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Preliminary
C8051F310/1
16K ISP FLASH MCU Family
ANALOG PERIPHERALS - 10-Bit ADC * Up to 200 ksps * Up to 21 or 17 External Single-Ended or Differential * * * Inputs VREF from External Pin or VDD Built-in Temperature Sensor External Conversion Start Input
HIGH SPEED 8051 C Core - Pipelined Instruction Architecture; Executes 70% of
Instructions in 1 or 2 System Clocks
- Up to 25 MIPS Throughput with 25 MHz Clock - Expanded Interrupt Handler MEMORY - 1280 Bytes Internal Data RAM (1024 + 256) - 16k Bytes FLASH; In-system programmable in 512-byte
Sectors
Comparators
* Programmable Hysteresis and Response Time * Configurable as Interrupt or Reset Source (Comparator0) * Low Current (< 0.5 A) ON-CHIP DEBUG - On-Chip Debug Circuitry Facilitates Full Speed, Non-Intrusive In-System Debug (No Emulator Required!) Provides Breakpoints, Single Stepping, Inspect/Modify Memory and Registers Superior Performance to Emulation Systems Using ICE-Chips, Target Pods, and Sockets Complete Development Kit: $99 11A @ 32 kHz Typical Stop Mode Current:0.1 A Temperature Range: -40C to +85C
DIGITAL PERIPHERALS - 29/25 Port I/O; All 5 V tolerant with High Sink Current - Hardware Enhanced UART, SMBusTM, and SPITM Serial Ports Four General Purpose 16-Bit Counter/Timers 16-Bit Programmable Counter Array (PCA) with Five Capture/Compare Modules Real Time Clock Mode using PCA or Timer and External Clock Source ports crystal-less UART Operation External Oscillator: Crystal, RC, C, or Clock (1 or 2 Pin Modes) Can Switch Between Clock Sources on-the-fly; Useful in Power Saving Modes
CLOCK SOURCES - Internal Oscillator: 24.5 MHz with 2% Accuracy Sup-
SUPPLY VOLTAGE 2.7V TO 3.6V - Typical Operating Current:5mA @ 25 MHz; -
PACKAGES - 32-pin LQFP (C8051F310) - 28-pin MLP (C8051F311)
CROSSBAR
ANALOG PERIPHERALS
A M U X
DIGITAL I/O
UART SMBus SPI PCA Timer 0 Timer 1 Timer 2 Timer 3 Port 0 Port 1 Port 2 Port 3
10-bit 200ksps ADC
+ + -
TEMP SENSOR
VOLTAGE COMPARATORS
PROGRAMMABLE PRECISION INTERNAL OSCILLATOR HIGH-SPEED CONTROLLER CORE 16KB ISP FLASH 14 INTERRUPTS 8051 CPU (25MIPS) DEBUG CIRCUITRY 1280 B SRAM POR WDT
DS009-1.3b MAY03
CYGNAL Integrated Products, Inc. (c) 2003
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C8051F310/1
Preliminary
Notes
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Preliminary
C8051F310/1
TABLE OF CONTENTS
1. SYSTEM OVERVIEW .........................................................................................................13 1.1. CIP-51TM Microcontroller Core ......................................................................................16 1.1.1. Fully 8051 Compatible ..........................................................................................16 1.1.2. Improved Throughput ............................................................................................16 1.1.3. Additional Features................................................................................................17 1.2. On-Chip Memory ............................................................................................................18 1.3. On-Chip Debug Circuitry ................................................................................................19 1.4. Programmable Digital I/O and Crossbar .........................................................................20 1.5. Serial Ports.......................................................................................................................20 1.6. Programmable Counter Array .........................................................................................21 1.7. 10-Bit Analog to Digital Converter.................................................................................22 1.8. Comparators ....................................................................................................................23 2. ABSOLUTE MAXIMUM RATINGS ..................................................................................24 3. GLOBAL DC ELECTRICAL CHARACTERISTICS ......................................................25 4. PINOUT AND PACKAGE DEFINITIONS........................................................................26 5. 10-BIT ADC (ADC0) .............................................................................................................35 5.1. Analog Multiplexer .........................................................................................................36 5.2. Temperature Sensor.........................................................................................................37 5.3. Modes of Operation.........................................................................................................39 5.3.1. Starting a Conversion.............................................................................................39 5.3.2. Tracking Modes .....................................................................................................40 5.3.3. Settling Time Requirements ..................................................................................41 5.4. Programmable Window Detector ....................................................................................47 5.4.1. Window Detector In Single-Ended Mode .............................................................49 5.4.2. Window Detector In Differential Mode.................................................................50 6. VOLTAGE REFERENCE....................................................................................................53 7. COMPARATORS ................................................................................................................55 8. CIP-51 MICROCONTROLLER .........................................................................................65 8.1. INSTRUCTION SET ......................................................................................................67 8.1.1. Instruction and CPU Timing..................................................................................67 8.1.2. MOVX Instruction and Program Memory.............................................................67 8.2. MEMORY ORGANIZATION........................................................................................71 8.2.1. Program Memory ...................................................................................................71 8.2.2. Data Memory .........................................................................................................72 8.2.3. General Purpose Registers .....................................................................................72 8.2.4. Bit Addressable Locations .....................................................................................72 8.2.5. Stack ...................................................................................................................72 8.2.6. Special Function Registers.....................................................................................73 8.2.7. Register Descriptions .............................................................................................76 8.3. Interrupt Handler .............................................................................................................79 8.3.1. MCU Interrupt Sources and Vectors .....................................................................79 8.3.2. External Interrupts .................................................................................................80 8.3.3. Interrupt Priorities..................................................................................................80
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8.3.4. Interrupt Latency....................................................................................................80 8.3.5. Interrupt Register Descriptions ..............................................................................82 8.4. Power Management Modes .............................................................................................87 8.4.1. Idle Mode ...............................................................................................................87 8.4.2. Stop Mode..............................................................................................................87 9. RESET SOURCES ................................................................................................................89 9.1. Power-On Reset...............................................................................................................90 9.2. Power-Fail Reset / VDD Monitor....................................................................................91 9.3. External Reset..................................................................................................................92 9.4. Missing Clock Detector Reset .........................................................................................92 9.5. Comparator0 Reset ..........................................................................................................92 9.6. PCA Watchdog Timer Reset ...........................................................................................92 9.7. FLASH Error Reset .........................................................................................................92 9.8. Software Reset.................................................................................................................92 10. FLASH MEMORY ..............................................................................................................95 10.1.Programming The FLASH Memory ...............................................................................95 10.1.1. FLASH Lock and Key Functions ..........................................................................95 10.1.2. FLASH Erase Procedure........................................................................................95 10.1.3. FLASH Write Procedure .......................................................................................96 10.2.Non-volatile Data Storage ...............................................................................................97 10.3.Security Options ..............................................................................................................97 11. EXTERNAL RAM...............................................................................................................101 12. OSCILLATORS...................................................................................................................103 12.1.Programmable Internal Oscillator .................................................................................103 12.2.External Oscillator Drive Circuit...................................................................................106 12.3.System Clock Selection.................................................................................................106 12.4.External Crystal Example..............................................................................................108 12.5.External RC Example ....................................................................................................108 12.6.External Capacitor Example..........................................................................................108 13. PORT INPUT/OUTPUT ...................................................................................................109 13.1.Priority Crossbar Decoder .............................................................................................111 13.2.Port I/O Initialization.....................................................................................................113 13.3.General Purpose Port I/O...............................................................................................116 14. SMBUS..................................................................................................................................125 14.1.Supporting Documents ..................................................................................................126 14.2.SMBus Configuration....................................................................................................126 14.3.SMBus Operation ..........................................................................................................127 14.3.1. Arbitration............................................................................................................127 14.3.2. Clock Low Extension...........................................................................................128 14.3.3. SCL Low Timeout ...............................................................................................128 14.3.4. SCL High (SMBus Free) Timeout.......................................................................128 14.4.Using the SMBus...........................................................................................................129 14.4.1. SMBus Configuration Register............................................................................130 14.4.2. SMB0CN Control Register ..................................................................................133 14.4.3. Data Register........................................................................................................136
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14.5.SMBus Transfer Modes.................................................................................................137 14.5.1. Master Transmitter Mode ....................................................................................137 14.5.2. Master Receiver Mode.........................................................................................138 14.5.3. Slave Receiver Mode ...........................................................................................139 14.5.4. Slave Transmitter Mode.......................................................................................140 14.6.SMBus Status Decoding................................................................................................141 15. UART0 ..................................................................................................................................143 15.1.Enhanced Baud Rate Generation...................................................................................144 15.2.Operational Modes ........................................................................................................145 15.2.1. 8-Bit UART .........................................................................................................145 15.2.2. 9-Bit UART .........................................................................................................146 15.3.Multiprocessor Communications...................................................................................147 16. ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0) .........................................153 16.1.Signal Descriptions........................................................................................................154 16.1.1. Master Out, Slave In (MOSI) ..............................................................................154 16.1.2. Master In, Slave Out (MISO) ..............................................................................154 16.1.3. Serial Clock (SCK) ..............................................................................................154 16.1.4. Slave Select (NSS)...............................................................................................154 16.2.SPI0 Master Mode Operation........................................................................................155 16.3.SPI0 Slave Mode Operation ..........................................................................................157 16.4.SPI0 Interrupt Sources...................................................................................................157 16.5.Serial Clock Timing ......................................................................................................158 16.6.SPI Special Function Registers .....................................................................................160 17. TIMERS ...............................................................................................................................167 17.1.Timer 0 and Timer 1......................................................................................................167 17.1.1. Mode 0: 13-bit Counter/Timer.............................................................................167 17.1.2. Mode 1: 16-bit Counter/Timer.............................................................................168 17.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload .................................................169 17.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only) ...........................................170 17.2.Timer 2 .......................................................................................................................175 17.2.1. 16-bit Timer with Auto-Reload ...........................................................................175 17.2.2. 8-bit Timers with Auto-Reload............................................................................176 17.3.Timer 3 .......................................................................................................................179 17.3.1. 16-bit Timer with Auto-Reload ...........................................................................179 17.3.2. 8-bit Timers with Auto-Reload............................................................................180 18. PROGRAMMABLE COUNTER ARRAY ......................................................................183 18.1.PCA Counter/Timer.......................................................................................................184 18.2.Capture/Compare Modules............................................................................................185 18.2.1. Edge-triggered Capture Mode .............................................................................186 18.2.2. Software Timer (Compare) Mode........................................................................187 18.2.3. High Speed Output Mode ....................................................................................188 18.2.4. Frequency Output Mode ......................................................................................189 18.2.5. 8-Bit Pulse Width Modulator Mode ....................................................................190 18.2.6. 16-Bit Pulse Width Modulator Mode ..................................................................191 18.3.Watchdog Timer Mode..................................................................................................192
