters in a system with multiple bus masters, for example, a processor with a DMA controller. Strongly-ordered memory is always shareable. If multiple bus masters can access a non-shareable memory region, software must ensure data coherency between the bus masters.
* Execute Never (XN)
Means the processor prevents instruction accesses. Any attempt to fetch an instruction from an XN region causes a memory management fault exception.
3.2.2 Memory system ordering of memory accesses
For most memory accesses caused by explicit memory access instructions, the memory system does not guarantee that the order in which the accesses complete matches the program order of the instructions, providing this does not affect the behavior of the instruction sequence. Normally, if correct program execution depends on two memory accesses completing in program order, software must insert a memory barrier instruction between the memory access instructions, see Section 34-3.2.4. However, the memory system does guarantee some ordering of accesses to Device and Strongly-ordered memory. For two memory access instructions A1 and A2, if A1 occurs before A2 in program order, the ordering of the memory accesses caused by two instructions is:
Where: `--' means that the memory system does not guarantee the ordering of the accesses.
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`<` means that accesses are observed in program order, that is, A1 is always observed before A2.
3.2.3 Behavior of memory accesses
The behavior of accesses to each region in the memory map is:
Table 636. Memory access behavior Address range Memory region Memory type XN Description
0x00000000 0x1FFFFFFF 0x20000000 0x3FFFFFFF
Code SRAM
Normal [1] Normal [1]
-
Executable region for program code. You can also put data here. Executable region for data. You can also put code here. This region includes bit band and bit band alias areas, see Table 34-637.
0x40000000 0x5FFFFFFF 0x60000000 0x9FFFFFFF 0xA0000000 0xDFFFFFFF 0xE0000000 0xE00FFFFF 0xE0100000 0xFFFFFFFF
[1]
Peripheral External RAM External device Private Peripheral Bus Vendorspecific device
Device [1] Normal[1] Device [1] Stronglyordered[1] Device [1]
XN[1] XN [1] XN [1] XN [1]
This region includes bit band and bit band alias areas, see Table 34-638. Executable region for data. External Device memory This region includes the NVIC, System timer, and system control block. Not used for NXP devices.
See Section 34-3.2.1 for more information.
The Code, SRAM, and external RAM regions can hold programs. However, the most efficient access to programs is from the Code region. This is because the processor has separate buses that enable instruction fetches and data accesses to occur simultaneously. The MPU can override the default memory access behavior described in this section. For more information, see Section 34-4.5 "Memory protection unit".
3.2.4 Software ordering of memory accesses
The order of instructions in the program flow does not always guarantee the order of the corresponding memory transactions. This is because:
* the processor can reorder some memory accesses to improve efficiency, providing
this does not affect the behavior of the instruction sequence.
* the processor has multiple bus interfaces * memory or devices in the memory map have different wait states * some memory accesses are buffered or speculative.
Section 34-3.2.2 describes the cases where the memory system guarantees the order of memory accesses. Otherwise, if the order of memory accesses is critical, software must include memory barrier instructions to force that ordering. The processor provides the following memory barrier instructions:
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* DMB
The Data Memory Barrier (DMB) instruction ensures that outstanding memory transactions complete before subsequent memory transactions. See Section 34-2.10.3 "DMB".
* DSB
The Data Synchronization Barrier (DSB) instruction ensures that outstanding memory transactions complete before subsequent instructions execute. See Section 34-2.10.4 "DSB".
* ISB
The Instruction Synchronization Barrier (ISB) ensures that the effect of all completed memory transactions is recognizable by subsequent instructions. See Section 34-2.10.5 "ISB". Use memory barrier instructions in, for example: Memory accesses to Strongly-ordered memory, such as the system control block, do not require the use of DMB instructions.
* MPU programming:
- Use a DSB instruction to ensure the effect of the MPU takes place immediately at the end of context switching. - Use an ISB instruction to ensure the new MPU setting takes effect immediately after programming the MPU region or regions, if the MPU configuration code was accessed using a branch or call. If the MPU configuration code is entered using exception mechanisms, then an ISB instruction is not required.
* Vector table. If the program changes an entry in the vector table, and then enables the
corresponding exception, use a DMB instruction between the operations. This ensures that if the exception is taken immediately after being enabled the processor uses the new exception vector.
* Self-modifying code. If a program contains self-modifying code, use an ISB instruction
immediately after the code modification in the program. This ensures subsequent instruction execution uses the updated program.
* Memory map switching. If the system contains a memory map switching mechanism,
use a DSB instruction after switching the memory map in the program. This ensures subsequent instruction execution uses the updated memory map.
* Dynamic exception priority change. When an exception priority has to change when
the exception is pending or active, use DSB instructions after the change. This ensures the change takes effect on completion of the DSB instruction.
* Using a semaphore in multi-master system. If the system contains more than one bus
master, for example, if another processor is present in the system, each processor must use a DMB instruction after any semaphore instructions, to ensure other bus masters see the memory transactions in the order in which they were executed.
3.2.5 Bit-banding
A bit-band region maps each word in a bit-band alias region to a single bit in the bit-band region. The bit-band regions occupy the lowest 1MB of the SRAM and peripheral memory regions.
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The memory map has two 32MB alias regions that map to two 1MB bit-band regions:
* accesses to the 32MB SRAM alias region map to the 1MB SRAM bit-band region, as
shown in Table 34-637
* accesses to the 32MB peripheral alias region map to the 1MB peripheral bit-band
region, as shown in Table 34-638.
Table 637. SRAM memory bit-banding regions Address range Memory region Instruction and data accesses
0x20000000 0x200FFFFF 0x22000000 0x23FFFFFF0
SRAM bit-band region SRAM bit-band alias
Direct accesses to this memory range behave as SRAM memory accesses, but this region is also bit addressable through bit-band alias. Data accesses to this region are remapped to bit band region. A write operation is performed as read-modify-write. Instruction accesses are not remapped.
Table 638. Peripheral memory bit-banding regions Address range
0x40000000 0x400FFFFF 0x42000000 0x44FFFFFF
Memory region
Instruction and data accesses
Peripheral bit-band alias Peripheral bit-band region
Direct accesses to this memory range behave as peripheral memory accesses, but this region is also bit addressable through bit-band alias. Data accesses to this region are remapped to bit band region. A write operation is performed as read-modify-write. Instruction accesses are not permitted.
Remark: A word access to the SRAM or peripheral bit-band alias regions map to a single bit in the SRAM or peripheral bit-band region. The following formula shows how the alias region maps onto the bit-band region: bit_word_offset = (byte_offset x 32) + (bit_number x 4) bit_word_addr = bit_band_base + bit_word_offset where:
* Bit_word_offset is the position of the target bit in the bit-band memory region. * Bit_word_addr is the address of the word in the alias memory region that maps to the
targeted bit.
* Bit_band_base is the starting address of the alias region. * Byte_offset is the number of the byte in the bit-band region that contains the targeted
bit.
* Bit_number is the bit position, 0-7, of the targeted bit.
Figure 34-145 shows examples of bit-band mapping between the SRAM bit-band alias region and the SRAM bit-band region:
* The alias word at 0x23FFFFE0 maps to bit[0] of the bit-band byte at 0x200FFFFF:
0x23FFFFE0 = 0x22000000 + (0xFFFFF*32) + (0*4).
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* The alias word at 0x23FFFFFC maps to bit[7] of the bit-band byte at 0x200FFFFF:
0x23FFFFFC = 0x22000000 + (0xFFFFF*32) + (7*4).
* The alias word at 0x22000000 maps to bit[0] of the bit-band byte at 0x20000000:
0x22000000 = 0x22000000 + (0*32) + (0 *4).
* The alias word at 0x2200001C maps to bit[7] of the bit-band byte at 0x20000000:
0x2200001C = 0x22000000+ (0*32) + (7*4).
Fig 145. Bit-band mapping
3.2.5.1
Directly accessing an alias region Writing to a word in the alias region updates a single bit in the bit-band region. Bit[0] of the value written to a word in the alias region determines the value written to the targeted bit in the bit-band region. Writing a value with bit[0] set to 1 writes a 1 to the bit-band bit, and writing a value with bit[0] set to 0 writes a 0 to the bit-band bit. Bits[31:1] of the alias word have no effect on the bit-band bit. Writing 0x01 has the same effect as writing 0xFF. Writing 0x00 has the same effect as writing 0x0E. Reading a word in the alias region:
* 0x00000000 indicates that the targeted bit in the bit-band region is set to zero * 0x00000001 indicates that the targeted bit in the bit-band region is set to 1
3.2.5.2 Directly accessing a bit-band region Section 34-3.2.3 describes the behavior of direct byte, halfword, or word accesses to the bit-band regions.
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3.2.6 Memory endianness
The processor views memory as a linear collection of bytes numbered in ascending order from zero. For example, bytes 0-3 hold the first stored word, and bytes 4-7 hold the second stored word. Section 34-3.2.6.1 describes how words of data are stored in memory. 3.2.6.1 Little-endian format In little-endian format, the processor stores the least significant byte of a word at the lowest-numbered byte, and the most significant byte at the highest-numbered byte. For example:
3.2.7 Synchronization primitives
The Cortex-M3 instruction set includes pairs of synchronization primitives. These provide a non-blocking mechanism that a thread or process can use to obtain exclusive access to a memory location. Software can use them to perform a guaranteed read-modify-write memory update sequence, or for a semaphore mechanism. A pair of synchronization primitives comprises:
* A Load-Exclusive instruction
Used to read the value of a memory location, requesting exclusive access to that location.
* A Store-Exclusive instruction
Used to attempt to write to the same memory location, returning a status bit to a register. If this bit is: - 0: it indicates that the thread or process gained exclusive access to the memory, and the write succeeds, - 1: it indicates that the thread or process did not gain exclusive access to the memory, and no write is performed, The pairs of Load-Exclusive and Store-Exclusive instructions are:
* the word instructions LDREX and STREX * the halfword instructions LDREXH and STREXH * the byte instructions LDREXB and STREXB.
Software must use a Load-Exclusive instruction with the corresponding Store-Exclusive instruction.
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To perform a guaranteed read-modify-write of a memory location, software must: 1. Use a Load-Exclusive instruction to read the value of the location. 2. Update the value, as required. 3. Use a Store-Exclusive instruction to attempt to write the new value back to the memory location, and tests the returned status bit. If this bit is: - 0: The read-modify-write completed successfully, - 1: No write was performed. This indicates that the value returned at step 1 might be out of date. The software must retry the read-modify-write sequence, Software can use the synchronization primitives to implement a semaphores as follows: 1. Use a Load-Exclusive instruction to read from the semaphore address to check whether the semaphore is free. 2. If the semaphore is free, use a Store-Exclusive to write the claim value to the semaphore address. 3. If the returned status bit from step 2 indicates that the Store-Exclusive succeeded then the software has claimed the semaphore. However, if the Store-Exclusive failed, another process might have claimed the semaphore after the software performed step 1. The Cortex-M3 includes an exclusive access monitor, that tags the fact that the processor has executed a Load-Exclusive instruction. The processor removes its exclusive access tag if:
* It executes a CLREX instruction * It executes a Store-Exclusive instruction, regardless of whether the write succeeds. * An exception occurs. This means the processor can resolve semaphore conflicts
between different threads. For more information about the synchronization primitive instructions, see Section 34-2.4.8 "LDREX and STREX" and Section 34-2.4.9.
3.2.8 Programming hints for the synchronization primitives
ANSI C cannot directly generate the exclusive access instructions. Some C compilers provide intrinsic functions for generation of these instructions:
Table 639. C compiler intrinsic functions for exclusive access instructions Instruction
LDREX, LDREXH, or LDREXB STREX, STREXH, or STREXB CLREX
Intrinsic function
unsigned int __ldrex(volatile void *ptr) int __strex(unsigned int val, volatile void *ptr) void __clrex(void)
The actual exclusive access instruction generated depends on the data type of the pointer passed to the intrinsic function. For example, the following C code generates the require LDREXB operation: __ldrex((volatile char *) 0xFF);
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3.3 Exception model
This section describes the exception model.
3.3.1 Exception states
Each exception is in one of the following states:
* Inactive
The exception is not active and not pending.
* Pending
The exception is waiting to be serviced by the processor. An interrupt request from a peripheral or from software can change the state of the corresponding interrupt to pending.
* Active
An exception that is being serviced by the processor but has not completed. Remark: An exception handler can interrupt the execution of another exception handler. In this case both exceptions are in the active state.
* Active and pending
The exception is being serviced by the processor and there is a pending exception from the same source.
3.3.2 Exception types
The exception types are:
* Reset
Reset is invoked on power up or a warm reset. The exception model treats reset as a special form of exception. When reset is asserted, the operation of the processor stops, potentially at any point in an instruction. When reset is deasserted, execution restarts from the address provided by the reset entry in the vector table. Execution restarts as privileged execution in Thread mode.
* NMI
A NonMaskable Interrupt (NMI) can be signalled by a peripheral or triggered by software. This is the highest priority exception other than reset. It is permanently enabled and has a fixed priority of -2. NMIs cannot be: - masked or prevented from activation by any other exception - preempted by any exception other than Reset.
* Hard fault
A hard fault is an exception that occurs because of an error during exception processing, or because an exception cannot be managed by any other exception mechanism. Hard faults have a fixed priority of -1, meaning they have higher priority than any exception with configurable priority.
* Memory management fault
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A memory management fault is an exception that occurs because of a memory protection related fault. The MPU or the fixed memory protection constraints determines this fault, for both instruction and data memory transactions. This fault is used to abort instruction accesses to Execute Never (XN) memory regions, even if the MPU is disabled.
* Bus fault
A bus fault is an exception that occurs because of a memory related fault for an instruction or data memory transaction. This might be from an error detected on a bus in the memory system.
* Usage fault
A usage fault is an exception that occurs because of a fault related to instruction execution. This includes: - an undefined instruction - an illegal unaligned access - invalid state on instruction execution - an error on exception return. The following can cause a usage fault when the core is configured to report them: - an unaligned address on word and halfword memory access - division by zero.
* SVCall
A supervisor call (SVC) is an exception that is triggered by the SVC instruction. In an OS environment, applications can use SVC instructions to access OS kernel functions and device drivers.
* PendSV
PendSV is an interrupt-driven request for system-level service. In an OS environment, use PendSV for context switching when no other exception is active.
* SysTick
A SysTick exception is an exception the system timer generates when it reaches zero. Software can also generate a SysTick exception. In an OS environment, the processor can use this exception as system tick.
* Interrupt (IRQ)
A interrupt, or IRQ, is an exception signalled by a peripheral, or generated by a software request. All interrupts are asynchronous to instruction execution. In the system, peripherals use interrupts to communicate with the processor.
Table 640. Properties of the different exception types Exception number [1] IRQ number [1] Exception type Priority Vector address or offset [2]
0x00000004 0x00000008 0x0000000C 0x00000010
Activation
1 2 3 4
-14 -13 -12
Reset NMI Hard fault Memory management fault
-3, the highest -2 -1 Configurable [3]
Asynchronous Asynchronous Synchronous
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Table 640. Properties of the different exception types Exception number [1] IRQ number [1] Exception type Priority Vector address or offset [2]
0x00000014
Activation
5
-11
Bus fault
Configurable [3]
Synchronous when precise, asynchronous when imprecise Synchronous Synchronous Asynchronous Asynchronous above [5] Asynchronous
6 7-10 11 12-13 14 15 16 and above
[1] [2] [3] [4] [5]
-10 -5 -2 -1 0 and above
Usage fault SVCall PendSV SysTick Interrupt (IRQ)
Configurable[3] Configurable [3] Configurable[3] Configurable[3] Configurable [4]
0x00000018
Reserved
0x0000002C
Reserved
0x00000038 0x0000003C 0x00000040 and
To simplify the software layer, the CMSIS only uses IRQ numbers and therefore uses negative values for exceptions other than interrupts. The IPSR returns the Exception number, see Table 34-630. See Section 34-3.3.4 for more information. See Section 34-4.3.9 "System Handler Priority Registers". See Section 34-4.2.7 "Interrupt Priority Registers". Increasing in steps of 4.
For an asynchronous exception, other than reset, the processor can execute another instruction between when the exception is triggered and when the processor enters the exception handler. Privileged software can disable the exceptions that Table 34-640 shows as having configurable priority, see:
* Section 34-4.3.10 "System Handler Control and State Register" * Section 34-4.2.3 "Interrupt Clear-enable Registers".
For more information about hard faults, memory management faults, bus faults, and usage faults, see Section 34-3.4.
3.3.3 Exception handlers
The processor handles exceptions using:
* Interrupt Service Routines (ISRs)
Interrupts IRQ0 and up are the exceptions handled by ISRs.
* Fault handlers
Hard fault, memory management fault, usage fault, bus fault are fault exceptions handled by the fault handlers.
* System handlers
NMI, PendSV, SVCall SysTick, and the fault exceptions are all system exceptions that are handled by system handlers.
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3.3.4 Vector table
The vector table contains the reset value of the stack pointer, and the start addresses, also called exception vectors, for all exception handlers. Figure 34-146 shows the order of the exception vectors in the vector table. The least-significant bit of each vector must be 1, indicating that the exception handler is Thumb code. Note that the upper limit of the IRQ number is device dependent.
Exception number 127 . . . 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
IRQ number 111
Offset 0x1FC . . . 0x004C 0x0048 0x0044 0x0040 0x003C 0x0038
Vector IRQ111 . . . IRQ2 IRQ1 IRQ0 Systick PendSV Reserved Reserved for debug SVCall
2 1 0 -1 -2
-5
0x002C Reserved
-10 -11 -12 -13 -14
0x0018 0x0014
Usage fault Bus fault
0x0010 Memory management fault Hard fault 0x000C NMI 0x0008 0x0004 0x0000 Reset Initial SP value.
Fig 146. Vector table
On system reset, the vector table is fixed at address 0x00000000. Privileged software can write to the VTOR to relocate the vector table start address to a different memory location, in the range 0x00000080 to 0x3FFFFF80, see Section 34-4.3.5 "Vector Table Offset Register".
3.3.5 Exception priorities
As Table 34-640 shows, all exceptions have an associated priority, with:
* a lower priority value indicating a higher priority * configurable priorities for all exceptions except Reset, Hard fault, and NMI.
If software does not configure any priorities, then all exceptions with a configurable priority have a priority of 0. For information about configuring exception priorities see
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* Section 34-4.3.9 "System Handler Priority Registers" * Section 34-4.2.7 "Interrupt Priority Registers".
Remark: Configurable priority values are in the range 0 to 31. This means that the Reset, Hard fault, and NMI exceptions, with fixed negative priority values, always have higher priority than any other exception. For example, assigning a higher priority value to IRQ[0] and a lower priority value to IRQ[1] means that IRQ[1] has higher priority than IRQ[0]. If both IRQ[1] and IRQ[0] are asserted, IRQ[1] is processed before IRQ[0]. If multiple pending exceptions have the same priority, the pending exception with the lowest exception number takes precedence. For example, if both IRQ[0] and IRQ[1] are pending and have the same priority, then IRQ[0] is processed before IRQ[1]. When the processor is executing an exception handler, the exception handler is preempted if a higher priority exception occurs. If an exception occurs with the same priority as the exception being handled, the handler is not preempted, irrespective of the exception number. However, the status of the new interrupt changes to pending.
3.3.6 Interrupt priority grouping
To increase priority control in systems with interrupts, the NVIC supports priority grouping. This divides each interrupt priority register entry into two fields: Only the group priority determines preemption of interrupt exceptions. When the processor is executing an interrupt exception handler, another interrupt with the same group priority as the interrupt being handled does not preempt the handler,
* an upper field that defines the group priority * a lower field that defines a subpriority within the group.
If multiple pending interrupts have the same group priority, the subpriority field determines the order in which they are processed. If multiple pending interrupts have the same group priority and subpriority, the interrupt with the lowest IRQ number is processed first. For information about splitting the interrupt priority fields into group priority and subpriority, see Section 34-4.3.6 "Application Interrupt and Reset Control Register".
3.3.7 Exception entry and return
Descriptions of exception handling use the following terms:
* Preemption
When the processor is executing an exception handler, an exception can preempt the exception handler if its priority is higher than the priority of the exception being handled. See Section 34-3.3.6 for more information about preemption by an interrupt. When one exception preempts another, the exceptions are called nested exceptions. See Section 34-3.3.7.1 more information.
* Return
This occurs when the exception handler is completed, and:
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- there is no pending exception with sufficient priority to be serviced - the completed exception handler was not handling a late-arriving exception. The processor pops the stack and restores the processor state to the state it had before the interrupt occurred. See Section 34-3.3.7.2 for more information.
* Tail-chaining
This mechanism speeds up exception servicing. On completion of an exception handler, if there is a pending exception that meets the requirements for exception entry, the stack pop is skipped and control transfers to the new exception handler.
* Late-arriving
This mechanism speeds up preemption. If a higher priority exception occurs during state saving for a previous exception, the processor switches to handle the higher priority exception and initiates the vector fetch for that exception. State saving is not affected by late arrival because the state saved is the same for both exceptions. Therefore the state saving continues uninterrupted. The processor can accept a late arriving exception until the first instruction of the exception handler of the original exception enters the execute stage of the processor. On return from the exception handler of the late-arriving exception, the normal tail-chaining rules apply. 3.3.7.1 Exception entry Exception entry occurs when there is a pending exception with sufficient priority and either:
* the processor is in Thread mode * the new exception is of higher priority than the exception being handled, in which case
the new exception preempts the original exception. When one exception preempts another, the exceptions are nested. Sufficient priority means the exception has more priority than any limits set by the mask registers, see Section 34-3.1.3.6. An exception with less priority than this is pending but is not handled by the processor. When the processor takes an exception, unless the exception is a tail-chained or a late-arriving exception, the processor pushes information onto the current stack. This operation is referred as stacking and the structure of eight data words is referred as stack frame. The stack frame contains the following information:
* * * *
R0-R3, R12 Return address PSR LR.
Immediately after stacking, the stack pointer indicates the lowest address in the stack frame. Unless stack alignment is disabled, the stack frame is aligned to a double-word address. If the STKALIGN bit of the Configuration Control Register (CCR) is set to 1, stack align adjustment is performed during stacking.
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The stack frame includes the return address. This is the address of the next instruction in the interrupted program. This value is restored to the PC at exception return so that the interrupted program resumes. In parallel to the stacking operation, the processor performs a vector fetch that reads the exception handler start address from the vector table. When stacking is complete, the processor starts executing the exception handler. At the same time, the processor writes an EXC_RETURN value to the LR. This indicates which stack pointer corresponds to the stack frame and what operation mode the was processor was in before the entry occurred. If no higher priority exception occurs during exception entry, the processor starts executing the exception handler and automatically changes the status of the corresponding pending interrupt to active. If another higher priority exception occurs during exception entry, the processor starts executing the exception handler for this exception and does not change the pending status of the earlier exception. This is the late arrival case. 3.3.7.2 Exception return Exception return occurs when the processor is in Handler mode and executes one of the following instructions to load the EXC_RETURN value into the PC:
* a POP instruction that includes the PC * a BX instruction with any register. * an LDR or LDM instruction with the PC as the destination.
EXC_RETURN is the value loaded into the LR on exception entry. The exception mechanism relies on this value to detect when the processor has completed an exception handler. The lowest four bits of this value provide information on the return stack and processor mode. Table 34-641 shows the EXC_RETURN[3:0] values with a description of the exception return behavior. The processor sets EXC_RETURN bits[31:4] to 0xFFFFFFF. When this value is loaded into the PC it indicates to the processor that the exception is complete, and the processor initiates the exception return sequence.
Table 641. Exception return behavior EXC_RETURN[3:0] Description
bXXX0 b0001
Reserved. Return to Handler mode. Exception return gets state from MSP. Execution uses MSP after return.
b0011 b01X1
Reserved. Reserved.
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Table 641. Exception return behavior EXC_RETURN[3:0] Description
b1001
Return to Thread mode. Exception return gets state from MSP. Execution uses MSP after return.
b1101
Return to Thread mode. Exception return gets state from PSP. Execution uses PSP after return.
b1X11
Reserved.
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3.4 Fault handling
Faults are a subset of the exceptions, see Section 34-3.3. The following generate a fault:
* a bus error on:
- an instruction fetch or vector table load - a data access
* an internally-detected error such as an undefined instruction or an attempt to change
state with a BX instruction
* attempting to execute an instruction from a memory region marked as
Non-Executable (XN)
* an MPU fault because of a privilege violation or an attempt to access an unmanaged
region
3.4.1 Fault types
Table 34-642 shows the types of fault, the handler used for the fault, the corresponding fault status register, and the register bit that indicates that the fault has occurred. See Section 34-4.3.11 "Configurable Fault Status Register" for more information about the fault status registers.
Table 642. Faults Fault Handler Bit name Fault status register
Bus error on a vector read Fault escalated to a hard fault MPU mismatch: on instruction access on data access during exception stacking during exception unstacking Bus error: during exception stacking during exception unstacking during instruction prefetch Precise data bus error Imprecise data bus error Attempt to access a coprocessor Undefined instruction Attempt to enter an invalid instruction set Invalid EXC_RETURN value Illegal unaligned load or store Divide By 0
[1] [2]
Hard fault Memory management fault
VECTTBL FORCED IACCVIOL[1] DACCVIOL MSTKERR MUNSKERR
Section 34-4.3.12 "Hard Fault Status Register" Section 34-4.3.13 "Memory Management Fault Address Register"
Bus fault
STKERR UNSTKERR IBUSERR PRECISERR IMPRECISERR
Section 34-4.3.14 "Bus Fault Address Register"
Usage fault state [2]
NOCP UNDEFINSTR INVSTATE INVPC UNALIGNED DIVBYZERO
Section 34-4.3.11.3 "Usage Fault Status Register"
Occurs on an access to an XN region even if the MPU is disabled. Attempting to use an instruction set other than the Thumb instruction set.
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3.4.2 Fault escalation and hard faults
All faults exceptions except for hard fault have configurable exception priority, see Section 34-4.3.9 "System Handler Priority Registers". Software can disable execution of the handlers for these faults, see Section 34-4.3.10 "System Handler Control and State Register". Usually, the exception priority, together with the values of the exception mask registers, determines whether the processor enters the fault handler, and whether a fault handler can preempt another fault handler. as described in Section 34-3.3. In some situations, a fault with configurable priority is treated as a hard fault. This is called priority escalation, and the fault is described as escalated to hard fault. Escalation to hard fault occurs when:
* A fault handler causes the same kind of fault as the one it is servicing. This escalation
to hard fault occurs because a fault handler cannot preempt itself because it must have the same priority as the current priority level.
* A fault handler causes a fault with the same or lower priority as the fault it is servicing.
This is because the handler for the new fault cannot preempt the currently executing fault handler.
* An exception handler causes a fault for which the priority is the same as or lower than
the currently executing exception.
* A fault occurs and the handler for that fault is not enabled.
If a bus fault occurs during a stack push when entering a bus fault handler, the bus fault does not escalate to a hard fault. This means that if a corrupted stack causes a fault, the fault handler executes even though the stack push for the handler failed. The fault handler operates but the stack contents are corrupted. Remark: Only Reset and NMI can preempt the fixed priority hard fault. A hard fault can preempt any exception other than Reset, NMI, or another hard fault.
3.4.3 Fault status registers and fault address registers
The fault status registers indicate the cause of a fault. For bus faults and memory management faults, the fault address register indicates the address accessed by the operation that caused the fault, as shown in Table 34-643.
Table 643. Fault status and fault address registers Handler Status register name Address register Register description name
Hard fault Memory management fault Bus fault Usage fault
HFSR MMFSR
MMFAR
Section 34-4.3.12 "Hard Fault Status Register" Section 34-4.3.13 "Memory Management Fault Address Register" Section 34-4.3.11.1 "Memory Management Fault Status Register"
BFSR UFSR
BFAR -
Section 34-4.3.11.2 "Bus Fault Status Register" Section 34-4.3.14 "Bus Fault Address Register" Section 34-4.3.11.3 "Usage Fault Status Register"
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3.4.4 Lockup
The processor enters a lockup state if a hard fault occurs when executing the NMI or hard fault handlers. When the processor is in lockup state it does not execute any instructions. The processor remains in lockup state until either:
* it is reset * an NMI occurs.
Remark: If lockup state occurs from the NMI handler a subsequent NMI does not cause the processor to leave lockup state.
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3.5 Power management
Note: NXP devices based on the Cortex-M3 processor, including the LPC17xx, support additional reduced power modes. See Section 4-8 "Power control" for information on all available reduced power modes. The Cortex-M3 processor sleep modes reduce power consumption:
* Sleep mode stops the processor clock * Deep sleep mode stops the system clock and switches off the PLL and flash memory.
The SLEEPDEEP bit of the SCR selects which sleep mode is used, see Section 34-4.3.7 "System Control Register". For more information about the behavior of the sleep modes see Section 4-8 "Power control". This section describes the mechanisms for entering sleep mode, and the conditions for waking up from sleep mode.
3.5.1 Entering sleep mode
This section describes the mechanisms software can use to put the processor into sleep mode. The system can generate spurious wakeup events, for example a debug operation wakes up the processor. Therefore software must be able to put the processor back into sleep mode after such an event. A program might have an idle loop to put the processor back to sleep mode. 3.5.1.1 Wait for interrupt The wait for interrupt instruction, WFI, causes immediate entry to sleep mode. When the processor executes a WFI instruction it stops executing instructions and enters sleep mode. See Section 34-2.10.12 "WFI" for more information. 3.5.1.2 Wait for event Note: LPC17xx devices based on the Cortex-M3 processor do not implement external events. The wait for event instruction, WFE, causes entry to sleep mode conditional on the value of an one-bit event register. When the processor executes a WFE instruction, it checks this register:
* if the register is 0 the processor stops executing instructions and enters sleep mode * if the register is 1 the processor clears the register to 0 and continues executing
instructions without entering sleep mode. See Section 34-2.10.11 "WFE" for more information. If the event register is 1, this indicate that the processor must not enter sleep mode on execution of a WFE instruction. Typically, this is because an external event signal is asserted, or a processor in the system has executed an SEV instruction, see Section 34-2.10.9 "SEV". Software cannot access this register directly.
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3.5.1.3
Sleep-on-exit If the SLEEPONEXIT bit of the SCR is set to 1, when the processor completes the execution of an exception handler it returns to Thread mode and immediately enters sleep mode. Use this mechanism in applications that only require the processor to run when an exception occurs.
3.5.2 Wakeup from sleep mode
The conditions for the processor to wakeup depend on the mechanism that cause it to enter sleep mode. 3.5.2.1 Wakeup from WFI or sleep-on-exit Normally, the processor wakes up only when it detects an exception with sufficient priority to cause exception entry. Some embedded systems might have to execute system restore tasks after the processor wakes up, and before it executes an interrupt handler. To achieve this set the PRIMASK bit to 1 and the FAULTMASK bit to 0. If an interrupt arrives that is enabled and has a higher priority than current exception priority, the processor wakes up but does not execute the interrupt handler until the processor sets PRIMASK to zero. For more information about PRIMASK and FAULTMASK see Section 34-3.1.3.6. 3.5.2.2 Wakeup from WFE The processor wakes up if:
* it detects an exception with sufficient priority to cause exception entry
In addition, if the SEVONPEND bit in the SCR is set to 1, any new pending interrupt triggers an event and wakes up the processor, even if the interrupt is disabled or has insufficient priority to cause exception entry. For more information about the SCR see Section 34-4.3.7 "System Control Register".
3.5.3 The Wakeup Interrupt Controller
The Wakeup Interrupt Controller (WIC) is a peripheral that can detect an interrupt and wake the processor from deep sleep mode or Power-down mode. The WIC is enabled only when the DEEPSLEEP bit in the SCR is set to 1, see Section 34-4.3.7 "System Control Register". Details of wakeup possibilities on the LPC17xx can be found in Section 4-8 "Power control". The WIC is not programmable, and does not have any registers or user interface. It operates entirely from hardware signals. When the WIC is enabled and the processor enters deep sleep mode or Power-down mode, the power management unit in the system can power down most of the Cortex-M3 processor. This has the side effect of stopping the SysTick timer. When the WIC receives an interrupt, it takes a number of clock cycles to wakeup the processor and restore its state, before it can process the interrupt. This means interrupt latency is increased in deep sleep mode. Wakeup from Power-down mode requires startup of many other portions of the device, and takes longer. Remark: If the processor detects a connection to a debugger it disables the WIC.
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3.5.4 Power management programming hints
ANSI C cannot directly generate the WFI and WFE instructions. The CMSIS provides the following intrinsic functions for these instructions: void __WFE(void) // Wait for Event void __WFE(void) // Wait for Interrupt
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4. ARM Cortex-M3 User Guide: Peripherals
4.1 About the Cortex-M3 peripherals
The address map of the Private peripheral bus (PPB) is:
Table 644. Core peripheral register regions Address
0xE000E008 - 0xE000E00F 0xE000E010 - 0xE000E01F 0xE000E100 - 0xE000E4EF 0xE000ED00 - 0xE000ED3F 0xE000ED90 - 0xE000EDB8 0xE000EF00 - 0xE000EF03
Core peripheral
Description
System control block System timer Nested Vectored Interrupt Controller System control block Memory Protection Unit Nested Vectored Interrupt Controller
Table 34-655 "Summary of the system control block registers" Table 34-675 "System timer registers summary" Table 34-645 "NVIC register summary" Table 34-655 "Summary of the system control block registers" Table 34-681 "MPU registers summary" Table 34-645 "NVIC register summary"
In register descriptions:
* the register type is described as follows:
- RW: Read and write. - RO: Read-only. - WO: Write-only.
* the required privilege gives the privilege level required to access the register, as
follows: - Privileged: Only privileged software can access the register - Unprivileged: Both unprivileged and privileged software can access the register.
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4.2 Nested Vectored Interrupt Controller
This section describes the Nested Vectored Interrupt Controller (NVIC) and the registers it uses. The NVIC supports:
* Up to 112 interrupts. The number of interrupts implemented is device dependent. * A programmable priority level of 0 to 31 for each interrupt. A higher level corresponds
to a lower priority, so level 0 is the highest interrupt priority.
* * * * *
Level and pulse detection of interrupt signals. Dynamic reprioritization of interrupts. Grouping of priority values into group priority and subpriority fields. Interrupt tail-chaining. An external Non-maskable interrupt (NMI).
The processor automatically stacks its state on exception entry and unstacks this state on exception exit, with no instruction overhead. This provides low latency exception handling. The hardware implementation of the NVIC registers is:
Table 645. NVIC register summary Address Name Type Required privilege Reset value Description
0xE000E100 - 0xE000E10C 0XE000E180 - 0xE000E18C 0XE000E200 - 0xE000E20C 0XE000E280 - 0xE000E28C 0xE000E300 - 0xE000E30C 0xE000E400 - 0xE000E46C 0xE000EF00
[1]
ISER0 - ISER3 ICER0 - ICER3 ISPR0 - ISPR3 ICPR0 - ICPR3 IABR0 - IABR3 IPR0 - IPR27 STIR
RW RW RW RW RO RW WO
Privileged Privileged Privileged Privileged Privileged Privileged Configurable[1]
0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000
Table 34-647 Table 34-648 Table 34-649 Table 34-650 Table 34-651 Table 34-652 Table 34-653
Each array element corresponds to a single NVIC register, for example the element ICER[1] corresponds to the ICER1 register.
4.2.1 The CMSIS mapping of the Cortex-M3 NVIC registers
To improve software efficiency, the CMSIS simplifies the NVIC register presentation. In the CMSIS:
* the Set-enable, Clear-enable, Set-pending, Clear-pending and Active Bit registers
map to arrays of 32-bit integers, so that: - the array ISER[0] to ISER[3] corresponds to the registers ISER0 - ISER3 - the array ICER[0] to ICER[3] corresponds to the registers ICER0 - ICER3 - the array ISPR[0] to ISPR[3] corresponds to the registers ISPR0 - ISPR3 - the array ICPR[0] to ICPR[3] corresponds to the registers ICPR0 - ICPR3 - the array IABR[0] to IABR[3] corresponds to the registers IABR0 - IABR3.
* the 8-bit fields of the Interrupt Priority Registers map to an array of 8-bit integers, so
that the array IP[0] to IP[112] corresponds to the registers IPR0 - IPR59, and the array entry IP[n] holds the interrupt priority for interrupt n.
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The CMSIS provides thread-safe code that gives atomic access to the Interrupt Priority Registers. For more information see the description of the NVIC_SetPriority function in Section 34-4.2.10.1 "NVIC programming hints". Table 34-646 shows how the interrupts, or IRQ numbers, map onto the interrupt registers and corresponding CMSIS variables that have one bit per interrupt.
Table 646. Mapping of interrupts to the interrupt variables Interrupts CMSIS array elements [1] Set-enable Clear-enable
ICER[0] ICER[1] ICER[2] ICER[3]
Set-pending
ISPR[0] ISPR[1] ISPR[2] ISPR[3]
Clear-pending
ICPR[0] ICPR[1] ICPR[2] ICPR[3]
Active Bit
IABR[0] IABR[1] IABR[2] IABR[3]
0-31 32-63 64-95 96-127
[1]
ISER[0] ISER[1] ISER[2] ISER[3]
Each array element corresponds to a single NVIC register, for example the element ICER[1] corresponds to the ICER1 register.
4.2.2 Interrupt Set-enable Registers
The ISER0-ISER3 registers enable interrupts, and show which interrupts are enabled. See:
* the register summary in Table 34-645 for the register attributes * Table 34-646 for which interrupts are controlled by each register.
The bit assignments are shown in Table 34-647.
Table 647. ISER bit assignments Bits Name Function
[31:0]
SETENA
Interrupt set-enable bits. Write: 0 = no effect 1 = enable interrupt. Read: 0 = interrupt disabled 1 = interrupt enabled.
If a pending interrupt is enabled, the NVIC activates the interrupt based on its priority. If an interrupt is not enabled, asserting its interrupt signal changes the interrupt state to pending, but the NVIC never activates the interrupt, regardless of its priority.