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18.3.1. Watchdog Timer Operation .................................................................................192 18.3.2. Watchdog Timer Usage .......................................................................................193 18.4.Register Descriptions for PCA ......................................................................................194 19. REVISION SPECIFIC BEHAVIOR .................................................................................199 19.1.Revision Identification ..................................................................................................199 19.2.Reset Behavior...............................................................................................................199 19.2.1. Weak Pull-ups on GPIO Pins...............................................................................199 19.2.2. VDD Monitor and the /RST Pin ..........................................................................199 19.3.PCA Counter .................................................................................................................200 20. C2 INTERFACE ..................................................................................................................201 20.1.C2 Interface Registers ...................................................................................................201 20.2.C2 Pin Sharing...............................................................................................................203
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C8051F310/1
LIST OF FIGURES AND TABLES
21. SYSTEM OVERVIEW Table 21.1. Product Selection Guide ......................................................................................13 Figure 21.1. C8051F310 Block Diagram.................................................................................14 Figure 21.2. C8051F311 Block Diagram.................................................................................15 Figure 21.3. Comparison of Peak MCU Execution Speeds.....................................................16 Figure 21.4. On-Chip Clock and Reset....................................................................................17 Figure 21.5. On-Board Memory Map ......................................................................................18 Figure 21.6. Development/In-System Debug Diagram ...........................................................19 Figure 21.7. Digital Crossbar Diagram....................................................................................20 Figure 21.8. PCA Block Diagram............................................................................................21 Figure 21.9. PCA Block Diagram............................................................................................21 Figure 21.10. 10-Bit ADC Block Diagram..............................................................................22 Figure 21.11. Comparator0 Block Diagram ............................................................................23 22. ABSOLUTE MAXIMUM RATINGS Table 22.1. Absolute Maximum Ratings*..............................................................................24 23. GLOBAL DC ELECTRICAL CHARACTERISTICS Table 23.1. Global DC Electrical Characteristics...................................................................25 24. PINOUT AND PACKAGE DEFINITIONS Table 24.1. Pin Definitions for the C8051F310/1 ..................................................................26 Figure 24.1. LQFP-32 Pinout Diagram (Top View)................................................................28 Figure 24.2. LQFP-32 Package Diagram.................................................................................29 Table 24.2. LQFP-32 Package Dimensions............................................................................29 Figure 24.3. MLP-28 Pinout Diagram (Top View) .................................................................30 Figure 24.4. MLP-28 Package Drawing ..................................................................................31 Table 24.3. MLP-28 Package Dimensions .............................................................................31 Figure 24.5. Typical MLP-28 Landing Diagram .....................................................................32 Figure 24.6. Typical MLP-28 Solder Mask .............................................................................33 25. 10-BIT ADC (ADC0) Figure 25.1. ADC0 Functional Block Diagram .......................................................................35 Figure 25.2. Typical Temperature Sensor Transfer Function..................................................37 Figure 25.3. Temperature Sensor Error with 1-Point Calibration ...........................................38 Figure 25.4. 10-Bit ADC Track and Conversion Example Timing.........................................40 Figure 25.5. ADC0 Equivalent Input Circuits .........................................................................41 Figure 25.6. AMX0P: AMUX0 Positive Channel Select Register..........................................42 Figure 25.7. AMX0N: AMUX0 Negative Channel Select Register........................................43 Figure 25.8. ADC0CF: ADC0 Configuration Register ...........................................................44 Figure 25.9. ADC0H: ADC0 Data Word MSB Register.........................................................44 Figure 25.10. ADC0L: ADC0 Data Word LSB Register ........................................................45 Figure 25.11. ADC0CN: ADC0 Control Register ...................................................................46 Figure 25.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register.............................47 Figure 25.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register ..............................47 Figure 25.14. ADC0LTH: ADC0 Less-Than Data High Byte Register ..................................48 Figure 25.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register ...................................48
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Figure 25.16. ADC Window Compare Example: Right-Justified Single-Ended Data............49 Figure 25.17. ADC Window Compare Example: Left-Justified Single-Ended Data ..............49 Figure 25.18. ADC Window Compare Example: Right-Justified Differential Data...............50 Figure 25.19. ADC Window Compare Example: Left-Justified Differential Data .................50 Table 25.1. ADC0 Electrical Characteristics..........................................................................51 26. VOLTAGE REFERENCE Figure 26.1. Voltage Reference Functional Block Diagram ...................................................53 Figure 26.2. REF0CN: Reference Control Register ................................................................54 Table 26.1. External Voltage Reference Circuit Electrical Characteristics ...........................54 27. COMPARATORS Figure 27.1. Comparator0 Functional Block Diagram ............................................................55 Figure 27.2. Comparator1 Functional Block Diagram ............................................................56 Figure 27.3. Comparator Hysteresis Plot.................................................................................57 Figure 27.4. CPT0CN: Comparator0 Control Register ...........................................................58 Figure 27.5. CPT0MX: Comparator0 MUX Selection Register .............................................59 Figure 27.6. CPT0MD: Comparator0 Mode Selection Register .............................................60 Figure 27.7. CPT1CN: Comparator1 Control Register ...........................................................61 Figure 27.8. CPT1MX: Comparator1 MUX Selection Register .............................................62 Figure 27.9. CPT1MD: Comparator1 Mode Selection Register .............................................63 Table 27.1. Comparator Electrical Characteristics.................................................................64 28. CIP-51 MICROCONTROLLER Figure 28.1. CIP-51 Block Diagram ........................................................................................65 Table 28.1. CIP-51 Instruction Set Summary.........................................................................67 Figure 28.2. Memory Map .......................................................................................................71 Table 28.2. Special Function Register (SFR) Memory Map..................................................73 Table 28.3. Special Function Registers ..................................................................................73 Figure 28.3. DPL: Data Pointer Low Byte ..............................................................................76 Figure 28.4. DPH: Data Pointer High Byte .............................................................................76 Figure 28.5. SP: Stack Pointer .................................................................................................77 Figure 28.6. PSW: Program Status Word ................................................................................77 Figure 28.7. ACC: Accumulator..............................................................................................78 Figure 28.8. B: B Register .......................................................................................................78 Table 28.4. Interrupt Summary...............................................................................................81 Figure 28.9. IE: Interrupt Enable .............................................................................................82 Figure 28.10. IP: Interrupt Priority ..........................................................................................83 Figure 28.11. EIE1: Extended Interrupt Enable 1 ...................................................................84 Figure 28.12. EIP1: Extended Interrupt Priority 1...................................................................85 Figure 28.13. IT01CF: INT0/INT1 Configuration Register ....................................................86 Figure 28.14. PCON: Power Control Register ........................................................................88 29. RESET SOURCES Figure 29.1. Reset Sources ......................................................................................................89 Figure 29.2. Power-On and VDD Monitor Reset Timing .......................................................90 Figure 29.3. VDM0CN: VDD Monitor Control ......................................................................91 Figure 29.4. RSTSRC: Reset Source Register.........................................................................93 Table 29.1. Reset Electrical Characteristics ...........................................................................94
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30. FLASH MEMORY Table 30.1. FLASH Electrical Characteristics .......................................................................96 Figure 30.1. FLASH Program Memory Map and Security Byte.............................................98 Figure 30.2. PSCTL: Program Store R/W Control ..................................................................98 Figure 30.3. FLKEY: FLASH Lock and Key Register ...........................................................99 Figure 30.4. FLSCL: FLASH Scale Register ..........................................................................99 31. EXTERNAL RAM Figure 31.1. EMI0CN: External Memory Interface Control .................................................101 32. OSCILLATORS Figure 32.1. Oscillator Diagram ............................................................................................103 Figure 32.2. OSCICL: Internal Oscillator Calibration Register ............................................104 Figure 32.3. OSCICN: Internal Oscillator Control Register .................................................104 Figure 32.4. CLKSEL: Clock Select Register .......................................................................105 Table 32.1. Internal Oscillator Electrical Characteristics.....................................................105 Figure 32.5. OSCXCN: External Oscillator Control Register...............................................107 33. PORT INPUT/OUTPUT Figure 33.1. Port I/O Functional Block Diagram ..................................................................109 Figure 33.2. Port I/O Cell Block Diagram.............................................................................110 Figure 33.3. Crossbar Priority Decoder with No Pins Skipped .............................................111 Figure 33.4. Crossbar Priority Decoder with Crystal Pins Skipped ......................................112 Figure 33.5. XBR0: Port I/O Crossbar Register 0 .................................................................114 Figure 33.6. XBR1: Port I/O Crossbar Register 1 .................................................................115 Figure 33.7. P0: Port0 Register..............................................................................................117 Figure 33.8. P0MDIN: Port0 Input Mode Register ...............................................................117 Figure 33.9. P0MDOUT: Port0 Output Mode Register.........................................................118 Figure 33.10. P0SKIP: Port0 Skip Register...........................................................................118 Figure 33.11. P1: Port1 Register............................................................................................119 Figure 33.12. P1MDIN: Port1 Input Mode Register .............................................................119 Figure 33.13. P1MDOUT: Port1 Output Mode Register.......................................................120 Figure 33.14. P1SKIP: Port1 Skip Register...........................................................................120 Figure 33.15. P2: Port2 Register............................................................................................121 Figure 33.16. P2MDIN: Port2 Input Mode Register .............................................................121 Figure 33.17. P2MDOUT: Port2 Output Mode Register.......................................................122 Figure 33.18. P2SKIP: Port2 Skip Register...........................................................................122 Figure 33.19. P3: Port3 Register............................................................................................123 Figure 33.20. P3MDIN: Port3 Input Mode Register .............................................................123 Figure 33.21. P3MDOUT: Port3 Output Mode Register.......................................................124 Table 33.1. Port I/O DC Electrical Characteristics ..............................................................124 34. SMBUS Figure 34.1. SMBus Block Diagram .....................................................................................125 Figure 34.2. Typical SMBus Configuration ..........................................................................126 Figure 34.3. SMBus Transaction ...........................................................................................127 Table 34.1. SMBus Clock Source Selection.........................................................................130 Figure 34.4. Typical SMBus SCL Generation.......................................................................131 Table 34.2. Minimum SDA Setup and Hold Times .............................................................131
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Figure 34.5. SMB0CF: SMBus Clock/Configuration Register .............................................132 Figure 34.6. SMB0CN: SMBus Control Register .................................................................134 Table 34.3. Sources for Hardware Changes to SMB0CN ....................................................135 Figure 34.7. SMB0DAT: SMBus Data Register ...................................................................136 Figure 34.8. Typical Master Transmitter Sequence...............................................................137 Figure 34.9. Typical Master Receiver Sequence ...................................................................138 Figure 34.10. Typical Slave Receiver Sequence ...................................................................139 Figure 34.11. Typical Slave Transmitter Sequence ...............................................................140 Table 34.4. SMBus Status Decoding....................................................................................141 35. UART0 Figure 35.1. UART0 Block Diagram.....................................................................................143 Figure 35.2. UART0 Baud Rate Logic ..................................................................................144 Figure 35.3. UART Interconnect Diagram ............................................................................145 Figure 35.4. 8-Bit UART Timing Diagram ...........................................................................145 Figure 35.5. 9-Bit UART Timing Diagram ...........................................................................146 Figure 35.6. UART Multi-Processor Mode Interconnect Diagram .......................................147 Figure 35.7. SCON0: Serial Port 0 Control Register.............................................................148 Figure 35.8. SBUF0: Serial (UART0) Port Data Buffer Register .........................................149 Table 35.1. Timer Settings for Standard Baud Rates Using The Internal Oscillator ...........150 Table 35.2. Timer Settings for Standard Baud Rates Using an External Oscillator.............150 Table 35.3. Timer Settings for Standard Baud Rates Using an External Oscillator.............151 Table 35.4. Timer Settings for Standard Baud Rates Using an External Oscillator.............151 Table 35.5. Timer Settings for Standard Baud Rates Using an External Oscillator.............152 Table 35.6. Timer Settings for Standard Baud Rates Using an External Oscillator.............152 36. ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0) Figure 36.1. SPI Block Diagram............................................................................................153 Figure 36.2. Multiple-Master Mode Connection Diagram ....................................................156 Figure 36.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram ...156 Figure 36.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram ....156 Figure 36.5. Master Mode Data/Clock Timing......................................................................158 Figure 36.6. Slave Mode Data/Clock Timing (CKPHA = 0) ................................................159 Figure 36.7. Slave Mode Data/Clock Timing (CKPHA = 1) ................................................159 Figure 36.8. SPI0CFG: SPI0 Configuration Register............................................................160 Figure 36.9. SPI0CN: SPI0 Control Register ........................................................................161 Figure 36.10. SPI0CKR: SPI0 Clock Rate Register ..............................................................162 Figure 36.11. SPI0DAT: SPI0 Data Register ........................................................................163 Figure 36.12. SPI Master Timing (CKPHA = 0) ...................................................................164 Figure 36.13. SPI Master Timing (CKPHA = 1) ...................................................................164 Figure 36.14. SPI Slave Timing (CKPHA = 0) .....................................................................165 Figure 36.15. SPI Slave Timing (CKPHA = 1) .....................................................................165 Table 36.1. SPI Slave Timing Parameters............................................................................166 37. TIMERS Figure 37.1. T0 Mode 0 Block Diagram................................................................................168 Figure 37.2. T0 Mode 2 Block Diagram................................................................................169 Figure 37.3. T0 Mode 3 Block Diagram................................................................................170