4.2.3 Interrupt Clear-enable Registers
The ICER0-ICER3 registers disable interrupts, and show which interrupts are enabled. See:
* the register summary in Table 34-645 for the register attributes * Table 34-646 for which interrupts are controlled by each register.
The bit assignments are shown in Table 34-648.
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Table 648. ICER bit assignments Bits Name Function
[31:0]
CLRENA
Interrupt clear-enable bits. Write: 0 = no effect 1 = disable interrupt. Read: 0 = interrupt disabled 1 = interrupt enabled.
4.2.4 Interrupt Set-pending Registers
The ISPR0-ISPR3 registers force interrupts into the pending state, and show which interrupts are pending. See:
* the register summary in Table 34-645 for the register attributes * Table 34-646 for which interrupts are controlled by each register.
The bit assignments are shown in Table 34-649.
Table 649. ISPR bit assignments Bits Name Function
[31:0]
SETPEND
Interrupt set-pending bits. Write: 0 = no effect 1 = changes interrupt state to pending. Read: 0 = interrupt is not pending 1 = interrupt is pending.
Remark: Writing 1 to the ISPR bit corresponding to:
* an interrupt that is pending has no effect * a disabled interrupt sets the state of that interrupt to pending.
4.2.5 Interrupt Clear-pending Registers
The ICPR0-ICPR3 registers remove the pending state from interrupts, and show which interrupts are pending. See:
* the register summary in Table 34-645 for the register attributes * Table 34-646 for which interrupts are controlled by each register.
The bit assignments are shown in Table 34-650.
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Table 650. ICPR bit assignments Bits Name Function
[31:0]
CLRPEND
Interrupt clear-pending bits. Write: 0 = no effect 1 = removes pending state an interrupt. Read: 0 = interrupt is not pending 1 = interrupt is pending.
Remark: Writing 1 to an ICPR bit does not affect the active state of the corresponding interrupt.
4.2.6 Interrupt Active Bit Registers
The IABR0-IABR3 registers indicate which interrupts are active. See:
* the register summary in Table 34-645 for the register attributes * Table 34-646 for which interrupts are controlled by each register.
The bit assignments are shown in Table 34-651.
Table 651. IABR bit assignments Bits Name Function
[31:0]
ACTIVE
Interrupt active flags: 0 = interrupt not active 1 = interrupt active.
A bit reads as one if the status of the corresponding interrupt is active or active and pending.
4.2.7 Interrupt Priority Registers
The IPR0-IPR27 registers provide a 5-bit priority field for each interrupt. These registers are byte-accessible. See the register summary in Table 34-645 for their attributes. Each register holds four priority fields, that map to four elements in the CMSIS interrupt priority array IP[0] to IP[111], as shown:
31
24 23
16 15
8
7
0
IPR27 . . . IPRm . . . IPR0
IP[111]
IP[110] . . .
IP[109]
IP[108]
IP[4m+3]
IP[4m+2] . . .
IP[4m+1]
IP[4m]
IP[3]
IP[2]
IP[1]
IP[0]
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Table 652. IPR bit assignments Bits Name Function
[31:24] [23:16] [15:8] [7:0]
Priority, byte offset 3 Each priority field holds a priority value, 0-31. The lower the Priority, byte offset 2 value, the greater the priority of the corresponding interrupt. The processor implements only bits[7:3] of each field, bits[2:0] Priority, byte offset 1 read as zero and ignore writes. Priority, byte offset 0
See Table 34-646 for more information about the IP[0] to IP[111] interrupt priority array, that provides the software view of the interrupt priorities. Find the IPR number and byte offset for interrupt N as follows:
* the corresponding IPR number, M, is given by M = N DIV 4 * the byte offset of the required Priority field in this register is N MOD 4, where:
- byte offset 0 refers to register bits[7:0] - byte offset 1 refers to register bits[15:8] - byte offset 2 refers to register bits[23:16] - byte offset 3 refers to register bits[31:24].
4.2.8 Software Trigger Interrupt Register
Write to the STIR to generate a Software Generated Interrupt (SGI). See the register summary in Table 34-645 for the STIR attributes. When the USERSETMPEND bit in the CCR is set to 1, unprivileged software can access the STIR, see Section 34-4.3.8 "Configuration and Control Register". Remark: Only privileged software can enable unprivileged access to the STIR. The bit assignments are shown in Table 34-653.
Table 653. STIR bit assignments Bits Field Function
[31:9] [8:0]
INTID
Reserved. Interrupt ID of the required SGI, in the range 0-111. For example, a value of b000000011 specifies interrupt IRQ3.
4.2.9 Level-sensitive and pulse interrupts
The processor supports both level-sensitive and pulse interrupts. Pulse interrupts are also described as edge-triggered interrupts. A level-sensitive interrupt is held asserted until the peripheral deasserts the interrupt signal. Typically this happens because the ISR accesses the peripheral, causing it to clear the interrupt request. A pulse interrupt is an interrupt signal sampled synchronously on the rising edge of the processor clock. To ensure the NVIC detects the interrupt, the peripheral must assert the interrupt signal for at least one clock cycle, during which the NVIC detects the pulse and latches the interrupt.
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When the processor enters the ISR, it automatically removes the pending state from the interrupt, see Section 34-4.2.9.1. For a level-sensitive interrupt, if the signal is not deasserted before the processor returns from the ISR, the interrupt becomes pending again, and the processor must execute its ISR again. This means that the peripheral can hold the interrupt signal asserted until it no longer needs servicing. 4.2.9.1 Hardware and software control of interrupts The Cortex-M3 latches all interrupts. A peripheral interrupt becomes pending for one of the following reasons:
* the NVIC detects that the interrupt signal is HIGH and the interrupt is not active * the NVIC detects a rising edge on the interrupt signal * software writes to the corresponding interrupt set-pending register bit, see
Table 34-649, or to the STIR to make an SGI pending, see Table 34-653. A pending interrupt remains pending until one of the following:
* The processor enters the ISR for the interrupt. This changes the state of the interrupt
from pending to active. Then: - For a level-sensitive interrupt, when the processor returns from the ISR, the NVIC samples the interrupt signal. If the signal is asserted, the state of the interrupt changes to pending, which might cause the processor to immediately re-enter the ISR. Otherwise, the state of the interrupt changes to inactive. - For a pulse interrupt, the NVIC continues to monitor the interrupt signal, and if this is pulsed the state of the interrupt changes to pending and active. In this case, when the processor returns from the ISR the state of the interrupt changes to pending, which might cause the processor to immediately re-enter the ISR. If the interrupt signal is not pulsed while the processor is in the ISR, when the processor returns from the ISR the state of the interrupt changes to inactive.
* Software writes to the corresponding interrupt clear-pending register bit.
For a level-sensitive interrupt, if the interrupt signal is still asserted, the state of the interrupt does not change. Otherwise, the state of the interrupt changes to inactive. For a pulse interrupt, state of the interrupt changes to: - inactive, if the state was pending - active, if the state was active and pending.
4.2.10 NVIC design hints and tips
Ensure software uses correctly aligned register accesses. The processor does not support unaligned accesses to NVIC registers. See the individual register descriptions for the supported access sizes. A interrupt can enter pending state even it is disabled. Before programming VTOR to relocate the vector table, ensure the vector table entries of the new vector table are setup for fault handlers, NMI and all enabled exception like interrupts. For more information see Table 34-659.
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4.2.10.1
NVIC programming hints Software uses the CPSIE I and CPSID I instructions to enable and disable interrupts. The CMSIS provides the following intrinsic functions for these instructions: void __disable_irq(void) // Disable Interrupts void __enable_irq(void) // Enable Interrupts In addition, the CMSIS provides a number of functions for NVIC control, including:
Table 654. CMSIS functions for NVIC control CMSIS interrupt control function
void NVIC_SetPriorityGrouping(uint32_t priority_grouping) void NVIC_EnableIRQ(IRQn_t IRQn) void NVIC_DisableIRQ(IRQn_t IRQn) uint32_t NVIC_GetPendingIRQ (IRQn_t IRQn) void NVIC_SetPendingIRQ (IRQn_t IRQn) void NVIC_ClearPendingIRQ (IRQn_t IRQn) uint32_t NVIC_GetActive (IRQn_t IRQn) void NVIC_SetPriority (IRQn_t IRQn, uint32_t priority) uint32_t NVIC_GetPriority (IRQn_t IRQn) void NVIC_SystemReset (void)
Description
Set the priority grouping Enable IRQn Disable IRQn Return true (IRQ-Number) if IRQn is pending Set IRQn pending Clear IRQn pending status Return the IRQ number of the active interrupt Set priority for IRQn Read priority of IRQn Reset the system
For more information about these functions see the CMSIS documentation.
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4.3 System control block
The System control block (SCB) provides system implementation information, and system control. This includes configuration, control, and reporting of the system exceptions. The system control block registers are:
Table 655. Summary of the system control block registers Address
0xE000E008 0xE000ED00 0xE000ED04 0xE000ED08 0xE000ED0C 0xE000ED10 0xE000ED14 0xE000ED18 0xE000ED1C 0xE000ED20 0xE000ED24 0xE000ED28 0xE000ED28 0xE000ED29 0xE000ED2A 0xE000ED2C 0xE000ED34 0xE000ED38
[1] [2]
Name
Type
Required privilege
Reset value
0x00000000 0x412FC230 0x00000000 0x00000000 0xFA050000 0x00000000 0x00000200 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00 0x00 0x0000 0x00000000
Description
ACTLR CPUID ICSR VTOR AIRCR SCR CCR SHPR1 SHPR2 SHPR3 SHCRS CFSR MMSR [2] BFSR [2] UFSR [2] HFSR MMFAR BFAR
RW RO RW[1] RW RW[1] RW RW RW RW RW RW RW RW RW RW RW RW RW
Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged
Table 34-656 Table 34-657 Table 34-658 Table 34-659 Table 34-660 Table 34-662 Table 34-663 Table 34-665 Table 34-666 Table 34-667 Table 34-668 Section 34-4.3.11 Table 34-669 Table 34-670 Table 34-671 Table 34-672 Table 34-673 Table 34-674
Undefined Undefined
See the register description for more information. A subregister of the CFSR.
4.3.1 The CMSIS mapping of the Cortex-M3 SCB registers
To improve software efficiency, the CMSIS simplifies the SCB register presentation. In the CMSIS, the byte array SHP[0] to SHP[12] corresponds to the registers SHPR1-SHPR3.
4.3.2 Auxiliary Control Register
The ACTLR provides disable bits for the following processor functions:
* IT folding * write buffer use for accesses to the default memory map * interruption of multi-cycle instructions.
See the register summary in Table 34-655 for the ACTLR attributes. The bit assignments are shown in Table 34-656.
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Table 656. ACTLR bit assignments Bits Name Function
[31:3] [2] [1]
DISFOLD DISDEFWBUF
Reserved When set to 1, disables IT folding. see Section 34-4.3.2.1 for more information. When set to 1, disables write buffer use during default memory map accesses. This causes all bus faults to be precise bus faults but decreases performance because any store to memory must complete before the processor can execute the next instruction.
Remark: This bit only affects write buffers implemented in the Cortex-M3 processor.
[0]
DISMCYCINT
When set to 1, disables interruption of load multiple and store multiple instructions. This increases the interrupt latency of the processor because any LDM or STM must complete before the processor can stack the current state and enter the interrupt handler.
4.3.2.1
About IT folding In some situations, the processor can start executing the first instruction in an IT block while it is still executing the IT instruction. This behavior is called IT folding, and improves performance, However, IT folding can cause jitter in looping. If a task must avoid jitter, set the DISFOLD bit to 1 before executing the task, to disable IT folding.
4.3.3 CPUID Base Register
The CPUID register contains the processor part number, version, and implementation information. See the register summary in Table 34-655 for its attributes. The bit assignments are shown in Table 34-657.
Table 657. CPUID register bit assignments Bits Name Function
[31:24] [23:20] [19:16] [15:4] [3:0]
Implementer Variant Constant PartNo Revision
Implementer code:
0x41 = ARM
Variant number, the r value in the rnpn product revision identifier: 0x2 = r2p0 Reads as 0xF Part number of the processor:
0xC23 = Cortex-M3
Revision number, the p value in the rnpn product revision identifier: 0x0 = r2p0
4.3.4 Interrupt Control and State Register
The ICSR:
* provides:
- a set-pending bit for the Non-Maskable Interrupt (NMI) exception - set-pending and clear-pending bits for the PendSV and SysTick exceptions
* indicates:
- the exception number of the exception being processed
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- whether there are preempted active exceptions - the exception number of the highest priority pending exception - whether any interrupts are pending. See the register summary in Table 34-655, and the Type descriptions in Table 34-658, for the ICSR attributes. The bit assignments are shown in Table 34-658.
Table 658. ICSR bit assignments Bits Name Type Function
[31]
NMIPENDSET
RW
NMI set-pending bit. Write: 0 = no effect 1 = changes NMI exception state to pending. Read: 0 = NMI exception is not pending 1 = NMI exception is pending. Because NMI is the highest-priority exception, normally the processor enter the NMI exception handler as soon as it registers a write of 1 to this bit, and entering the handler clears this bit to 0. A read of this bit by the NMI exception handler returns 1 only if the NMI signal is reasserted while the processor is executing that handler.
[30:29] [28] PENDSVSET
RW
Reserved. PendSV set-pending bit. Write: 0 = no effect 1 = changes PendSV exception state to pending. Read: 0 = PendSV exception is not pending 1 = PendSV exception is pending. Writing 1 to this bit is the only way to set the PendSV exception state to pending.
[27]
PENDSVCLR
WO
PendSV clear-pending bit. Write: 0 = no effect 1 = removes the pending state from the PendSV exception.
[26]
PENDSTSET
RW
SysTick exception set-pending bit. Write: 0 = no effect 1 = changes SysTick exception state to pending. Read: 0 = SysTick exception is not pending 1 = SysTick exception is pending.
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Table 658. ICSR bit assignments Bits Name Type Function
[25]
PENDSTCLR
WO
SysTick exception clear-pending bit. Write: 0 = no effect 1 = removes the pending state from the SysTick exception. This bit is WO. On a register read its value is Unknown.
[24] [23] [22]
Reserved for Debug use ISRPENDING
RO RO
Reserved. This bit is reserved for Debug use and reads-as-zero when the processor is not in Debug. Interrupt pending flag, excluding NMI and Faults: 0 = interrupt not pending 1 = interrupt pending.
[21:18] [17:12] VECTPENDING
RO
Reserved. Indicates the exception number of the highest priority pending enabled exception: 0 = no pending exceptions Nonzero = the exception number of the highest priority pending enabled exception. The value indicated by this field includes the effect of the BASEPRI and FAULTMASK registers, but not any effect of the PRIMASK register.
[11]
RETTOBASE
RO
Indicates whether there are preempted active exceptions: 0 = there are preempted active exceptions to execute 1 = there are no active exceptions, or the currently-executing exception is the only active exception.
[10:9] [8:0]
VECTACTIVE[1]
RO
Reserved. Contains the active exception number: 0 = Thread mode Nonzero = The exception number[1] of the currently active exception.
Remark: Subtract 16 from this value to obtain the IRQ number required to index into the Interrupt Clear-Enable, Set-Enable, Clear-Pending, Set-Pending, or Priority Registers, see Table 34-630 "IPSR bit assignments".
[1]
This is the same value as IPSR bits[8:0], see Table 34-630 "IPSR bit assignments".
When you write to the ICSR, the effect is unpredictable if you:
* write 1 to the PENDSVSET bit and write 1 to the PENDSVCLR bit * write 1 to the PENDSTSET bit and write 1 to the PENDSTCLR bit.
4.3.5 Vector Table Offset Register
The VTOR indicates the offset of the vector table base address from memory address 0x00000000. See the register summary in Table 34-655 for its attributes. The bit assignments are shown in Table 34-659.
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Table 659. VTOR bit assignments Bits Name Function
[31:30] [29:8]
TBLOFF
Reserved. Vector table base offset field. It contains bits[29:8] of the offset of the table base from the bottom of the memory map.
Remark: Bit[29] determines whether the vector table is in the code or SRAM memory region:
Bit[29] is sometimes called the TBLBASE bit.
* *
[7:0] -
0 = code 1 = SRAM.
Reserved.
When setting TBLOFF, you must align the offset to the number of exception entries in the vector table. The recommended alignment is 256 words, allowing for 128 interrupts. Remark: Table alignment requirements mean that bits[7:0] of the table offset are always zero.
4.3.6 Application Interrupt and Reset Control Register
The AIRCR provides priority grouping control for the exception model, endian status for data accesses, and reset control of the system. See the register summary in Table 34-655 and Table 34-660 for its attributes. To write to this register, you must write 0x5VA to the VECTKEY field, otherwise the processor ignores the write. The bit assignments are shown in Table 34-660.
Table 660. AIRCR bit assignments Bits Name Type Function
[31:16]
Write: VECTKEYSTAT Read: VECTKEY
RW
Register key: Reads as 0x05FA On writes, write 0x5FA to VECTKEY, otherwise the write is ignored.
[15] [14:11] [10:8]
ENDIANESS PRIGROUP
RO R/W
Data endianness bit: 0 = Little-endian. Reserved Interrupt priority grouping field. This field determines the split of group priority from subpriority, see Section 34-4.3.6.1. Reserved.
[7:3]
-
-
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Table 660. AIRCR bit assignments Bits Name Type Function
[2]
SYSRESETREQ
WO
System reset request: 0 = no system reset request 1 = asserts a signal to the outer system that requests a reset. This is intended to force a large system reset of all major components except for debug. Note: support for SYSRESETREQ is not included in LPC17xx devices. This bit reads as 0.
[1]
VECTCLRACTIVE
WO
Reserved for Debug use. This bit reads as 0. When writing to the register you must write 0 to this bit, otherwise behavior is Unpredictable. Reserved for Debug use. This bit reads as 0. When writing to the register you must write 0 to this bit, otherwise behavior is Unpredictable.
[0]
VECTRESET
WO
4.3.6.1
Binary point The PRIGROUP field indicates the position of the binary point that splits the PRI_n fields in the Interrupt Priority Registers into separate group priority and subpriority fields. Table 34-661 shows how the PRIGROUP value controls this split.
Table 661. Priority grouping Interrupt priority level value, PRI_N[7:0] PRIGROUP Binary point [1] Group priority bits Subpriority bits Number of Group priorities Subpriorities
b010 b011 b100 b101 b110 b111
[1]
bxxxxxy000 bxxxx.y000 bxxx.yy000 bxx.yyy000 bx.yyyy000 b.yyyyy000
[7:3] [7:4] [7:5] [7:6] [7] None
none [3] [4:3] [5:3] [6:3] [7:3]
32 16 8 4 2 1
1 2 3 8 16 32
PRI_n[7:0] field showing the binary point. x denotes a group priority field bit, and y denotes a subpriority field bit. Bits [2:0] are not used in LPC17xx devices.
Remark: Determining preemption of an exception uses only the group priority field, see Section 34-3.3.6 "Interrupt priority grouping".
4.3.7 System Control Register
The SCR controls features of entry to and exit from low power state. See the register summary in Table 34-655 for its attributes. The bit assignments are shown in Table 34-662.
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Table 662. SCR bit assignments Bits Name Function
[31:5] [4]
SEVONPEND
Reserved. Send Event on Pending bit: 0 = only enabled interrupts or events can wakeup the processor, disabled interrupts are excluded 1 = enabled events and all interrupts, including disabled interrupts, can wakeup the processor. When an event or interrupt enters pending state, the event signal wakes up the processor from WFE. If the processor is not waiting for an event, the event is registered and affects the next WFE. The processor also wakes up on execution of an SEV instruction or an external event.
[3] [2]
SLEEPDEEP
Reserved. Controls whether the processor uses sleep or deep sleep as its low power mode: 0 = sleep 1 = deep sleep.
[1]
SLEEPONEXIT Indicates sleep-on-exit when returning from Handler mode to Thread mode: 0 = do not sleep when returning to Thread mode. 1 = enter sleep, or deep sleep, on return from an ISR. Setting this bit to 1 enables an interrupt driven application to avoid returning to an empty main application.
[0]
-
Reserved.
4.3.8 Configuration and Control Register
The CCR controls entry to Thread mode and enables:
* the handlers for NMI, hard fault and faults escalated by FAULTMASK to ignore bus
faults
* trapping of divide by zero and unaligned accesses * access to the STIR by unprivileged software, see Table 34-653.
See the register summary in Table 34-655 for the CCR attributes. The bit assignments are shown in Table 34-663.
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Table 663. CCR bit assignments Bits Name Function
[31:10] [9]
STKALIGN
Reserved. Indicates stack alignment on exception entry: 0 = 4-byte aligned 1 = 8-byte aligned. On exception entry, the processor uses bit[9] of the stacked PSR to indicate the stack alignment. On return from the exception it uses this stacked bit to restore the correct stack alignment.
[8]
BFHFNMIGN Enables handlers with priority -1 or -2 to ignore data bus faults caused by load and store instructions. This applies to the hard fault, NMI, and FAULTMASK escalated handlers: 0 = data bus faults caused by load and store instructions cause a lock-up 1 = handlers running at priority -1 and -2 ignore data bus faults caused by load and store instructions. Set this bit to 1 only when the handler and its data are in absolutely safe memory. The normal use of this bit is to probe system devices and bridges to detect control path problems and fix them.
[7:5] [4]
DIV_0_TRP
Reserved. Enables faulting or halting when the processor executes an SDIV or UDIV instruction with a divisor of 0: 0 = do not trap divide by 0 1 = trap divide by 0. When this bit is set to 0,a divide by zero returns a quotient of 0.
[3]
UNALIGN_T RP
Enables unaligned access traps: 0 = do not trap unaligned halfword and word accesses 1 = trap unaligned halfword and word accesses. If this bit is set to 1, an unaligned access generates a usage fault. Unaligned LDM, STM, LDRD, and STRD instructions always fault irrespective of whether UNALIGN_TRP is set to 1.
[2] [1]
USERSETM PEND
Reserved. Enables unprivileged software access to the STIR, see Table 34-653: 0 = disable 1 = enable. Indicates how the processor enters Thread mode: 0 = processor can enter Thread mode only when no exception is active. 1 = processor can enter Thread mode from any level under the control of an EXC_RETURN value, see Section 34-3.3.7.2 "Exception return".
[0]
NONEBASE THRDENA
4.3.9 System Handler Priority Registers
The SHPR1-SHPR3 registers set the priority level, 0 to 31 of the exception handlers that have configurable priority. SHPR1-SHPR3 are byte accessible. See the register summary in Table 34-655 for their attributes. The system fault handlers and the priority field and register for each handler are:
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Table 664. System fault handler priority fields Handler Field Register description
Memory management fault Bus fault Usage fault SVCall PendSV SysTick
PRI_4 PRI_5 PRI_6 PRI_11 PRI_14 PRI_15
Table 34-665
Table 34-666 Table 34-667
Each PRI_N field is 8 bits wide, but the processor implements only bits[7:3] of each field, and bits[2:0] read as zero and ignore writes. 4.3.9.1 System Handler Priority Register 1 The bit assignments are shown in Table 34-665.
Table 665. SHPR1 register bit assignments Bits Name Function
[31:24] [23:16] [15:8] [7:0]
PRI_7 PRI_6 PRI_5 PRI_4
Reserved Priority of system handler 6, usage fault Priority of system handler 5, bus fault Priority of system handler 4, memory management fault
4.3.9.2
System Handler Priority Register 2 The bit assignments are shown in Table 34-666.
Table 666. SHPR2 register bit assignments Bits Name Function
[31:24] [23:0]
PRI_11 -
Priority of system handler 11, SVCall Reserved
4.3.9.3
System Handler Priority Register 3 The bit assignments are shown in Table 34-667.
Table 667. SHPR3 register bit assignments Bits Name Function
[31:24] [23:16] [15:0]
PRI_15 PRI_14 -
Priority of system handler 15, SysTick exception Priority of system handler 14, PendSV Reserved
4.3.10 System Handler Control and State Register
The SHCSR enables the system handlers, and indicates:
* the pending status of the bus fault, memory management fault, and SVC exceptions * the active status of the system handlers.
See the register summary in Table 34-655 for the SHCSR attributes. The bit assignments are shown in Table 34-668.
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Table 668. SHCSR bit assignments Bits Name Function
[31:19] [18] [17] [16] [15] [14] [13] [12] [11] [10] [9] [8] [7] [6:4] [3] [2] [1] [0]
[1] [2] [3]
USGFAULTENA BUSFAULTENA MEMFAULTENA SVCALLPENDED BUSFAULTPENDED
Reserved Usage fault enable bit, set to 1 to enable [1] Bus fault enable bit, set to 1 to enable [1] Memory management fault enable bit, set to 1 to enable [1] SVC call pending bit, reads as 1 if exception is pending [2] Bus fault exception pending bit, reads as 1 if exception is pending [2]
MEMFAULTPENDED Memory management fault exception pending bit, reads as 1 if exception is pending [2] USGFAULTPENDED Usage fault exception pending bit, reads as 1 if exception is pending [2] SYSTICKACT PENDSVACT MONITORACT SVCALLACT USGFAULTACT BUSFAULTACT MEMFAULTACT SysTick exception active bit, reads as 1 if exception is active [3] PendSV exception active bit, reads as 1 if exception is active Reserved Debug monitor active bit, reads as 1 if Debug monitor is active SVC call active bit, reads as 1 if SVC call is active Reserved Usage fault exception active bit, reads as 1 if exception is active Reserved Bus fault exception active bit, reads as 1 if exception is active Memory management fault exception active bit, reads as 1 if exception is active
Enable bits, set to 1 to enable the exception, or set to 0 to disable the exception. Pending bits, read as 1 if the exception is pending, or as 0 if it is not pending. You can write to these bits to change the pending status of the exceptions. Active bits, read as 1 if the exception is active, or as 0 if it is not active. You can write to these bits to change the active status of the exceptions, but see the Caution in this section.
If you disable a system handler and the corresponding fault occurs, the processor treats the fault as a hard fault. You can write to this register to change the pending or active status of system exceptions. An OS kernel can write to the active bits to perform a context switch that changes the current exception type. Caution
* Software that changes the value of an active bit in this register without correct
adjustment to the stacked content can cause the processor to generate a fault exception. Ensure software that writes to this register retains and subsequently restores the current active status.
* After you have enabled the system handlers, if you have to change the value of a bit
in this register you must use a read-modify-write procedure to ensure that you change only the required bit.
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4.3.11 Configurable Fault Status Register
The CFSR indicates the cause of a memory management fault, bus fault, or usage fault. See the register summary in Table 34-655 for its attributes. The bit assignments are:
The following subsections describe the subregisters that make up the CFSR:
* Table 34-669 "MMFSR bit assignments" * Table 34-674 "BFAR bit assignments" * Table 34-671 "UFSR bit assignments".
The CFSR is byte accessible. You can access the CFSR or its subregisters as follows:
* * * * *
4.3.11.1
access the complete CFSR with a word access to 0xE000ED28 access the MMFSR with a byte access to 0xE000ED28 access the MMFSR and BFSR with a halfword access to 0xE000ED28 access the BFSR with a byte access to 0xE000ED29 access the UFSR with a halfword access to 0xE000ED2A.
Memory Management Fault Status Register The flags in the MMFSR indicate the cause of memory access faults. The bit assignments are shown in Table 34-669.
Table 669. MMFSR bit assignments Bits Name Function Memory Management Fault Address Register (MMAR) valid flag:
[7]
MMARVALID
0 = value in MMAR is not a valid fault address 1 = MMAR holds a valid fault address. If a memory management fault occurs and is escalated to a hard fault because of priority, the hard fault handler must set this bit to 0. This prevents problems on return to a stacked active memory management fault handler whose MMAR value has been overwritten. [6:5] [4] MSTKERR Reserved. Memory manager fault on stacking for exception entry: 0 = no stacking fault 1 = stacking for an exception entry has caused one or more access violations. When this bit is 1, the SP is still adjusted but the values in the context area on the stack might be incorrect. The processor has not written a fault address to the MMAR.
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Table 669. MMFSR bit assignments Bits Name Function
[3]
MUNSTKERR
Memory manager fault on unstacking for a return from exception: 0 = no unstacking fault 1 = unstack for an exception return has caused one or more access violations. This fault is chained to the handler. This means that when this bit is 1, the original return stack is still present. The processor has not adjusted the SP from the failing return, and has not performed a new save. The processor has not written a fault address to the MMAR.
[2] [1]
DACCVIOL
Reserved Data access violation flag: 0 = no data access violation fault 1 = the processor attempted a load or store at a location that does not permit the operation. When this bit is 1, the PC value stacked for the exception return points to the faulting instruction. The processor has loaded the MMAR with the address of the attempted access.
[0]
IACCVIOL
Instruction access violation flag: 0 = no instruction access violation fault 1 = the processor attempted an instruction fetch from a location that does not permit execution. This fault occurs on any access to an XN region, even when the MPU is disabled. When this bit is 1, the PC value stacked for the exception return points to the faulting instruction. The processor has not written a fault address to the MMAR.
4.3.11.2
Bus Fault Status Register The flags in the BFSR indicate the cause of a bus access fault. The bit assignments are shown in Table 34-670.
Table 670. BFSR bit assignments Bits Name Function Bus Fault Address Register (BFAR) valid flag:
[7]
BFARVALID
0 = value in BFAR is not a valid fault address 1 = BFAR holds a valid fault address. The processor sets this bit to 1 after a bus fault where the address is known. Other faults can set this bit to 0, such as a memory management fault occurring later. If a bus fault occurs and is escalated to a hard fault because of priority, the hard fault handler must set this bit to 0. This prevents problems if returning to a stacked active bus fault handler whose BFAR value has been overwritten. [6:5] Reserved.
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Table 670. BFSR bit assignments Bits Name Function
[4]
STKERR
Bus fault on stacking for exception entry: 0 = no stacking fault 1 = stacking for an exception entry has caused one or more bus faults. When the processor sets this bit to 1, the SP is still adjusted but the values in the context area on the stack might be incorrect. The processor does not write a fault address to the BFAR.
[3]
UNSTKERR
Bus fault on unstacking for a return from exception: 0 = no unstacking fault 1 = unstack for an exception return has caused one or more bus faults. This fault is chained to the handler. This means that when the processor sets this bit to 1, the original return stack is still present. The processor does not adjust the SP from the failing return, does not performed a new save, and does not write a fault address to the BFAR.
[2]
IMPRECISERR
Imprecise data bus error: 0 = no imprecise data bus error 1 = a data bus error has occurred, but the return address in the stack frame is not related to the instruction that caused the error. When the processor sets this bit to 1, it does not write a fault address to the BFAR. This is an asynchronous fault. Therefore, if it is detected when the priority of the current process is higher than the bus fault priority, the bus fault becomes pending and becomes active only when the processor returns from all higher priority processes. If a precise fault occurs before the processor enters the handler for the imprecise bus fault, the handler detects both IMPRECISERR set to 1 and one of the precise fault status bits set to 1.
[1]
PRECISERR
Precise data bus error: 0 = no precise data bus error 1 = a data bus error has occurred, and the PC value stacked for the exception return points to the instruction that caused the fault. When the processor sets this bit is 1, it writes the faulting address to the BFAR.
[0]
IBUSERR
Instruction bus error: 0 = no instruction bus error 1 = instruction bus error. The processor detects the instruction bus error on prefetching an instruction, but it sets the IBUSERR flag to 1 only if it attempts to issue the faulting instruction. When the processor sets this bit is 1, it does not write a fault address to the BFAR.
4.3.11.3
Usage Fault Status Register The UFSR indicates the cause of a usage fault. The bit assignments are shown in Table 34-671.
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Table 671. UFSR bit assignments Bits Name Function
[15:10] [9]
DIVBYZERO
Reserved. Divide by zero usage fault: 0 = no divide by zero fault, or divide by zero trapping not enabled 1 = the processor has executed an SDIV or UDIV instruction with a divisor of 0. When the processor sets this bit to 1, the PC value stacked for the exception return points to the instruction that performed the divide by zero. Enable trapping of divide by zero by setting the DIV_0_TRP bit in the CCR to 1, see Table 34-663.
[8]
UNALIGNED
Unaligned access usage fault: 0 = no unaligned access fault, or unaligned access trapping not enabled 1 = the processor has made an unaligned memory access. Enable trapping of unaligned accesses by setting the UNALIGN_TRP bit in the CCR to 1, see Table 34-663. Unaligned LDM, STM, LDRD, and STRD instructions always fault irrespective of the setting of UNALIGN_TRP.
[7:4] [3]
NOCP
Reserved. No coprocessor usage fault. The processor does not support coprocessor instructions: 0 = no usage fault caused by attempting to access a coprocessor 1 = the processor has attempted to access a coprocessor.
[2]
INVPC
Invalid PC load usage fault, caused by an invalid PC load by EXC_RETURN: 0 = no invalid PC load usage fault 1 = the processor has attempted an illegal load of EXC_RETURN to the PC, as a result of an invalid context, or an invalid EXC_RETURN value. When this bit is set to 1, the PC value stacked for the exception return points to the instruction that tried to perform the illegal load of the PC.
[1]
INVSTATE
Invalid state usage fault: 0 = no invalid state usage fault 1 = the processor has attempted to execute an instruction that makes illegal use of the EPSR. When this bit is set to 1, the PC value stacked for the exception return points to the instruction that attempted the illegal use of the EPSR. This bit is not set to 1 if an undefined instruction uses the EPSR.
[0]
UNDEFINSTR Undefined instruction usage fault: 0 = no undefined instruction usage fault 1 = the processor has attempted to execute an undefined instruction. When this bit is set to 1, the PC value stacked for the exception return points to the undefined instruction. An undefined instruction is an instruction that the processor cannot decode.
Remark: The UFSR bits are sticky. This means as one or more fault occurs, the associated bits are set to 1. A bit that is set to 1 is cleared to 0 only by writing 1 to that bit, or by a reset.
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4.3.12 Hard Fault Status Register
The HFSR gives information about events that activate the hard fault handler. See the register summary in Table 34-655 for its attributes. This register is read, write to clear. This means that bits in the register read normally, but writing 1 to any bit clears that bit to 0. The bit assignments are shown in Table 34-672.
Table 672. HFSR bit assignments Bits Name Function
[31] [30]
DEBUGEVT FORCED
Reserved for Debug use. When writing to the register you must write 0 to this bit, otherwise behavior is Unpredictable. Indicates a forced hard fault, generated by escalation of a fault with configurable priority that cannot be handles, either because of priority or because it is disabled: 0 = no forced hard fault 1 = forced hard fault. When this bit is set to 1, the hard fault handler must read the other fault status registers to find the cause of the fault.
[29:2] [1]
VECTTBL
Reserved. Indicates a bus fault on a vector table read during exception processing: 0 = no bus fault on vector table read 1 = bus fault on vector table read. This error is always handled by the hard fault handler. When this bit is set to 1, the PC value stacked for the exception return points to the instruction that was preempted by the exception.
[0]
-
Reserved.
Remark: The HFSR bits are sticky. This means as one or more fault occurs, the associated bits are set to 1. A bit that is set to 1 is cleared to 0 only by writing 1 to that bit, or by a reset.
4.3.13 Memory Management Fault Address Register
The MMFAR contains the address of the location that generated a memory management fault. See the register summary in Table 34-655 for its attributes. The bit assignments are:
Table 673. MMFAR bit assignments Bits Name Function
[31:0]
ADDRESS
When the MMARVALID bit of the MMFSR is set to 1, this field holds the address of the location that generated the memory management fault
When an unaligned access faults, the address is the actual address that faulted. Because a single read or write instruction can be split into multiple aligned accesses, the fault address can be any address in the range of the requested access size. Flags in the MMFSR indicate the cause of the fault, and whether the value in the MMFAR is valid. See Table 34-669.
4.3.14 Bus Fault Address Register
The BFAR contains the address of the location that generated a bus fault. See the register summary in Table 34-655 for its attributes. The bit assignments are:
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Table 674. BFAR bit assignments Bits Name Function
[31:0]
ADDRESS
When the BFARVALID bit of the BFSR is set to 1, this field holds the address of the location that generated the bus fault
When an unaligned access faults the address in the BFAR is the one requested by the instruction, even if it is not the address of the fault. Flags in the BFSR indicate the cause of the fault, and whether the value in the BFAR is valid. See Table 34-670.
4.3.15 System control block design hints and tips
Ensure software uses aligned accesses of the correct size to access the system control block registers:
* except for the CFSR and SHPR1-SHPR3, it must use aligned word accesses * for the CFSR and SHPR1-SHPR3 it can use byte or aligned halfword or word
accesses. The processor does not support unaligned accesses to system control block registers. In a fault handler. to determine the true faulting address: 1. Read and save the MMFAR or BFAR value. 2. Read the MMARVALID bit in the MMFSR, or the BFARVALID bit in the BFSR. The MMFAR or BFAR address is valid only if this bit is 1. Software must follow this sequence because another higher priority exception might change the MMFAR or BFAR value. For example, if a higher priority handler preempts the current fault handler, the other fault might change the MMFAR or BFAR value.
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4.4 System timer, SysTick
The processor has a 24-bit system timer, SysTick, that counts down from the reload value to zero, reloads (wraps to) the value in the LOAD register on the next clock edge, then counts down on subsequent clocks. Note: refer to the separate chapter in the LPC17xx User Manual Section 23-1 for device specific information on the System Timer. Remark: when the processor is halted for debugging the counter does not decrement. The system timer registers are:
Table 675. System timer registers summary Address
0xE000E010 0xE000E014 0xE000E018 0xE000E01C
[1]
Name
Type
Required privilege
Reset value
0x00000004 0x00000000 0x00000000 0x000F423F [1]
Description
CTRL LOAD VAL CALIB
RW RW RW RO
Privileged Privileged Privileged Privileged
Table 34-676 Table 34-677 Table 34-678 Table 34-679
SysTick calibration value. This value is specific to LPC17xx devices.