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Figure 37.4. TCON: Timer Control Register.........................................................................171 Figure 37.5. TMOD: Timer Mode Register...........................................................................172 Figure 37.6. CKCON: Clock Control Register......................................................................173 Figure 37.7. TL0: Timer 0 Low Byte ....................................................................................174 Figure 37.8. TL1: Timer 1 Low Byte ....................................................................................174 Figure 37.9. TH0: Timer 0 High Byte ...................................................................................174 Figure 37.10. TH1: Timer 1 High Byte .................................................................................174 Figure 37.11. Timer 2 16-Bit Mode Block Diagram .............................................................175 Figure 37.12. Timer 2 8-Bit Mode Block Diagram ...............................................................176 Figure 37.13. TMR2CN: Timer 2 Control Register ..............................................................177 Figure 37.14. TMR2RLL: Timer 2 Reload Register Low Byte ............................................178 Figure 37.15. TMR2RLH: Timer 2 Reload Register High Byte ...........................................178 Figure 37.16. TMR2L: Timer 2 Low Byte ............................................................................178 Figure 37.17. TMR2H Timer 2 High Byte ............................................................................178 Figure 37.18. Timer 3 16-Bit Mode Block Diagram .............................................................179 Figure 37.19. Timer 3 8-Bit Mode Block Diagram ...............................................................180 Figure 37.20. TMR3CN: Timer 3 Control Register ..............................................................181 Figure 37.21. TMR3RLL: Timer 3 Reload Register Low Byte ............................................182 Figure 37.22. TMR3RLH: Timer 3 Reload Register High Byte ...........................................182 Figure 37.23. TMR3L: Timer 3 Low Byte ............................................................................182 Figure 37.24. TMR3H Timer 3 High Byte ............................................................................182 38. PROGRAMMABLE COUNTER ARRAY Figure 38.1. PCA Block Diagram..........................................................................................183 Figure 38.2. PCA Counter/Timer Block Diagram .................................................................184 Table 38.1. PCA Timebase Input Options............................................................................184 Figure 38.3. PCA Interrupt Block Diagram...........................................................................185 Table 38.2. PCA0CPM Register Settings for PCA Capture/Compare Modules..................185 Figure 38.4. PCA Capture Mode Diagram ............................................................................186 Figure 38.5. PCA Software Timer Mode Diagram................................................................187 Figure 38.6. PCA High Speed Output Mode Diagram ..........................................................188 Figure 38.7. PCA Frequency Output Mode ...........................................................................189 Figure 38.8. PCA 8-Bit PWM Mode Diagram ......................................................................190 Figure 38.9. PCA 16-Bit PWM Mode ...................................................................................191 Figure 38.10. PCA Module 4 with Watchdog Timer Enabled ..............................................192 Table 38.3. Watchdog Timer Timeout Intervals ................................................................193 Figure 38.11. PCA0CN: PCA Control Register ....................................................................194 Figure 38.12. PCA0MD: PCA Mode Register ......................................................................195 Figure 38.13. PCA0CPMn: PCA Capture/Compare Mode Registers ...................................196 Figure 38.14. PCA0L: PCA Counter/Timer Low Byte .........................................................197 Figure 38.15. PCA0H: PCA Counter/Timer High Byte ........................................................197 Figure 38.16. PCA0CPLn: PCA Capture Module Low Byte ................................................198 Figure 38.17. PCA0CPHn: PCA Capture Module High Byte ...............................................198 39. REVISION SPECIFIC BEHAVIOR Figure 39.1. Reading Package Marking.................................................................................199 40. C2 INTERFACE
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Figure 40.1. C2ADD: C2 Address Register ..........................................................................201 Figure 40.2. DEVICEID: C2 Device ID Register .................................................................201 Figure 40.3. REVID: C2 Revision ID Register .....................................................................202 Figure 40.4. FPCTL: C2 FLASH Programming Control Register ........................................202 Figure 40.5. FPDAT: C2 FLASH Programming Data Register ............................................202 Figure 40.6. Typical C2 Pin Sharing .....................................................................................203
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1.
SYSTEM OVERVIEW
C8051F310/1 devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are listed below. Refer to Table 1.1 for specific product feature selection. * * * * * * * * * * * * High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS) In-system, full-speed, non-intrusive debug interface (on-chip) True 10-bit 200 ksps 25-channel single-ended/differential ADC with analog multiplexer Precision programmable 25 MHz internal oscillator 16k bytes of on-chip FLASH memory 1280 bytes of on-chip RAM SMBus/I2C, Enhanced UART, and Enhanced SPI serial interfaces implemented in hardware Four general-purpose 16-bit timers Programmable Counter/Timer Array (PCA) with five capture/compare modules and Watchdog Timer function On-chip Power-On Reset, VDD Monitor, and Temperature Sensor On-chip Voltage Comparators (2) 29/25 Port I/O (5V tolerant)
With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F310/1 devices are truly stand-alone System-on-a-Chip solutions. The FLASH memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually shut down any or all peripherals for power savings. The on-chip Cygnal 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the production MCU installed in the final application. This debug logic supports inspection and modification of memory and registers, setting breakpoints, single stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying package pins. Each device is specified for 2.7 V-to-3.6 V operation over the industrial temperature range (-45C to +85C). The Port I/O and /RST pins are tolerant of input signals up to 5 V. The C8051F310/1 are available in a 32-pin LQFP or a 28-pin MLP package as shown in Figure 1.1 and Figure 1.2, respectively.
Table 1.1. Product Selection Guide
Programmable Counter Array Calibrated Internal Oscillator
Analog Comparators
10-bit 200ksps ADC
Temperature Sensor
FLASH Memory
Digital Port I/Os
Timers (16-bit)
Enhanced SPI
MIPS (Peak)
SMBus/I2C
C8051F310 C8051F311
25 25
16k 16k
1280 1280
4 4
29 25
2 2
LQFP-32 MLP-28
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Package Page 13
UART
RAM
C8051F310/1
Preliminary
Figure 1.1. C8051F310 Block Diagram
Analog/Digital Power
VDD
Port 0 Latch Port 1 Latch
P 0 D r v C R O S S B A R P 1 D r v P 2 D r v P 3
GND
UART
C2D
P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D P3.1 P3.2 P3.3 P3.4
Debug HW
Reset
/RST/C2CK
POR
BrownOut
8 0 5 1
16kbyte FLASH 256 byte SRAM 1K byte SRAM
Timer 0,1,2,3 / RTC PCA/ WDT SMBus SPI Port 2 Latch
XTAL1 XTAL2
External Oscillator Circuit 2% Internal Oscillator
System Clock
C o SFR Bus r e
Port 3 Latch
D r v
CP0
+ + Temp
CP1
VDD
VREF
10-bit 200ksps ADC
A M U X
VDD
AIN0-AIN20
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Preliminary
C8051F310/1
Figure 1.2. C8051F311 Block Diagram
P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D
VDD
Analog/Digital Power
Port 0 Latch Port 1 Latch
P 0 D r v C R O S S B A R P 1 D r v P 2 D r v P 3
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
BrownOut
8 0 5 1
16kbyte FLASH 256 byte SRAM 1K byte SRAM
Timer 0,1,2,3 / RTC PCA/ WDT SMBus SPI Port 2 Latch
XTAL1 XTAL2
External Oscillator Circuit 2% Internal Oscillator
System Clock
C o SFR Bus r e
Port 3 Latch
D r v
CP0
+ + Temp
CP1
VDD
VREF
10-bit 200ksps ADC
A M U X
VDD
AIN0-AIN20
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Page 15
C8051F310/1
1.1.
1.1.1.
Preliminary
CIP-51TM Microcontroller Core
Fully 8051 Compatible
The C8051F310/1 family utilizes Cygnal's proprietary CIP-51 microcontroller core. The CIP-51 is fully compatible with the MCS-51TM instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The CIP-51 core offers all the peripherals included with a standard 8052, including four 16-bit counter/timers, a fullduplex UART with extended baud rate configuration, an enhanced SPI port, 1280 bytes of internal RAM, 128 byte Special Function Register (SFR) address space, and 29/25 I/O pins.
1.1.2.
Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than four system clock cycles. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute Number of Instructions 1 26 2 50 2/3 5 3 14 3/4 7 4 3 4/5 1 5 2 8 1
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. Figure 1.3 shows a comparison of peak throughputs for various 8-bit microcontroller cores with their maximum system clocks.
Figure 1.3. Comparison of Peak MCU Execution Speeds
25
20
MIPS
15
10
5
Cygnal Microchip Philips ADuC812 CIP-51 PIC17C75x 80C51 8051 (25MHz clk) (33MHz clk) (33MHz clk) (16MHz clk)
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Preliminary
C8051F310/1
1.1.3.
Additional Features
The C8051F310/1 SoC family includes several key enhancements to the CIP-51 core and peripherals to improve performance and ease of use in end applications. The extended interrupt handler provides 14 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), allowing numerous analog and digital peripherals to interrupt the controller. An interrupt driven system requires less intervention by the MCU, giving it more effective throughput. The extra interrupt sources are very useful when building multi-tasking, real-time systems. Eight reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor (forces reset when power supply voltage drops below VRST as given in Table 9.1 on page 94), a Watchdog Timer, a Missing Clock Detector, a voltage level detection from Comparator0, a forced software reset, an external reset pin, and an errant FLASH read/write protection circuit. Each reset source except for the POR, Reset Input Pin, or FLASH error may be disabled by the user in software. The WDT may be permanently enabled in software after a power-on reset during MCU initialization. The internal oscillator factory calibrated to 24.5 MHz 2%. Additionally, the internal oscillator period may be user programmed in ~0.5% increments. An external oscillator drive circuit is also included, allowing an external crystal, ceramic resonator, capacitor, RC, or CMOS clock source to generate the system clock. If desired, the system clock source may be switched on-the-fly between the internal and external oscillator circuits. An external oscillator can be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switching to the fast (up to 25 MHz) internal oscillator as needed.
Figure 1.4. On-Chip Clock and Reset
VDD
Power On Reset
Supply Monitor Px.x Px.x Comparator 0
+ C0RSEF
+ -
Enable
'0' (wired-OR)
/RST
Missing Clock Detector (oneshot)
EN
Reset Funnel
PCA WDT (Software Reset)
SWRSF
EN
Internal Oscillator
XTAL1 XTAL2
External Oscillator Drive
System Clock Clock Select
MCD Enable
CIP-51 Microcontroller Core
Extended Interrupt Handler
WDT Enable
Errant FLASH Operation
System Reset
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
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C8051F310/1
1.2. On-Chip Memory
Preliminary
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of general purpose registers, and the next 16 bytes can be byte addressable or bit addressable. Program memory consists of 16k bytes of FLASH. This memory may be reprogrammed in-system in 512 byte sectors, and requires no special off-chip programming voltage. See Figure 1.5 for the MCU system memory map.
Figure 1.5. On-Board Memory Map
PROGRAM/DATA MEMORY (FLASH)
0xFF 0x3E00 0x3DFF RESERVED 0x80 0x7F
DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE
Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) Special Function Register's (Direct Addressing Only)
16K FLASH (In-System Programmable in 512 Byte Sectors)
0x30 0x2F 0x20 0x1F 0x00
Bit Addressable General Purpose Registers
Lower 128 RAM (Direct and Indirect Addressing)
EXTERNAL DATA ADDRESS SPACE
0x0000 0xFFFF
Same 1024 bytes as from 0x0000 to 0x03FF, wrapped on 1K-byte boundaries
0x0400 0x03FF 0x0000
XRAM - 1024 Bytes
(accessable using MOVX instruction)
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Preliminary
C8051F310/1
1.3.
On-Chip Debug Circuitry
The C8051F310/1 devices include on-chip Cygnal 2-Wire (C2) debug circuitry that provides non-intrusive, full speed, in-circuit debugging of the production part installed in the end application. Cygnal's debugging system supports inspection and modification of memory and registers, breakpoints, and single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized. The C8051F310DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F310/1 MCUs. The kit includes software with a developer's studio and debugger, an integrated 8051 assembler, and an RS-232 to C2 serial adapter. It also has a target application board with the associated MCU installed and prototyping area, plus the RS-232 and C2 cables, and wall-mount power supply. The Development Kit requires a Windows 95/98/NT/ME/2000 computer with one available RS-232 serial port. As shown in Figure 1.6, the PC is connected via RS-232 to the Serial Adapter. A six-inch ribbon cable connects the Serial Adapter to the user's application board, picking up the two C2 pins and VDD and GND. The Serial Adapter takes its power from the application board. For applications where there is not sufficient power available from the target board, the provided power supply can be connected directly to the Serial Adapter. The Cygnal IDE interface is a vastly superior developing and debugging configuration, compared to standard MCU emulators that use on-board "ICE Chips" and require the MCU in the application board to be socketed. Cygnal's debug paradigm increases ease of use and preserves the performance of the precision analog peripherals.
Figure 1.6. Development/In-System Debug Diagram
CYGNAL Integrated Development Environment WINDOWS 95/98/NT/ME/2000
RS-232
Serial Adapter
C2 (x2), VDD, GND
VDD
GND
TARGET PCB
C8051F310
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Page 19
C8051F310/1
1.4.
Preliminary
Programmable Digital I/O and Crossbar
C8051F310 devices include 29 I/O pins (three byte-wide Ports and one 5-bit-wide Port); C8051F311 devices include 25 I/O pins (three byte-wide Ports and one 1-bit-wide Port). The C8051F310/1 Ports behave like typical 8051 Ports with a few enhancements. Each Port pin may be configured as an analog input or a digital I/O pin. Pins selected as digital I/Os may additionally be configured for push-pull or open-drain output. The "weak pull-ups" that are fixed on typical 8051 devices may be globally disabled, providing power savings capabilities. The Digital Crossbar allows mapping of internal digital system resources to Port I/O pins (See Figure 1.7). On-chip counter/timers, serial buses, HW interrupts, comparator output, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in the Crossbar Control registers. This allows the user to select the exact mix of general purpose Port I/O and digital resources needed for the particular application.