4.4.1 SysTick Control and Status Register
The SysTick CTRL register enables the SysTick features. See the register summary in Table 34-675 for its attributes. The bit assignments are shown in Table 34-676.
Table 676. SysTick CTRL register bit assignments Bits Name Function
[31:17] [16] [15:3] [2]
COUNTFLAG CLKSOURCE
Reserved. Returns 1 if timer counted to 0 since last time this was read. Reserved. Indicates the clock source: 0 = external clock 1 = processor clock.
[1]
TICKINT
Enables SysTick exception request: 0 = counting down to zero does not assert the SysTick exception request 1 = counting down to zero to asserts the SysTick exception request. Software can use COUNTFLAG to determine if SysTick has ever counted to zero.
[0]
ENABLE
Enables the counter: 0 = counter disabled 1 = counter enabled.
When ENABLE is set to 1, the counter loads the RELOAD value from the LOAD register and then counts down. On reaching 0, it sets the COUNTFLAG to 1 and optionally asserts the SysTick depending on the value of TICKINT. It then loads the RELOAD value again, and begins counting.
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4.4.2 SysTick Reload Value Register
The LOAD register specifies the start value to load into the VAL register. See the register summary in Table 34-675 for its attributes. The bit assignments are shown in Table 34-677.
Table 677. LOAD register bit assignments Bits Name Function
[31:24] [23:0]
RELOAD
Reserved. Value to load into the VAL register when the counter is enabled and when it reaches 0, see Section 34-4.4.2.1.
4.4.2.1
Calculating the RELOAD value The RELOAD value can be any value in the range 0x00000001-0x00FFFFFF. A start value of 0 is possible, but has no effect because the SysTick exception request and COUNTFLAG are activated when counting from 1 to 0. The RELOAD value is calculated according to its use:
* To generate a multi-shot timer with a period of N processor clock cycles, use a
RELOAD value of N-1. For example, if the SysTick interrupt is required every 100 clock pulses, set RELOAD to 99.
* To deliver a single SysTick interrupt after a delay of N processor clock cycles, use a
RELOAD of value N. For example, if a SysTick interrupt is required after 400 clock pulses, set RELOAD to 400.
4.4.3 SysTick Current Value Register
The VAL register contains the current value of the SysTick counter. See the register summary in Table 34-675 for its attributes. The bit assignments are shown in Table 34-678.
Table 678. VAL register bit assignments Bits Name Function
[31:24] [23:0]
CURRENT
Reserved. Reads return the current value of the SysTick counter. A write of any value clears the field to 0, and also clears the SysTick CTRL.COUNTFLAG bit to 0.
4.4.4 SysTick Calibration Value Register
The CALIB register indicates the SysTick calibration properties. See the register summary in Table 34-675 for its attributes. The bit assignments are shown in Table 34-679.
Table 679. CALIB register bit assignments Bits Name Function
[31]
NOREF
Indicates whether a separate reference clock is available. This value is factory preset as described in Section 23-1.
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Table 679. CALIB register bit assignments Bits Name Function
[30]
SKEW
Indicates whether the value of TENMS is precise. This can affect the suitability of SysTick as a software real time clock. This value is factory preset as described in Section 23-1. Reserved. This value is factory preset as described in Section 23-1.
[29:24] [23:0]
TENMS
If a different frequency is used than that intended by the factory preset value, calculate the calibration value required from the frequency of the processor clock or external clock.
4.4.5 SysTick design hints and tips
The SysTick counter runs on the processor clock. If this clock signal is stopped for low power mode while the SysTick counter is running from it, the SysTick counter will stop. Ensure software uses aligned word accesses to access the SysTick registers.
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4.5 Memory protection unit
This section describes the Memory protection unit (MPU). The MPU divides the memory map into a number of regions, and defines the location, size, access permissions, and memory attributes of each region. It supports:
* independent attribute settings for each region * overlapping regions * export of memory attributes to the system.
The memory attributes affect the behavior of memory accesses to the region. The Cortex-M3 MPU defines:
* eight separate memory regions, 0-7 * a background region.
When memory regions overlap, a memory access is affected by the attributes of the region with the highest number. For example, the attributes for region 7 take precedence over the attributes of any region that overlaps region 7. The background region has the same memory access attributes as the default memory map, but is accessible from privileged software only. The Cortex-M3 MPU memory map is unified. This means instruction accesses and data accesses have same region settings. If a program accesses a memory location that is prohibited by the MPU, the processor generates a memory management fault. This causes a fault exception, and might cause termination of the process in an OS environment. In an OS environment, the kernel can update the MPU region setting dynamically based on the process to be executed. Typically, an embedded OS uses the MPU for memory protection. Configuration of MPU regions is based on memory types, see Section 34-3.2.1 "Memory regions, types and attributes". Table 34-680 shows the possible MPU region attributes. These include Shareability and cache behavior attributes that are not relevant to most microcontroller implementations. See Table 34-691 for guidelines for programming such an implementation.
Table 680. Memory attributes summary Memory type Shareability Other attributes Description
Strongly- ordered
-
-
All accesses to Strongly-ordered memory occur in program order. All Strongly-ordered regions are assumed to be shared. Memory-mapped peripherals that several processors share.
Device
Shared
-
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Table 680. Memory attributes summary Memory type Shareability Other attributes Description
Non-shared Normal Shared
Non-cacheable Write-through Cacheable Write-back Cacheable Non-cacheable Write-through Cacheable Write-back Cacheable
Memory-mapped peripherals that only a single processor uses. Normal memory that is shared between several processors.
Non-shared
Normal memory that only a single processor uses.
Use the MPU registers to define the MPU regions and their attributes. The MPU registers are:
Table 681. MPU registers summary Address
0xE000ED90 0xE000ED94 0xE000ED98 0xE000ED9C 0xE000EDA0 0xE000EDA4 0xE000EDA8 0xE000EDAC 0xE000EDB0 0xE000EDB4 0xE000EDB8
Name
Type
Required privilege
Reset value
0x00000800 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000
Description
TYPE CTRL RNR RBAR RASR RBAR_A1 RASR_A1 RBAR_A2 RASR_A2 RBAR_A3 RASR_A3
RO RW RW RW RW RW RW RW RW RW RW
Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged Privileged
Table 34-682 Table 34-683 Table 34-684 Table 34-685 Table 34-686 Alias of RBAR, see Table 34-685 Alias of RASR, see Table 34-686 Alias of RBAR, see Table 34-685 Alias of RASR, see Table 34-686 Alias of RBAR, see Table 34-685 Alias of RASR, see Table 34-686
4.5.1 MPU Type Register
The TYPE register indicates whether the MPU is present, and if so, how many regions it supports. See the register summary in Table 34-681 for its attributes. The bit assignments are shown in Table 34-682.
Table 682. TYPE register bit assignments Bits Name Function
[31:24] [23:16]
IREGION
Reserved. Indicates the number of supported MPU instruction regions. Always contains 0x00. The MPU memory map is unified and is described by the DREGION field.
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Table 682. TYPE register bit assignments Bits Name Function
[15:8] [7:0] [0]
DREGION SEPARATE
Indicates the number of supported MPU data regions:
0x08 = Eight MPU regions.
Reserved. Indicates support for unified or separate instruction and date memory maps: 0 = unified.
4.5.2 MPU Control Register
The MPU CTRL register:
* enables the MPU * enables the default memory map background region * enables use of the MPU when in the hard fault, Non-maskable Interrupt (NMI), and
FAULTMASK escalated handlers. See the register summary in Table 34-681 for the MPU CTRL attributes. The bit assignments are shown in Table 34-683.
Table 683. MPU CTRL register bit assignments Bits Name Function
[31:3] [2]
PRIVDEFENA
Reserved. Enables privileged software access to the default memory map: 0 = If the MPU is enabled, disables use of the default memory map. Any memory access to a location not covered by any enabled region causes a fault. 1 = If the MPU is enabled, enables use of the default memory map as a background region for privileged software accesses. When enabled, the background region acts as if it is region number -1. Any region that is defined and enabled has priority over this default map. If the MPU is disabled, the processor ignores this bit.
[1]
HFNMIENA
Enables the operation of MPU during hard fault, NMI, and FAULTMASK handlers. When the MPU is enabled: 0 = MPU is disabled during hard fault, NMI, and FAULTMASK handlers, regardless of the value of the ENABLE bit 1 = the MPU is enabled during hard fault, NMI, and FAULTMASK handlers. When the MPU is disabled, if this bit is set to 1 the behavior is Unpredictable.
[0]
ENABLE
Enables the MPU: 0 = MPU disabled 1 = MPU enabled.
When ENABLE and PRIVDEFENA are both set to 1:
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* For privileged accesses, the default memory map is as described in Section 34-3.2
"Memory model". Any access by privileged software that does not address an enabled memory region behaves as defined by the default memory map.
* Any access by unprivileged software that does not address an enabled memory
region causes a memory management fault. XN and Strongly-ordered rules always apply to the System Control Space regardless of the value of the ENABLE bit. When the ENABLE bit is set to 1, at least one region of the memory map must be enabled for the system to function unless the PRIVDEFENA bit is set to 1. If the PRIVDEFENA bit is set to 1 and no regions are enabled, then only privileged software can operate. When the ENABLE bit is set to 0, the system uses the default memory map. This has the same memory attributes as if the MPU is not implemented, see Table 34-636 "Memory access behavior". The default memory map applies to accesses from both privileged and unprivileged software. When the MPU is enabled, accesses to the System Control Space and vector table are always permitted. Other areas are accessible based on regions and whether PRIVDEFENA is set to 1. Unless HFNMIENA is set to 1, the MPU is not enabled when the processor is executing the handler for an exception with priority -1 or -2. These priorities are only possible when handling a hard fault or NMI exception, or when FAULTMASK is enabled. Setting the HFNMIENA bit to 1 enables the MPU when operating with these two priorities.
4.5.3 MPU Region Number Register
The RNR selects which memory region is referenced by the RBAR and RASR registers. See the register summary in Table 34-681 for its attributes. The bit assignments are shown in Table 34-684.
Table 684. RNR bit assignments Bits Name Function
[31:8] [7:0]
REGION
Reserved. Indicates the MPU region referenced by the RBAR and RASR registers. The MPU supports 8 memory regions, so the permitted values of this field are 0-7.
Normally, you write the required region number to this register before accessing the RBAR or RASR. However you can change the region number by writing to the RBAR with the VALID bit set to 1, see Table 34-685. This write updates the value of the REGION field.
4.5.4 MPU Region Base Address Register
The RBAR defines the base address of the MPU region selected by the RNR, and can update the value of the RNR. See the register summary in Table 34-681 for its attributes. Write RBAR with the VALID bit set to 1 to change the current region number and update the RNR. The bit assignments are shown in Table 34-685.
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Table 685. RBAR bit assignments
[31:N] [(N-1):5] [4]
ADDR VALID
Region base address field. The value of N depends on the region size. For more information see Section 34-4.5.4.1. Reserved. MPU Region Number valid bit: Write: 0 = RNR not changed, and the processor:
* * * *
[3:0]
updates the base address for the region specified in the RNR ignores the value of the REGION field updates the value of the RNR to the value of the REGION field updates the base address for the region specified in the REGION field.
1 = the processor:
Always reads as zero. REGION MPU region field: For the behavior on writes, see the description of the VALID field. On reads, returns the current region number, as specified by the RNR.
4.5.4.1
The ADDR field The ADDR field is bits[31:N] of the RBAR. The region size, as specified by the SIZE field in the RASR, defines the value of N: N = Log2(Region size in bytes), If the region size is configured to 4GB, in the RASR, there is no valid ADDR field. In this case, the region occupies the complete memory map, and the base address is 0x00000000. The base address is aligned to the size of the region. For example, a 64KB region must be aligned on a multiple of 64KB, for example, at 0x00010000 or 0x00020000.
4.5.5 MPU Region Attribute and Size Register
The RASR defines the region size and memory attributes of the MPU region specified by the RNR, and enables that region and any subregions. See the register summary in Table 34-681 for its attributes. RASR is accessible using word or halfword accesses: The bit assignments are shown in Table 34-686.
* the most significant halfword holds the region attributes * the least significant halfword holds the region size and the region and subregion
enable bits.
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Table 686. RASR bit assignments Bits Name Function
[31:29] [28]
XN
Reserved. Instruction access disable bit: 0 = instruction fetches enabled 1 = instruction fetches disabled.
[27] [26:24] [23:22] [21:19, 17, 16] [18] [15:8]
AP TEX, C, B S SRD
Reserved. Access permission field, see Table 34-690. Reserved. Memory access attributes, see Table 34-688. Shareable bit, see Table 34-688. Subregion disable bits. For each bit in this field: 0 = corresponding sub-region is enabled 1 = corresponding sub-region is disabled See Section 34-4.5.8.3 for more information. Region sizes of 128 bytes and less do not support subregions. When writing the attributes for such a region, write the SRD field as 0x00.
[7:6] [5:1]
SIZE
Reserved. Specifies the size of the MPU protection region. The minimum permitted value is 3 (b00010), see See Section 34-4.5.5.1 for more information. Region enable bit.
[0]
ENABLE
For information about access permission, see Section 34-4.5.6. 4.5.5.1 SIZE field values The SIZE field defines the size of the MPU memory region specified by the RNR. as follows: (Region size in bytes) = 2(SIZE+1) The smallest permitted region size is 32B, corresponding to a SIZE value of 4. Table 34-687 gives example SIZE values, with the corresponding region size and value of N in the RBAR.
Table 687. Example SIZE field values SIZE value Region size Value of N [1] Note
b00100 (4) b01001 (9) b10011 (19) b11101 (29) b11111 (31)
[1]
32B 1KB 1MB 1GB 4GB
5 10 20 30 b01100
Minimum permitted size Maximum possible size
In the RBAR, see Table 34-685.
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4.5.6 MPU access permission attributes
This section describes the MPU access permission attributes. The access permission bits, TEX, C, B, S, AP, and XN, of the RASR, control access to the corresponding memory region. If an access is made to an area of memory without the required permissions, then the MPU generates a permission fault. Table 34-688 shows the encodings for the TEX, C, B, and S access permission bits.
Table 688. TEX, C, B, and S encoding TEX C B S Memory type Shareability Other attributes
b000
0 1
0 1 0 1
x [1] x [1] 0 1 0 1 0 1 x [1] x [1] 0 1 x [1] x [1] x [1] 0 1
Strongly-ordered Device Normal Normal Normal Reserved encoding
Shareable Shareable Not shareable Shareable Not shareable Shareable Not shareable Shareable
Outer and inner write-through. No write allocate. Outer and inner write-back. No write allocate. Outer and inner noncacheable. Outer and inner write-back. Write and read allocate. Nonshared Device. -
b001
0
0 1
1
0 1
Implementation defined attributes. Normal Device Reserved encoding Reserved encoding Normal Not shareable Shareable Not shareable Shareable Not shareable
b010
0 1
0 1 x [1] A
b1BB
A
Cached memory [2], BB = outer policy, AA = inner policy.
[1] [2]
The MPU ignores the value of this bit. See Table 34-689 for the encoding of the AA and BB bits.
Table 34-689 shows the cache policy for memory attribute encodings with a TEX value is in the range 4-7.
Table 689. Cache policy for memory attribute encoding Encoding, AA or BB Corresponding cache policy
00 01 10 11
Non-cacheable Write back, write and read allocate Write through, no write allocate Write back, no write allocate
Table 34-690 shows the AP encodings that define the access permissions for privileged and unprivileged software.
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Table 690. AP encoding AP[2:0] Privileged permissions Unprivileged permissions Description
000 001 010 011 100 101 110 111
No access RW RW RW RO RO RO
No access No access RO RW No access RO RO
All accesses generate a permission fault Access from privileged software only Writes by unprivileged software generate a permission fault Full access Reserved Reads by privileged software only Read only, by privileged or unprivileged software Read only, by privileged or unprivileged software
Unpredictable Unpredictable
4.5.7 MPU mismatch
When an access violates the MPU permissions, the processor generates a memory management fault, see Section 34-3.1.4 "Exceptions and interrupts". The MMFSR indicates the cause of the fault. See Table 34-669 for more information.
4.5.8 Updating an MPU region
To update the attributes for an MPU region, update the RNR, RBAR and RASR registers. You can program each register separately, or use a multiple-word write to program all of these registers. You can use the RBAR and RASR aliases to program up to four regions simultaneously using an STM instruction. 4.5.8.1 Updating an MPU region using separate words Simple code to configure one region: ; R1 = region number ; R2 = size/enable ; R3 = attributes ; R4 = address LDR R0,=MPU_RNR STR R1, [R0, #0x0] STR R4, [R0, #0x4] STRH R2, [R0, #0x8] STRH R3, [R0, #0xA] ; 0xE000ED98, MPU region number register ; Region Number ; Region Base Address ; Region Size and Enable ; Region Attribute
Disable a region before writing new region settings to the MPU if you have previously enabled the region being changed. For example: ; R1 = region number ; R2 = size/enable
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; R3 = attributes ; R4 = address LDR R0,=MPU_RNR STR R1, [R0, #0x0] BIC R2, R2, #1 STRH R2, [R0, #0x8] STR R4, [R0, #0x4] STRH R3, [R0, #0xA] ORR R2, #1 STRH R2, [R0, #0x8] ; 0xE000ED98, MPU region number register ; Region Number ; Disable ; Region Size and Enable ; Region Base Address ; Region Attribute ; Enable ; Region Size and Enable
Software must use memory barrier instructions:
* before MPU setup if there might be outstanding memory transfers, such as buffered
writes, that might be affected by the change in MPU settings
* after MPU setup if it includes memory transfers that must use the new MPU settings.
However, memory barrier instructions are not required if the MPU setup process starts by entering an exception handler, or is followed by an exception return, because the exception entry and exception return mechanism cause memory barrier behavior. Software does not need any memory barrier instructions during MPU setup, because it accesses the MPU through the PPB, which is a Strongly-Ordered memory region. For example, if you want all of the memory access behavior to take effect immediately after the programming sequence, use a DSB instruction and an ISB instruction. A DSB is required after changing MPU settings, such as at the end of context switch. An ISB is required if the code that programs the MPU region or regions is entered using a branch or call. If the programming sequence is entered using a return from exception, or by taking an exception, then you do not require an ISB. 4.5.8.2 Updating an MPU region using multi-word writes You can program directly using multi-word writes, depending on how the information is divided. Consider the following reprogramming: ; R1 = region number ; R2 = address ; R3 = size, attributes in one LDR R0, =MPU_RNR ; 0xE000ED98, MPU region number register
STR R1, [R0, #0x0] ; Region Number STR R2, [R0, #0x4] ; Region Base Address STR R3, [R0, #0x8] ; Region Attribute, Size and Enable
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Use an STM instruction to optimize this: ; R1 = region number ; R2 = address ; R3 = size, attributes in one LDR R0, =MPU_RNR STM R0, {R1-R3} ; 0xE000ED98, MPU region number register ; Region Number, address, attribute, size and enable
You can do this in two words for pre-packed information. This means that the RBAR contains the required region number and had the VALID bit set to 1, see Table 34-685. Use this when the data is statically packed, for example in a boot loader: ; R1 = address and region number in one ; R2 = size and attributes in one LDR R0, =MPU_RBAR ; 0xE000ED9C, MPU Region Base register
STR R1, [R0, #0x0] ; Region base address and ; region number combined with VALID (bit 4) set to 1 STR R2, [R0, #0x4] ; Region Attribute, Size and Enable Use an STM instruction to optimize this: ; R1 = address and region number in one ; R2 = size and attributes in one LDR R0,=MPU_RBAR STM R0, {R1-R2} ; 0xE000ED9C, MPU Region Base register ; Region base address, region number and VALID bit, ; and Region Attribute, Size and Enable 4.5.8.3 Subregions Regions of 256 bytes or more are divided into eight equal-sized subregions. Set the corresponding bit in the SRD field of the RASR to disable a subregion, see Table 34-686. The least significant bit of SRD controls the first subregion, and the most significant bit controls the last subregion. Disabling a subregion means another region overlapping the disabled range matches instead. If no other enabled region overlaps the disabled subregion the MPU issues a fault. Regions of 32, 64, and 128 bytes do not support subregions, With regions of these sizes, you must set the SRD field to 0x00, otherwise the MPU behavior is Unpredictable. Example of SRD use: Two regions with the same base address overlap. Region one is 128KB, and region two is 512KB. To ensure the attributes from region one apply to the first128KB region, set the SRD field for region two to b00000011 to disable the first two subregions, as the figure shows.
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4.5.9 MPU design hints and tips
To avoid unexpected behavior, disable the interrupts before updating the attributes of a region that the interrupt handlers might access. Ensure software uses aligned accesses of the correct size to access MPU registers:
* except for the RASR, it must use aligned word accesses * for the RASR it can use byte or aligned halfword or word accesses.
The processor does not support unaligned accesses to MPU registers. When setting up the MPU, and if the MPU has previously been programmed, disable unused regions to prevent any previous region settings from affecting the new MPU setup. 4.5.9.1 MPU configuration for a microcontroller Usually, a microcontroller system has only a single processor and no caches. In such a system, program the MPU as follows:
Table 691. Memory region attributes for a microcontroller Memory region TEX C B S Memory type and attributes
Flash memory Internal SRAM External SRAM Peripherals
b000 b000 b000 b000
1 1 1 0
0 0 1 1
0 1 1 1
Normal memory, Non-shareable, write-through Normal memory, Shareable, write-through Normal memory, Shareable, write-back, write-allocate Device memory, Shareable
In most microcontroller implementations, the shareability and cache policy attributes do not affect the system behavior. However, using these settings for the MPU regions can make the application code more portable. The values given are for typical situations. In special systems, such as multiprocessor designs or designs with a separate DMA engine, the shareability attribute might be important. In these cases refer to the recommendations of the memory device manufacturer.
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5. ARM Cortex-M3 User Guide: Glossary
Abort -- A mechanism that indicates to a processor that the value associated with a memory access is invalid. An abort can be caused by the external or internal memory system as a result of attempting to access invalid instruction or data memory. Aligned -- A data item stored at an address that is divisible by the number of bytes that defines the data size is said to be aligned. Aligned words and halfwords have addresses that are divisible by four and two respectively. The terms word-aligned and halfword-aligned therefore stipulate addresses that are divisible by four and two respectively. Banked register -- A register that has multiple physical copies, where the state of the processor determines which copy is used. The Stack Pointer, SP (R13) is a banked register. Base register -- In instruction descriptions, a register specified by a load or store instruction that is used to hold the base value for the instruction's address calculation. Depending on the instruction and its addressing mode, an offset can be added to or subtracted from the base register value to form the address that is sent to memory. See also Index register. Big-endian (BE) -- Byte ordering scheme in which bytes of decreasing significance in a data word are stored at increasing addresses in memory. See also Byte-invariant, Endianness, Little-endian. Big-endian memory -- Memory in which:
* a byte or halfword at a word-aligned address is the most significant byte or halfword
within the word at that address
* a byte at a halfword-aligned address is the most significant byte within the halfword at
that address. See also Little-endian memory. Breakpoint -- A breakpoint is a mechanism provided by debuggers to identify an instruction at which program execution is to be halted. Breakpoints are inserted by the programmer to enable inspection of register contents, memory locations, variable values at fixed points in the program execution to test that the program is operating correctly. Breakpoints are removed after the program is successfully tested. Byte-invariant -- In a byte-invariant system, the address of each byte of memory remains unchanged when switching between little-endian and big-endian operation. When a data item larger than a byte is loaded from or stored to memory, the bytes making up that data item are arranged into the correct order depending on the endianness of the memory access. An ARM byte-invariant implementation also supports unaligned halfword and word memory accesses. It expects multi-word accesses to be word-aligned. Cache -- A block of on-chip or off-chip fast access memory locations, situated between the processor and main memory, used for storing and retrieving copies of often used instructions, data, or instructions and data. This is done to greatly increase the average speed of memory accesses and so improve processor performance.
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Condition field -- A four-bit field in an instruction that specifies a condition under which the instruction can execute. Context -- The environment that each process operates in for a multitasking operating system. In ARM processors, this is limited to mean the physical address range that it can access in memory and the associated memory access permissions. Coprocessor -- A processor that supplements the main processor. Cortex-M3 does not support any coprocessors. Debugger -- A debugging system that includes a program, used to detect, locate, and correct software faults, together with custom hardware that supports software debugging. Direct Memory Access (DMA) -- An operation that accesses main memory directly, without the processor performing any accesses to the data concerned. Doubleword -- A 64-bit data item. The contents are taken as being an unsigned integer unless otherwise stated. Doubleword-aligned -- A data item having a memory address that is divisible by eight. Endianness -- Byte ordering. The scheme that determines the order that successive bytes of a data word are stored in memory. An aspect of the system's memory mapping. See also Little-endian and Big-endian. Exception -- An event that interrupts program execution. When an exception occurs, the processor suspends the normal program flow and starts execution at the address indicated by the corresponding exception vector. The indicated address contains the first instruction of the handler for the exception. An exception can be an interrupt request, a fault, or a software-generated system exception. Faults include attempting an invalid memory access, attempting to execute an instruction in an invalid processor state, and attempting to execute an undefined instruction. Exception service routine -- See also Interrupt handler. Exception vector -- See also Interrupt vector. Flat address mapping -- A system of organizing memory in which each physical address in the memory space is the same as the corresponding virtual address. Halfword -- A 16-bit data item. Illegal instruction -- An instruction that is architecturally Undefined. Implementation-defined -- The behavior is not architecturally defined, but is defined and documented by individual implementations. Implementation-specific -- The behavior is not architecturally defined, and does not have to be documented by individual implementations. Used when there are a number of implementation options available and the option chosen does not affect software compatibility.
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Index register -- In some load and store instruction descriptions, the value of this register is used as an offset to be added to or subtracted from the base register value to form the address that is sent to memory. Some addressing modes optionally enable the index register value to be shifted prior to the addition or subtraction. See also Base register. Instruction cycle count -- The number of cycles that an instruction occupies the Execute stage of the pipeline. Interrupt handler -- A program that control of the processor is passed to when an interrupt occurs. Interrupt vector -- One of a number of fixed addresses in low memory, or in high memory if high vectors are configured, that contains the first instruction of the corresponding interrupt handler. Little-endian (LE) -- Byte ordering scheme in which bytes of increasing significance in a data word are stored at increasing addresses in memory. See also Big-endian, Byte-invariant, Endianness. Little-endian memory -- Memory in which:
* a byte or halfword at a word-aligned address is the least significant byte or halfword
within the word at that address
* a byte at a halfword-aligned address is the least significant byte within the halfword at
that address. See also Big-endian memory. Load/store architecture -- A processor architecture where data-processing operations only operate on register contents, not directly on memory contents. Memory Protection Unit (MPU) -- Hardware that controls access permissions to blocks of memory. An MPU does not perform any address translation. Prefetching -- In pipelined processors, the process of fetching instructions from memory to fill up the pipeline before the preceding instructions have finished executing. Prefetching an instruction does not mean that the instruction has to be executed. Read -- Reads are defined as memory operations that have the semantics of a load. Reads include the Thumb instructions LDM, LDR, LDRSH, LDRH, LDRSB, LDRB, and POP. Region -- A partition of memory space. Reserved -- A field in a control register or instruction format is reserved if the field is to be defined by the implementation, or produces Unpredictable results if the contents of the field are not zero. These fields are reserved for use in future extensions of the architecture or are implementation-specific. All reserved bits not used by the implementation must be written as 0 and read as 0. Should Be One (SBO) -- Write as 1, or all 1s for bit fields, by software. Writing as 0 produces Unpredictable results. Should Be Zero (SBZ) -- Write as 0, or all 0s for bit fields, by software. Writing as 1 produces Unpredictable results.
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Should Be Zero or Preserved (SBZP) -- Write as 0, or all 0s for bit fields, by software, or preserved by writing the same value back that has been previously read from the same field on the same processor. Thread-safe -- In a multi-tasking environment, thread-safe functions use safeguard mechanisms when accessing shared resources, to ensure correct operation without the risk of shared access conflicts. Thumb instruction -- One or two halfwords that specify an operation for a processor to perform. Thumb instructions must be halfword-aligned. Unaligned -- A data item stored at an address that is not divisible by the number of bytes that defines the data size is said to be unaligned. For example, a word stored at an address that is not divisible by four. Unpredictable (UNP) -- You cannot rely on the behavior. Unpredictable behavior must not represent security holes. Unpredictable behavior must not halt or hang the processor, or any parts of the system. Warm reset -- Also known as a core reset. Initializes the majority of the processor excluding the debug controller and debug logic. This type of reset is useful if you are using the debugging features of a processor. WA -- See Write-allocate. WB -- See Write-back. Word -- A 32-bit data item. Write -- Writes are defined as operations that have the semantics of a store. Writes include the Thumb instructions STM, STR, STRH, STRB, and PUSH. Write-allocate (WA) -- In a write-allocate cache, a cache miss on storing data causes a cache line to be allocated into the cache. Write-back (WB) -- In a write-back cache, data is only written to main memory when it is forced out of the cache on line replacement following a cache miss. Otherwise, writes by the processor only update the cache. This is also known as copyback. Write buffer -- A block of high-speed memory, arranged as a FIFO buffer, between the data cache and main memory, whose purpose is to optimize stores to main memory. Write-through (WT) -- In a write-through cache, data is written to main memory at the same time as the cache is updated.
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1. Abbreviations
Table 692. Abbreviations Acronym Description
ADC AHB AMBA APB BOD CAN DAC DCC DMA DSP EOP ETM GPIO IrDA JTAG MIIM PHY PLL PWM RMII SE0 SPI SSI SSP TTL UART USB
Analog-to-Digital Converter Advanced High-performance Bus Advanced Microcontroller Bus Architecture Advanced Peripheral Bus BrownOut Detection Controller Area Network Digital-to-Analog Converter Debug Communication Channel Direct Memory Access Digital Signal Processing End Of Packet Embedded Trace Macrocell General Purpose Input/Output Infrared Data Association Joint Test Action Group Media Independent Interface Management Physical Layer Phase-Locked Loop Pulse Width Modulator Reduced Media Independent Interface Single Ended Zero Serial Peripheral Interface Serial Synchronous Interface Synchronous Serial Port Transistor-Transistor Logic Universal Asynchronous Receiver/Transmitter Universal Serial Bus
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2. Legal information
2.1 Definitions
Suitability for use -- NXP Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of an NXP Semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. NXP Semiconductors accepts no liability for inclusion and/or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer's own risk. Applications -- Applications that are described herein for any of these products are for illustrative purposes only. NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Export control -- This document as well as the item(s) described herein may be subject to export control regulations. Export might require a prior authorization from national authorities.
Draft -- The document is a draft version only. The content is still under internal review and subject to formal approval, which may result in modifications or additions. NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information.
2.2
Disclaimers
General -- Information in this document is believed to be accurate and reliable. However, NXP Semiconductors does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. Right to make changes -- NXP Semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof.
2.3
Trademarks
Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners. I2C-bus -- logo is a trademark of NXP B.V.
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Notes
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3. Tables
Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Ordering information . . . . . . . . . . . . . . . . . . . . .7 Ordering options for LPC17xx parts . . . . . . . . . .7 LPC17xx memory usage and details . . . . . . . .12 APB0 peripherals and base addresses . . . . . .14 APB1 peripherals and base addresses . . . . . .15 Pin summary. . . . . . . . . . . . . . . . . . . . . . . . . . .17 Summary of system control registers . . . . . . . .18 Reset Source Identification register (RSID address 0x400F C180) bit description . . . . . . .21 External Interrupt registers . . . . . . . . . . . . . . . .24 External Interrupt Flag register (EXTINT - address 0x400F C140) bit description . . . . . . . . . . . . . .25 External Interrupt Mode register (EXTMODE address 0x400F C148) bit description . . . . . . .26 External Interrupt Polarity register (EXTPOLAR address 0x400F C14C) bit description . . . . . . .26 System Controls and Status register (SCS address 0x400F C1A0) bit description . . . . . . .28 Summary of system control registers . . . . . . . .30 Recommended values for CX1/X2 in oscillation mode (crystal and external components parameters) low frequency mode (OSCRANGE = 0, see Table 3-13) . . . . . . . . . . . . . . . . . . . . . .32 Recommended values for CX1/X2 in oscillation mode (crystal and external components parameters) high frequency mode (OSCRANGE = 1, see Table 3-13) . . . . . . . . . . . . . . . . . . . . . .32 Clock Source Select register (CLKSRCSEL address 0x400F C10C) bit description . . . . . . .34 PLL0 registers . . . . . . . . . . . . . . . . . . . . . . . . .36 PLL Control register (PLL0CON - address 0x400F C080) bit description . . . . . . . . . . . . . .37 PLL0 Configuration register (PLL0CFG - address 0x400F C084) bit description . . . . . . . . . . . . . .37 Multiplier values for PLL0 with a 32 kHz input .38 PLL Status register (PLL0STAT - address 0x400F C088) bit description . . . . . . . . . . . . . .39 PLL control bit combinations . . . . . . . . . . . . . .40 PLL Feed register (PLL0FEED - address 0x400F C08C) bit description . . . . . . . . . . . . . .40 PLL frequency parameter . . . . . . . . . . . . . . . . .41 Additional Multiplier Values for use with a Low Frequency Clock Input . . . . . . . . . . . . . . . . . . .42 Summary of PLL0 examples . . . . . . . . . . . . . .43 Potential values for PLL example . . . . . . . . . . .45 PLL1 registers . . . . . . . . . . . . . . . . . . . . . . . . .47 PLL1 Control register (PLL1CON - address 0x400F C0A0) bit description . . . . . . . . . . . . . .50 Table 31. PLL Configuration register (PLL1CFG - address 0x400F C0A4) bit description. . . . . . . . . . . . . . 50 Table 32. PLL1 Status register (PLL1STAT - address 0x400F C0A8) bit description. . . . . . . . . . . . . . 51 Table 33. PLL1 control bit combinations . . . . . . . . . . . . . 51 Table 34. PLL1 Feed register (PLL1FEED - address 0x400F C0AC) bit description . . . . . . . . . . . . . 52 Table 35. Elements determining PLL frequency . . . . . . . 53 Table 36. PLL1 Divider values . . . . . . . . . . . . . . . . . . . . 54 Table 37. PLL1 Multiplier values . . . . . . . . . . . . . . . . . . . 54 Table 38. CPU Clock Configuration register (CCLKCFG address 0x400F C104) bit description . . . . . . . 55 Table 39. USB Clock Configuration register (USBCLKCFG address 0x400F C108) bit description . . . . . . . 56 Table 40. Peripheral Clock Selection register 0 (PCLKSEL0 - address 0x400F C1A8) bit description. . . . . . 57 Table 41. Peripheral Clock Selection register 1 (PCLKSEL1 - address 0x400F C1AC) bit description . . . . . 57 Table 42. Peripheral Clock Selection register bit values . 58 Table 43. Power Control registers . . . . . . . . . . . . . . . . . . 61 Table 44. Power Mode Control register (PCON - address 0x400F C0C0) bit description . . . . . . . . . . . . . 62 Table 45. Encoding of reduced power modes . . . . . . . . . 63 Table 46. Power Control for Peripherals register (PCONP address 0x400F C0C4) bit description. . . . . . . 64 Table 47. Clock Output Configuration register (CLKOUTCFG - 0x400F C1C8) bit description 67 Table 48. Summary of flash accelerator registers . . . . . . 70 Table 49. Flash Accelerator Configuration register (FLASHCFG - address 0x400F C000) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Table 50. Connection of interrupt sources to the Vectored Interrupt Controller . . . . . . . . . . . . . . . . . . . . . . 74 Table 51. NVIC register map . . . . . . . . . . . . . . . . . . . . . 77 Table 52. Interrupt Set-Enable Register 0 register (ISER0 0xE000 E100) . . . . . . . . . . . . . . . . . . . . . . . . . 78 Table 53. Interrupt Set-Enable Register 1 register (ISER1 0xE000 E104) . . . . . . . . . . . . . . . . . . . . . . . . . 79 Table 54. Interrupt Clear-Enable Register 0 (ICER0 0xE000 E180) . . . . . . . . . . . . . . . . . . . . . . . . . 80 Table 55. Interrupt Clear-Enable Register 1 register (ICER1 - 0xE000 E184) . . . . . . . . . . . . . . . . . . . . . . . . 81 Table 56. Interrupt Set-Pending Register 0 register (ISPR0 0xE000 E200) . . . . . . . . . . . . . . . . . . . . . . . . . 82 Table 57. Interrupt Set-Pending Register 1 register (ISPR1 0xE000 E204) . . . . . . . . . . . . . . . . . . . . . . . . . 83 Table 58. Interrupt Clear-Pending Register 0 register (ICPR0 - 0xE000 E280) . . . . . . . . . . . . . . . . . 84
Table 16.
Table 17. Table 18. Table 19. Table 20. Table 21. Table 22. Table 23. Table 24. Table 25. Table 26. Table 27. Table 28. Table 29. Table 30.