Figure 1.7. Digital Crossbar Diagram
XBR0, XBR1, PnSKIP Registers PnMDOUT, PnMDIN Registers
Priority Decoder
Highest Priority UART SPI (Internal Digital Signals) SMBus CP0 Outputs CP1 Outputs SYSCLK 4 PCA Lowest Priority T0, T1 6 5 2 8 P0 (P0.0-P0.7) 8 (Port Latches) P1 (P1.0-P1.7) 4 (P2.0-P2.3) P2 4 (P2.4-P2.7) 5 P3 (P3.0-P3.4) P3 I/O Cells P3.0 P3.4 2 4 2 2 2 4 8 P2 I/O Cells P2.0 P2.7 8 P0 I/O Cells P0.0 P0.7 P1.0 P1.7
Digital Crossbar
8
P1 I/O Cells
Note: P3.1-P3.4 only available on the C8051F310
1.5.
Serial Ports
The C8051F310/1 Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud rate configuration, and an Enhanced SPI interface. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention.
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Preliminary
C8051F310/1
1.6.
Programmable Counter Array
An on-chip Programmable Counter/Timer Array (PCA) is included in addition to the four 16-bit general purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with five programmable capture/compare modules. The PCA clock is derived from one of six sources: the system clock divided by 12, the system clock divided by 4, Timer 0 overflows, an External Clock Input (ECI), the system clock, or the external oscillator clock source divided by 8. The external clock source selection is useful for real-time clock functionality, where the PCA is clocked by an external source while the internal oscillator drives the system clock. Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture, Software Timer, High Speed Output, 8- or 16-bit Pulse Width Modulator, or Frequency Output. Additionally, Capture/Compare Module 4 offers watchdog timer (WDT) capabilities. Following a system reset, Module 4 is configured and enabled in WDT mode. The PCA Capture/Compare Module I/O and External Clock Input may be routed to Port I/O via the Digital Crossbar.
Figure 1.8. PCA Block Diagram
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 PCA CLOCK MUX 16-Bit Counter/Timer
Capture/Compare Module 0
Capture/Compare Module 1
Capture/Compare Module 2
Capture/Compare Module 3
Capture/Compare Module 4 / WDT
CEX0
CEX1
CEX2
CEX3
CEX4
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
ECI
Crossbar
Port I/O
Page 21
C8051F310/1
1.7.
Preliminary
10-Bit Analog to Digital Converter
The C8051F310/1 devices include an on-chip 10-bit SAR ADC with a 25-channel differential input multiplexer. With a maximum throughput of 200 ksps, the ADC offers true 10-bit accuracy with an INL of 1LSB. The ADC system includes a configurable analog multiplexer that selects both positive and negative ADC inputs. Ports1-3 are available as an ADC inputs; additionally, the on-chip Temperature Sensor output and the power supply voltage (VDD) are available as ADC inputs. User firmware may shut down the ADC to save power. Conversions can be started in six ways: a software command, an overflow of Timer 0, 1, 2, or 3, or an external convert start signal. This flexibility allows the start of conversion to be triggered by software events, a periodic signal (timer overflows), or external HW signals. Conversion completions are indicated by a status bit and an interrupt (if enabled). The resulting 10-bit data word is latched into the ADC data SFRs upon completion of a conversion. Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is either within or outside of a specified range. The ADC can monitor a key voltage continuously in background mode, but not interrupt the controller unless the converted data is within/outside the specified range.
Figure 1.9. 10-Bit ADC Block Diagram
Analog Multiplexer
P1.0
Configuration, Control, and Data Registers
P1.7 P2.0 23-to-1 AMUX P3.1-3.4 available on C8051F310
Temp Sensor Start Conversion 000 001 010 011 100 101 AD0BUSY (W) Timer 0 Overflow Timer 2 Overflow Timer 1 Overflow CNVSTR Input Timer 3 Overflow
P2.7 P3.0 P3.4 VDD
(+)
10-Bit SAR
P1.0
(-)
ADC
End of Conversion Interrupt
16
ADC Data Registers
P1.7 P2.0 22-to-1 AMUX P2.7 P3.0 P3.4 GND
Window Compare Logic
Window Compare Interrupt
P3.1-3.4 available on C8051F310
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Preliminary
C8051F310/1
1.8.
Comparators
C8051F310/1 devices include two on-chip voltage comparators that are enabled/disabled and configured via user software. Port I/O pins may be configured as comparator inputs via a selection mux. Two comparator outputs may be routed to a Port pin if desired: a latched output and/or an unlatched (asynchronous) output. Comparator response time is programmable, allowing the user to select between high-speed and low-power modes. Positive and negative hysteresis are also configurable. Comparator interrupts may be generated on rising, falling, or both edges. When in IDLE mode, these interrupts may be used as a "wake-up" source. Comparator0 may also be configured as a reset source. Figure 1.10 shows he Comparator0 block diagram.
Figure 1.10. Comparator0 Block Diagram
CP0EN CP0OUT
CPT0CN
CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0
VDD
CPT0MX
CMX0N1 CMX0N0
CP0 Interrupt
CMX0P1 CMX0P0 P1.0 P1.4 P2.0 P2.4 CP0 + Interrupt Logic CP0 Rising-edge CP0 Falling-edge
+
D
SET
CP0
Q D
SET
Q
P1.1 P1.5 P2.1 P2.5 CP0 GND Reset Decision Tree CP0RIE CP0FIE
CLR
Q
CLR
Q
Crossbar
(SYNCHRONIZER)
CP0A
CPT0MD
CP0MD1 CP0MD0
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Page 23
C8051F310/1
2.
Preliminary
ABSOLUTE MAXIMUM RATINGS
Table 2.1. Absolute Maximum Ratings*
PARAMETER CONDITIONS MIN -55 -65 -0.3 -0.3 TYP MAX 125 150 5.8 4.2 500 100 UNITS C C V V mA mA
Ambient temperature under bias Storage Temperature Voltage on any Port I/O Pin or /RST with respect to GND Voltage on VDD with respect to GND Maximum Total current through VDD and GND Maximum output current sunk by /RST or any Port pin
*
Note: stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
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Preliminary
C8051F310/1
3.
GLOBAL DC ELECTRICAL CHARACTERISTICS
Table 3.1. Global DC Electrical Characteristics
-40C to +85C, 25 MHz System Clock unless otherwise specified. PARAMETER Digital Supply Voltage Digital Supply Current with CPU active Digital Supply Current with CPU inactive (not accessing FLASH) Digital Supply Current (shutdown) Digital Supply RAM Data Retention Voltage Specified Operating Temperature Range SYSCLK (system clock frequency) Tsysl (SYSCLK low time) Tsysh (SYSCLK high time)

CONDITIONS
MIN VRST
TYP 3.0 6.4 0.36 9 3.2 180 5.5 < 0.1 1.5
MAX 3.6
UNITS V mA mA A mA A A A V
VDD=2.7V, Clock=25MHz VDD=2.7V, Clock=1MHz VDD=2.7V, Clock=32kHz VDD=2.7V, Clock=25MHz VDD=2.7V, Clock=1MHz VDD=2.7V, Clock=32kHz Oscillator not running
-40 0 18 18
+85 25
C MHz ns ns
Given in Table 9.1 on page 94. SYSCLK must be at least 32 kHz to enable debugging.