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0x4002 C044) bit description . . . . . . . . . . . . . 110 Table 88. Pin Mode select register 2 (PINMODE2 - address 0x4002 C048) bit description . . . . . . . . . . . . . 111 Table 89. Pin Mode select register 3 (PINMODE3 - address 0x4002 C04C) bit description. . . . . . . . . . . . . 111 Table 90. Pin Mode select register 4 (PINMODE4 - address 0x4002 C050) bit description . . . . . . . . . . . . . 112 Table 91. Pin Mode select register 7 (PINMODE7 - address 0x4002 C05C) bit description. . . . . . . . . . . . . 113 Table 92. Pin Mode select register 9 (PINMODE9 - address 0x4002 C064) bit description . . . . . . . . . . . . . 113 Table 93. Open Drain Pin Mode select register 0 (PINMODE_OD0 - address 0x4002 C068) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Table 94. Open Drain Pin Mode select register 1 (PINMODE_OD1 - address 0x4002 C06C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Table 95. Open Drain Pin Mode select register 2 (PINMODE_OD2 - address 0x4002 C070) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Table 96. Open Drain Pin Mode select register 3 (PINMODE_OD3 - address 0x4002 C074) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Table 97. Open Drain Pin Mode select register 4 (PINMODE_OD4 - address 0x4002 C078) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Table 98. I2C Pin Configuration register (I2CPADCFG address 0x4002 C07C) bit description. . . . . . 117 Table 99. GPIO pin description . . . . . . . . . . . . . . . . . . . 119 Table 100.GPIO register map (local bus accessible registers - enhanced GPIO features) . . . . . . . . . . . . . . 120 Table 101.GPIO interrupt register map. . . . . . . . . . . . . . 121 Table 102.Fast GPIO port Direction register FIO0DIR to FIO4DIR - addresses 0x2009 C000 to 0x2009 C080) bit description . . . . . . . . . . . . . . . . . . . 121 Table 103.Fast GPIO port Direction control byte and half-word accessible register description . . . . 122 Table 104.Fast GPIO port output Set register (FIO0SET to FIO4SET - addresses 0x2009 C018 to 0x2009 C098) bit description . . . . . . . . . . . . . . . . . . . 123 Table 105.Fast GPIO port output Set byte and half-word accessible register description. . . . . . . . . . . . 123 Table 106.Fast GPIO port output Clear register (FIO0CLR to FIO4CLR- addresses 0x2009 C01C to 0x2009 C09C) bit description . . . . . . . . . . . . . . . . . . . 124 Table 107.Fast GPIO port output Clear byte and half-word accessible register description. . . . . . . . . . . . 124 Table 108.Fast GPIO port Pin value register (FIO0PIN to FIO4PIN- addresses 0x2009 C014 to 0x2009 C094) bit description . . . . . . . . . . . . . . . . . . . 125 Table 109.Fast GPIO port Pin value byte and half-word
Table 59. Interrupt Set-Pending Register 1 register (ISPR1 0xE000 E204) . . . . . . . . . . . . . . . . . . . . . . . . .85 Table 60. Interrupt Active Bit Register 0 (IABR0 - 0xE000 E300) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86 Table 61. Interrupt Active Bit Register 1 (IABR1 - 0xE000 E304) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Table 62. Interrupt Priority Register 0 (IPR0 - 0xE000 E400) 88 Table 63. Interrupt Priority Register 1 (IPR1 - 0xE000 E404) 88 Table 64. Interrupt Priority Register 2 (IPR2 - 0xE000 E408) 88 Table 65. Interrupt Priority Register 3 (IPR3 - 0xE000 E40C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89 Table 66. Interrupt Priority Register 4 (IPR4 - 0xE000 E410) 89 Table 67. Interrupt Priority Register 5 (IPR5 - 0xE000 E414) 89 Table 68. Interrupt Priority Register 6 (IPR6 - 0xE000 E418) 90 Table 69. Interrupt Priority Register 7 (IPR7 - 0xE000 E41C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90 Table 70. Interrupt Priority Register 8 (IPR8 0xE000 E420) . . . . . . . . . . . . . . . . . . . . . . . . .90 Table 71. Software Trigger Interrupt Register (STIR 0xE000 EF00) . . . . . . . . . . . . . . . . . . . . . . . . .91 Table 72. Pin description . . . . . . . . . . . . . . . . . . . . . . . . .93 Table 73. Summary of PINSEL registers . . . . . . . . . . . .102 Table 74. Pin function select register bits . . . . . . . . . . . .102 Table 75. Pin Mode Select register Bits . . . . . . . . . . . . .103 Table 76. Open Drain Pin Mode Select register Bits . . .104 Table 77. Pin Connect Block Register Map . . . . . . . . . .105 Table 78. Pin function select register 0 (PINSEL0 - address 0x4002 C000) bit description . . . . . . . . . . . . .106 Table 79. Pin function select register 1 (PINSEL1 - address 0x4002 C004) bit description . . . . . . . . . . . . .106 Table 80. Pin function select register 2 (PINSEL2 - address 0x4002 C008) bit description . . . . . . . . . . . . .107 Table 81. Pin function select register 3 (PINSEL3 - address 0x4002 C00C) bit description . . . . . . . . . . . .107 Table 82. Pin function select register 4 (PINSEL4 - address 0x4002 C010) bit description . . . . . . . . . . . . .108 Table 83. Pin function select register 7 (PINSEL7 - address 0x4002 C01C) bit description . . . . . . . . . . . .109 Table 84. Pin function select register 9 (PINSEL9 - address 0x4002 C024) bit description . . . . . . . . . . . . .109 Table 85. Pin function select register 10 (PINSEL10 address 0x4002 C028) bit description . . . . . .109 Table 86. Pin Mode select register 0 (PINMODE0 - address 0x4002 C040) bit description . . . . . . . . . . . . . 110 Table 87. Pin Mode select register 1 (PINMODE1 - address
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Table 134.Maximum Frame register (MAXF - address 0x5000 0014) bit description . . . . . . . . . . . . . 151 Table 135.PHY Support register (SUPP - address 0x5000 0018) bit description . . . . . . . . . . . . . 151 Table 136. Test register (TEST - address 0x5000 ) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Table 137.MII Mgmt Configuration register (MCFG - address 0x5000 0020) bit description . . . . . . . . . . . . . 152 Table 138. Clock select encoding . . . . . . . . . . . . . . . . . . 152 Table 139.MII Mgmt Command register (MCMD - address 0x5000 0024) bit description . . . . . . . . . . . . . 153 Table 140.MII Mgmt Address register (MADR - address 0x5000 0028) bit description . . . . . . . . . . . . . 153 Table 141.MII Mgmt Write Data register (MWTD - address 0x5000 002C) bit description . . . . . . . . . . . . . 154 Table 142.MII Mgmt Read Data register (MRDD - address 0x5000 0030) bit description . . . . . . . . . . . . . 154 Table 143.MII Mgmt Indicators register (MIND - address 0x5000 0034) bit description . . . . . . . . . . . . . 154 Table 144.Station Address register (SA0 - address 0x5000 0040) bit description . . . . . . . . . . . . . 155 Table 145.Station Address register (SA1 - address 0x5000 0044) bit description . . . . . . . . . . . . . 155 Table 146.Station Address register (SA2 - address 0x5000 0048) bit description . . . . . . . . . . . . . 155 Table 147.Command register (Command - address 0x5000 0100) bit description . . . . . . . . . . . . . 156 Table 148.Status register (Status - address 0x5000 0104) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Table 149.Receive Descriptor Base Address register (RxDescriptor - address 0x5000 0108) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 Table 150.receive Status Base Address register (RxStatus address 0x5000 010C) bit description . . . . . . 157 Table 151.Receive Number of Descriptors register (RxDescriptor - address 0x5000 0110) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Table 152.Receive Produce Index register (RxProduceIndex - address 0x5000 0114) bit description . . . . . 158 Table 153.Receive Consume Index register (RxConsumeIndex - address 0x5000 0118) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Table 154.Transmit Descriptor Base Address register (TxDescriptor - address 0x5000 011C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Table 155.Transmit Status Base Address register (TxStatus address 0x5000 0120) bit description . . . . . . 159 Table 156.Transmit Number of Descriptors register (TxDescriptorNumber - address 0x5000 0124) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Table 157.Transmit Produce Index register (TxProduceIndex
accessible register description . . . . . . . . . . . .126 Table 110. Fast GPIO port Mask register (FIO0MASK to FIO4MASK - addresses 0x2009 C010 to 0x2009 C090) bit description. . . . . . . . . . . . . . . . . . . .127 Table 111. Fast GPIO port Mask byte and half-word accessible register description . . . . . . . . . . . .127 Table 112. GPIO overall Interrupt Status register (IOIntStatus - address 0x4002 8080) bit description . . . . .129 Table 113. GPIO Interrupt Enable for port 0 Rising Edge (IO0IntEnR - 0x4002 8090) bit description . . .129 Table 114. GPIO Interrupt Enable for port 2 Rising Edge (IO2IntEnR - 0x4002 80B0) bit description . . .130 Table 115. GPIO Interrupt Enable for port 0 Falling Edge (IO0IntEnF - address 0x4002 8094) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .131 Table 116. GPIO Interrupt Enable for port 2 Falling Edge (IO2IntEnF - 0x4002 80B4) bit description . . .132 Table 117. GPIO Interrupt Status for port 0 Rising Edge Interrupt (IO0IntStatR - 0x4002 8084) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .133 Table 118. GPIO Interrupt Status for port 2 Rising Edge Interrupt (IO2IntStatR - 0x4002 80A4) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .134 Table 119. GPIO Interrupt Status for port 0 Falling Edge Interrupt (IO0IntStatF - 0x4002 8088) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .134 Table 120.GPIO Interrupt Status for port 2 Falling Edge Interrupt (IO2IntStatF - 0x4002 80A8) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .135 Table 121.GPIO Interrupt Clear register for port 0 (IO0IntClr - 0x4002 808C)) bit description . . . . . . . . . . .136 Table 122.GPIO Interrupt Clear register for port 0 (IO2IntClr - 0x4002 80AC) bit description . . . . . . . . . . . .137 Table 123.Ethernet acronyms, abbreviations, and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . .139 Table 124.Example PHY Devices . . . . . . . . . . . . . . . . . .145 Table 125.Ethernet RMII pin descriptions . . . . . . . . . . . .145 Table 126.Ethernet MIIM pin descriptions . . . . . . . . . . . .145 Table 127.Ethernet register definitions . . . . . . . . . . . . . .146 Table 128.MAC Configuration register 1 (MAC1 - address 0x5000 0000) bit description . . . . . . . . . . . . .148 Table 129.MAC Configuration register 2 (MAC2 - address 0x5000 0004) bit description . . . . . . . . . . . . .149 Table 130. Pad operation . . . . . . . . . . . . . . . . . . . . . . . .150 Table 131.Back-to-back Inter-packet-gap register (IPGT address 0x5000 0008) bit description. . . . . . .150 Table 132. Non Back-to-back Inter-packet-gap register (IPGR - address 0x5000 000C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .150 Table 133.Collision Window / Retry register (CLRT - address 0x5000 0010) bit description . . . . . . . . . . . . .151
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
803 of 835
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UM10360
Chapter 35: LPC17xx Supplementary information
Table 187.USB device register map . . . . . . . . . . . . . . . . 218 Table 188.USBClkCtrl register (USBClkCtrl - address 0x5000 CFF4) bit description. . . . . . . . . . . . . 219 Table 189.USB Clock Status register (USBClkSt - address 0x5000 CFF8) bit description. . . . . . . . . . . . . 220 Table 190.USB Interrupt Status register (USBIntSt - address 0x5000 C1C0) bit description. . . . . . . . . . . . . 220 Table 191.USB Device Interrupt Status register (USBDevIntSt - address 0x5000 C200) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 Table 192.USB Device Interrupt Status register (USBDevIntSt - address 0x5000 C200) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 Table 193.USB Device Interrupt Enable register (USBDevIntEn - address 0x5000 C204) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Table 194.USB Device Interrupt Enable register (USBDevIntEn - address 0x5000 C204) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Table 195.USB Device Interrupt Clear register (USBDevIntClr - address 0x5000 C208) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Table 196.USB Device Interrupt Clear register (USBDevIntClr - address 0x5000 C208) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Table 197.USB Device Interrupt Set register (USBDevIntSet - address 0x5000 C20C) bit allocation . . . . . 223 Table 198.USB Device Interrupt Set register (USBDevIntSet - address 0x5000 C20C) bit description . . . . 223 Table 199.USB Device Interrupt Priority register (USBDevIntPri - address 0x5000 C22C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Table 200.USB Endpoint Interrupt Status register (USBEpIntSt - address 0x5000 C230) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Table 201.USB Endpoint Interrupt Status register (USBEpIntSt - address 0x5000 C230) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Table 202.USB Endpoint Interrupt Enable register (USBEpIntEn - address 0x5000 C234) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Table 203.USB Endpoint Interrupt Enable register (USBEpIntEn - address 0x5000 C234) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Table 204.USB Endpoint Interrupt Clear register (USBEpIntClr - address 0x5000 C238) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Table 205.USB Endpoint Interrupt Clear register (USBEpIntClr - address 0x5000 C238) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 Table 206.USB Endpoint Interrupt Set register (USBEpIntSet
- address 0x5000 0128) bit description . . . . .160 Table 158.Transmit Consume Index register (TxConsumeIndex - address 0x5000 012C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .160 Table 159. Transmit Status Vector 0 register (TSV0 - address 0x5000 0158) bit description . . . . . . . . . . . . .161 Table 160.Transmit Status Vector 1 register (TSV1 - address 0x5000 015C) bit description . . . . . . . . . . . . .162 Table 161.Receive Status Vector register (RSV - address 0x5000 0160) bit description . . . . . . . . . . . . .162 Table 162.Flow Control Counter register (FlowControlCounter - address 0x5000 0170) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .163 Table 163.Flow Control Status register (FlowControlStatus address 0x5000 8174) bit description. . . . . . .163 Table 164.Receive Filter Control register (RxFilterCtrl address 0x5000 0200) bit description. . . . . . .164 Table 165.Receive Filter WoL Status register (RxFilterWoLStatus - address 0x5000 0204) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .164 Table 166.Receive Filter WoL Clear register (RxFilterWoLClear - address 0x5000 0208) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .165 Table 167.Hash Filter Table LSBs register (HashFilterL address 0x5000 0210) bit description. . . . . . .165 Table 168.Hash Filter MSBs register (HashFilterH - address 0x5000 0214) bit description . . . . . . . . . . . . .166 Table 169.Interrupt Status register (IntStatus - address 0x5000 0FE0) bit description . . . . . . . . . . . . .166 Table 170.Interrupt Enable register (intEnable - address 0x5000 0FE4) bit description . . . . . . . . . . . . .167 Table 171.Interrupt Clear register (IntClear - address 0x5000 0FE8) bit description . . . . . . . . . . . . .168 Table 172.Interrupt Set register (IntSet - address 0x5000 0FEC) bit description . . . . . . . . . . . . .168 Table 173.Power-Down register (PowerDown - address 0x5000 0FF4) bit description . . . . . . . . . . . . .169 Table 174.Receive Descriptor Fields. . . . . . . . . . . . . . . .171 Table 175.Receive Descriptor Control Word . . . . . . . . . .171 Table 176.Receive Status Fields . . . . . . . . . . . . . . . . . . .171 Table 177.Receive Status HashCRC Word . . . . . . . . . . .172 Table 178.Receive status information word. . . . . . . . . . .172 Table 179.Transmit descriptor fields . . . . . . . . . . . . . . . .174 Table 180.Transmit descriptor control word . . . . . . . . . .174 Table 181.Transmit status fields . . . . . . . . . . . . . . . . . . .174 Table 182.Transmit status information word . . . . . . . . . .175 Table 183.USB related acronyms, abbreviations, and definitions used in this chapter . . . . . . . . . . . .212 Table 184.Fixed endpoint configuration. . . . . . . . . . . . . .213 Table 185.USB external interface . . . . . . . . . . . . . . . . . .216 Table 186.USB device controller clock sources . . . . . . .217
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UM10360_1
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User manual
Rev. 01 -- 4 January 2010
804 of 835
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UM10360
Chapter 35: LPC17xx Supplementary information
(USBDMAIntEn - address 0x5000 C294) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Table 231.USB End of Transfer Interrupt Status register (USBEoTIntSt - address 0x5000 C2A0s) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Table 232.USB End of Transfer Interrupt Clear register (USBEoTIntClr - address 0x5000 C2A4) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Table 233.USB End of Transfer Interrupt Set register (USBEoTIntSet - address 0x5000 C2A8) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Table 234.USB New DD Request Interrupt Status register (USBNDDRIntSt - address 0x5000 C2AC) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Table 235.USB New DD Request Interrupt Clear register (USBNDDRIntClr - address 0x5000 C2B0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Table 236.USB New DD Request Interrupt Set register (USBNDDRIntSet - address 0x5000 C2B4) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Table 237.USB System Error Interrupt Status register (USBSysErrIntSt - address 0x5000 C2B8) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Table 238.USB System Error Interrupt Clear register (USBSysErrIntClr - address 0x5000 C2BC) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Table 239.USB System Error Interrupt Set register (USBSysErrIntSet - address 0x5000 C2C0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Table 240.SIE command code table . . . . . . . . . . . . . . . . 243 Table 241.Set Address command bit description . . . . . . 243 Table 242.Configure Device command bit description . . 244 Table 243.Set Mode command bit description . . . . . . . . 244 Table 244.Set Device Status command bit description. . 245 Table 245.Get Error Code command bit description. . . . 247 Table 246.Read Error Status command bit description . 247 Table 247.Select Endpoint command bit description . . . 248 Table 248.Set Endpoint Status command bit description 249 Table 249.Clear Buffer command bit description . . . . . . 250 Table 250.DMA descriptor . . . . . . . . . . . . . . . . . . . . . . . 255 Table 251.USB (OHCI) related acronyms and abbreviations used in this chapter . . . . . . . . . . . . . . . . . . . . 267 Table 252.USB Host port pins . . . . . . . . . . . . . . . . . . . . 269 Table 253.USB Host register address definitions . . . . . 269 Table 254.USB OTG port pins . . . . . . . . . . . . . . . . . . . . 273 Table 255.USB OTG and I2C register address definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 Table 256.USB Interrupt Status register - (USBIntSt address 0x5000 C1C0) bit description. . . . . . 275 Table 257.OTG Interrupt Status register (OTGIntSt - address 0x5000 C100) bit description . . . . . . . . . . . . . 276
- address 0x5000 C23C) bit allocation . . . . .227 Table 207.USB Endpoint Interrupt Set register (USBEpIntSet - address 0x5000 C23C) bit description . . . .227 Table 208.USB Endpoint Interrupt Priority register (USBEpIntPri - address 0x5000 C240) bit allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . .227 Table 209.USB Endpoint Interrupt Priority register (USBEpIntPri - address 0x5000 C240) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .228 Table 210.USB Realize Endpoint register (USBReEp address 0x5000 C244) bit allocation . . . . . .229 Table 211. USB Realize Endpoint register (USBReEp address 0x5000 C244) bit description . . . . . .229 Table 212.USB Endpoint Index register (USBEpIn - address 0x5000 C248) bit description . . . . . . . . . . . . .230 Table 213.USB MaxPacketSize register (USBMaxPSize address 0x5000 C24C) bit description. . . . . .230 Table 214.USB Receive Data register (USBRxData address 0x5000 C218) bit description . . . . . .231 Table 215.USB Receive Packet Length register (USBRxPlen - address 0x5000 C220) bit description . . . . .231 Table 216.USB Transmit Data register (USBTxData address 0x5000 C21C) bit description. . . . . .231 Table 217.USB Transmit Packet Length register (USBTxPLen - address 0x5000 C224) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .232 Table 218.USB Control register (USBCtrl - address 0x5000 C228) bit description . . . . . . . . . . . . . . . . . . .232 Table 219.USB Command Code register (USBCmdCode address 0x5000 C210) bit description . . . . . .233 Table 220.USB Command Data register (USBCmdData address 0x5000 C214) bit description . . . . . .233 Table 221.USB DMA Request Status register (USBDMARSt - address 0x5000 C250) bit allocation . . . . .233 Table 222.USB DMA Request Status register (USBDMARSt - address 0x5000 C250) bit description . . . . .234 Table 223.USB DMA Request Clear register (USBDMARClr - address 0x5000 C254) bit description . . . . .234 Table 224.USB DMA Request Set register (USBDMARSet address 0x5000 C258) bit description . . . . . .235 Table 225.USB UDCA Head register (USBUDCAH - address 0x5000 C280) bit description . . . . . . . . . . . . .235 Table 226.USB EP DMA Status register (USBEpDMASt address 0x5000 C284) bit description . . . . . .235 Table 227.USB EP DMA Enable register (USBEpDMAEn address 0x5000 C288) bit description . . . . . .236 Table 228.USB EP DMA Disable register (USBEpDMADis address 0x5000 C28C) bit description. . . . . .236 Table 229.USB DMA Interrupt Status register (USBDMAIntSt - address 0x5000 C290) bit description . . . . .236 Table 230.USB DMA Interrupt Enable register
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
805 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
0x4009 C00C) bit description. . . . . . . . . . . . . 304 Table 279:UARTn Line Status Register (U0LSR - address 0x4000 C014, U2LSR - 0x4009 8014, U3LSR 0x4009 C014) bit description . . . . . . . . . . . . . 305 Table 280:UARTn Scratch Pad Register (U0SCR - address 0x4000 C01C, U2SCR - 0x4009 801C, U3SCR 0x4009 C01C) bit description. . . . . . . . . . . . . 306 Table 281:UARTn Auto-baud Control Register (U0ACR address 0x4000 C020, U2ACR - 0x4009 8020, U3ACR - 0x4009 C020) bit description . . . . . 306 Table 282:UARTn IrDA Control Register (U0ICR - 0x4000 C024, U2ICR - 0x4009 8024, U3ICR - 0x4009 C024) bit description . . . . . . . . . . . . . . . . . . . 309 Table 283:IrDA Pulse Width . . . . . . . . . . . . . . . . . . . . . . 310 Table 284:UARTn Fractional Divider Register (U0FDR address 0x4000 C028, U2FDR - 0x4009 8028, U3FDR - 0x4009 C028) bit description . . . . . 310 Table 285.Fractional Divider setting look-up table . . . . . 313 Table 286:UARTn Transmit Enable Register (U0TER address 0x4000 C030, U2TER - 0x4009 8030, U3TER - 0x4009 C030) bit description . . . . . 314 Table 287.UARTn FIFO Level register (U0FIFOLVL - 0x4000 C058, U2FIFOLVL - 0x4009 8058, U3FIFOLVL 0x4009 C058) bit description . . . . . . . . . . . . . 314 Table 288:UART1 Pin Description . . . . . . . . . . . . . . . . . 317 Table 289:UART1 register map . . . . . . . . . . . . . . . . . . . 318 Table 290:UART1 Receiver Buffer Register (U1RBR address 0x4001 0000 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Table 291:UART1 Transmitter Holding Register (U1THR address 0x4001 0000 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Table 292:UART1 Divisor Latch LSB Register (U1DLL address 0x4001 0000 when DLAB = 1) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Table 293:UART1 Divisor Latch MSB Register (U1DLM address 0x4001 0004 when DLAB = 1) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Table 294:UART1 Interrupt Enable Register (U1IER address 0x4001 0004 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Table 295:UART1 Interrupt Identification Register (U1IIR address 0x4001 0008) bit description . . . . . . 321 Table 296:UART1 Interrupt Handling . . . . . . . . . . . . . . . 322 Table 297:UART1 FIFO Control Register (U1FCR - address 0x4001 0008) bit description . . . . . . . . . . . . . 323 Table 298:UART1 Line Control Register (U1LCR - address 0x4001 000C) bit description . . . . . . . . . . . . . 324 Table 299:UART1 Modem Control Register (U1MCR address 0x4001 0010) bit description . . . . . . 325 Table 300:Modem status interrupt generation . . . . . . . . 326
Table 258.OTG Status Control register (OTGStCtrl - address 0x5000 C110) bit description . . . . . . . . . . . . .277 Table 259.OTG Timer register (OTGTmr - address 0x5000 C114) bit description . . . . . . . . . . . . .278 Table 260.OTG clock control register (OTG_clock_control address 0x5000 CFF4) bit description . . . . . .278 Table 261.OTG clock status register (OTGClkSt - address 0x5000 CFF8) bit description . . . . . . . . . . . . .279 Table 262.I2C Receive register (I2C_RX - address 0x5000 C300) bit description . . . . . . . . . . . . .280 Table 263.I2C Transmit register (I2C_TX - address 0x5000 C300) bit description . . . . . . . . . . . . .280 Table 264.I2C status register (I2C_STS - address 0x5000 C304) bit description . . . . . . . . . . . . .280 Table 265.I2C Control register (I2C_CTL - address 0x5000 C308) bit description . . . . . . . . . . . . .282 Table 266.I2C_CLKHI register (I2C_CLKHI - address 0x5000 C30C) bit description . . . . . . . . . . . . .283 Table 267.I2C_CLKLO register (I2C_CLKLO - address 0x5000 C310) bit description . . . . . . . . . . . . .283 Table 268:UARTn Pin description . . . . . . . . . . . . . . . . . .297 Table 269.UART0/2/3 Register Map . . . . . . . . . . . . . . . .298 Table 270:UARTn Receiver Buffer Register (U0RBR address 0x4000 C000, U2RBR - 0x4009 8000, U3RBR - 04009 C000 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .299 Table 271:UARTn Transmit Holding Register (U0THR address 0x4000 C000, U2THR - 0x4009 8000, U3THR - 0x4009 C000 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .299 Table 272:UARTn Divisor Latch LSB register (U0DLL address 0x4000 C000, U2DLL - 0x4009 8000, U3DLL - 0x4009 C000 when DLAB = 1) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .300 Table 273:UARTn Divisor Latch MSB register (U0DLM address 0x4000 C004, U2DLM - 0x4009 8004, U3DLM - 0x4009 C004 when DLAB = 1) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .300 Table 274:UARTn Interrupt Enable Register (U0IER address 0x4000 C004, U2IER - 0x4009 8004, U3IER - 0x4009 C004 when DLAB = 0) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .300 Table 275:UARTn Interrupt Identification Register (U0IIR address 0x4000 C008, U2IIR - 0x4009 8008, U3IIR - 0x4009 C008) bit description . . . . . . .301 Table 276:UARTn Interrupt Handling . . . . . . . . . . . . . . .302 Table 277:UARTn FIFO Control Register (U0FCR - address 0x4000 C008, U2FCR - 0x4009 8008, U3FCR 0x4007 C008) bit description . . . . . . . . . . . . .303 Table 278:UARTn Line Control Register (U0LCR - address 0x4000 C00C, U2LCR - 0x4009 800C, U3LCR -
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
806 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
Table 325.CAN Status Register (CAN1SR - address 0x4004 401C, CAN2SR - address 0x4004 801C) bit description. . . . . . . . . . . . . . . . . . . . . . . . . 361 Table 326.CAN Receive Frame Status register (CAN1RFS address 0x4004 4020, CAN2RFS - address 0x4004 8020) bit description . . . . . . . . . . . . . 363 Table 327.CAN Receive Identifier register (CAN1RID address 0x4004 4024, CAN2RID - address 0x4004 8024) bit description . . . . . . . . . . . . . 364 Table 328.RX Identifier register when FF = 1 . . . . . . . . . 364 Table 329.CAN Receive Data register A (CAN1RDA address 0x4004 4028, CAN2RDA - address 0x4004 8028) bit description . . . . . . . . . . . . . 364 Table 330.CAN Receive Data register B (CAN1RDB address 0x4004 402C, CAN2RDB - address 0x4004 802C) bit description . . . . . . . . . . . . . 364 Table 331.CAN Transmit Frame Information register (CAN1TFI[1/2/3] - address 0x4004 40[30/40/50], CAN2TFI[1/2/3] - 0x4004 80[30/40/50]) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 Table 332.CAN Transfer Identifier register (CAN1TID[1/2/3] address 0x4004 40[34/44/54], CAN2TID[1/2/3] address 0x4004 80[34/44/54]) bit description 366 Table 333.Transfer Identifier register when FF = 1. . . . . 367 Table 334.CAN Transmit Data register A (CAN1TDA[1/2/3] address 0x4004 40[38/48/58], CAN2TDA[1/2/3] address 0x4004 80[38/48/58]) bit description 367 Table 335.CAN Transmit Data register B (CAN1TDB[1/2/3] address 0x4004 40[3C/4C/5C], CAN2TDB[1/2/3] address 0x4004 80[3C/4C/5C]) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 367 Table 336.CAN Sleep Clear register (CANSLEEPCLR address 0x400F C110) bit description . . . . . . 368 Table 337.CAN Wake-up Flags register (CANWAKEFLAGS - address 0x400F C114) bit description . . . . . 368 Table 338.Central Transit Status Register (CANTxSR address 0x4004 0000) bit description . . . . . . 370 Table 339.Central Receive Status Register (CANRxSR address 0x4004 0004) bit description . . . . . . 370 Table 340.Central Miscellaneous Status Register (CANMSR - address 0x4004 0008) bit description . . . . . 371 Table 341.Acceptance filter modes and access control . 371 Table 342.Section configuration register settings . . . . . . 372 Table 343.Acceptance Filter Mode Register (AFMR address 0x4003 C000) bit description . . . . . . 375 Table 344.Standard Frame Individual Start Address register (SFF_sa - address 0x4003 C004) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 376 Table 345.Standard Frame Group Start Address register (SFF_GRP_sa - address 0x4003 C008) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 376
Table 301:UART1 Line Status Register (U1LSR - address 0x4001 0014) bit description . . . . . . . . . . . . .327 Table 302:UART1 Modem Status Register (U1MSR address 0x4001 0018) bit description. . . . . . .328 Table 303:UART1 Scratch Pad Register (U1SCR - address 0x4001 0014) bit description . . . . . . . . . . . . .329 Table 304:Auto-baud Control Register (U1ACR - address 0x4001 0020) bit description . . . . . . . . . . . . .329 Table 305:UART1 Fractional Divider Register (U1FDR address 0x4001 0028) bit description. . . . . . .333 Table 306.Fractional Divider setting look-up table. . . . . .335 Table 307:UART1 Transmit Enable Register (U1TER address 0x4001 0030) bit description. . . . . . .336 Table 308:UART1 RS485 Control register (U1RS485CTRL address 0x4001 004C) bit description . . . . . .336 Table 309.UART1 RS-485 Address Match register (U1RS485ADRMATCH - address 0x4001 0050) bit description . . . . . . . . . . . . . . . . . . . . . . . . .337 Table 310.UART1 RS-485 Delay value register (U1RS485DLY - address 0x4001 0054) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .337 Table 311. UART1 FIFO Level register (U1FIFOLVL address 0x4001 0058) bit description. . . . . . .339 Table 312.CAN Pin descriptions . . . . . . . . . . . . . . . . . . .342 Table 313.Memory map of the CAN block. . . . . . . . . . . .347 Table 314.CAN acceptance filter and central CAN registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347 Table 315.CAN1 and CAN2 controller register map . . . .347 Table 316.CAN1 and CAN2 controller register summary 349 Table 317.CAN Wake and Sleep registers . . . . . . . . . . .349 Table 318.CAN Mode register (CAN1MOD - address 0x4004 4000, CAN2MOD - address 0x4004 8000) bit description . . . . . . . . . . . . .350 Table 319.CAN Command Register (CAN1CMR - address 0x4004 4004, CAN2CMR - address 0x4004 8004) bit description . . . . . . . . . . . . . . . . . . . . . . . . .351 Table 320.CAN Global Status Register (CAN1GSR - address 0x4004 4008, CAN2GSR - address 0x4004 8008) bit description . . . . . . . . . . . . . . . . . . . . . . . . .353 Table 321.CAN Interrupt and Capture Register (CAN1ICR address 0x4004 400C, CAN2ICR - address 0x4004 800C) bit description . . . . . . . . . . . . .355 Table 322.CAN Interrupt Enable Register (CAN1IER address 0x4004 4010, CAN2IER - address 0x4004 8010) bit description . . . . . . . . . . . . .358 Table 323.CAN Bus Timing Register (CAN1BTR - address 0x4004 4014, CAN2BTR - address 0x4004 8014) bit description . . . . . . . . . . . . . . . . . . . . . . . . .359 Table 324.CAN Error Warning Limit register (CAN1EWL address 0x4004 4018, CAN2EWL - address 0x4004 8018) bit description . . . . . . . . . . . . .361
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
807 of 835
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Chapter 35: LPC17xx Supplementary information
0x4008 8008, SSP1DR - 0x4003 0008) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 421 Table 374:SSPn Status Register (SSP0SR - address 0x4008 800C, SSP1SR - 0x4003 000C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 422 Table 375:SSPn Clock Prescale Register (SSP0CPSR address 0x4008 8010, SSP1CPSR 0x4003 0010) bit description . . . . . . . . . . . . . 422 Table 376:SSPn Interrupt Mask Set/Clear register (SSP0IMSC - address 0x4008 8014, SSP1IMSC 0x4003 0014) bit description . . . . . . . . . . . . . 423 Table 377:SSPn Raw Interrupt Status register (SSP0RIS address 0x4008 8018, SSP1RIS - 0x4003 0018) bit description. . . . . . . . . . . . . . . . . . . . . . . . . 423 Table 378:SSPn Masked Interrupt Status register (SSPnMIS -address 0x4008 801C, SSP1MIS 0x4003 001C) bit description . . . . . . . . . . . . . 424 Table 379:SSPn interrupt Clear Register (SSP0ICR address 0x4008 8020, SSP1ICR - 0x4003 0020) bit description. . . . . . . . . . . . . . . . . . . . . . . . . 424 Table 380:SSPn DMA Control Register (SSP0DMACR address 0x4008 8024, SSP1DMACR 0x4003 0024) bit description . . . . . . . . . . . . . 424 Table 381.I2C Pin Description. . . . . . . . . . . . . . . . . . . . . 427 Table 382.I2C0CONSET and I2C1CONSET used to configure Master mode . . . . . . . . . . . . . . . . . 428 Table 383.I2C0CONSET and I2C1CONSET used to configure Slave mode . . . . . . . . . . . . . . . . . . 430 Table 384.I2C register map . . . . . . . . . . . . . . . . . . . . . . . 436 Table 385.I2C Control Set register (I2CONSET: I2C0, I2C0CONSET - address 0x4001 C000, I2C1, I2C1CONSET - address 0x4005 C000, I2C2, I2C2CONSET - address 0x400A 0000) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 Table 386.I2C Control Clear register (I2CONCLR: I2C0, I2C0CONCLR - 0x4001 C018; I2C1, I2C1CONCLR - 0x4005 C018; I2C2, I2C2CONCLR - 0x400A 0018) bit description 439 Table 387.I2C Status register (I2STAT: I2C0, I2C0STAT 0x4001 C004; I2C1, I2C1STAT - 0x4005 C004; I2C2, I2C2STAT - 0x400A 0004) bit description. . 440 Table 388.I2C Data register (I2DAT: I2C0, I2C0DAT 0x4001 C008; I2C1, I2C1DAT - 0x4005 C008; I2C2, I2C2DAT - 0x400A 0008) bit description441 Table 389.I2C Monitor mode control register (I2MMCTRL: I2C0, I2C0MMCTRL - 0x4001 C01C; I2C1, I2C1MMCTRL- 0x4005 C01C; I2C2, I2C2MMCTRL- 0x400A 001C) bit description 441 Table 390.I2C Data buffer register (I2DATA_BUFFER: I2C0, I2CDATA_BUFFER - 0x4001 C02C; I2C1,
Table 346.Extended Frame Start Address register (EFF_sa address 0x4003 C00C) bit description . . . . . .376 Table 347.Extended Frame Group Start Address register (EFF_GRP_sa - address 0x4003 C010) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .377 Table 348.End of AF Tables register (ENDofTable - address 0x4003 C014) bit description . . . . . . . . . . . . .377 Table 349.LUT Error Address register (LUTerrAd - address 0x4003 C018) bit description . . . . . . . . . . . . .378 Table 350.LUT Error register (LUTerr - address 0x4003 C01C) bit description . . . . . . . . . . . . .378 Table 351.Global FullCAN Enable register (FCANIE address 0x4003 C020) bit description . . . . . .378 Table 352.FullCAN Interrupt and Capture register 0 (FCANIC0 - address 0x4003 C024) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .378 Table 353.FullCAN Interrupt and Capture register 1 (FCANIC1 - address 0x4003 C028) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .379 Table 354.Format of automatically stored Rx messages.382 Table 355.FullCAN semaphore operation . . . . . . . . . . . .382 Table 356.Example of Acceptance Filter Tables and ID index Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .392 Table 357.Used ID-Look-up Table sections. . . . . . . . . . .394 Table 358.Used ID-Look-up Table sections. . . . . . . . . . .395 Table 359.SPI pin description . . . . . . . . . . . . . . . . . . . . .400 Table 360.SPI Data To Clock Phase Relationship. . . . . .401 Table 361.SPI register map . . . . . . . . . . . . . . . . . . . . . . .404 Table 362:SPI Control Register (S0SPCR - address 0x4002 0000) bit description . . . . . . . . . . . . .405 Table 363:SPI Status Register (S0SPSR - address 0x4002 0004) bit description . . . . . . . . . . . . .406 Table 364:SPI Data Register (S0SPDR - address 0x4002 0008) bit description . . . . . . . . . . . . .406 Table 365:SPI Clock Counter Register (S0SPCCR - address 0x4002 000C) bit description . . . . . . . . . . . . .407 Table 366:SPI Test Control Register (SPTCR - address 0x4002 0010) bit description . . . . . . . . . . . . .407 Table 367:SPI Test Status Register (SPTSR - address 0x4002 0014) bit description . . . . . . . . . . . . .407 Table 368:SPI Interrupt Register (S0SPINT - address 0x4002 001C) bit description . . . . . . . . . . . . .408 Table 369.SSP pin descriptions . . . . . . . . . . . . . . . . . . . 411 Table 370.SSP Register Map . . . . . . . . . . . . . . . . . . . . .419 Table 371:SSPn Control Register 0 (SSP0CR0 - address 0x4008 8000, SSP1CR0 - 0x4003 0000) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .420 Table 372:SSPn Control Register 1 (SSP0CR1 - address 0x4008 8004, SSP1CR1 - 0x4003 0004) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .421 Table 373:SSPn Data Register (SSP0DR - address
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
808 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
Table 413:Interrupt Request Control register (I2SIRQ address 0x400A 801C) bit description . . . . . . 476 Table 414:Transmit Clock Rate register (I2TXRATE address 0x400A 8020) bit description . . . . . . 477 Table 415:Receive Clock Rate register (I2SRXRATE address 0x400A 8024) bit description . . . . . . 478 Table 416:Transmit Clock Rate register (I2TXBITRATE address 0x400A 8028) bit description . . . . . . 478 Table 417:Receive Clock Rate register (I2SRXBITRATE address 0x400A 802C) bit description . . . . . . 478 Table 418:Transmit Mode Control register (I2STXMODE 0x400A 8030) bit description . . . . . . . . . . . . . 479 Table 419:Receive Mode Control register (I2SRXMODE 0x400A 8034) bit description . . . . . . . . . . . . . 479 Table 420:I2S transmit modes . . . . . . . . . . . . . . . . . . . . 481 Table 421:I2S receive modes . . . . . . . . . . . . . . . . . . . . . 483 Table 422.Conditions for FIFO level comparison . . . . . . 485 Table 423.DMA and interrupt request generation. . . . . . 485 Table 424.Status feedback in the I2SSTATE register . . . 485 Table 425.Timer/Counter pin description . . . . . . . . . . . . 488 Table 426.TIMER/COUNTER0-3 register map. . . . . . . . 489 Table 427.Interrupt Register (T[0/1/2/3]IR - addresses 0x4000 4000, 0x4000 8000, 0x4009 0000, 0x4009 4000) bit description . . . . . . . . . . . . . 490 Table 428.Timer Control Register (TCR, TIMERn: TnTCR addresses 0x4000 4004, 0x4000 8004, 0x4009 0004, 0x4009 4004) bit description . . 491 Table 429.Count Control Register (T[0/1/2/3]CTCR addresses 0x4000 4070, 0x4000 8070, 0x4009 0070, 0x4009 4070) bit description . . 491 Table 430.Match Control Register (T[0/1/2/3]MCR addresses 0x4000 4014, 0x4000 8014, 0x4009 0014, 0x4009 4014) bit description . . 493 Table 431.Capture Control Register (T[0/1/2/3]CCR addresses 0x4000 4028, 0x4000 8020, 0x4009 0028, 0x4009 4028) bit description . . 494 Table 432.External Match Register (T[0/1/2/3]EMR addresses 0x4000 403C, 0x4000 803C, 0x4009 003C, 0x4009 403C) bit description . 495 Table 433.External Match Control . . . . . . . . . . . . . . . . . 495 Table 434.Repetitive Interrupt Timer register map . . . . . 498 Table 435.RI Compare Value register (RICOMPVAL address 0x400B 0000) bit description . . . . . . 498 Table 436.RI Compare Value register (RICOMPVAL address 0x400B 0004) bit description . . . . . . 498 Table 437.RI Control register (RICTRL - address 0x400B 0008) bit description. . . . . . . . . . . . . . . . . . . . 499 Table 438.RI Counter register (RICOUNTER - address 0x400B 000C) bit description. . . . . . . . . . . . . 499 Table 439.System Tick Timer register map. . . . . . . . . . . 502 Table 440.System Timer Control and status register
I2C1DATA_BUFFER- 0x4005 C02C; I2C2, I2C2DATA_BUFFER- 0x400A 002C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .443 Table 391.I2C Slave Address registers (I2ADR0 to 3: I2C0, I2C0ADR[0, 1, 2, 3]- 0x4001 C0[0C, 20, 24, 28]; I2C1, I2C1ADR[0, 1, 2, 3] - address 0x4005 C0[0C, 20, 24, 28]; I2C2, I2C2ADR[0, 1, 2, 3] - address 0x400A 00[0C, 20, 24, 28]) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .443 Table 392.I2C Mask registers (I2MASK0 to 3: I2C0, I2C0MASK[0, 1, 2, 3] - 0x4001 C0[30, 34, 38, 3C]; I2C1, I2C1MASK[0, 1, 2, 3] - address 0x4005 C0[30, 34, 38, 3C]; I2C2, I2C2MASK[0, 1, 2, 3] - address 0x400A 00[30, 34, 38, 3C]) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .444 Table 393.I2C SCL HIGH Duty Cycle register (I2SCLH: I2C0, I2C0SCLH - address 0x4001 C010; I2C1, I2C1SCLH - address 0x4005 C010; I2C2, I2C2SCLH - 0x400A 0010) bit description . . .444 Table 394.I2C SCL Low duty cycle register (I2SCLL: I2C0 I2C0SCLL: 0x4001 C014; I2C1 - I2C1SCLL: 0x4005 C014; I2C2 - I2C2SCLL: 0x400A 0014) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .444 Table 395.Example I2C clock rates . . . . . . . . . . . . . . . . .445 Table 396.Abbreviations used to describe an I2C operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . .446 Table 397.I2CONSET used to initialize Master Transmitter mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .447 Table 398.I2CONSET used to initialize Slave Receiver mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451 Table 399.Master Transmitter mode . . . . . . . . . . . . . . . .454 Table 400.Master Receiver mode . . . . . . . . . . . . . . . . . .455 Table 401.Slave Receiver mode . . . . . . . . . . . . . . . . . . .456 Table 402.Slave Transmitter mode . . . . . . . . . . . . . . . . .458 Table 403.Miscellaneous States . . . . . . . . . . . . . . . . . . .459 Table 404.Pin descriptions . . . . . . . . . . . . . . . . . . . . . . .472 Table 405.I2S register map . . . . . . . . . . . . . . . . . . . . . . .473 Table 406:Digital Audio Output register (I2SDAO - address 0x400A 8000) bit description . . . . . . . . . . . . .473 Table 407:Digital Audio Input register (I2SDAI - address 0x400A 8004) bit description . . . . . . . . . . . . .474 Table 408:Transmit FIFO register (I2STXFIFO - address 0x400A 8008) bit description . . . . . . . . . . . . .474 Table 409:Receive FIFO register (I2RXFIFO - address 0x400A 800C) bit description . . . . . . . . . . . . .475 Table 410:Status Feedback register (I2SSTATE - address 0x400A 8010) bit description . . . . . . . . . . . . .475 Table 411: DMA Configuration register 1 (I2SDMA1 - address 0x400A 8014) bit description . . . . . . . . . . . . .475 Table 412:DMA Configuration register 2 (I2SDMA2 - address 0x400A 8018) bit description . . . . . . . . . . . . .476
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
809 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
Table 467.MCPWM Interrupt Flags read address (MCINTF 0x400B 8068) bit description . . . . . . . . . . . . . 527 Table 468.MCPWM Interrupt Flags set address (PWMINTF_SET - 0x400B 806C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 527 Table 469.MCPWM Interrupt Flags clear address (PWMINTF_CLR - 0x400B 8070) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 528 Table 470.MCPWM Count Control read address (MCCNTCON - 0x400B 805C) bit description 528 Table 471.MCPWM Count Control set address (MCCNTCON_SET - 0x400B 8060) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 529 Table 472.MCPWM Count Control clear address (MCCAPCON_CLR - 0x400B 8064) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 529 Table 473.MCPWM Timer/Counter 0-2 registers (MCTC0-2 0x400B 8018, 0x400B 801C, 0x400B 8020) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 530 Table 474.MCPWM Limit 0-2 registers (MCLIM0-2 0x400B 8024, 0x400B 8028, 0x400B 802C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 530 Table 475.MCPWM Match 0-2 registers (MCMAT0-2 addresses 0x400B 8030, 0x400B 8034, 0x400B 8038) bit description . . . . . . . . . . . . . 531 Table 476.MCPWM Dead-time register (MCDT - address 0x400B 803C) bit description. . . . . . . . . . . . . 532 Table 477.MCPWM Commutation Pattern register (MCCP address 0x400B 8040) bit description . . . . . . 532 Table 478.MCPWM Capture read addresses (MCCAP0/1/2 0x400B 8044, 0x400B 8048, 0x400B 804C) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 532 Table 479.MCPWM Capture clear address (CAP_CLR 0x400B 8074) bit description . . . . . . . . . . . . . 533 Table 480.Encoder states . . . . . . . . . . . . . . . . . . . . . . . . 542 Table 481.Encoder state transitions[1] . . . . . . . . . . . . . . 542 Table 482.Encoder direction . . . . . . . . . . . . . . . . . . . . . 543 Table 483.QEI pin description. . . . . . . . . . . . . . . . . . . . . 545 Table 484.QEI Register summary. . . . . . . . . . . . . . . . . . 546 Table 485:QEI Control register (QEICON - address 0x400B C000) bit description. . . . . . . . . . . . . 547 Table 486:QEI Configuration register (QEICONF - address 0x400B C008) bit description. . . . . . . . . . . . . 547 Table 487:QEI Interrupt Status register (QEISTAT - address 0x400B C004) bit description. . . . . . . . . . . . . 547 Table 488:QEI Position register (QEIPOS - address 0x400B C00C) bit description . . . . . . . . . . . . 548 Table 489:QEI Maximum Position register (QEIMAXPOS address 0x400B C010) bit description . . . . . . 548 Table 490:QEI Position Compare register 0 (CMPOS0 address 0x400B C014) bit description . . . . . . 548
(STCTRL - 0xE000 E010) bit description . . . .502 Table 441.System Timer Reload value register (STRELOAD - 0xE000 E014) bit description . . . . . . . . . . . .503 Table 442.System Timer Current value register (STCURR 0xE000 E018) bit description . . . . . . . . . . . . .503 Table 443.System Timer Calibration value register (STCALIB - 0xE000 E01C) bit description . . .504 Table 444.Set and reset inputs for PWM Flip-Flops . . . .509 Table 445.Pin summary. . . . . . . . . . . . . . . . . . . . . . . . . .510 Table 446.PWM1 register map . . . . . . . . . . . . . . . . . . . . 511 Table 447:PWM Interrupt Register (PWM1IR - address 0x4001 8000) bit description . . . . . . . . . . . . .512 Table 448:PWM Timer Control Register (PWM1TCR address 0x4001 8004) bit description . . . . . . . . . . . . .513 Table 449:PWM Count control Register (PWM1CTCR address 0x4001 8004) bit description. . . . . . .513 Table 450:Match Control Register (PWM1MCR - address 0x4000 4014) bit description . . . . . . . . . . . . .514 Table 451:PWM Capture Control Register (PWM1CCR address 0x4001 8028) bit description. . . . . . .515 Table 452:PWM Control Register (PWM1PCR - address 0x4001 804C) bit description . . . . . . . . . . . . .516 Table 453:PWM Latch Enable Register (PWM1LER address 0x4001 8050) bit description. . . . . . .517 Table 454.Pin summary. . . . . . . . . . . . . . . . . . . . . . . . . .519 Table 455.Motor Control Pulse Width Modulator (MCPWM) register map . . . . . . . . . . . . . . . . . . . . . . . . . .522 Table 456.MCPWM Control read address (MCCON 0x400B 8000) bit description . . . . . . . . . . . . .523 Table 457.MCPWM Control set address (MCCON_SET 0x400B 8004) bit description . . . . . . . . . . . . .524 Table 458.MCPWM Control clear address (MCCON_CLR 0x400B 8008) bit description . . . . . . . . . . . . .525 Table 459.MCPWM Capture Control read address (MCCAPCON - 0x400B 800C) bit description 525 Table 460.MCPWM Capture Control set address (MCCAPCON_SET - 0x400B 8010) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .526 Table 461.MCPWM Capture control clear register (MCCAPCON_CLR - address 0x400B 8014) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .526 Table 462.Motor Control PWM interrupts . . . . . . . . . . . .526 Table 463.Interrupt sources bit allocation table . . . . . . . .526 Table 464.MCPWM Interrupt Enable read address (MCINTEN - 0x400B 8050) bit description . . .526 Table 465.PWM interrupt enable set register (MCINTEN_SET - address 0x400B 8054) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .527 Table 466.PWM interrupt enable clear register (MCINTEN_CLR - address 0x400B 8058) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . .527
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0x4002 401C) bit description . . . . . . . . . . . . . 563 Table 518.Time Counter relationships and values . . . . . 563 Table 519.Time Counter registers. . . . . . . . . . . . . . . . . . 563 Table 520.Calibration register (CALIBRATION - address 0x4002 4040) bit description . . . . . . . . . . . . . 564 Table 521.General purpose registers 0 to 4 (GPREG0 to GPREG4 - addresses 0x4002 4044 to 0x4002 4054) bit description. . . . . . . . . . . . . . . . . . . . 565 Table 522.Alarm registers. . . . . . . . . . . . . . . . . . . . . . . . 565 Table 523.Watchdog register map . . . . . . . . . . . . . . . . . 567 Table 524:Watchdog Mode register (WDMOD - address 0x4000 0000) bit description . . . . . . . . . . . . . 568 Table 525.Watchdog operating modes selection . . . . . . 568 Table 526:Watchdog Constant register (WDTC - address 0x4000 0004) bit description . . . . . . . . . . . . . 569 Table 527:Watchdog Feed register (WDFEED - address 0x4000 0008) bit description . . . . . . . . . . . . . 569 Table 528:Watchdog Timer Value register (WDTV - address 0x4000 000C) bit description . . . . . . . . . . . . . 569 Table 529:Watchdog Timer Clock Source Selection register (WDCLKSEL - address 0x4000 0010) bit description . . . . . . . . . . . . . . . . . . . . . . . . . . . 570 Table 530.ADC pin description . . . . . . . . . . . . . . . . . . . . 572 Table 531.ADC registers. . . . . . . . . . . . . . . . . . . . . . . . . 573 Table 532:A/D Control Register (AD0CR - address 0x4003 4000) bit description . . . . . . . . . . . . . 574 Table 533:A/D Global Data Register (AD0GDR - address 0x4003 4004) bit description . . . . . . . . . . . . . 575 Table 534:A/D Status register (AD0INTEN - address 0x4003 400C) bit description . . . . . . . . . . . . . 575 Table 535:A/D Data Registers (AD0DR0 to AD0DR7 0x4003 4010 to 0x4003 402C) bit description 576 Table 536:A/D Status register (AD0STAT - address 0x4003 4030) bit description . . . . . . . . . . . . . 577 Table 537:A/D Trim register (ADTRM - address 0x4003 4034) bit description . . . . . . . . . . . . . 577 Table 538.D/A Pin Description . . . . . . . . . . . . . . . . . . . . 579 Table 539.DAC registers. . . . . . . . . . . . . . . . . . . . . . . . . 580 Table 540:D/A Converter Register (DACR - address 0x4008 C000) bit description . . . . . . . . . . . . . 580 Table 541.D/A Control register (DACCTRL - address 0x4008 C004) bit description . . . . . . . . . . . . . 581 Table 542:D/A Converter register (DACR - address 0x4008 C000) bit description . . . . . . . . . . . . . 581 Table 543.Endian behavior . . . . . . . . . . . . . . . . . . . . . . 586 Table 544.DMA Connections . . . . . . . . . . . . . . . . . . . . . 589 Table 545.GPDMA register map. . . . . . . . . . . . . . . . . . . 590 Table 546.DMA Interrupt Status register (DMACIntStat 0x5000 4000) . . . . . . . . . . . . . . . . . . . . . . . . 592 Table 547.DMA Interrupt Terminal Count Request Status register (DMACIntTCStat - 0x5000 4004) . . . 592
Table 491:QEI Position Compare register 1 (CMPOS1 address 0x400B C018) bit description . . . . . .548 Table 492:QEI Position Compare register 2 (CMPOS2 address 0x400B C01C) bit description . . . . . .549 Table 493:QEI Index Count register (CMPOS - address 0x400B C020) bit description . . . . . . . . . . . . .549 Table 494:QEI Index Compare register (CMPOS - address 0x400B C024) bit description . . . . . . . . . . . . .549 Table 495:QEI Timer Load register (QEILOAD - address 0x400B C028) bit description . . . . . . . . . . . . .549 Table 496:QEI Timer register (QEITIME - address 0x400B C02C) bit description . . . . . . . . . . . . .549 Table 497:QEI Velocity register (QEIVEL - address 0x400B C030) bit description . . . . . . . . . . . . .550 Table 498:QEI Velocity Capture register (QEICAP - address 0x400B C034) bit description . . . . . . . . . . . . .550 Table 499:QEI Velocity Compare register (VELCOMP address 0x400B C038) bit description . . . . . .550 Table 500:QEI Digital Filter register (FILTER - address 0x400B C03C) bit description . . . . . . . . . . . . .550 Table 501:QEI Interrupt Status register (QEIINTSTAT address 0x400B CFE0) bit description . . . . . .551 Table 502:QEI Interrupt Set register (QEISET - address 0x400B CFEC) bit description . . . . . . . . . . . .551 Table 503:QEI Interrupt Clear register (QEICLR 0x400B CFE8) bit description . . . . . . . . . . . . .552 Table 504:QEI Interrupt Enable register (QEIIE - address 0x400B CFE4) bit description . . . . . . . . . . . . .552 Table 505:QEI Interrupt Enable Set register (QEIIES address 0x400B CFDC) bit description . . . . .553 Table 506:QEI Interrupt Enable Clear register (QEIIEC address 0x400B CFD8) bit description . . . . . .554 Table 507.RTC pin description . . . . . . . . . . . . . . . . . . . .557 Table 508.Real-Time Clock register map . . . . . . . . . . . .558 Table 509.Interrupt Location Register (ILR - address 0x4002 4000) bit description . . . . . . . . . . . . .559 Table 510.Clock Control Register (CCR - address 0x4002 4008) bit description . . . . . . . . . . . . .559 Table 511. Counter Increment Interrupt Register (CIIR address 0x4002 400C) bit description . . . . . .560 Table 512.Alarm Mask Register (AMR - address 0x4002 4010) bit description . . . . . . . . . . . . .561 Table 513.RTC Auxiliary control register (RTC_AUX address 0x4002 405C) bit description . . . . . .561 Table 514.RTC Auxiliary Enable register (RTC_AUXEN address 0x4002 4058) bit description. . . . . . .561 Table 515.Consolidated Time register 0 (CTIME0 - address 0x4002 4014) bit description . . . . . . . . . . . . .562 Table 516.Consolidated Time register 1 (CTIME1 - address 0x4002 4018) bit description . . . . . . . . . . . . .562 Table 517.Consolidated Time register 2 (CTIME2 - address
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Rev. 01 -- 4 January 2010
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command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623 Table 579.ISP Copy command . . . . . . . . . . . . . . . . . . . . 623 Table 580.ISP Go command. . . . . . . . . . . . . . . . . . . . . . 624 Table 581.ISP Erase sector command . . . . . . . . . . . . . . 624 Table 582.ISP Blank check sector command . . . . . . . . . 625 Table 583.ISP Read Part Identification command . . . . . 625 Table 584.LPC17xx part identification numbers . . . . . . . 625 Table 585.ISP Read Boot Code version number command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626 Table 586.ISP Read device serial number command. . . 626 Table 587.ISP Compare command. . . . . . . . . . . . . . . . . 626 Table 588.ISP Return Codes Summary . . . . . . . . . . . . . 627 Table 589.IAP Command Summary . . . . . . . . . . . . . . . . 629 Table 590.IAP Prepare sector(s) for write operation command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630 Table 591.IAP Copy RAM to Flash command . . . . . . . . 630 Table 592.IAP Erase Sector(s) command . . . . . . . . . . . 631 Table 593.IAP Blank check sector(s) command . . . . . . . 631 Table 594.IAP Read part identification number command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631 Table 595.IAP Read Boot Code version number command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632 Table 596.IAP Read device serial number command. . . 632 Table 597.IAP Compare command. . . . . . . . . . . . . . . . . 632 Table 598.Re-invoke ISP . . . . . . . . . . . . . . . . . . . . . . . . 633 Table 599.IAP Status Codes Summary . . . . . . . . . . . . . 633 Table 600.Register overview: FMC (base address 0x2020 0000) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634 Table 601.Flash Module Signature Start register (FMSSTART - 0x4008 4020) bit description . 635 Table 602.Flash Module Signature Stop register (FMSSTOP - 0x4008 4024) bit description . . . . . . . . . . . . 635 Table 603.FMSW0 register bit description (FMSW0, address: 0x2020 002C) . . . . . . . . . . . . . . . . . 635 Table 604.FMSW1 register bit description (FMSW1, address: 0x2020 0030) . . . . . . . . . . . . . . . . . 635 Table 605.FMSW2 register bit description (FMSW2, address: 0x2020 0034) . . . . . . . . . . . . . . . . . 636 Table 606.FMSW3 register bit description (FMSW3, address: 0x2020 0038) . . . . . . . . . . . . . . . . 636 Table 607.Flash module Status register (FMSTAT - 0x4008 4FE0) bit description . . . . . . . . . . . . . . . . . . . 636 Table 608.Flash Module Status Clear register (FMSTATCLR - 0x0x4008 4FE8) bit description . . . . . . . . . . 636 Table 609.JTAG pin description . . . . . . . . . . . . . . . . . . . 639 Table 610.Serial Wire Debug pin description . . . . . . . . . 639 Table 611. Parallel Trace pin description. . . . . . . . . . . . . 639 Table 612.Memory Mapping Control register (MEMMAP 0x400F C040) bit description . . . . . . . . . . . . . 640 Table 613.Cortex-M3 instructions . . . . . . . . . . . . . . . . . 644 Table 614.CMSIS intrinsic functions to generate some
Table 548.DMA Interrupt Terminal Count Request Clear register (DMACIntTCClear - 0x5000 4008) . .592 Table 549.DMA Interrupt Error Status register (DMACIntErrStat - 0x5000 400C) . . . . . . . . .593 Table 550.DMA Interrupt Error Clear register (DMACIntErrClr - 0x5000 4010) . . . . . . . . . .593 Table 551.DMA Raw Interrupt Terminal Count Status register (DMACRawIntTCStat - 0x5000 4014) . . . . . .593 Table 552.DMA Raw Error Interrupt Status register (DMACRawIntErrStat - 0x5000 4018) . . . . . .594 Table 553.DMA Enabled Channel register (DMACEnbldChns - 0x5000 401C) . . . . . . . .594 Table 554.DMA Software Burst Request register (DMACSoftBReq - 0x5000 4020) . . . . . . . . .594 Table 555.DMA Software Single Request register (DMACSoftSReq - 0x5000 4024) . . . . . . . . .595 Table 556.DMA Software Last Burst Request register (DMACSoftLBReq - 0x5000 4028) . . . . . . . .595 Table 557.DMA Software Last Single Request register (DMACSoftLSReq - 0x5000 402C) . . . . . . . .596 Table 558.DMA Configuration register (DMACConfig 0x5000 4030) . . . . . . . . . . . . . . . . . . . . . . . . .596 Table 559.DMA Synchronization register (DMACSync 0x5000 4034) . . . . . . . . . . . . . . . . . . . . . . . . .596 Table 560.DMA Request Select register (DMAReqSel 0x400F C1C4) . . . . . . . . . . . . . . . . . . . . . . . .597 Table 561.DMA Channel Source Address registers (DMACCxSrcAddr - 0x5000 41x0) . . . . . . . . .598 Table 562.DMA Channel Destination Address registers (DMACCxDestAddr - 0x5000 41x4) . . . . . . . .598 Table 563.DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8) . . . . . . . . . . . . .599 Table 564.DMA channel control registers (DMACCxControl 0x5000 41xC) . . . . . . . . . . . . . . . . . . . . . . . .600 Table 565.DMA Channel Configuration registers (DMACCxConfig - 0x5000 41x0) . . . . . . . . . .602 Table 566.Transfer type bits . . . . . . . . . . . . . . . . . . . . . .603 Table 567.DMA request signal usage . . . . . . . . . . . . . .606 Table 568.Sectors in a LPC17xx device . . . . . . . . . . . . .617 Table 569.Code Read Protection options . . . . . . . . . . . .618 Table 570.Code Read Protection hardware/software interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . .619 Table 571.ISP command summary . . . . . . . . . . . . . . . . .620 Table 572.ISP Unlock command . . . . . . . . . . . . . . . . . . .620 Table 573.ISP Set Baud Rate command. . . . . . . . . . . . .621 Table 574.Correlation between possible ISP baudrates and CCLK frequency (in MHz). . . . . . . . . . . . . . . .621 Table 575.ISP Echo command . . . . . . . . . . . . . . . . . . . .621 Table 576.ISP Write to RAM command. . . . . . . . . . . . . .622 Table 577.ISP Read Memory command . . . . . . . . . . . . .622 Table 578.ISP Prepare sector(s) for write operation
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(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
812 of 835
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Chapter 35: LPC17xx Supplementary information
Table 660.AIRCR bit assignments . . . . . . . . . . . . . . . . . 768 Table 661.Priority grouping. . . . . . . . . . . . . . . . . . . . . . . 769 Table 662.SCR bit assignments . . . . . . . . . . . . . . . . . . . 770 Table 663.CCR bit assignments . . . . . . . . . . . . . . . . . . . 771 Table 664.System fault handler priority fields . . . . . . . . . 772 Table 665.SHPR1 register bit assignments . . . . . . . . . . 772 Table 666.SHPR2 register bit assignments . . . . . . . . . . 772 Table 667.SHPR3 register bit assignments . . . . . . . . . . 772 Table 668.SHCSR bit assignments . . . . . . . . . . . . . . . . 773 Table 669.MMFSR bit assignments . . . . . . . . . . . . . . . . 774 Table 670.BFSR bit assignments . . . . . . . . . . . . . . . . . . 775 Table 671.UFSR bit assignments . . . . . . . . . . . . . . . . . . 777 Table 672.HFSR bit assignments . . . . . . . . . . . . . . . . . . 778 Table 673.MMFAR bit assignments . . . . . . . . . . . . . . . . 778 Table 674.BFAR bit assignments . . . . . . . . . . . . . . . . . . 779 Table 675.System timer registers summary . . . . . . . . . . 780 Table 676.SysTick CTRL register bit assignments . . . . . 780 Table 677.LOAD register bit assignments . . . . . . . . . . . 781 Table 678.VAL register bit assignments . . . . . . . . . . . . . 781 Table 679.CALIB register bit assignments . . . . . . . . . . . 781 Table 680.Memory attributes summary . . . . . . . . . . . . . 783 Table 681.MPU registers summary . . . . . . . . . . . . . . . . 784 Table 682.TYPE register bit assignments. . . . . . . . . . . . 784 Table 683.MPU CTRL register bit assignments . . . . . . . 785 Table 684.RNR bit assignments . . . . . . . . . . . . . . . . . . . 786 Table 685.RBAR bit assignments . . . . . . . . . . . . . . . . . . 787 Table 686.RASR bit assignments . . . . . . . . . . . . . . . . . . 788 Table 687.Example SIZE field values . . . . . . . . . . . . . . . 788 Table 688.TEX, C, B, and S encoding . . . . . . . . . . . . . . 789 Table 689.Cache policy for memory attribute encoding . 789 Table 690.AP encoding. . . . . . . . . . . . . . . . . . . . . . . . . . 790 Table 691.Memory region attributes for a microcontroller793 Table 692.Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 798
Cortex-M3 instructions . . . . . . . . . . . . . . . . . .647 Table 615.CMSIS intrinsic functions to access the special registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .647 Table 616.Condition code suffixes. . . . . . . . . . . . . . . . . .654 Table 617.Memory access instructions . . . . . . . . . . . . . .657 Table 618.Offset ranges . . . . . . . . . . . . . . . . . . . . . . . . .660 Table 619.Offset ranges . . . . . . . . . . . . . . . . . . . . . . . . .666 Table 620.Data processing instructions. . . . . . . . . . . . . .674 Table 621.Multiply and divide instructions . . . . . . . . . . . .689 Table 622.Packing and unpacking instructions . . . . . . . .697 Table 623.Branch and control instructions . . . . . . . . . . .702 Table 624.Branch ranges . . . . . . . . . . . . . . . . . . . . . . . .703 Table 625.Miscellaneous instructions . . . . . . . . . . . . . . . 711 Table 626.Summary of processor mode, execution privilege level, and stack use options . . . . . . . . . . . . . .725 Table 627.Core register set summary . . . . . . . . . . . . . . .725 Table 628.PSR register combinations . . . . . . . . . . . . . . .727 Table 629.APSR bit assignments . . . . . . . . . . . . . . . . . .728 Table 630.IPSR bit assignments . . . . . . . . . . . . . . . . . . .729 Table 631.EPSR bit assignments . . . . . . . . . . . . . . . . . .729 Table 632.PRIMASK register bit assignments. . . . . . . . .730 Table 633.FAULTMASK register bit assignments . . . . . .730 Table 634.BASEPRI register bit assignments . . . . . . . . .731 Table 635.CONTROL register bit assignments . . . . . . . .731 Table 636.Memory access behavior . . . . . . . . . . . . . . . .736 Table 637.SRAM memory bit-banding regions . . . . . . . .738 Table 638.Peripheral memory bit-banding regions . . . . .738 Table 639.C compiler intrinsic functions for exclusive access instructions . . . . . . . . . . . . . . . . . . . . . . . . . . .741 Table 640.Properties of the different exception types . . .743 Table 641.Exception return behavior. . . . . . . . . . . . . . . .748 Table 642.Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .750 Table 643.Fault status and fault address registers . . . . .751 Table 644.Core peripheral register regions . . . . . . . . . . .756 Table 645.NVIC register summary . . . . . . . . . . . . . . . . .757 Table 646.Mapping of interrupts to the interrupt variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . .758 Table 647.ISER bit assignments . . . . . . . . . . . . . . . . . . .758 Table 648.ICER bit assignments . . . . . . . . . . . . . . . . . . .759 Table 649.ISPR bit assignments . . . . . . . . . . . . . . . . . . .759 Table 650.ICPR bit assignments . . . . . . . . . . . . . . . . . . .760 Table 651.IABR bit assignments . . . . . . . . . . . . . . . . . . .760 Table 652.IPR bit assignments . . . . . . . . . . . . . . . . . . . .761 Table 653.STIR bit assignments . . . . . . . . . . . . . . . . . . .761 Table 654.CMSIS functions for NVIC control . . . . . . . . .763 Table 655.Summary of the system control block registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .764 Table 656.ACTLR bit assignments . . . . . . . . . . . . . . . . .765 Table 657.CPUID register bit assignments . . . . . . . . . . .765 Table 658.ICSR bit assignments . . . . . . . . . . . . . . . . . . .766 Table 659.VTOR bit assignments . . . . . . . . . . . . . . . . . .768
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(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
813 of 835
NXP Semiconductors
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Chapter 35: LPC17xx Supplementary information
4. Figures
Fig 1. Fig 2. Fig 3. Fig 4. Fig 5. Fig 6. Fig 7. Fig 8. LPC1768 simplified block diagram. . . . . . . . . . . . .8 LPC1768 block diagram, CPU and buses . . . . . . 11 LPC17xx system memory map . . . . . . . . . . . . . .13 Reset block diagram including the wake-up timer19 Example of start-up after reset. . . . . . . . . . . . . . .20 External interrupt logic . . . . . . . . . . . . . . . . . . . . .23 Clock generation for the LPC17xx . . . . . . . . . . . .29 Oscillator modes and models: a) slave mode of operation, b) oscillation mode of operation, c) external crystal model used for CX1/X2 evaluation32 PLL0 block diagram . . . . . . . . . . . . . . . . . . . . . . .36 PLL1 block diagram . . . . . . . . . . . . . . . . . . . . . . .49 PLLs and clock dividers . . . . . . . . . . . . . . . . . . . .55 CLKOUT selection . . . . . . . . . . . . . . . . . . . . . . . .67 Simplified block diagram of the flash accelerator showing potential bus connections . . . . . . . . . . .69 LPC176x LQFP100 pin configuration . . . . . . . . .92 LPC175x LQFP80 pin configuration . . . . . . . . . .92 Ethernet block diagram . . . . . . . . . . . . . . . . . . .141 Ethernet packet fields . . . . . . . . . . . . . . . . . . . .143 Receive descriptor memory layout. . . . . . . . . . .170 Transmit descriptor memory layout . . . . . . . . . .173 Transmit example memory and registers. . . . . .184 Receive Example Memory and Registers . . . . .190 Transmit Flow Control . . . . . . . . . . . . . . . . . . . .195 Receive filter block diagram. . . . . . . . . . . . . . . .197 Receive Active/Inactive state machine . . . . . . .201 Transmit Active/Inactive state machine . . . . . . .202 USB device controller block diagram . . . . . . . . .214 USB MaxPacketSize register array indexing . . .230 Interrupt event handling . . . . . . . . . . . . . . . . . . .241 UDCA Head register and DMA Descriptors . . . .254 Isochronous OUT endpoint operation example .261 Data transfer in ATLE mode. . . . . . . . . . . . . . . .262 USB Host controller block diagram . . . . . . . . . .268 USB OTG controller block diagram . . . . . . . . . .272 USB OTG port configuration . . . . . . . . . . . . . . .273 USB host port configuration . . . . . . . . . . . . . . . .274 USB device port configuration . . . . . . . . . . . . . .274 USB OTG interrupt handling . . . . . . . . . . . . . . .284 USB OTG controller with software stack . . . . . .285 Hardware support for B-device switching from peripheral state to host state . . . . . . . . . . . . . . .286 State transitions implemented in software during B-device switching from peripheral to host . . . .287 Hardware support for A-device switching from host state to peripheral state . . . . . . . . . . . . . . . . . . .289 State transitions implemented in software during Fig 43. Fig 44. Fig 45. Fig 46. Fig 47. Fig 48. Fig 49. Fig 50. Fig 51. Fig 52. Fig 53. Fig 54. Fig 55. Fig 56. Fig 57. Fig 58. Fig 59. Fig 60. Fig 61. Fig 62. Fig 63. Fig 64. Fig 65. Fig 66. Fig 67. Fig 68. Fig 69. Fig 70. Fig 71. Fig 72. Fig 73. Fig 74. Fig 75. A-device switching from host to peripheral . . . . 290 Clocking and power control. . . . . . . . . . . . . . . . 293 Auto-baud a) mode 0 and b) mode 1 waveform 309 Algorithm for setting UART dividers . . . . . . . . . 312 UART0, 2 and 3 block diagram . . . . . . . . . . . . . 315 Auto-RTS Functional Timing . . . . . . . . . . . . . . . 326 Auto-CTS Functional Timing . . . . . . . . . . . . . . . 327 Auto-baud a) mode 0 and b) mode 1 waveform 332 Algorithm for setting UART dividers . . . . . . . . . 334 UART1 block diagram . . . . . . . . . . . . . . . . . . . . 340 CAN controller block diagram . . . . . . . . . . . . . . 343 Transmit buffer layout for standard and extended frame format configurations . . . . . . . . . . . . . . . 344 Receive buffer layout for standard and extended frame format configurations . . . . . . . . . . . . . . . 345 Global Self-Test (high-speed CAN Bus example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 Local self test (high-speed CAN Bus example). 346 Entry in FullCAN and individual standard identifier tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Entry in standard identifier range table . . . . . . . 373 Entry in either extended identifier table . . . . . . . 374 ID Look-up table example explaining the search algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 Semaphore procedure for reading an auto-stored message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 FullCAN section example of the ID look-up table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385 FullCAN message object layout . . . . . . . . . . . . 385 Normal case, no messages lost . . . . . . . . . . . . 387 Message lost . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 Message gets overwritten . . . . . . . . . . . . . . . . . 388 Message overwritten indicated by semaphore bits and message lost . . . . . . . . . . . . . . . . . . . . . . . 389 Message overwritten indicated by message lost390 Clearing message lost. . . . . . . . . . . . . . . . . . . . 391 Detailed example of acceptance filter tables and ID index values . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 ID Look-up table configuration example (no FullCAN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395 ID Look-up table configuration example (FullCAN activated and enabled) . . . . . . . . . . . . . . . . . . . 397 SPI data transfer format (CPHA = 0 and CPHA = 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 SPI block diagram . . . . . . . . . . . . . . . . . . . . . . . 409 Texas Instruments Synchronous Serial Frame Format: a) Single and b) Continuous/back-to-back Two Frames Transfer . . . . . . . . . . . . . . . . . . . . 412
Fig 9. Fig 10. Fig 11. Fig 12. Fig 13. Fig 14. Fig 15. Fig 16. Fig 17. Fig 18. Fig 19. Fig 20. Fig 21. Fig 22. Fig 23. Fig 24. Fig 25. Fig 26. Fig 27. Fig 28. Fig 29. Fig 30. Fig 31. Fig 32. Fig 33. Fig 34. Fig 35. Fig 36. Fig 37. Fig 38. Fig 39. Fig 40. Fig 41. Fig 42.
continued >>
UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
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Chapter 35: LPC17xx Supplementary information
Fig 110. Receiver slave mode sharing the transmitter reference clock . . . . . . . . . . . . . . . . . . . . . . . . . 484 Fig 111. 4-wire receiver slave mode sharing the transmitter bit clock and WS . . . . . . . . . . . . . . . . . . . . . . . . 485 Fig 112. FIFO contents for various I2S modes . . . . . . . . 486 Fig 113. A timer cycle in which PR=2, MRx=6, and both interrupt and reset on match are enabled. . . . . 496 Fig 114. A timer Cycle in Which PR=2, MRx=6, and both interrupt and stop on match are enabled . . . . . 496 Fig 115. Timer block diagram . . . . . . . . . . . . . . . . . . . . . 497 Fig 116. RI timer block diagram . . . . . . . . . . . . . . . . . . . 500 Fig 117. System Tick Timer block diagram . . . . . . . . . . . 502 Fig 118. PWM block diagram . . . . . . . . . . . . . . . . . . . . . 508 Fig 119. Sample PWM waveforms . . . . . . . . . . . . . . . . . 509 Fig 120. MCPWM Block Diagram . . . . . . . . . . . . . . . . . . 520 Fig 121. Edge-aligned PWM waveform without dead time, POLA = 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534 Fig 122. Center-aligned PWM waveform without dead time, POLA = 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535 Fig 123. Edge-aligned PWM waveform with dead time, POLA = 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535 Fig 124. Center-aligned waveform with dead time, POLA = 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536 Fig 125. Three-phase DC mode sample waveforms. . . . 538 Fig 126. Three-phase AC mode sample waveforms, edge aligned PWM mode. . . . . . . . . . . . . . . . . . . . . . 539 Fig 127. Encoder interface block diagram. . . . . . . . . . . . 541 Fig 128. Quadrature Encoder Basic Operation . . . . . . . . 543 Fig 129. RTC domain conceptual diagram . . . . . . . . . . . 556 Fig 130. RTC functional block diagram . . . . . . . . . . . . . . 556 Fig 131. Watchdog block diagram. . . . . . . . . . . . . . . . . . 570 Fig 132. DAC control with DMA interrupt and timer . . . . 582 Fig 133. DMA controller block diagram . . . . . . . . . . . . . . 584 Fig 134. LLI example. . . . . . . . . . . . . . . . . . . . . . . . . . . . 610 Fig 135. Map of lower memory . . . . . . . . . . . . . . . . . . . . 613 Fig 136. Boot process flowchart . . . . . . . . . . . . . . . . . . . 616 Fig 137. IAP parameter passing . . . . . . . . . . . . . . . . . . . 629 Fig 138. Algorithm for generating a 128 bit signature . . . 637 Fig 139. Typical Cortex-M3 implementation . . . . . . . . . . 641 Fig 140. ASR #3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 Fig 141. LSR#3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651 Fig 142. LSL#3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651 Fig 143. ROR#3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 652 Fig 144. RRX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 652 Fig 145. Bit-band mapping . . . . . . . . . . . . . . . . . . . . . . . 739 Fig 146. Vector table . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745
Fig 76. SPI frame format with CPOL=0 and CPHA=0 (a) Single and b) Continuous Transfer) . . . . . . . . . .413 Fig 77. SPI frame format with CPOL=0 and CPHA=1 . .414 Fig 78. SPI frame format with CPOL = 1 and CPHA = 0 (a) Single and b) Continuous Transfer) . . . . . . . . . .415 Fig 79. SPI Frame Format with CPOL = 1 and CPHA = 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416 Fig 80. Microwire frame format (single transfer) . . . . . .417 Fig 81. Microwire frame format (continuos transfers) . .418 Fig 82. Microwire frame format setup and hold details .418 Fig 83. I2C-bus configuration . . . . . . . . . . . . . . . . . . . . .427 Fig 84. Format in the Master Transmitter mode. . . . . . .429 Fig 85. Format of Master Receiver mode . . . . . . . . . . .430 Fig 86. A Master Receiver switches to Master Transmitter after sending repeated START . . . . . . . . . . . . .430 Fig 87. Format of Slave Receiver mode . . . . . . . . . . . .431 Fig 88. Format of Slave Transmitter mode . . . . . . . . . .431 Fig 89. I2C serial interface block diagram . . . . . . . . . . .432 Fig 90. Arbitration procedure . . . . . . . . . . . . . . . . . . . . .434 Fig 91. Serial clock synchronization. . . . . . . . . . . . . . . .434 Fig 92. Format and states in the Master Transmitter mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .448 Fig 93. Format and states in the Master Receiver mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .450 Fig 94. Format and states in the Slave Receiver mode .452 Fig 95. Format and states in the Slave Transmitter mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .453 Fig 96. Simultaneous repeated START conditions from two masters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .461 Fig 97. Forced access to a busy I2C-bus. . . . . . . . . . . .461 Fig 98. Recovering from a bus obstruction caused by a LOW level on SDA . . . . . . . . . . . . . . . . . . . . . . .461 Fig 99. Simple I2S configurations and bus timing . . . . .472 Fig 100. Typical transmitter master mode, with or without MCLK output . . . . . . . . . . . . . . . . . . . . . . . . . . .482 Fig 101. Transmitter master mode sharing the receiver reference clock . . . . . . . . . . . . . . . . . . . . . . . . .482 Fig 102. 4-wire transmitter master mode sharing the receiver bit clock and WS . . . . . . . . . . . . . . . . . . . . . . . .482 Fig 103. Typical transmitter slave mode . . . . . . . . . . . . .482 Fig 104. Transmitter slave mode sharing the receiver reference clock . . . . . . . . . . . . . . . . . . . . . . . . .482 Fig 105. 4-wire transmitter slave mode sharing the receiver bit clock and WS . . . . . . . . . . . . . . . . . . . . . . . .483 Fig 106. Typical receiver master mode, with or without MCLK output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .484 Fig 107. Receiver master mode sharing the transmitter reference clock . . . . . . . . . . . . . . . . . . . . . . . . .484 Fig 108. 4-wire receiver master mode sharing the transmitter bit clock and WS . . . . . . . . . . . . . . . . . . . . . . . .484 Fig 109. Typical receiver slave mode. . . . . . . . . . . . . . . .484
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UM10360_1
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User manual
Rev. 01 -- 4 January 2010
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Chapter 35: LPC17xx Supplementary information
5. Contents
Chapter 1: LPC17xx Introductory information
1 2 3 4 4.1 5 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ordering information . . . . . . . . . . . . . . . . . . . . . Part options summary. . . . . . . . . . . . . . . . . . . . Simplified block diagram . . . . . . . . . . . . . . . . . 3 4 6 7 7 8 6 7 7.1 8 9 10 Architectural overview . . . . . . . . . . . . . . . . . . . 9 ARM Cortex-M3 processor . . . . . . . . . . . . . . . . 9 Cortex-M3 Configuration Options . . . . . . . . . . 9 On-chip flash memory system. . . . . . . . . . . . 10 On-chip Static RAM. . . . . . . . . . . . . . . . . . . . . 10 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 2: LPC17xx Memory map
1 2 3 Memory map and peripheral addressing. . . . 12 Memory maps. . . . . . . . . . . . . . . . . . . . . . . . . . 12 APB peripheral addresses . . . . . . . . . . . . . . . 14 4 5 6 Memory re-mapping . . . . . . . . . . . . . . . . . . . . 15 AHB arbitration . . . . . . . . . . . . . . . . . . . . . . . . 15 Bus fault exceptions . . . . . . . . . . . . . . . . . . . . 16
Chapter 3: LPC17xx System control
1 2 3 4 4.1 5 6 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . . Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reset Source Identification Register (RSID 0x400F C180) . . . . . . . . . . . . . . . . . . . . . . . . . Brown-out detection . . . . . . . . . . . . . . . . . . . . External interrupt inputs . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . . 17 17 18 18
6.2 6.3 6.4
7 7.1
21 22 23 24
External Interrupt flag register (EXTINT 0x400F C140) . . . . . . . . . . . . . . . . . . . . . . . . 24 External Interrupt Mode register (EXTMODE 0x400F C148) . . . . . . . . . . . . . . . . . . . . . . . . 25 External Interrupt Polarity register (EXTPOLAR 0x400F C14C) . . . . . . . . . . . . . . . . . . . . . . . . 26 Other system controls and status flags . . . . 28 System Controls and Status register (SCS 0x400F C1A0) . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter 4: LPC17xx Clocking and power control
1 2 3 3.1 3.2 3.3 4 4.1 5 5.1 5.1.1 5.2 5.3 Summary of clocking and power control functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . . Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internal RC oscillator . . . . . . . . . . . . . . . . . . . Main oscillator. . . . . . . . . . . . . . . . . . . . . . . . . RTC oscillator . . . . . . . . . . . . . . . . . . . . . . . . . Clock source selection multiplexer . . . . . . . . Clock Source Select register (CLKSRCSEL 0x400F C10C) . . . . . . . . . . . . . . . . . . . . . . . . PLL0 (Phase Locked Loop 0) . . . . . . . . . . . . . PLL0 operation . . . . . . . . . . . . . . . . . . . . . . . . PLL0 and startup/boot code interaction . . . . . PLL0 register description . . . . . . . . . . . . . . . . PLL0 Control register (PLL0CON 0x400F C080) . . . . . . . . . . . . . . . . . . . . . . . . .
5.4
29 30 31 31 31 33 34
5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 6 6.1 6.2
34 35 35 35 36 36
PLL0 Configuration register (PLL0CFG 0x400F C084) . . . . . . . . . . . . . . . . . . . . . . . . PLL0 Status register (PLL0STAT 0x400F C088) . . . . . . . . . . . . . . . . . . . . . . . . PLL0 Interrupt: PLOCK0 . . . . . . . . . . . . . . . . PLL0 Modes. . . . . . . . . . . . . . . . . . . . . . . . . . PLL0 Feed register (PLL0FEED 0x400F C08C) . . . . . . . . . . . . . . . . . . . . . . . . PLL0 and Power-down mode. . . . . . . . . . . . . PLL0 frequency calculation . . . . . . . . . . . . . . Procedure for determining PLL0 settings. . . . Examples of PLL0 settings . . . . . . . . . . . . . . PLL0 setup sequence . . . . . . . . . . . . . . . . . . PLL1 (Phase Locked Loop 1) . . . . . . . . . . . . . PLL1 register description . . . . . . . . . . . . . . . . PLL1 Control register (PLL1CON 0x400F C0A0) . . . . . . . . . . . . . . . . . . . . . . . .
37 39 39 40 40 40 40 42 43 46 47 47 49
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
816 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Power control . . . . . . . . . . . . . . . . . . . . . . . . . 59 Sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Deep Sleep mode . . . . . . . . . . . . . . . . . . . . . 59 Power-down mode . . . . . . . . . . . . . . . . . . . . . 60 Deep Power-down mode . . . . . . . . . . . . . . . . 61 Peripheral power control . . . . . . . . . . . . . . . . 61 Register description . . . . . . . . . . . . . . . . . . . . 61 Power Mode Control register (PCON 0x400F C0C0) . . . . . . . . . . . . . . . . . . . . . . . . 62 Encoding of Reduced Power Modes . . . . . . . 63 Wake-up from Reduced Power Modes . . . . . 63 Power Control for Peripherals register (PCONP 0x400F C0C4) . . . . . . . . . . . . . . . . . . . . . . . . 63 Power control usage notes . . . . . . . . . . . . . . 65 Power domains . . . . . . . . . . . . . . . . . . . . . . . 65 Wake-up timer . . . . . . . . . . . . . . . . . . . . . . . . . 66 External clock output pin . . . . . . . . . . . . . . . . 67 Clock Output Configuration register (CLKOUTCFG - 0x400F C1C8) . . . . . . . . . . . 67
6.3 6.4 6.4.1 6.5 6.6 6.7 6.8 6.9 7 7.1 7.2 7.3
PLL1 Configuration register (PLL1CFG 0x400F C0A4) . . . . . . . . . . . . . . . . . . . . . . . . 50 PLL1 Status register (PLL1STAT 0x400F C0A8) . . . . . . . . . . . . . . . . . . . . . . . . 50 PLL1 modes . . . . . . . . . . . . . . . . . . . . . . . . . . 51 PLL1 Interrupt: PLOCK1. . . . . . . . . . . . . . . . . 51 PLL1 Feed register (PLL1FEED 0x400F C0AC) . . . . . . . . . . . . . . . . . . . . . . . . 52 PLL1 and Power-down mode . . . . . . . . . . . . . 52 PLL1 frequency calculation . . . . . . . . . . . . . . 53 Procedure for determining PLL1 settings . . . . 53 Clock dividers . . . . . . . . . . . . . . . . . . . . . . . . . 55 CPU Clock Configuration register (CCLKCFG 0x400F C104) . . . . . . . . . . . . . . . . . . . . . . . . . 55 USB Clock Configuration register (USBCLKCFG 0x400F C108) . . . . . . . . . . . . . . . . . . . . . . . . . 56 Peripheral Clock Selection registers 0 and 1 (PCLKSEL0 - 0x400F C1A8 and PCLKSEL1 0x400F C1AC) . . . . . . . . . . . . . . . . . . . . . . . . 56
8.7.1 8.8 8.9 8.10 8.11 9 10 10.1
Chapter 5: LPC17xx Flash accelerator
1 2 2.1 2.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . Flash accelerator blocks . . . . . . . . . . . . . . . . . Flash memory bank . . . . . . . . . . . . . . . . . . . . Flash programming Issues . . . . . . . . . . . . . . . 69 69 69 70 3 4 5 Register description . . . . . . . . . . . . . . . . . . . . 70 Flash Accelerator Configuration register (FLASHCFG - 0x400F C000) . . . . . . . . . . . . . . 71 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Chapter 6: LPC17xx Nested Vectored Interrupt Controller (NVIC)
1 2 3 4 5 5.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Interrupt sources . . . . . . . . . . . . . . . . . . . . . . . 73 Vector table remapping . . . . . . . . . . . . . . . . . . 76 Register description . . . . . . . . . . . . . . . . . . . . 77 Interrupt Set-Enable Register 0 register (ISER0 0xE000 E100) . . . . . . . . . . . . . . . . . . . . . . . . . 78 Interrupt Set-Enable Register 1 register (ISER1 0xE000 E104) . . . . . . . . . . . . . . . . . . . . . . . . . 79 Interrupt Clear-Enable Register 0 (ICER0 0xE000 E180) . . . . . . . . . . . . . . . . . . . . . . . . . 80 Interrupt Clear-Enable Register 1 register (ICER1 - 0xE000 E184). . . . . . . . . . . . . . . . . . . . . . . . 81 Interrupt Set-Pending Register 0 register (ISPR0 0xE000 E200) . . . . . . . . . . . . . . . . . . . . . . . . . 82 Interrupt Set-Pending Register 1 register (ISPR1 0xE000 E204) . . . . . . . . . . . . . . . . . . . . . . . . . 83 . . . . . Interrupt Clear-Pending Register 0 register (ICPR0 - 0xE000 E280) . . . . . . . . . . . . . . . . . 84 . . . . . Interrupt Clear-Pending Register 1 register (ICPR1 - 0xE000 E284) . . . . . . . . . . . . . . . . . 85
5.9 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18
5.2 5.3 5.4 5.5 5.6 5.7 5.8
Interrupt Active Bit Register 0 (IABR0 - 0xE000 E300) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Interrupt Active Bit Register 1 (IABR1 - 0xE000 E304) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Interrupt Priority Register 0 (IPR0 0xE000 E400) . . . . . . . . . . . . . . . . . . . . . . . . 88 Interrupt Priority Register 1 (IPR1 0xE000 E404) . . . . . . . . . . . . . . . . . . . . . . . . 88 Interrupt Priority Register 2 (IPR2 0xE000 E408) . . . . . . . . . . . . . . . . . . . . . . . . 88 Interrupt Priority Register 3 (IPR3 0xE000 E40C) . . . . . . . . . . . . . . . . . . . . . . . . 89 Interrupt Priority Register 4 (IPR4 0xE000 E410) . . . . . . . . . . . . . . . . . . . . . . . . 89 Interrupt Priority Register 5 (IPR5 0xE000 E414) . . . . . . . . . . . . . . . . . . . . . . . . 89 Interrupt Priority Register 6 (IPR6 0xE000 E418) . . . . . . . . . . . . . . . . . . . . . . . . 90 Interrupt Priority Register 7 (IPR7 0xE000 E41C) . . . . . . . . . . . . . . . . . . . . . . . . 90
continued >>
UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
817 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
5.20 Software Trigger Interrupt Register (STIR 0xE000 EF00) . . . . . . . . . . . . . . . . . . . . . . . . 91
5.19
Interrupt Priority Register 8 (IPR8 0xE000 E420) . . . . . . . . . . . . . . . . . . . . . . . . . 90
Chapter 7: LPC17xx Pin configuration
1 LPC17xx pin configuration . . . . . . . . . . . . . . . 92
1.1
LPC17xx pin description . . . . . . . . . . . . . . . . 92
Chapter 8: LPC17xx Pin connect block
1 2 3 4 5 5.1 How to read this chapter . . . . . . . . . . . . . . . . 102 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Pin function select register values. . . . . . . . 102 Pin mode select register values . . . . . . . . . . 103 Register description . . . . . . . . . . . . . . . . . . . 105 Pin Function Select register 0 (PINSEL0 0x4002 C000) . . . . . . . . . . . . . . . . . . . . . . . . 106 Pin Function Select Register 1 (PINSEL1 0x4002 C004) . . . . . . . . . . . . . . . . . . . . . . . . 106 Pin Function Select register 2 (PINSEL2 0x4002 C008) . . . . . . . . . . . . . . . . . . . . . . . . 107 Pin Function Select Register 3 (PINSEL3 0x4002 C00C) . . . . . . . . . . . . . . . . . . . . . . . 107 Pin Function Select Register 4 (PINSEL4 0x4002 C010) . . . . . . . . . . . . . . . . . . . . . . . . 108 Pin Function Select Register 7 (PINSEL7 0x4002 C01C) . . . . . . . . . . . . . . . . . . . . . . . 109 Pin Function Select Register 9 (PINSEL9 0x4002 C024) . . . . . . . . . . . . . . . . . . . . . . . . 109 Pin Function Select Register 10 (PINSEL10 0x4002 C028) . . . . . . . . . . . . . . . . . . . . . . . . 109 Pin Mode select register 0 (PINMODE0 0x4002 C040) . . . . . . . . . . . . . . . . . . . . . . . . 110
5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21
5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9
Pin Mode select register 1 (PINMODE1 0x4002 C044) . . . . . . . . . . . . . . . . . . . . . . . . Pin Mode select register 2 (PINMODE2 0x4002 C048) . . . . . . . . . . . . . . . . . . . . . . . . Pin Mode select register 3 (PINMODE3 0x4002 C04C) . . . . . . . . . . . . . . . . . . . . . . . . Pin Mode select register 4 (PINMODE4 0x4002 C050) . . . . . . . . . . . . . . . . . . . . . . . . Pin Mode select register 7 (PINMODE7 0x4002 C05C) . . . . . . . . . . . . . . . . . . . . . . . . Pin Mode select register 9 (PINMODE9 0x4002 C064) . . . . . . . . . . . . . . . . . . . . . . . . Open Drain Pin Mode select register 0 (PINMODE_OD0 - 0x4002 C068) . . . . . . . . . Open Drain Pin Mode select register 1 (PINMODE_OD1 - 0x4002 C06C) . . . . . . . . . Open Drain Pin Mode select register 2 (PINMODE_OD2 - 0x4002 C070) . . . . . . . . . Open Drain Pin Mode select register 3 (PINMODE_OD3 - 0x4002 C074) . . . . . . . . . Open Drain Pin Mode select register 4 (PINMODE_OD4 - 0x4002 C078) . . . . . . . . . I2C Pin Configuration register (I2CPADCFG 0x4002 C07C) . . . . . . . . . . . . . . . . . . . . . . . .
110 111 111 112 113 113 113 114 115 116 116 117
Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
1 2 2.1 2.2 3 4 5 5.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 118 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Digital I/O ports . . . . . . . . . . . . . . . . . . . . . . . 118 Interrupt generating digital ports . . . . . . . . . . 118 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 119 Register description . . . . . . . . . . . . . . . . . . . 120 GPIO port Direction register FIOxDIR (FIO0DIR to FIO4DIR- 0x2009 C000 to 0x2009 C080) . . 121 GPIO port output Set register FIOxSET (FIO0SET to FIO4SET - 0x2009 C018 to 0x2009 C098) 122 GPIO port output Clear register FIOxCLR (FIO0CLR to FIO4CLR- 0x2009 C01C to 0x2009 C09C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
5.4 5.5
5.6 5.6.1 5.6.2 5.6.3 5.6.4 5.6.5
5.2 5.3
GPIO port Pin value register FIOxPIN (FIO0PIN to FIO4PIN- 0x2009 C014 to 0x2009 C094) . . 125 Fast GPIO port Mask register FIOxMASK (FIO0MASK to FIO4MASK - 0x2009 C010 to 0x2009 C090) . . . . . . . . . . . . . . . . . . . . . . . 126 GPIO interrupt registers . . . . . . . . . . . . . . . . 129 GPIO overall Interrupt Status register (IOIntStatus - 0x4002 8080). . . . . . . . . . . . . . . . . . . . . . . 129 GPIO Interrupt Enable for port 0 Rising Edge (IO0IntEnR - 0x4002 8090) . . . . . . . . . . . . . 129 GPIO Interrupt Enable for port 2 Rising Edge (IO2IntEnR - 0x4002 80B0) . . . . . . . . . . . . . 130 GPIO Interrupt Enable for port 0 Falling Edge (IO0IntEnF - 0x4002 8094) . . . . . . . . . . . . . 131 GPIO Interrupt Enable for port 2 Falling Edge (IO2IntEnF - 0x4002 80B4) . . . . . . . . . . . . . 132
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
818 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
5.6.10 133 5.6.11 134 134 135
6 6.1
5.6.6 5.6.7 5.6.8 5.6.9
GPIO Interrupt Status for port 0 Rising Edge Interrupt (IO0IntStatR - 0x4002 8084) . . . . . GPIO Interrupt Status for port 2 Rising Edge Interrupt (IO2IntStatR - 0x4002 80A4) . . . . . GPIO Interrupt Status for port 0 Falling Edge Interrupt (IO0IntStatF - 0x4002 8088). . . . . . GPIO Interrupt Status for port 2 Falling Edge Interrupt (IO2IntStatF - 0x4002 80A8) . . . . .
6.2
GPIO Interrupt Clear register for port 0 (IO0IntClr - 0x4002 808C) . . . . . . . . . . . . . . . . . . . . . . 136 GPIO Interrupt Clear register for port 0 (IO2IntClr - 0x4002 80AC) . . . . . . . . . . . . . . . . . . . . . . 137 GPIO usage notes . . . . . . . . . . . . . . . . . . . . . 138 Example: An instantaneous output of 0s and 1s on a GPIO port . . . . . . . . . . . . . . . . . . . . . . . . . 138 Writing to FIOSET/FIOCLR vs. FIOPIN . . . . 138
Chapter 10: LPC17xx Ethernet
1 2 3 4 5 6 7 8 8.1 8.2 9 10 10.1 11 11.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 139 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Architecture and operation . . . . . . . . . . . . . . 141 DMA engine functions . . . . . . . . . . . . . . . . . . 142 Overview of DMA operation . . . . . . . . . . . . . 142 Ethernet Packet . . . . . . . . . . . . . . . . . . . . . . . 143 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Example PHY Devices . . . . . . . . . . . . . . . . . 145 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 145 Registers and software interface . . . . . . . . . 146 Register map . . . . . . . . . . . . . . . . . . . . . . . . 146 Ethernet MAC register definitions . . . . . . . . 148 MAC Configuration Register 1 (MAC1 0x5000 0000) . . . . . . . . . . . . . . . . . . . . . . . . 148 MAC Configuration Register 2 (MAC2 0x5000 0004) . . . . . . . . . . . . . . . . . . . . . . . . 148 Back-to-Back Inter-Packet-Gap Register (IPGT 0x5000 0008) . . . . . . . . . . . . . . . . . . . . . . . . 150 Non Back-to-Back Inter-Packet-Gap Register (IPGR - 0x5000 000C) . . . . . . . . . . . . . . . . . 150 Collision Window / Retry Register (CLRT 0x5000 0010) . . . . . . . . . . . . . . . . . . . . . . . . 151 Maximum Frame Register (MAXF 0x5000 0014) . . . . . . . . . . . . . . . . . . . . . . . . 151 PHY Support Register (SUPP 0x5000 0018) . . . . . . . . . . . . . . . . . . . . . . . . 151 Test Register (TEST - 0x5000 001C) . . . . . . 151 MII Mgmt Configuration Register (MCFG 0x5000 0020) . . . . . . . . . . . . . . . . . . . . . . . . 152 MII Mgmt Command Register (MCMD 0x5000 0024) . . . . . . . . . . . . . . . . . . . . . . . . 153 MII Mgmt Address Register (MADR 0x5000 0028) . . . . . . . . . . . . . . . . . . . . . . . . 153 MII Mgmt Write Data Register (MWTD 0x5000 002C) . . . . . . . . . . . . . . . . . . . . . . . . 153
11.13 11.14 11.15 11.16 11.17
12 12.1
12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 12.10 12.11 12.12 12.13 12.14
11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 11.11 11.12
MII Mgmt Read Data Register (MRDD 0x5000 0030) . . . . . . . . . . . . . . . . . . . . . . . . 154 MII Mgmt Indicators Register (MIND 0x5000 0034) . . . . . . . . . . . . . . . . . . . . . . . . 154 Station Address 0 Register (SA0 0x5000 0040) . . . . . . . . . . . . . . . . . . . . . . . . 155 Station Address 1 Register (SA1 0x5000 0044) . . . . . . . . . . . . . . . . . . . . . . . . 155 Station Address 2 Register (SA2 0x5000 0048) . . . . . . . . . . . . . . . . . . . . . . . . 155 Control register definitions . . . . . . . . . . . . . 156 Command Register (Command 0x5000 0100) . . . . . . . . . . . . . . . . . . . . . . . . 156 Status Register (Status - 0x5000 0104) . . . . 156 Receive Descriptor Base Address Register (RxDescriptor - 0x5000 0108) . . . . . . . . . . . 157 Receive Status Base Address Register (RxStatus - 0x5000 010C) . . . . . . . . . . . . . . . . . . . . . . 157 Receive Number of Descriptors Register (RxDescriptor - 0x5000 0110) . . . . . . . . . . . 157 Receive Produce Index Register (RxProduceIndex - 0x5000 0114) . . . . . . . . 158 Receive Consume Index Register (RxConsumeIndex - 0x5000 0118) . . . . . . . 158 Transmit Descriptor Base Address Register (TxDescriptor - 0x5000 011C) . . . . . . . . . . . 159 Transmit Status Base Address Register (TxStatus - 0x5000 0120). . . . . . . . . . . . . . . . . . . . . . . 159 Transmit Number of Descriptors Register (TxDescriptorNumber - 0x5000 0124) . . . . . 159 Transmit Produce Index Register (TxProduceIndex - 0x5000 0128) . . . . . . . . 160 Transmit Consume Index Register (TxConsumeIndex - 0x5000 012C) . . . . . . . 160 Transmit Status Vector 0 Register (TSV0 0x5000 0158) . . . . . . . . . . . . . . . . . . . . . . . . 160 Transmit Status Vector 1 Register (TSV1 0x5000 015C) . . . . . . . . . . . . . . . . . . . . . . . 161
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
819 of 835
NXP Semiconductors
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Chapter 35: LPC17xx Supplementary information
15.2 16 16.1 16.2 17 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 17.10 17.11 17.12 17.13 17.14 17.15 17.16 17.17 17.18 17.19 18 18.1 18.2 18.3 19 Transmit descriptors and statuses . . . . . . . . Ethernet block functional description. . . . . Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . AHB interface. . . . . . . . . . . . . . . . . . . . . . . . Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direct Memory Access (DMA) . . . . . . . . . . . Initialization . . . . . . . . . . . . . . . . . . . . . . . . . Transmit process . . . . . . . . . . . . . . . . . . . . . Receive process . . . . . . . . . . . . . . . . . . . . . Transmission retry . . . . . . . . . . . . . . . . . . . . Status hash CRC calculations . . . . . . . . . . . Duplex modes . . . . . . . . . . . . . . . . . . . . . . . IEE 802.3/Clause 31 flow control. . . . . . . . . Half-Duplex mode backpressure . . . . . . . . . Receive filtering . . . . . . . . . . . . . . . . . . . . . . Power management. . . . . . . . . . . . . . . . . . . Wake-up on LAN . . . . . . . . . . . . . . . . . . . . . Enabling and disabling receive and transmit Transmission padding and CRC . . . . . . . . . Huge frames and frame length checking . . . Statistics counters . . . . . . . . . . . . . . . . . . . . MAC status vectors . . . . . . . . . . . . . . . . . . . Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ethernet errors . . . . . . . . . . . . . . . . . . . . . . . AHB bandwidth . . . . . . . . . . . . . . . . . . . . . . . DMA access. . . . . . . . . . . . . . . . . . . . . . . . . Types of CPU access. . . . . . . . . . . . . . . . . . Overall bandwidth . . . . . . . . . . . . . . . . . . . . CRC calculation. . . . . . . . . . . . . . . . . . . . . . . 173 175 175 176 176 176 179 180 186 192 192 193 193 195 196 198 198 200 202 203 203 203 204 205 206 206 207 207 209
12.15 12.16 12.17
13 13.1
13.2 13.3 13.4 13.5
14 14.1
14.2 14.3 14.4 14.5
15 15.1
Receive Status Vector Register (RSV 0x5000 0160) . . . . . . . . . . . . . . . . . . . . . . . . 162 Flow Control Counter Register (FlowControlCounter - 0x5000 0170) . . . . . . 163 Flow Control Status Register (FlowControlStatus 0x5000 0174) . . . . . . . . . . . . . . . . . . . . . . . . 163 Receive filter register definitions . . . . . . . . . 164 Receive Filter Control Register (RxFilterCtrl 0x5000 0200) . . . . . . . . . . . . . . . . . . . . . . . . 164 Receive Filter WoL Status Register (RxFilterWoLStatus - 0x5000 0204) . . . . . . . 164 Receive Filter WoL Clear Register (RxFilterWoLClear - 0x5000 0208) . . . . . . . . 165 Hash Filter Table LSBs Register (HashFilterL 0x5000 0210) . . . . . . . . . . . . . . . . . . . . . . . . 165 Hash Filter Table MSBs Register (HashFilterH 0x5000 0214) . . . . . . . . . . . . . . . . . . . . . . . . 166 Module control register definitions . . . . . . . 166 Interrupt Status Register (IntStatus 0x5000 0FE0) . . . . . . . . . . . . . . . . . . . . . . . . 166 Interrupt Enable Register (IntEnable 0x5000 0FE4) . . . . . . . . . . . . . . . . . . . . . . . . 167 Interrupt Clear Register (IntClear 0x5000 0FE8) . . . . . . . . . . . . . . . . . . . . . . . . 167 Interrupt Set Register (IntSet 0x5000 0FEC) . . . . . . . . . . . . . . . . . . . . . . . 168 Power-Down Register (PowerDown 0x5000 0FF4) . . . . . . . . . . . . . . . . . . . . . . . . 169 Descriptor and status formats . . . . . . . . . . . 170 Receive descriptors and statuses. . . . . . . . . 170
Chapter 11: LPC17xx USB device controller
1 2 3 4 5 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 7 8 How to read this chapter . . . . . . . . . . . . . . . . Basic configuration . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fixed endpoint configuration . . . . . . . . . . . . Functional description . . . . . . . . . . . . . . . . . Analog transceiver . . . . . . . . . . . . . . . . . . . . Serial Interface Engine (SIE) . . . . . . . . . . . . Endpoint RAM (EP_RAM) . . . . . . . . . . . . . . EP_RAM access control . . . . . . . . . . . . . . . . DMA engine and bus master interface . . . . . Register interface . . . . . . . . . . . . . . . . . . . . . SoftConnect . . . . . . . . . . . . . . . . . . . . . . . . . GoodLink . . . . . . . . . . . . . . . . . . . . . . . . . . . Operational overview . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . 211 211 211 212 212 213 214 214 214 214 215 215 215 215 215 216 9 9.1 9.2 9.3 9.4 10 10.1 10.1.1 Clocking and power management. . . . . . . . 216 Power requirements . . . . . . . . . . . . . . . . . . . 216 Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 Power management support . . . . . . . . . . . . 217 Remote wake-up . . . . . . . . . . . . . . . . . . . . . 218 Register description . . . . . . . . . . . . . . . . . . . 218 Clock control registers . . . . . . . . . . . . . . . . . 219 USB Clock Control register (USBClkCtrl 0x5000 CFF4) . . . . . . . . . . . . . . . . . . . . . . . 219 USB Clock Status register (USBClkSt - 0x5000 CFF8). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Device interrupt registers . . . . . . . . . . . . . . . 220 USB Interrupt Status register (USBIntSt 0x5000 C1C0) . . . . . . . . . . . . . . . . . . . . . . . 220 USB Device Interrupt Status register (USBDevIntSt - 0x5000 C200) . . . . . . . . . . 221
10.1.2 10.2 10.2.1 10.2.2
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
820 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
10.7.4 10.7.5 10.7.6 10.7.7 10.7.8 10.7.9 10.7.10 10.7.11 10.7.12 10.7.13 10.7.14 10.7.15 10.7.16 10.7.17 10.7.18
11 12
10.2.3 10.2.4 10.2.5 10.2.6 10.3 10.3.1 10.3.2 10.3.3 10.3.4 10.3.5 10.4 10.4.1 10.4.2 10.4.3 10.4.4 10.5 10.5.1 10.5.2 10.5.3 10.5.4 10.5.5 10.6 10.6.1 10.6.2 10.7 10.7.1 10.7.2 10.7.3
USB Device Interrupt Enable register (USBDevIntEn - 0x5000 C204) . . . . . . . . . . 222 USB Device Interrupt Clear register (USBDevIntClr - 0x5000 C208) . . . . . . . . . . 222 USB Device Interrupt Set register (USBDevIntSet - 0x5000 C20C) . . . . . . . . . . . . . . . . . . . . . . 223 USB Device Interrupt Priority register (USBDevIntPri - 0x5000 C22C) . . . . . . . . . . 223 Endpoint interrupt registers. . . . . . . . . . . . . . 224 USB Endpoint Interrupt Status register (USBEpIntSt - 0x5000 C230). . . . . . . . . . . . 224 USB Endpoint Interrupt Enable register (USBEpIntEn - 0x5000 C234) . . . . . . . . . . . 225 USB Endpoint Interrupt Clear register (USBEpIntClr - 0x5000 C238) . . . . . . . . . . . 226 USB Endpoint Interrupt Set register (USBEpIntSet - 0x5000 C23C) . . . . . . . . . . . . . . . . . . . . . . 227 USB Endpoint Interrupt Priority register (USBEpIntPri - 0x5000 C240) . . . . . . . . . . . 227 Endpoint realization registers . . . . . . . . . . . . 228 EP RAM requirements . . . . . . . . . . . . . . . . . 228 USB Realize Endpoint register (USBReEp 0x5000 C244) . . . . . . . . . . . . . . . . . . . . . . . 228 USB Endpoint Index register (USBEpIn - 0x5000 C248). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 USB MaxPacketSize register (USBMaxPSize 0x5000 C24C) . . . . . . . . . . . . . . . . . . . . . . . 230 USB transfer registers . . . . . . . . . . . . . . . . . 230 USB Receive Data register (USBRxData - 0x5000 C218). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 USB Receive Packet Length register (USBRxPLen - 0x5000 C220) . . . . . . . . . . . 231 USB Transmit Data register (USBTxData - 0x5000 C21C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 USB Transmit Packet Length register (USBTxPLen - 0x5000 C224) . . . . . . . . . . . 232 USB Control register (USBCtrl 0x5000 C228) . . . . . . . . . . . . . . . . . . . . . . . 232 SIE command code registers . . . . . . . . . . . . 232 USB Command Code register (USBCmdCode 0x5000 C210) . . . . . . . . . . . . . . . . . . . . . . . 233 USB Command Data register (USBCmdData 0x5000 C214) . . . . . . . . . . . . . . . . . . . . . . . 233 DMA registers . . . . . . . . . . . . . . . . . . . . . . . . 233 USB DMA Request Status register (USBDMARSt - 0x5000 C250) . . . . . . . . . . . . . . . . . . . . . . 233 USB DMA Request Clear register (USBDMARClr - 0x5000 C254) . . . . . . . . . . . . . . . . . . . . . . 234 USB DMA Request Set register (USBDMARSet 0x5000 C258) . . . . . . . . . . . . . . . . . . . . . . . 234
12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8
USB UDCA Head register (USBUDCAH - 0x5000 C280) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 USB EP DMA Status register (USBEpDMASt 0x5000 C284) . . . . . . . . . . . . . . . . . . . . . . . 235 USB EP DMA Enable register (USBEpDMAEn 0x5000 C288) . . . . . . . . . . . . . . . . . . . . . . . 236 USB EP DMA Disable register (USBEpDMADis 0x5000 C28C). . . . . . . . . . . . . . . . . . . . . . . 236 USB DMA Interrupt Status register (USBDMAIntSt - 0x5000 C290) . . . . . . . . . . . . . . . . . . . . . . 236 USB DMA Interrupt Enable register (USBDMAIntEn - 0x5000 C294) . . . . . . . . . 237 USB End of Transfer Interrupt Status register (USBEoTIntSt - 0x5000 C2A0) . . . . . . . . . . 237 USB End of Transfer Interrupt Clear register (USBEoTIntClr - 0x5000 C2A4) . . . . . . . . . 237 USB End of Transfer Interrupt Set register (USBEoTIntSet - 0x5000 C2A8) . . . . . . . . . 238 USB New DD Request Interrupt Status register (USBNDDRIntSt - 0x5000 C2AC) . . . . . . . . 238 USB New DD Request Interrupt Clear register (USBNDDRIntClr - 0x5000 C2B0) . . . . . . . 238 USB New DD Request Interrupt Set register (USBNDDRIntSet - 0x5000 C2B4) . . . . . . . 238 USB System Error Interrupt Status register (USBSysErrIntSt - 0x5000 C2B8) . . . . . . . . 239 USB System Error Interrupt Clear register (USBSysErrIntClr - 0x5000 C2BC) . . . . . . . 239 USB System Error Interrupt Set register (USBSysErrIntSet - 0x5000 C2C0). . . . . . . 239 Interrupt handling . . . . . . . . . . . . . . . . . . . . 239 Serial interface engine command description. . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Set Address (Command: 0xD0, Data: write 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . 243 Configure Device (Command: 0xD8, Data: write 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Set Mode (Command: 0xF3, Data: write 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Read Current Frame Number (Command: 0xF5, Data: read 1 or 2 bytes) . . . . . . . . . . . . . . . . 244 Read Test Register (Command: 0xFD, Data: read 2 bytes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Set Device Status (Command: 0xFE, Data: write 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Get Device Status (Command: 0xFE, Data: read 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 Get Error Code (Command: 0xFF, Data: read 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
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(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
821 of 835
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Chapter 35: LPC17xx Supplementary information
15.4.9 15.4.10 15.4.11 15.4.12 15.4.13 15.4.14 15.4.15 15.5 15.5.1 15.5.2 15.5.3 15.5.4 15.5.5 15.5.6 15.6 15.6.1 15.6.2 15.6.3 15.6.4 15.6.5 15.7 15.7.1 15.7.2 15.7.3 15.7.4 16 16.1 16.2 DD_status . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Packet_valid. . . . . . . . . . . . . . . . . . . . . . . . . 257 LS_byte_extracted . . . . . . . . . . . . . . . . . . . . 257 MS_byte_extracted . . . . . . . . . . . . . . . . . . . 257 Present_DMA_count . . . . . . . . . . . . . . . . . . 257 Message_length_position . . . . . . . . . . . . . . 257 Isochronous_packetsize_memory_address. 257 Non-isochronous endpoint operation . . . . . . 258 Setting up DMA transfers. . . . . . . . . . . . . . . 258 Finding DMA Descriptor. . . . . . . . . . . . . . . . 258 Transferring the data . . . . . . . . . . . . . . . . . . 258 Optimizing descriptor fetch . . . . . . . . . . . . . 258 Ending the packet transfer . . . . . . . . . . . . . . 259 No_Packet DD . . . . . . . . . . . . . . . . . . . . . . . 259 Isochronous endpoint operation. . . . . . . . . . 259 Setting up DMA transfers. . . . . . . . . . . . . . . 259 Finding the DMA Descriptor. . . . . . . . . . . . . 260 Transferring the Data . . . . . . . . . . . . . . . . . . 260 DMA descriptor completion . . . . . . . . . . . . . 260 Isochronous OUT Endpoint Operation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 Auto Length Transfer Extraction (ATLE) mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 Setting up the DMA transfer. . . . . . . . . . . . . 263 Finding the DMA Descriptor. . . . . . . . . . . . . 263 Transferring the Data . . . . . . . . . . . . . . . . . . 263 Ending the packet transfer . . . . . . . . . . . . . . 264 Double buffered endpoint operation . . . . . . 264 Bulk endpoints . . . . . . . . . . . . . . . . . . . . . . . 264 Isochronous endpoints . . . . . . . . . . . . . . . . . 266
12.9 12.10 12.11 12.12 12.13 12.14
13 14 14.1 14.2 14.3 15 15.1 15.2 15.3 15.4 15.4.1 15.4.2 15.4.3 15.4.4 15.4.5 15.4.6 15.4.7 15.4.8
Read Error Status (Command: 0xFB, Data: read 1 byte) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Select Endpoint (Command: 0x00 - 0x1F, Data: read 1 byte (optional)) . . . . . . . . . . . . . . . . . 247 Select Endpoint/Clear Interrupt (Command: 0x40 - 0x5F, Data: read 1 byte) . . . . . . . . . . 248 Set Endpoint Status (Command: 0x40 - 0x55, Data: write 1 byte (optional)). . . . . . . . . . . . . 249 Clear Buffer (Command: 0xF2, Data: read 1 byte (optional)) . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 Validate Buffer (Command: 0xFA, Data: none) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 USB device controller initialization . . . . . . . 250 Slave mode operation . . . . . . . . . . . . . . . . . . 251 Interrupt generation . . . . . . . . . . . . . . . . . . . 251 Data transfer for OUT endpoints. . . . . . . . . . 252 Data transfer for IN endpoints. . . . . . . . . . . . 252 DMA operation . . . . . . . . . . . . . . . . . . . . . . . . 252 Transfer terminology. . . . . . . . . . . . . . . . . . . 253 USB device communication area . . . . . . . . . 253 Triggering the DMA engine. . . . . . . . . . . . . . 254 The DMA descriptor . . . . . . . . . . . . . . . . . . . 254 Next_DD_pointer . . . . . . . . . . . . . . . . . . . . . 255 DMA_mode. . . . . . . . . . . . . . . . . . . . . . . . . . 256 Next_DD_valid . . . . . . . . . . . . . . . . . . . . . . . 256 Isochronous_endpoint . . . . . . . . . . . . . . . . . 256 Max_packet_size . . . . . . . . . . . . . . . . . . . . . 256 DMA_buffer_length. . . . . . . . . . . . . . . . . . . . 256 DMA_buffer_start_addr . . . . . . . . . . . . . . . . 256 DD_retired . . . . . . . . . . . . . . . . . . . . . . . . . . 256
Chapter 12: LPC17xx USB Host controller
1 2 3 3.1 3.2 How to read this chapter . . . . . . . . . . . . . . . . Basic configuration . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 267 267 267 268 268 4 4.1 4.1.1 4.2 4.2.1 4.2.2 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . USB host usage note . . . . . . . . . . . . . . . . . . Software interface . . . . . . . . . . . . . . . . . . . . Register map . . . . . . . . . . . . . . . . . . . . . . . . USB Host Register Definitions . . . . . . . . . . . 268 269 269 269 269 270
Chapter 13: LPC17xx USB OTG controller
1 2 3 4 5 6 7 How to read this chapter . . . . . . . . . . . . . . . . Basic configuration . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . Modes of operation . . . . . . . . . . . . . . . . . . . . Pin configuration . . . . . . . . . . . . . . . . . . . . . . 271 271 271 271 272 272 273
7.1 7.2 7.3 8 8.1
Connecting the USB port to an external OTG transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . 273 Connecting USB as a host. . . . . . . . . . . . . . 274 Connecting USB as device . . . . . . . . . . . . . 274 Register description . . . . . . . . . . . . . . . . . . . 275 USB Interrupt Status Register (USBIntSt 0x5000 C1C0) . . . . . . . . . . . . . . . . . . . . . . . 275
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
822 of 835
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8.11 8.12 8.13 8.14 8.15 8.16 9 9.1 9.2 10 10.1 10.1.1 10.2 11 I2C Transmit Register (I2C_TX 0x5000 C300) . . . . . . . . . . . . . . . . . . . . . . . I2C Status Register (I2C_STS 0x5000 C304) . . . . . . . . . . . . . . . . . . . . . . . I2C Control Register (I2C_CTL 0x5000 C308) . . . . . . . . . . . . . . . . . . . . . . . I2C Clock High Register (I2C_CLKHI 0x5000 C30C) . . . . . . . . . . . . . . . . . . . . . . . I2C Clock Low Register (I2C_CLKLO 0x5000 C310) . . . . . . . . . . . . . . . . . . . . . . . Interrupt handling . . . . . . . . . . . . . . . . . . . . . HNP support . . . . . . . . . . . . . . . . . . . . . . . . . B-device: peripheral to host switching . . . . . A-device: host to peripheral HNP switching. Clocking and power management. . . . . . . . Device clock request signals . . . . . . . . . . . . Host clock request signals . . . . . . . . . . . . . . Power-down mode support . . . . . . . . . . . . . USB OTG controller initialization . . . . . . . .
8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10
OTG Interrupt Status Register (OTGIntSt 0x5000 C100) . . . . . . . . . . . . . . . . . . . . . . . . 276 OTG Interrupt Enable Register (OTGIntEn 0x5000 C104) . . . . . . . . . . . . . . . . . . . . . . . . 276 OTG Interrupt Set Register (OTGIntSet 0x5000 C20C) . . . . . . . . . . . . . . . . . . . . . . . 276 OTG Interrupt Clear Register (OTGIntClr 0x5000 C10C) . . . . . . . . . . . . . . . . . . . . . . . 277 OTG Status and Control Register (OTGStCtrl 0x5000 C110) . . . . . . . . . . . . . . . . . . . . . . . . 277 OTG Timer Register (OTGTmr 0x5000 C114) . . . . . . . . . . . . . . . . . . . . . . . . 278 OTG Clock Control Register (OTGClkCtrl 0x5000 CFF4). . . . . . . . . . . . . . . . . . . . . . . . 278 OTG Clock Status Register (OTGClkSt 0x5000 CFF8). . . . . . . . . . . . . . . . . . . . . . . . 279 I2C Receive Register (I2C_RX 0x5000 C300) . . . . . . . . . . . . . . . . . . . . . . . . 279
280 280 282 283 283 283 284 285 288 292 293 294 294 294
Chapter 14: LPC17xx UART0/2/3
1 2 3 4 14.4.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 296 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 297 Register description . . . . . . . . . . . . . . . . . . . 297 UARTn Receiver Buffer Register (U0RBR 0x4000 C000, U2RBR - 0x4009 8000, U3RBR 0x4009 C000 when DLAB = 0) . . . . . . . . . . . 299 UARTn Transmit Holding Register (U0THR 0x4000 C000, U2THR - 0x4009 8000, U3THR 0x4009 C000 when DLAB = 0) . . . . . . . . . . . 299 UARTn Divisor Latch LSB register (U0DLL 0x4000 C000, U2DLL - 0x4009 8000, U3DLL 0x4009 C000 when DLAB = 1) and UARTn Divisor Latch MSB register (U0DLM - 0x4000 C004, U2DLL - 0x4009 8004, U3DLL - 0x4009 C004 when DLAB = 1) . . . . . . . . . . . . . . . . . . . . . . 299 UARTn Interrupt Enable Register (U0IER 0x4000 C004, U2IER - 0x4009 8004, U3IER 0x4009 C004 when DLAB = 0) . . . . . . . . . . . 300 UARTn Interrupt Identification Register (U0IIR 0x4000 C008, U2IIR - 0x4009 8008, U3IIR 0x4009 C008) . . . . . . . . . . . . . . . . . . . . . . . . 301 UARTn FIFO Control Register (U0FCR 0x4000 C008, U2FCR - 0x4009 8008, U3FCR 0x4009 C008) . . . . . . . . . . . . . . . . . . . . . . . . 303 DMA Operation . . . . . . . . . . . . . . . . . . . . . . . 303
4.7
4.2
4.3
4.4
4.5
4.6
4.6.1
UARTn Line Control Register (U0LCR 0x4000 C00C, U2LCR - 0x4009 800C, U3LCR 0x4009 C00C) . . . . . . . . . . . . . . . . . . . . . . . 304 4.8 UARTn Line Status Register (U0LSR 0x4000 C014, U2LSR - 0x4009 8014, U3LSR 0x4009 C014) . . . . . . . . . . . . . . . . . . . . . . . 304 4.9 UARTn Scratch Pad Register (U0SCR 0x4000 C01C, U2SCR - 0x4009 801C U3SCR 0x4009 C01C) . . . . . . . . . . . . . . . . . . . . . . . 306 4.10 UARTn Auto-baud Control Register (U0ACR 0x4000 C020, U2ACR - 0x4009 8020, U3ACR 0x4009 C020) . . . . . . . . . . . . . . . . . . . . . . . 306 14.4.10.1 Auto-baud . . . . . . . . . . . . . . . . . . . . . . . . . . 307 14.4.10.2 Auto-baud modes. . . . . . . . . . . . . . . . . . . . . 308 4.11 UARTn IrDA Control Register (U0ICR - 0x4000 C024, U2ICR - 0x4009 8024, U3ICR 0x4009 C024) . . . . . . . . . . . . . . . . . . . . . . . 309 4.12 UARTn Fractional Divider Register (U0FDR 0x4000 C028, U2FDR - 0x4009 8028, U3FDR 0x4009 C028) . . . . . . . . . . . . . . . . . . . . . . . 310 4.12.1 Baud rate calculation . . . . . . . . . . . . . . . . . . . 311 4.13 UARTn Transmit Enable Register (U0TER 0x4000 C030, U2TER - 0x4009 8030, U3TER 0x4009 C030) . . . . . . . . . . . . . . . . . . . . . . . 313 4.14 UARTn FIFO Level register (U0FIFOLVL 0x4000 C058, U2FIFOLVL - 0x4009 8058, U3FIFOLVL - 0x4009 C058) . . . . . . . . . . . . 314 5 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 314
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
823 of 835
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Chapter 35: LPC17xx Supplementary information
Chapter 15: LPC17xx UART1
Basic configuration . . . . . . . . . . . . . . . . . . . . 316 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 317 Register description . . . . . . . . . . . . . . . . . . . 318 UART1 Receiver Buffer Register (U1RBR 0x4001 0000, when DLAB = 0). . . . . . . . . . . 319 4.2 UART1 Transmitter Holding Register (U1THR 0x4001 0000 when DLAB = 0) . . . . . . . . . . . 319 4.3 UART1 Divisor Latch LSB and MSB Registers (U1DLL - 0x4001 0000 and U1DLM 0x4001 0004, when DLAB = 1). . . . . . . . . . . 319 4.4 UART1 Interrupt Enable Register (U1IER 0x4001 0004, when DLAB = 0). . . . . . . . . . . 320 4.5 UART1 Interrupt Identification Register (U1IIR 0x4001 0008) . . . . . . . . . . . . . . . . . . . . . . . . 321 4.6 UART1 FIFO Control Register (U1FCR 0x4001 0008) . . . . . . . . . . . . . . . . . . . . . . . . 323 4.6.1 DMA Operation . . . . . . . . . . . . . . . . . . . . . . . 323 4.7 UART1 Line Control Register (U1LCR 0x4001 000C) . . . . . . . . . . . . . . . . . . . . . . . . 324 4.8 UART1 Modem Control Register (U1MCR 0x4001 0010) . . . . . . . . . . . . . . . . . . . . . . . . 324 4.9 Auto-flow control . . . . . . . . . . . . . . . . . . . . . . 325 15.4.9.1 Auto-RTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 15.4.9.2 Auto-CTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 1 2 3 4 4.1
4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.16.1 4.17 4.18 4.19 4.20 4.21 4.22
5
UART1 Line Status Register (U1LSR 0x4001 0014) . . . . . . . . . . . . . . . . . . . . . . . . 327 UART1 Modem Status Register (U1MSR 0x4001 0018) . . . . . . . . . . . . . . . . . . . . . . . . 328 UART1 Scratch Pad Register (U1SCR 0x4001 001C) . . . . . . . . . . . . . . . . . . . . . . . 329 UART1 Auto-baud Control Register (U1ACR 0x4001 0020) . . . . . . . . . . . . . . . . . . . . . . . . 329 Auto-baud . . . . . . . . . . . . . . . . . . . . . . . . . . 330 Auto-baud modes. . . . . . . . . . . . . . . . . . . . . 331 UART1 Fractional Divider Register (U1FDR 0x4001 0028) . . . . . . . . . . . . . . . . . . . . . . . . 332 Baud rate calculation . . . . . . . . . . . . . . . . . . 333 UART1 Transmit Enable Register (U1TER 0x4001 0030) . . . . . . . . . . . . . . . . . . . . . . . . 335 UART1 RS485 Control register (U1RS485CTRL 0x4001 004C) . . . . . . . . . . . . . . . . . . . . . . . 336 UART1 RS-485 Address Match register (U1RS485ADRMATCH - 0x4001 0050) . . . . 337 UART1 RS-485 Delay value register (U1RS485DLY - 0x4001 0054) . . . . . . . . . . 337 RS-485/EIA-485 modes of operation . . . . . . 337 UART1 FIFO Level register (U1FIFOLVL 0x4001 0058) . . . . . . . . . . . . . . . . . . . . . . . . 339 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 339
Chapter 16: LPC17xx CAN1/2
1 2 3 3.1 3.2 3.3 4 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 6 7 Basic configuration . . . . . . . . . . . . . . . . . . . . CAN controllers . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General CAN features . . . . . . . . . . . . . . . . . CAN controller features . . . . . . . . . . . . . . . . Acceptance filter features . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . CAN controller architecture . . . . . . . . . . . . . APB Interface Block (AIB) . . . . . . . . . . . . . . Interface Management Logic (IML). . . . . . . . Transmit Buffers (TXB) . . . . . . . . . . . . . . . . . Receive Buffer (RXB) . . . . . . . . . . . . . . . . . Error Management Logic (EML) . . . . . . . . . Bit Timing Logic (BTL) . . . . . . . . . . . . . . . . . Bit Stream Processor (BSP) . . . . . . . . . . . . . CAN controller self-tests . . . . . . . . . . . . . . . . Memory map of the CAN block. . . . . . . . . . . CAN controller registers . . . . . . . . . . . . . . . . 341 341 341 341 342 342 342 342 343 343 343 344 345 345 345 345 347 347
7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.9.1
CAN Mode register (CAN1MOD - 0x4004 4000, CAN2MOD - 0x4004 8000) . . . . . . . . . . . . . 349 CAN Command Register (CAN1CMR 0x4004 x004, CAN2CMR - 0x4004 8004) . . 351 CAN Global Status Register (CAN1GSR 0x4004 x008, CAN2GSR - 0x4004 8008) . . 352 CAN Interrupt and Capture Register (CAN1ICR 0x4004 400C, CAN2ICR - 0x4004 800C) . . 355 CAN Interrupt Enable Register (CAN1IER 0x4004 4010, CAN2IER - 0x4004 8010) . . . 358 CAN Bus Timing Register (CAN1BTR 0x4004 4014, CAN2BTR - 0x4004 8014) . . 359 CAN Error Warning Limit register (CAN1EWL 0x4004 4018, CAN2EWL - 0x4004 8018) . . 360 CAN Status Register (CAN1SR - 0x4004 401C, CAN2SR - 0x4004 801C). . . . . . . . . . . . . . . 361 CAN Receive Frame Status register (CAN1RFS 0x4004 4020, CAN2RFS - 0x4004 8020) . . 363 ID index field . . . . . . . . . . . . . . . . . . . . . . . . 363
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User manual
Rev. 01 -- 4 January 2010
824 of 835
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14.4 14.5 14.6 14.7 14.8 14.9 14.10 14.11 14.12 Standard Frame Group Start Address register (SFF_GRP_sa - 0x4003 C008) . . . . . . . . . . 376 Extended Frame Start Address register (EFF_sa 0x4003 C00C) . . . . . . . . . . . . . . . . . . . . . . . 376 Extended Frame Group Start Address register (EFF_GRP_sa - 0x4003 C010) . . . . . . . . . . 377 End of AF Tables register (ENDofTable 0x4003 C014) . . . . . . . . . . . . . . . . . . . . . . . 377 Status registers . . . . . . . . . . . . . . . . . . . . . . 377 LUT Error Address register (LUTerrAd 0x4003 C018) . . . . . . . . . . . . . . . . . . . . . . . 378 LUT Error register (LUTerr - 0x4003 C01C). 378 Global FullCANInterrupt Enable register (FCANIE - 0x4003 C020) . . . . . . . . . . . . . . . . . . . . . . 378 FullCAN Interrupt and Capture registers (FCANIC0 - 0x4003 C024 and FCANIC1 0x4003 C028) . . . . . . . . . . . . . . . . . . . . . . . 378 Configuration and search algorithm . . . . . . 379 Acceptance filter search algorithm . . . . . . . . 379 FullCAN mode . . . . . . . . . . . . . . . . . . . . . . . . 380 FullCAN message layout . . . . . . . . . . . . . . . 382 FullCAN interrupts . . . . . . . . . . . . . . . . . . . . 384 FullCAN message interrupt enable bit . . . . . 384 Message lost bit and CAN channel number. 385 Setting the interrupt pending bits (IntPnd 63 to 0) . . . . . . . . . . . . . . . . . . . . . . 386 Clearing the interrupt pending bits (IntPnd 63 to 0) . . . . . . . . . . . . . . . . . . . . . . 386 Setting the message lost bit of a FullCAN message object (MsgLost 63 to 0). . . . . . . . 386 Clearing the message lost bit of a FullCAN message object (MsgLost 63 to 0). . . . . . . . 386 Set and clear mechanism of the FullCAN interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386 Scenario 1: Normal case, no message lost . 386 Scenario 2: Message lost. . . . . . . . . . . . . . . 387 Scenario 3: Message gets overwritten indicated by Semaphore bits . . . . . . . . . . . . . . . . . . . . 388 Scenario 3.1: Message gets overwritten indicated by Semaphore bits and Message Lost. . . . . 388 Scenario 3.2: Message gets overwritten indicated by Message Lost . . . . . . . . . . . . . . . . . . . . . 389 Scenario 4: Clearing Message Lost bit . . . . 390 Examples of acceptance filter tables and ID index values. . . . . . . . . . . . . . . . . . . . . . . . . . 391 Example 1: only one section is used . . . . . . 391 Example 2: all sections are used . . . . . . . . . 391 Example 3: more than one but not all sections are used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Configuration example 4 . . . . . . . . . . . . . . . 392
7.10 7.11 7.12 7.13
7.14
7.15
7.16
7.17 7.18
8 8.1 8.2 8.3 8.4 9 9.1
9.2 9.3
10 11 11.1 11.2 11.3 11.4 12 13 14 14.1
14.2 14.3
CAN Receive Identifier register (CAN1RID 0x4004 4024, CAN2RID - 0x4004 8024) . . . 363 CAN Receive Data register A (CAN1RDA 0x4004 4028, CAN2RDA - 0x4004 8028) . . 364 CAN Receive Data register B (CAN1RDB 0x4004 402C, CAN2RDB - 0x4004 802C) . . 364 CAN Transmit Frame Information register (CAN1TFI[1/2/3] - 0x4004 40[30/ 40/50], CAN2TFI[1/2/3] - 0x4004 80[30/40/50]) . . . . 365 CAN Transmit Identifier register (CAN1TID[1/2/3] 0x4004 40[34/44/54], CAN2TID[1/2/3] 0x4004 80[34/44/54]) . . . . . . . . . . . . . . . . . . 366 CAN Transmit Data register A (CAN1TDA[1/2/3] 0x4004 40[38/48/58], CAN2TDA[1/2/3] 0x4004 80[38/48/58]) . . . . . . . . . . . . . . . . . . 367 CAN Transmit Data register B (CAN1TDB[1/2/3] 0x4004 40[3C/4C/5C], CAN2TDB[1/2/3] 0x4004 80[3C/4C/5C]) . . . . . . . . . . . . . . . . . 367 CAN Sleep Clear register (CANSLEEPCLR 0x400F C110) . . . . . . . . . . . . . . . . . . . . . . . . 367 CAN Wake-up Flags register (CANWAKEFLAGS - 0x400F C114) . . . . . . . . . . . . . . . . . . . . . . . 368 CAN controller operation . . . . . . . . . . . . . . . 368 Error handling . . . . . . . . . . . . . . . . . . . . . . . . 368 Sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . 369 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 369 Transmit priority . . . . . . . . . . . . . . . . . . . . . . 369 Centralized CAN registers. . . . . . . . . . . . . . . 370 Central Transmit Status Register (CANTxSR 0x4004 0000) . . . . . . . . . . . . . . . . . . . . . . . . 370 Central Receive Status Register (CANRxSR 0x4004 0004) . . . . . . . . . . . . . . . . . . . . . . . . 370 Central Miscellaneous Status Register (CANMSR - 0x4004 0008) . . . . . . . . . . . . . . . . . . . . . . . 371 Global acceptance filter . . . . . . . . . . . . . . . . 371 Acceptance filter modes . . . . . . . . . . . . . . . . 371 Acceptance filter Off mode . . . . . . . . . . . . . . 372 Acceptance filter Bypass mode . . . . . . . . . . 372 Acceptance filter Operating mode . . . . . . . . 372 FullCAN mode . . . . . . . . . . . . . . . . . . . . . . . 372 Sections of the ID look-up table RAM . . . . . 372 ID look-up table RAM. . . . . . . . . . . . . . . . . . . 373 Acceptance filter registers . . . . . . . . . . . . . . 375 Acceptance Filter Mode Register (AFMR 0x4003 C000) . . . . . . . . . . . . . . . . . . . . . . . . 375 Section configuration registers . . . . . . . . . . . 375 Standard Frame Individual Start Address register (SFF_sa - 0x4003 C004) . . . . . . . . . . . . . . . 376
15 15.1 16 16.1 16.2 16.2.1 16.2.2 16.2.3
16.2.4 16.2.5 16.2.6 16.3 16.3.1 16.3.2 16.3.3 16.3.4 16.3.5 16.3.6 17 17.1 17.2 17.3 17.4
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(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
825 of 835
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Chapter 35: LPC17xx Supplementary information
17.7 17.8 Configuration example 7 . . . . . . . . . . . . . . . 395 Look-up table programming guidelines . . . . 397
17.5 17.6
Configuration example 5. . . . . . . . . . . . . . . . 392 Configuration example 6. . . . . . . . . . . . . . . . 393
Chapter 17: LPC17xx SPI
1 2 3 4 5 6 6.1 6.2 6.3 6.4 7 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SPI overview. . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . SPI data transfers . . . . . . . . . . . . . . . . . . . . . SPI peripheral details . . . . . . . . . . . . . . . . . . General information . . . . . . . . . . . . . . . . . . . Master operation. . . . . . . . . . . . . . . . . . . . . . Slave operation. . . . . . . . . . . . . . . . . . . . . . . Exception conditions. . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . 399 399 399 400 400 402 402 402 403 403 404
7.1 7.2 7.3 7.4 7.5 7.6 7.7
8
SPI Control Register (S0SPCR 0x4002 0000) . . . . . . . . . . . . . . . . . . . . . . . . SPI Status Register (S0SPSR 0x4002 0004) . . . . . . . . . . . . . . . . . . . . . . . . SPI Data Register (S0SPDR - 0x4002 0008) SPI Clock Counter Register (S0SPCCR 0x4002 000C) . . . . . . . . . . . . . . . . . . . . . . . SPI Test Control Register (SPTCR 0x4002 0010) . . . . . . . . . . . . . . . . . . . . . . . . SPI Test Status Register (SPTSR 0x4002 0014) . . . . . . . . . . . . . . . . . . . . . . . . SPI Interrupt Register (S0SPINT 0x4002 001C) . . . . . . . . . . . . . . . . . . . . . . . Architecture . . . . . . . . . . . . . . . . . . . . . . . . . .
404 406 406 406 407 407 408 409
Chapter 18: LPC17xx SSP0/1 interface
1 2 3 4 5 5.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 410 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . 411 Bus description . . . . . . . . . . . . . . . . . . . . . . . 411 Texas Instruments synchronous serial frame format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411 SPI frame format . . . . . . . . . . . . . . . . . . . . . 412 Clock Polarity (CPOL) and Phase (CPHA) control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412 SPI format with CPOL=0,CPHA=0 . . . . . . . . 413 SPI format with CPOL=0,CPHA=1 . . . . . . . . 414 SPI format with CPOL = 1,CPHA = 0 . . . . . . 414 SPI format with CPOL = 1,CPHA = 1 . . . . . . 416 National Semiconductor Microwire frame format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416 Setup and hold time requirements on CS with respect to SK in Microwire mode . . . . . . . . . 418 Register description . . . . . . . . . . . . . . . . . . . 419
6.1 6.2 6.3 6.4 6.5 6.6
5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.3 5.3.1
6
6.7 6.8
6.9 6.10
SSPn Control Register 0 (SSP0CR0 0x4008 8000, SSP1CR0 - 0x4003 0000). . . 419 SSPn Control Register 1 (SSP0CR1 0x4008 8004, SSP1CR1 - 0x4003 0004). . . 420 SSPn Data Register (SSP0DR - 0x4008 8008, SSP1DR - 0x4003 0008) . . . . . . . . . . . . . . . 421 SSPn Status Register (SSP0SR - 0x4008 800C, SSP1SR - 0x4003 000C) . . . . . . . . . . . . . . . 422 SSPn Clock Prescale Register (SSP0CPSR 0x4008 8010, SSP1CPSR - 0x4003 0010) . 422 SSPn Interrupt Mask Set/Clear Register (SSP0IMSC - 0x4008 8014, SSP1IMSC 0x4003 0014) . . . . . . . . . . . . . . . . . . . . . . . . 422 SSPn Raw Interrupt Status Register (SSP0RIS 0x4008 8018, SSP1RIS - 0x4003 0018) . . . 423 SSPn Masked Interrupt Status Register (SSP0MIS - 0x4008 801C, SSP1MIS 0x4003 001C) . . . . . . . . . . . . . . . . . . . . . . . 423 SSPn Interrupt Clear Register (SSP0ICR 0x4008 8020, SSP1ICR - 0x4003 0020) . . . 424 SSPn DMA Control Register (SSP0DMACR 0x4008 8024, SSP1DMACR - 0x4003 0024) 424
Chapter 19: LPC17xx I2C0/1/2 interface
1 2 3 4 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 425 426 426
4.1 5 6 6.1
I2C FAST Mode Plus . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . I2C operating modes . . . . . . . . . . . . . . . . . . . Master Transmitter mode . . . . . . . . . . . . . . .
427 427 428 428
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User manual
Rev. 01 -- 4 January 2010
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Chapter 35: LPC17xx Supplementary information
8.9 I2C SCL HIGH duty cycle register (I2SCLH: I2C0, I2C0SCLH - 0x4001 C010; I2C1, I2C1SCLH 0x4005 C010; I2C2, I2C2SCLH 0x400A 0010). . . . . . . . . . . . . . . . . . . . . . . . 444 I2C SCL Low duty cycle register (I2SCLL: I2C0 I2C0SCLL: 0x4001 C014; I2C1 - I2C1SCLL: 0x4005 C014; I2C2 - I2C2SCLL: 0x400A 0014). . . . . . . . . . . . . . . . . . . . . . . . 444 Selecting the appropriate I2C data rate and duty cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445 Details of I2C operating modes . . . . . . . . . . 446 Master Transmitter mode . . . . . . . . . . . . . . . 447 Master Receiver mode. . . . . . . . . . . . . . . . . 449 Slave Receiver mode. . . . . . . . . . . . . . . . . . 451 Slave Transmitter mode . . . . . . . . . . . . . . . . 453 Detailed state tables. . . . . . . . . . . . . . . . . . . 454 Miscellaneous states . . . . . . . . . . . . . . . . . . 459 I2STAT = 0xF8 . . . . . . . . . . . . . . . . . . . . . . . 459 I2STAT = 0x00 . . . . . . . . . . . . . . . . . . . . . . . 459 Some special cases . . . . . . . . . . . . . . . . . . . 459 Simultaneous repeated START conditions from two masters . . . . . . . . . . . . . . . . . . . . . . . . . 459 Data transfer after loss of arbitration . . . . . . 460 Forced access to the I2C-bus. . . . . . . . . . . . 460 I2C-bus obstructed by a LOW level on SCL or SDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460 Bus error . . . . . . . . . . . . . . . . . . . . . . . . . . . 460 I2C state service routines . . . . . . . . . . . . . . . 462 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . 462 I2C interrupt service . . . . . . . . . . . . . . . . . . . 462 The state service routines . . . . . . . . . . . . . . 462 Adapting state services to an application. . . 462 Software example . . . . . . . . . . . . . . . . . . . . . 463 Initialization routine . . . . . . . . . . . . . . . . . . . 463 Start Master Transmit function . . . . . . . . . . . 463 Start Master Receive function . . . . . . . . . . . 463 I2C interrupt routine . . . . . . . . . . . . . . . . . . . 463 Non mode specific states. . . . . . . . . . . . . . . 463 State: 0x00 . . . . . . . . . . . . . . . . . . . . . . . . . . 463 Master States . . . . . . . . . . . . . . . . . . . . . . . . 464 State: 0x08 . . . . . . . . . . . . . . . . . . . . . . . . . . 464 State: 0x10 . . . . . . . . . . . . . . . . . . . . . . . . . . 464 Master Transmitter states . . . . . . . . . . . . . . 464 State: 0x18 . . . . . . . . . . . . . . . . . . . . . . . . . . 464 State: 0x20 . . . . . . . . . . . . . . . . . . . . . . . . . . 465 State: 0x28 . . . . . . . . . . . . . . . . . . . . . . . . . . 465 State: 0x30 . . . . . . . . . . . . . . . . . . . . . . . . . . 465 State: 0x38 . . . . . . . . . . . . . . . . . . . . . . . . . . 465 Master Receive states . . . . . . . . . . . . . . . . . 465 State: 0x40 . . . . . . . . . . . . . . . . . . . . . . . . . . 465
6.2 6.3 6.4 7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 8 8.1
8.2
8.3
8.4
8.5
8.5.1 8.5.2 8.6
8.7
8.8
Master Receiver mode . . . . . . . . . . . . . . . . . 429 Slave Receiver mode . . . . . . . . . . . . . . . . . . 430 Slave Transmitter mode . . . . . . . . . . . . . . . . 431 2C implementation and operation . . . . . . . . 431 I Input filters and output stages. . . . . . . . . . . . 432 Address Registers, I2ADR0 to I2ADR3 . . . . 433 Address mask registers, I2MASK0 to I2MASK3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 Comparator. . . . . . . . . . . . . . . . . . . . . . . . . . 433 Shift register, I2DAT . . . . . . . . . . . . . . . . . . . 433 Arbitration and synchronization logic . . . . . . 433 Serial clock generator . . . . . . . . . . . . . . . . . . 434 Timing and control . . . . . . . . . . . . . . . . . . . . 435 Control register, I2CONSET and I2CONCLR 435 Status decoder and status register . . . . . . . . 435 Register description . . . . . . . . . . . . . . . . . . . 436 I2C Control Set register (I2CONSET: I2C0, I2C0CONSET - 0x4001 C000; I2C1, I2C1CONSET - 0x4005 C000; I2C2, I2C2CONSET - 0x400A 0000) . . . . . . . . . . . 437 I2C Control Clear register (I2CONCLR: I2C0, I2C0CONCLR - 0x4001 C018; I2C1, I2C1CONCLR - 0x4005 C018; I2C2, I2C2CONCLR - 0x400A 0018) . . . . . . . . . . . 439 I2C Status register (I2STAT: I2C0, I2C0STAT 0x4001 C004; I2C1, I2C1STAT - 0x4005 C004; I2C2, I2C2STAT - 0x400A 0004). . . . . . . . . . 440 I2C Data register (I2DAT: I2C0, I2C0DAT 0x4001 C008; I2C1, I2C1DAT - 0x4005 C008; I2C2, I2C2DAT - 0x400A 0008) . . . . . . . . . . 440 I2C Monitor mode control register (I2MMCTRL: I2C0, I2C0MMCTRL - 0x4001 C01C; I2C1, I2C1MMCTRL- 0x4005 C01C; I2C2, I2C2MMCTRL- 0x400A 001C) . . . . . . . . . . . 441 Interrupt in Monitor mode . . . . . . . . . . . . . . . 442 Loss of arbitration in Monitor mode . . . . . . . 442 I2C Data buffer register (I2DATA_BUFFER: I2C0, I2CDATA_BUFFER - 0x4001 C02C; I2C1, I2C1DATA_BUFFER- 0x4005 C02C; I2C2, I2C2DATA_BUFFER- 0x400A 002C) . . . . . . 443 I2C Slave Address registers (I2ADR0 to 3: I2C0, I2C0ADR[0, 1, 2, 3]- 0x4001 C0[0C, 20, 24, 28]; I2C1, I2C1ADR[0, 1, 2, 3] - address 0x4005 C0[0C, 20, 24, 28]; I2C2, I2C2ADR[0, 1, 2, 3] - address 0x400A 00[0C, 20, 24, 28]). . . . 443 I2C Mask registers (I2MASK0 to 3: I2C0, I2C0MASK[0, 1, 2, 3] - 0x4001 C0[30, 34, 38, 3C]; I2C1, I2C1MASK[0, 1, 2, 3] - address 0x4005 C0[30, 34, 38, 3C]; I2C2, I2C2MASK[0, 1, 2, 3] - address 0x400A 00[30, 34, 38, 3C]). . 444
8.10
8.11
9 9.1 9.2 9.3 9.4 9.5 9.6 9.6.1 9.6.2 9.7 9.7.1
9.7.2 9.7.3 9.7.4 9.7.5 9.8 9.8.1 9.8.2 9.8.3 9.8.4 10 10.1 10.2 10.3 10.4 10.5 10.5.1 10.5.2 10.5.3 10.5.4 10.6 10.6.1 10.6.2 10.6.3 10.6.4 10.6.5 10.7 10.7.1
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UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
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NXP Semiconductors
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Chapter 35: LPC17xx Supplementary information
466 466 466 466 466 467 467 467 467 468 10.8.7 10.8.8 10.8.9 10.9 10.9.1 10.9.2 10.9.3 10.9.4 10.9.5 State: 0x90 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x98 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0xA0. . . . . . . . . . . . . . . . . . . . . . . . . . Slave Transmitter states . . . . . . . . . . . . . . . State: 0xA8. . . . . . . . . . . . . . . . . . . . . . . . . . State: 0xB0. . . . . . . . . . . . . . . . . . . . . . . . . . State: 0xB8. . . . . . . . . . . . . . . . . . . . . . . . . . State: 0xC0 . . . . . . . . . . . . . . . . . . . . . . . . . State: 0xC8 . . . . . . . . . . . . . . . . . . . . . . . . . 468 468 468 468 468 469 469 469 469
10.7.2 10.7.3 10.7.4 10.8 10.8.1 10.8.2 10.8.3 10.8.4 10.8.5 10.8.6
State: 0x48 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x50 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x58 . . . . . . . . . . . . . . . . . . . . . . . . . . Slave Receiver states . . . . . . . . . . . . . . . . . . State: 0x60 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x68 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x70 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x78 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x80 . . . . . . . . . . . . . . . . . . . . . . . . . . State: 0x88 . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 20: LPC17xx I2S interface
1 2 3 4 5 5.1 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . Digital Audio Output register (I2SDAO 0x400A 8000) . . . . . . . . . . . . . . . . . . . . . . . . Digital Audio Input register (I2SDAI 0x400A 8004) . . . . . . . . . . . . . . . . . . . . . . . . Transmit FIFO register (I2STXFIFO 0x400A 8008) . . . . . . . . . . . . . . . . . . . . . . . . Receive FIFO register (I2SRXFIFO 0x400A 800C). . . . . . . . . . . . . . . . . . . . . . . . Status Feedback register (I2SSTATE 0x400A 8010) . . . . . . . . . . . . . . . . . . . . . . . . DMA Configuration Register 1 (I2SDMA1 0x400A 8014) . . . . . . . . . . . . . . . . . . . . . . . . DMA Configuration Register 2 (I2SDMA2 0x400A 8018) . . . . . . . . . . . . . . . . . . . . . . . . 470 470 471 472 473
5.8 5.9 5.9.1 5.10 5.11 5.12 5.13 5.14
6 7 8
473 474 474 474 475 475 476
5.2 5.3 5.4 5.5 5.6 5.7
Interrupt Request Control register (I2SIRQ 0x400A 801C) . . . . . . . . . . . . . . . . . . . . . . . 476 Transmit Clock Rate register (I2STXRATE 0x400A 8020). . . . . . . . . . . . . . . . . . . . . . . . 476 Notes on fractional rate generators . . . . . . . 477 Receive Clock Rate register (I2SRXRATE 0x400A 8024). . . . . . . . . . . . . . . . . . . . . . . . 477 Transmit Clock Bit Rate register (I2STXBITRATE - 0x400A 8028) . . . . . . . . . . . . . . . . . . . . . . 478 Receive Clock Bit Rate register (I2SRXBITRATE 0x400A 802C) . . . . . . . . . . . . . . . . . . . . . . . 478 Transmit Mode Control register (I2STXMODE 0x400A 8030). . . . . . . . . . . . . . . . . . . . . . . . 478 Receive Mode Control register (I2SRXMODE 0x400A 8034). . . . . . . . . . . . . . . . . . . . . . . . 479 I2S transmit and receive interfaces . . . . . . . 480 I2S operating modes . . . . . . . . . . . . . . . . . . . 481 FIFO controller . . . . . . . . . . . . . . . . . . . . . . . 485
Chapter 21: LPC17xx Timer 0/1/2/3
1 2 3 4 5 5.1 6 6.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 487 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 488 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 488 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 488 Multiple CAP and MAT pins . . . . . . . . . . . . . 488 Register description . . . . . . . . . . . . . . . . . . . 489 Interrupt Register (T[0/1/2/3]IR - 0x4000 4000, 0x4000 8000, 0x4009 0000, 0x4009 4000) . 490 Timer Control Register (T[0/1/2/3]CR 0x4000 4004, 0x4000 8004, 0x4009 0004, 0x4009 4004) . . . . . . . . . . . . . . . . . . . . . . . . 490
6.3
6.4
6.5 6.6
6.2
6.7 6.8
6.9
Count Control Register (T[0/1/2/3]CTCR 0x4000 4070, 0x4000 8070, 0x4009 0070, 0x4009 4070) . . . . . . . . . . . . . . . . . . . . . . . . 491 Timer Counter . . . . . . . . registers (T0TC - T3TC, 0x4000 4008, 0x4000 8008, 0x4009 0008, 0x4009 4008) . . . . . . . . . . . . . . . . . . . . . . . . 492 Prescale register (T0PR - T3PR, 0x4000 400C, 0x4000 800C, 0x4009 000C, 0x4009 400C) 492 Prescale Counter register (T0PC - T3PC, 0x4000 4010, 0x4000 8010, 0x4009 0010, 0x4009 4010) . . . . . . . . . . . . . . . . . . . . . . . . 492 Match Registers (MR0 - MR3) . . . . . . . . . . . 493 Match Control Register (T[0/1/2/3]MCR 0x4000 4014, 0x4000 8014, 0x4009 0014, 0x4009 4014) . . . . . . . . . . . . . . . . . . . . . . . . 493 Capture Registers (CR0 - CR1) . . . . . . . . . . 494
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User manual
Rev. 01 -- 4 January 2010
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6.12 7 8 DMA operation . . . . . . . . . . . . . . . . . . . . . . . 495 Example timer operation . . . . . . . . . . . . . . . 496 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 497
6.10
6.11
Capture Control Register (T[0/1/2/3]CCR 0x4000 4028, 0x4000 8028, 0x4009 0028, 0x4009 4028) . . . . . . . . . . . . . . . . . . . . . . . . 494 External Match Register (T[0/1/2/3]EMR 0x4000 403C, 0x4000 803C, 0x4009 003C, 0x4009 403C) . . . . . . . . . . . . . . . . . . . . . . . . 494
Chapter 22: LPC17xx Repetitive Interrupt Timer (RIT)
1 2 3 3.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . RI Compare Value register (RICOMPVAL 0x400B 0000) . . . . . . . . . . . . . . . . . . . . . . . . 498 498 498
3.2 3.3 3.4
4
498
RI Mask register (RIMASK - 0x400B 0004) . RI Control register (RICTRL - 0x400B 0008) RI Counter register (RICOUNTER - 0x400B 000C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RI timer operation . . . . . . . . . . . . . . . . . . . . .
498 499 499 499
Chapter 23: LPC17xx System Tick Timer
1 2 3 4 5 5.1 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . System Timer Control and status register (STCTRL - 0xE000 E010) . . . . . . . . . . . . . . 501 501 501 501 502
5.2 5.3 5.4
6
502
System Timer Reload value register (STRELOAD - 0xE000 E014) . . . . . . . . . . . . . . . . . . . . . . 503 System Timer Current value register (STCURR 0xE000 E018) . . . . . . . . . . . . . . . . . . . . . . . 503 System Timer Calibration value register (STCALIB - 0xE000 E01C) . . . . . . . . . . . . . 503 Example timer calculations . . . . . . . . . . . . . 505
Chapter 24: LPC17xx Pulse Width Modulator (PWM)
1 2 3 4 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Sample waveform with rules for single and double edge control. . . . . . . . . . . . . . . . . . . . Rules for Single Edge Controlled PWM Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rules for Double Edge Controlled PWM Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . 506 506 507 509
6.1 6.2 6.3 6.4 6.5 6.6 6.7
4.1 4.2
5 6
510 510 510 511
PWM Interrupt Register (PWM1IR 0x4001 8000) . . . . . . . . . . . . . . . . . . . . . . . . 512 PWM Timer Control Register (PWM1TCR 0x4001 8004) . . . . . . . . . . . . . . . . . . . . . . . . 513 PWM Count Control Register (PWM1CTCR 0x4001 8070) . . . . . . . . . . . . . . . . . . . . . . . . 513 PWM Match Control Register (PWM1MCR 0x4001 8014) . . . . . . . . . . . . . . . . . . . . . . . . 514 PWM Capture Control Register (PWM1CCR 0x4001 8028) . . . . . . . . . . . . . . . . . . . . . . . . 515 PWM Control Register (PWM1PCR 0x4001 804C) . . . . . . . . . . . . . . . . . . . . . . . 516 PWM Latch Enable Register (PWM1LER 0x4001 8050) . . . . . . . . . . . . . . . . . . . . . . . . 517
Chapter 25: LPC17xx Motor Control PWM
1 2 3 4 5 6 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 519 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 519 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . 520 Configuring other modules for MCPWM use 521 General Operation . . . . . . . . . . . . . . . . . . . . . 521 7 7.1 7.1.1 Register description . . . . . . . . . . . . . . . . . . . 522 MCPWM Control register . . . . . . . . . . . . . . . 523 MCPWM Control read address (MCCON 0x400B 8000). . . . . . . . . . . . . . . . . . . . . . . . 523 MCPWM Control set address (MCCON_SET 0x400B 8004). . . . . . . . . . . . . . . . . . . . . . . . 524
7.1.2
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(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
829 of 835
NXP Semiconductors
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Chapter 35: LPC17xx Supplementary information
7.5 7.6 7.7 7.7.1 7.7.2 7.7.3 7.8 7.9 7.10 7.10.1 7.10.2
8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8
7.1.3 7.2 7.2.1 7.2.2 7.2.3 7.3 7.3.1 7.3.2 7.3.3 7.3.4 7.3.5 7.3.6 7.4 7.4.1 7.4.2 7.4.3
MCPWM Control clear address (MCCON_CLR 0x400B 8008) . . . . . . . . . . . . . . . . . . . . . . . . 524 MCPWM Capture Control register . . . . . . . . 525 MCPWM Capture Control read address (MCCAPCON - 0x400B 800C) . . . . . . . . . . . 525 MCPWM Capture Control set address (MCCAPCON_SET - 0x400B 8010) . . . . . . . 525 MCPWM Capture control clear address (MCCAPCON_CLR - 0x400B 8014). . . . . . . 526 MCPWM Interrupt registers . . . . . . . . . . . . . 526 MCPWM Interrupt Enable read address (MCINTEN - 0x400B 8050) . . . . . . . . . . . . . 526 MCPWM Interrupt Enable set address (MCINTEN_SET - 0x400B 8054) . . . . . . . . . 527 MCPWM Interrupt Enable clear address (MCINTEN_CLR - 0x400B 8058) . . . . . . . . 527 MCPWM Interrupt Flags read address (MCINTF 0x400B 8068) . . . . . . . . . . . . . . . . . . . . . . . 527 MCPWM Interrupt Flags set address (MCINTF_SET - 0x400B 806C) . . . . . . . . . . 527 MCPWM Interrupt Flags clear address (MCINTF_CLR - 0x400B 8070) . . . . . . . . . . 527 MCPWM Count Control register . . . . . . . . . . 528 MCPWM Count Control read address (MCCNTCON - 0x400B 805C) . . . . . . . . . . . 528 MCPWM Count Control set address (MCCNTCON_SET - 0x400B 8060) . . . . . . . 529 MCPWM Count Control clear address (MCCNTCON_CLR - 0x400B 8064). . . . . . . 529
MCPWM Timer/Counter 0-2 registers (MCTC0-2 0x400B 8018, 0x400B 801C, 0x400B 8020) 529 MCPWM Limit 0-2 registers (MCLIM0-2 0x400B 8024, 0x400B 8028, 0x400B 802C) 530 MCPWM Match 0-2 registers (MCMAT0-2 0x400B 8030, 0x400B 8034, 0x400B 8038) 530 Match register in Edge-Aligned mode . . . . . 531 Match register in Center-Aligned mode . . . . 531 0 and 100% duty cycle. . . . . . . . . . . . . . . . . 531 MCPWM Dead-time register (MCDT 0x400B 803C) . . . . . . . . . . . . . . . . . . . . . . . 531 MCPWM Commutation Pattern register (MCCP 0x400B 8040). . . . . . . . . . . . . . . . . . . . . . . . 532 MCPWM Capture Registers. . . . . . . . . . . . . 532 MCPWM Capture read addresses (MCCAP0-2 0x400B 8044, 0x400B 8048, 0x400B 804C) 532 MCPWM Capture clear address (MCCAP_CLR 0x400B 8074). . . . . . . . . . . . . . . . . . . . . . . . 532 PWM operation . . . . . . . . . . . . . . . . . . . . . . . 534 Pulse-width modulation . . . . . . . . . . . . . . . . 534 Shadow registers and simultaneous updates 536 Fast Abort (ABORT). . . . . . . . . . . . . . . . . . . 536 Capture events. . . . . . . . . . . . . . . . . . . . . . . 536 External event counting (Counter mode) . . . 537 Three-phase DC mode . . . . . . . . . . . . . . . . 537 Three phase AC mode. . . . . . . . . . . . . . . . . 538 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
Chapter 26: LPC17xx Quadrature Encoder Interface (QEI)
1 2 3 4 4.1 4.1.1 4.1.2 4.2 4.3 4.4 5 6 6.1 6.2 6.2.1 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Functional description . . . . . . . . . . . . . . . . . Input signals . . . . . . . . . . . . . . . . . . . . . . . . . Quadrature input signals . . . . . . . . . . . . . . . Digital input filtering . . . . . . . . . . . . . . . . . . . Position capture . . . . . . . . . . . . . . . . . . . . . . Velocity capture . . . . . . . . . . . . . . . . . . . . . . Velocity compare . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . Register summary . . . . . . . . . . . . . . . . . . . . Control registers . . . . . . . . . . . . . . . . . . . . . . QEI Control register (QEICON 0x400B C000). . . . . . . . . . . . . . . . . . . . . . . . QEI Configuration register (QEICONF 0x400B C008). . . . . . . . . . . . . . . . . . . . . . . . 540 540 540 542 542 542 543 543 543 544 545 546 546 547
6.2.3 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7
547 6.3.8 547
6.2.2
QEI Status register (QEISTAT 0x400B C004) . . . . . . . . . . . . . . . . . . . . . . . 547 Position, index and timer registers. . . . . . . . 548 QEI Position register (QEIPOS 0x400B C00C) . . . . . . . . . . . . . . . . . . . . . . . 548 QEI Maximum Position register (QEIMAXPOS 0x400B C010) . . . . . . . . . . . . . . . . . . . . . . . 548 QEI Position Compare register 0 (CMPOS0 0x400B C014) . . . . . . . . . . . . . . . . . . . . . . . 548 QEI Position Compare register 1 (CMPOS1 0x400B C018) . . . . . . . . . . . . . . . . . . . . . . . 548 QEI Position Compare register 2 (CMPOS2 0x400B C01C) . . . . . . . . . . . . . . . . . . . . . . . 549 QEI Index Count register (INXCNT - 0x400B C020) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549 QEI Index Compare register (INXCMP - 0x400B C024) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549 QEI Timer Reload register (QEILOAD - 0x400B C028) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
continued >>
UM10360_1
(c) NXP B.V. 2010. All rights reserved.
User manual
Rev. 01 -- 4 January 2010
830 of 835
NXP Semiconductors
UM10360
Chapter 35: LPC17xx Supplementary information
6.4.1 6.4.2 6.4.3 6.4.4 6.4.5 6.4.6 QEI Interrupt Status register (QEIINTSTAT) 551 QEI Interrupt Set register (QEISET - 0x400B CFEC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551 QEI Interrupt Clear register (QEICLR - 0x400B CFE8). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 QEI Interrupt Enable register (QEIIE - 0x400B CFE4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 QEI Interrupt Enable Set register (QEIIES 0x400B CFDC). . . . . . . . . . . . . . . . . . . . . . . 553 QEI Interrupt Enable Clear register (QEIIEC 0x400B CFD8) . . . . . . . . . . . . . . . . . . . . . . . 554
6.3.9 6.3.10 6.3.11 6.3.12 6.3.13 6.4
QEI Timer register (QEITIME 0x400B C02C) . . . . . . . . . . . . . . . . . . . . . . . 549 QEI Velocity register (QEIVEL 0x400B C030). . . . . . . . . . . . . . . . . . . . . . . . 550 QEI Velocity Capture register (QEICAP - 0x400B C034) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550 QEI Velocity Compare register (VELCOMP 0x400B C038). . . . . . . . . . . . . . . . . . . . . . . . 550 QEI Digital Filter register (FILTER 0x400B C03C) . . . . . . . . . . . . . . . . . . . . . . . 550 Interrupt registers . . . . . . . . . . . . . . . . . . . . . 551
Chapter 27: LPC17xx Real-Time Clock (RTC) and backup registers
1 2 3 4 5 6 6.1 6.2 6.2.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 555 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 557 Register description . . . . . . . . . . . . . . . . . . . 557 RTC interrupts . . . . . . . . . . . . . . . . . . . . . . . 559 Miscellaneous register group . . . . . . . . . . . . 559 Interrupt Location Register (ILR 0x4002 4000) . . . . . . . . . . . . . . . . . . . . . . . . 559 Clock Control Register (CCR - 0x4002 4008) 559 Counter Increment Interrupt Register (CIIR 0x4002 400C) . . . . . . . . . . . . . . . . . . . . . . . . 560 Alarm Mask Register (AMR - 0x4002 4010) . 560 RTC Auxiliary control register (RTC_AUX 0x4002 405C) . . . . . . . . . . . . . . . . . . . . . . . . 561 RTC Auxiliary Enable register (RTC_AUXEN 0x4002 4058) . . . . . . . . . . . . . . . . . . . . . . . . 561
6.3 6.3.1 6.3.2 6.3.3 6.4 6.4.1 6.4.2 6.5 6.6 6.6.1
6.2.2 6.2.3 6.2.4 6.2.5 6.2.6
6.7 7
Consolidated time registers . . . . . . . . . . . . . 562 Consolidated Time Register 0 (CTIME0 0x4002 4014) . . . . . . . . . . . . . . . . . . . . . . . . 562 Consolidated Time Register 1 (CTIME1 0x4002 4018) . . . . . . . . . . . . . . . . . . . . . . . . 562 Consolidated Time Register 2 (CTIME2 0x4002 401C) . . . . . . . . . . . . . . . . . . . . . . . 562 Time Counter Group . . . . . . . . . . . . . . . . . . 563 Leap year calculation . . . . . . . . . . . . . . . . . . 563 Calibration register (CALIBRATION - address 0x4002 4040) . . . . . . . . . . . . . . . . . . . . . . . . 563 Calibration procedure. . . . . . . . . . . . . . . . . . 564 General purpose registers . . . . . . . . . . . . . 565 General purpose registers 0 to 4 (GPREG0 to GPREG4 - addresses 0x4002 4044 to 0x4002 4054) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565 Alarm register group . . . . . . . . . . . . . . . . . . 565 RTC usage notes. . . . . . . . . . . . . . . . . . . . . . 565
Chapter 28: LPC17xx Watchdog Timer (WDT)
1 2 3 4 4.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . Watchdog Mode register (WDMOD 0x4000 0000) . . . . . . . . . . . . . . . . . . . . . . . . Watchdog Timer Constant register (WDTC 0x4000 0004) . . . . . . . . . . . . . . . . . . . . . . . . 566 566 567 567
4.3 4.4 4.5
5
568 569
4.2
Watchdog Feed register (WDFEED 0x4000 0008) . . . . . . . . . . . . . . . . . . . . . . . . 569 Watchdog Timer Value register (WDTV 0x4000 000C) . . . . . . . . . . . . . . . . . . . . . . . 569 Watchdog Timer Clock Source Selection register (WDCLKSEL - 0x4000 0010). . . . . . . . . . . . 569 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . 570
Chapter 29: LPC17xx Analog-to-Digital Converter (ADC)
1 2 3 4 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . 571 571 571 572 5 5.1 Register description . . . . . . . . . . . . . . . . . . . 573 A/D Control Register (AD0CR 0x4003 4000) . . . . . . . . . . . . . . . . . . . . . . . . 574
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5.6 6 6.1 6.2 6.3 6.4 A/D Trim register (ADTRIM - 0x4003 4034). Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hardware-triggered conversion . . . . . . . . . . Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . Accuracy vs. digital receiver . . . . . . . . . . . . DMA control . . . . . . . . . . . . . . . . . . . . . . . . . 577 578 578 578 578 578
5.2 5.3 5.4 5.5
A/D Global Data Register (AD0GDR 0x4003 4004) . . . . . . . . . . . . . . . . . . . . . . . . A/D Interrupt Enable register (AD0INTEN 0x4003 400C) . . . . . . . . . . . . . . . . . . . . . . . . A/D Data Registers (AD0DR0 to AD0DR7 0x4003 4010 to 0x4003 402C) . . . . . . . . . . . A/D Status register (ADSTAT - 0x4003 4030)
575 575 576 577
Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
1 2 3 4 4.1 Basic configuration . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin description . . . . . . . . . . . . . . . . . . . . . . . . Register description . . . . . . . . . . . . . . . . . . . D/A Converter Register (DACR 0x4008 C000) . . . . . . . . . . . . . . . . . . . . . . . . 579 579 579 580
4.2 4.3
5 5.1 5.2
580
D/A Converter Control register (DACCTRL 0x4008 C004) . . . . . . . . . . . . . . . . . . . . . . . D/A Converter Counter Value register (DACCNTVAL - 0x4008 C008). . . . . . . . . . . Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . DMA counter . . . . . . . . . . . . . . . . . . . . . . . . Double buffering. . . . . . . . . . . . . . . . . . . . . .
580 581 581 581 581
Chapter 31: LPC17xx General Purpose DMA (GPDMA) controller
1 2 3 4 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9 4.2 4.2.1 4.2.2 4.2.3 5 5.1 Basic configuration . . . . . . . . . . . . . . . . . . . . 583 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 583 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583 Functional description . . . . . . . . . . . . . . . . . 584 DMA controller functional description . . . . . . 584 AHB slave interface . . . . . . . . . . . . . . . . . . . 584 Control logic and register bank . . . . . . . . . . . 585 DMA request and response interface . . . . . . 585 Channel logic and channel register bank . . . 585 Interrupt request . . . . . . . . . . . . . . . . . . . . . . 585 AHB master interface . . . . . . . . . . . . . . . . . . 585 Channel hardware . . . . . . . . . . . . . . . . . . . . 588 DMA request priority . . . . . . . . . . . . . . . . . . . 588 Interrupt generation . . . . . . . . . . . . . . . . . . . 588 DMA system connections . . . . . . . . . . . . . . . 588 DMA request signals . . . . . . . . . . . . . . . . . . 588 DMA response signals . . . . . . . . . . . . . . . . . 588 DMA request connections . . . . . . . . . . . . . . 589 Register description . . . . . . . . . . . . . . . . . . . 590 DMA Interrupt Status register (DMACIntStat 0x5000 4000) . . . . . . . . . . . . . . . . . . . . . . . . 592 DMA Interrupt Terminal Count Request Status register (DMACIntTCStat - 0x5000 4004). . . 592 DMA Interrupt Terminal Count Request Clear register (DMACIntTCClear - 0x5000 4008) . 592 DMA Interrupt Error Status register (DMACIntErrStat - 0x5000 400C) . . . . . . . . . 592 DMA Interrupt Error Clear register (DMACIntErrClr - 0x5000 4010) . . . . . . . . . . 593
5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.20.1
5.2 5.3 5.4 5.5
DMA Raw Interrupt Terminal Count Status register (DMACRawIntTCStat - 0x5000 4014) . . . . . 593 DMA Raw Error Interrupt Status register (DMACRawIntErrStat - 0x5000 4018) . . . . . 593 DMA Enabled Channel register (DMACEnbldChns - 0x5000 401C) . . . . . . . 594 DMA Software Burst Request register (DMACSoftBReq - 0x5000 4020). . . . . . . . . 594 DMA Software Single Request register (DMACSoftSReq - 0x5000 4024). . . . . . . . . 595 DMA Software Last Burst Request register (DMACSoftLBReq - 0x5000 4028). . . . . . . . 595 DMA Software Last Single Request register (DMACSoftLSReq - 0x5000 402C) . . . . . . . 595 DMA Configuration register (DMACConfig 0x5000 4030) . . . . . . . . . . . . . . . . . . . . . . . . 596 DMA Synchronization register (DMACSync 0x5000 4034) . . . . . . . . . . . . . . . . . . . . . . . . 596 DMA Request Select register (DMAReqSel 0x400F C1C4) . . . . . . . . . . . . . . . . . . . . . . . 597 DMA Channel registers . . . . . . . . . . . . . . . . 597 DMA Channel Source Address registers (DMACCxSrcAddr - 0x5000 41x0). . . . . . . . 598 DMA Channel Destination Address registers (DMACCxDestAddr - 0x5000 41x4). . . . . . . 598 DMA Channel Linked List Item registers (DMACCxLLI - 0x5000 41x8). . . . . . . . . . . . 598 DMA channel control registers (DMACCxControl 0x5000 41xC). . . . . . . . . . . . . . . . . . . . . . . . 599 Protection and access information. . . . . . . . 599
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6.1.7 6.2 6.2.1 6.2.2 6.2.3 6.3 6.3.1 6.4 6.4.1 6.5 6.5.1 Programming a DMA channel . . . . . . . . . . . 605 Flow control . . . . . . . . . . . . . . . . . . . . . . . . . 605 Peripheral-to-memory or memory-to-peripheral DMA flow . . . . . . . . . . . . . . . . . . . . . . . . . . . 606 Peripheral-to-peripheral DMA flow. . . . . . . . 606 Memory-to-memory DMA flow . . . . . . . . . . . 607 Interrupt requests . . . . . . . . . . . . . . . . . . . . . 607 Hardware interrupt sequence flow . . . . . . . . 608 Address generation . . . . . . . . . . . . . . . . . . . 608 Word-aligned transfers across a boundary . 608 Scatter/gather . . . . . . . . . . . . . . . . . . . . . . . 608 Linked list items . . . . . . . . . . . . . . . . . . . . . . 609
5.21 5.21.1 5.21.2 6 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6
DMA Channel Configuration registers (DMACCxConfig - 0x5000 41x0) . . . . . . . . . Lock control . . . . . . . . . . . . . . . . . . . . . . . . . Transfer type. . . . . . . . . . . . . . . . . . . . . . . . . Using the DMA controller . . . . . . . . . . . . . . . Programming the DMA controller . . . . . . . . . Enabling the DMA controller . . . . . . . . . . . . . Disabling the DMA controller . . . . . . . . . . . . Enabling a DMA channel . . . . . . . . . . . . . . . Disabling a DMA channel . . . . . . . . . . . . . . . Setting up a new DMA transfer. . . . . . . . . . . Halting a DMA channel . . . . . . . . . . . . . . . . .
601 603 603 604 604 604 604 604 604 604 605
Chapter 32: LPC17xx Flash memory interface and programming
1 2 3 3.1 3.1.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 4 5 6 7 7.1 7.2 7.3 7.4 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 612 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 612 Memory map after any reset. . . . . . . . . . . . . 613 Criterion for Valid User Code . . . . . . . . . . . . 613 Communication protocol . . . . . . . . . . . . . . . . 614 ISP command format . . . . . . . . . . . . . . . . . . 614 ISP response format . . . . . . . . . . . . . . . . . . . 614 ISP data format. . . . . . . . . . . . . . . . . . . . . . . 614 ISP flow control. . . . . . . . . . . . . . . . . . . . . . . 615 ISP command abort . . . . . . . . . . . . . . . . . . . 615 Interrupts during IAP. . . . . . . . . . . . . . . . . . . 615 RAM used by ISP command handler . . . . . . 615 RAM used by IAP command handler . . . . . . 615 Boot process flowchart . . . . . . . . . . . . . . . . . 616 Sector numbers . . . . . . . . . . . . . . . . . . . . . . . 617 Code Read Protection (CRP) . . . . . . . . . . . . 618 ISP commands . . . . . . . . . . . . . . . . . . . . . . . . 620 Unlock . . . . . . . . . . . . . . . . . 620 Set Baud Rate . . . . 621 Echo . . . . . . . . . . . . . . . . . . . . . . . 621 Write to RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621 Read Memory

. . . 622 Prepare sector(s) for write operation . . . . . . . . . . 623 Copy RAM to Flash . . . . . . . . . . . . . . . . 623 Go

. . . . . . . . . . . . . . . . . 624 Erase sector(s) . . . . . . . . . . . . . . . . . . . . . . . 624 Blank check sector(s) . . . . . . . . . . . . . . . . . . . . . . . 625 Read Part Identification number . . . . . . . . . . 625
7.12 7.13 7.14
7.5 7.6 7.7 7.8 7.9 7.10 7.11
Read Boot Code version number. . . . . . . . . 626 Read device serial number . . . . . . . . . . . . . 626 Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626 7.15 ISP Return Codes . . . . . . . . . . . . . . . . . . . . 627 8 IAP commands . . . . . . . . . . . . . . . . . . . . . . . 628 8.1 Prepare sector(s) for write operation . . . . . . 630 8.2 Copy RAM to Flash . . . . . . . . . . . . . . . . . . . 630 8.3 Erase Sector(s) . . . . . . . . . . . . . . . . . . . . . . 631 8.4 Blank check sector(s). . . . . . . . . . . . . . . . . . 631 8.5 Read part identification number . . . . . . . . . . 631 8.6 Read Boot Code version number. . . . . . . . . 632 8.7 Read device serial number . . . . . . . . . . . . . 632 8.8 Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632 8.9 Re-invoke ISP . . . . . . . . . . . . . . . . . . . . . . . 633 8.10 IAP Status Codes . . . . . . . . . . . . . . . . . . . . . 633 9 JTAG flash programming interface . . . . . . . 633 10 Flash signature generation . . . . . . . . . . . . . 634 10.1 Register description for signature generation 634 10.1.1 Signature generation address and control registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635 10.1.2 Signature generation result registers . . . . . . 635 10.1.3 Flash Module Status register (FMSTAT 0x0x4008 4FE0). . . . . . . . . . . . . . . . . . . . . . 636 10.1.4 Flash Module Status Clear register (FMSTATCLR - 0x0x4008 4FE8) . . . . . . . . . . . . . . . . . . . . 636 10.2 Algorithm and procedure for signature generation . . . . . . . . . . . . . . . . . . . . . . . . . . 637
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User manual
Rev. 01 -- 4 January 2010
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Chapter 33: LPC17xx JTAG, Serial Wire Debug, and Trace
1 2 3 4 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin Description . . . . . . . . . . . . . . . . . . . . . . . 638 638 638 638 5 6 6.1 7 Debug Notes . . . . . . . . . . . . . . . . . . . . . . . . . 639 Debug memory re-mapping . . . . . . . . . . . . . 640 Memory Mapping Control register (MEMMAP 0x400F C040) . . . . . . . . . . . . . . . . . . . . . . . 640 JTAG TAP Identification . . . . . . . . . . . . . . . . 640
Chapter 34: Appendix: Cortex-M3 User Guide
1 1.1 1.1.1 1.1.2 1.1.3 ARM Cortex-M3 User Guide: Introduction. . About the processor and core peripherals . . System level interface . . . . . . . . . . . . . . . . . Integrated configurable debug . . . . . . . . . . . Cortex-M3 processor features and benefits summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cortex-M3 core peripherals . . . . . . . . . . . . . ARM Cortex-M3 User Guide: Instruction Set Instruction set summary . . . . . . . . . . . . . . . . Intrinsic functions . . . . . . . . . . . . . . . . . . . . . About the instruction descriptions. . . . . . . . . Operands . . . . . . . . . . . . . . . . . . . . . . . . . . . Restrictions when using PC or SP . . . . . . . . Flexible second operand . . . . . . . . . . . . . . . Shift Operations . . . . . . . . . . . . . . . . . . . . . . Address alignment . . . . . . . . . . . . . . . . . . . . PC-relative expressions . . . . . . . . . . . . . . . . Conditional execution . . . . . . . . . . . . . . . . . . Instruction width selection. . . . . . . . . . . . . . . Memory access instructions . . . . . . . . . . . . . ADR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LDR and STR, immediate offset . . . . . . . . . . LDR and STR, register offset . . . . . . . . . . . . LDR and STR, unprivileged . . . . . . . . . . . . . LDR, PC-relative. . . . . . . . . . . . . . . . . . . . . . LDM and STM . . . . . . . . . . . . . . . . . . . . . . . PUSH and POP . . . . . . . . . . . . . . . . . . . . . . LDREX and STREX . . . . . . . . . . . . . . . . . . . CLREX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General data processing instructions . . . . . . ADD, ADC, SUB, SBC, and RSB . . . . . . . . . AND, ORR, EOR, BIC, and ORN . . . . . . . . . ASR, LSL, LSR, ROR, and RRX . . . . . . . . . CLZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CMP and CMN . . . . . . . . . . . . . . . . . . . . . . . MOV and MVN . . . . . . . . . . . . . . . . . . . . . . . MOVT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REV, REV16, REVSH, and RBIT . . . . . . . . . TST and TEQ . . . . . . . . . . . . . . . . . . . . . . . . Multiply and divide instructions . . . . . . . . . . . 641 641 642 642
1.1.4 2 2.1 2.2 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 2.3.8 2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6 2.4.7 2.4.8 2.4.9 2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 2.5.9 2.6
643 643 644 644 647 647 648 648 648 649 652 653 653 655 657 658 659 662 664 666 668 670 671 673 674 675 678 680 682 683 684 686 687 688 689
2.6.1 MUL, MLA, and MLS . . . . . . . . . . . . . . . . . . 690 2.6.2 UMULL, UMLAL, SMULL, and SMLAL . . . . 692 2.6.3 SDIV and UDIV . . . . . . . . . . . . . . . . . . . . . . 694 2.7 Saturating instructions . . . . . . . . . . . . . . . . . 695 2.7.1 SSAT and USAT. . . . . . . . . . . . . . . . . . . . . . 695 2.8 Bitfield instructions . . . . . . . . . . . . . . . . . . . . 697 2.8.1 BFC and BFI . . . . . . . . . . . . . . . . . . . . . . . . 698 2.8.2 SBFX and UBFX . . . . . . . . . . . . . . . . . . . . . 699 2.8.3 SXT and UXT. . . . . . . . . . . . . . . . . . . . . . . . 700 2.9 Branch and control instructions . . . . . . . . . . 702 2.9.1 B, BL, BX, and BLX . . . . . . . . . . . . . . . . . . . 703 2.9.2 CBZ and CBNZ . . . . . . . . . . . . . . . . . . . . . . 705 2.9.3 IT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 706 2.9.4 TBB and TBH. . . . . . . . . . . . . . . . . . . . . . . . 709 2.10 Miscellaneous instructions . . . . . . . . . . . . . . . 711 2.10.1 BKPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 712 2.10.2 CPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713 2.10.3 DMB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 714 2.10.4 DSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715 2.10.5 ISB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716 2.10.6 MRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717 2.10.7 MSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 2.10.8 NOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719 2.10.9 SEV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720 2.10.10 SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 721 2.10.11 WFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 722 2.10.12 WFI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 723 3 ARM Cortex-M3 User Guide: Processor . . . 724 3.1 Programmers model . . . . . . . . . . . . . . . . . . 724 3.1.1 Processor mode and privilege levels for software execution . . . . . . . . . . . . . . . . . . . . . . . . . . . 724 3.1.2 Stacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724 3.1.3 Core registers . . . . . . . . . . . . . . . . . . . . . . . 725 3.1.4 Exceptions and interrupts . . . . . . . . . . . . . . 732 3.1.5 Data types . . . . . . . . . . . . . . . . . . . . . . . . . . 732 3.1.6 The Cortex Microcontroller Software Interface Standard. . . . . . . . . . . . . . . . . . . . . . . . . . . . 732 3.2 Memory model . . . . . . . . . . . . . . . . . . . . . . . 734 3.2.1 Memory regions, types and attributes . . . . . 734
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Chapter 35: LPC17xx Supplementary information
4.2.8 4.2.9 4.2.10 4.3 4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8 4.3.9 4.3.10 4.3.11 4.3.12 4.3.13 4.3.14 4.3.15 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 4.5 4.5.1 4.5.2 4.5.3 4.5.4 4.5.5 4.5.6 4.5.7 4.5.8 4.5.9 5 Software Trigger Interrupt Register . . . . . . . Level-sensitive and pulse interrupts. . . . . . . NVIC design hints and tips. . . . . . . . . . . . . . System control block . . . . . . . . . . . . . . . . . . The CMSIS mapping of the Cortex-M3 SCB registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Auxiliary Control Register . . . . . . . . . . . . . . CPUID Base Register . . . . . . . . . . . . . . . . . Interrupt Control and State Register . . . . . . Vector Table Offset Register . . . . . . . . . . . . Application Interrupt and Reset Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Control Register . . . . . . . . . . . . . . . Configuration and Control Register . . . . . . . System Handler Priority Registers . . . . . . . . System Handler Control and State Register Configurable Fault Status Register . . . . . . . Hard Fault Status Register. . . . . . . . . . . . . . Memory Management Fault Address Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bus Fault Address Register . . . . . . . . . . . . . System control block design hints and tips . System timer, SysTick . . . . . . . . . . . . . . . . . SysTick Control and Status Register . . . . . . SysTick Reload Value Register . . . . . . . . . . SysTick Current Value Register . . . . . . . . . . SysTick Calibration Value Register . . . . . . . SysTick design hints and tips. . . . . . . . . . . . Memory protection unit . . . . . . . . . . . . . . . . MPU Type Register . . . . . . . . . . . . . . . . . . . MPU Control Register . . . . . . . . . . . . . . . . . MPU Region Number Register . . . . . . . . . . MPU Region Base Address Register. . . . . . MPU Region Attribute and Size Register. . . MPU access permission attributes. . . . . . . . MPU mismatch. . . . . . . . . . . . . . . . . . . . . . . Updating an MPU region . . . . . . . . . . . . . . . MPU design hints and tips . . . . . . . . . . . . . . ARM Cortex-M3 User Guide: Glossary . . . . 761 761 762 764 764 764 765 765 767 768 769 770 771 772 774 778 778 778 779 780 780 781 781 781 782 783 784 785 786 786 787 789 790 790 793 794
3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.5 3.5.1 3.5.2 3.5.3 3.5.4 4 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.7
Memory system ordering of memory accesses. . . . . . . . . . . . . . . . . . . . . . . . . . . . Behavior of memory accesses . . . . . . . . . . . Software ordering of memory accesses . . . . Bit-banding . . . . . . . . . . . . . . . . . . . . . . . . . . Memory endianness . . . . . . . . . . . . . . . . . . . Synchronization primitives . . . . . . . . . . . . . . Programming hints for the synchronization primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . Exception model . . . . . . . . . . . . . . . . . . . . . . Exception states . . . . . . . . . . . . . . . . . . . . . . Exception types . . . . . . . . . . . . . . . . . . . . . . Exception handlers . . . . . . . . . . . . . . . . . . . . Vector table. . . . . . . . . . . . . . . . . . . . . . . . . . Exception priorities . . . . . . . . . . . . . . . . . . . . Interrupt priority grouping . . . . . . . . . . . . . . . Exception entry and return . . . . . . . . . . . . . . Fault handling . . . . . . . . . . . . . . . . . . . . . . . . Fault types . . . . . . . . . . . . . . . . . . . . . . . . . . Fault escalation and hard faults . . . . . . . . . . Fault status registers and fault address registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lockup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power management . . . . . . . . . . . . . . . . . . . Entering sleep mode. . . . . . . . . . . . . . . . . . . Wakeup from sleep mode. . . . . . . . . . . . . . . The Wakeup Interrupt Controller . . . . . . . . . Power management programming hints. . . . ARM Cortex-M3 User Guide: Peripherals . . About the Cortex-M3 peripherals . . . . . . . . . Nested Vectored Interrupt Controller . . . . . . The CMSIS mapping of the Cortex-M3 NVIC registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interrupt Set-enable Registers . . . . . . . . . . . Interrupt Clear-enable Registers. . . . . . . . . . Interrupt Set-pending Registers . . . . . . . . . . Interrupt Clear-pending Registers. . . . . . . . . Interrupt Active Bit Registers . . . . . . . . . . . . Interrupt Priority Registers . . . . . . . . . . . . . .
735 736 736 737 740 740 741 742 742 742 744 745 745 746 746 750 750 751 751 752 753 753 754 754 755 756 756 757 757 758 758 759 759 760 760
Chapter 35: LPC17xx Supplementary information
1 2 2.1 2.2 2.3 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . Legal information. . . . . . . . . . . . . . . . . . . . . . Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . 798 799 799 799 799 3 4 5 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801 Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814 Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 816
835
Please be aware that important notices concerning this document and the product(s) described herein, have been included in section `Legal information'.
(c) NXP B.V. 2010.
All rights reserved.
For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: salesaddresses@nxp.com Date of release: 4 January 2010 Document identifier: UM10360_1

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