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Page 25
C8051F310/1
4.
Preliminary
PINOUT AND PACKAGE DEFINITIONS
Table 4.1. Pin Definitions for the C8051F310/1
Pin Numbers Name `F310 VDD GND /RST/ 5 C2CK P3.0/ 6 C2D P0.0/ 2 VREF P0.1 P0.2/ 32 XTAL1 P0.3/ 31 XTAL2 P0.4 P0.5 P0.6/ 28 CNVSTR P0.7 P1.0 P1.1 P1.2 27 26 25 24 23 22 21 20 D I/O 24 ADC0 External Convert Start Input. Port 0.7. See Section 13 for a complete description. 30 29 26 25 27 28 A In D I/O 1 1 2 A In D I/O D I/O External VREF input. Port 0.1. See Section 13 for a complete description. Port 0.2. See Section 13 for a complete description. External Clock Input. This pin is the external oscillator return for a crystal or resonator. Port 0.3. See Section 13 for a complete description. 6 D I/O D I/O Bi-directional data signal for the C2 Debug Interface. Port 0.0. See Section 13 for a complete description. 5 D I/O D I/O 4 3 `F311 4 3 D I/O Power Supply Voltage. Ground. Device Reset. Open-drain output of internal POR. An external source can initiate a system reset by driving this pin low for at least 10 s. Clock signal for the C2 Debug Interface. Port 3.0. See Section 13 for a complete description. Type Description
External Clock Output. For an external crystal or resonator, this A Out or pin is the excitation driver. This pin is the external clock input for CMOS, capacitor, or RC oscillator configurations. D In D I/O D I/O Port 0.4. See Section 13 for a complete description. Port 0.5. See Section 13 for a complete description. Port 0.6. See Section 13 for a complete description.
D I/O or Port 1.0. See Section 13 for a complete description. A In D I/O or Port 1.1. See Section 13 for a complete description. A In D I/O or Port 1.2. See Section 13 for a complete description. A In
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Preliminary
C8051F310/1
Table 4.1. Pin Definitions for the C8051F310/1
Pin Numbers Name `F310 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.1 P3.2 P3.3 P3.4 23 22 21 20 19 18 17 16 15 14 13 12 11 7 8 9 10 `F311 19 18 17 16 15 14 13 12 11 10 9 8 7 D I/O or Port 1.3. See Section 13 for a complete description. A In D I/O or Port 1.4. See Section 13 for a complete description. A In D I/O or Port 1.5. See Section 13 for a complete description. A In D I/O or Port 1.6. See Section 13 for a complete description. A In D I/O or Port 1.7. See Section 13 for a complete description. A In D I/O or Port 2.0. See Section 13 for a complete description. A In D I/O or Port 2.1. See Section 13 for a complete description. A In D I/O or Port 2.2. See Section 13 for a complete description. A In D I/O or Port 2.3. See Section 13 for a complete description. A In D I/O or Port 2.4. See Section 13 for a complete description. A In D I/O or Port 2.5. See Section 13 for a complete description. A In D I/O or Port 2.6. See Section 13 for a complete description. A In D I/O or Port 2.7. See Section 13 for a complete description. A In D I/O or Port 3.1. See Section 13 for a complete description. A In D I/O or Port 3.2. See Section 13 for a complete description. A In D I/O or Port 3.3. See Section 13 for a complete description. A In D I/O or Port 3.4. See Section 13 for a complete description. A In Type Description
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
Page 27
C8051F310/1
Preliminary
Figure 4.1. LQFP-32 Pinout Diagram (Top View)
P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 P1.0 P1.1
32
31
30
29
28
27
26
P0.1 P0.0 GND VDD /RST/C2CK P3.0/C2D P3.1 P3.2
1 2 3 4 5 6 7 8
25
24 23 22
P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1
C8051F310 Top View
21 20 19 18 17
10
11
12
13
14
15
P2.3
P3.3
P3.4
P2.7
P2.6
P2.5
P2.4
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DS009-1.3b MAY03 (c) 2003 Cygnal Integrated Products, Inc.
P2.2
16
9
Preliminary
C8051F310/1
Figure 4.2. LQFP-32 Package Diagram
D D1
Table 4.2. LQFP-32 Package Dimensions
A A1 A2 b D D1 e E E1 MIN 0.05 1.35 0.30 MM TYP 1.40 0.37 9.00 7.00 0.80 9.00 7.00 MAX 1.60 0.15 1.45 0.45 -
E1 E
32
PIN 1 IDENTIFIER
1
A2 A b A1 e
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
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C8051F310/1
Preliminary
Figure 4.3. MLP-28 Pinout Diagram (Top View)
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7 23
28
27
26
25
24
GND P0.1 P0.0 GND VDD /RST/C2CK P3.0/C2D P2.7 1 2 3 4 5 6
22
P1.0
21 20 19
P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7
C8051F311 Top View
18 17 16
GND 7 15
10
11
12
13 P2.1
P2.6
P2.5
P2.4
P2.3
P2.2
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DS009-1.3b MAY03 (c) 2003 Cygnal Integrated Products, Inc.
P2.0
14
8
9
Preliminary
C8051F310/1
Figure 4.4. MLP-28 Package Drawing
Bottom View
Table 4.2. MLP-28 Package Dimensions
15 D2 D2 2 E2 R 19 20 DETAIL 1 28 27 26 25 24 23 22 21 16 17 18 6xe E
A A1 A2 A3 b D D2 E E2 e L N ND NE R AA BB CC DD MIN 0.80 0 0 0.18 2.90 2.90 0.45 0.09 MM TYP 0.90 0.02 0.65 0.25 0.23 5.00 3.15 5.00 3.15 0.5 0.55 28 7 7 0.435 0.435 0.18 0.18 MAX 1.00 0.05 1.00 0.30 3.35 3.35 0.65 -
10
11
12
13
L 7
6 5 4 e b
2 1
6xe D
Side View
A2 A DD BB A1
A3
e
DETAIL 1 AA
CC
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
E2 2
3
14
8
9
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C8051F310/1
Preliminary
Figure 4.5. Typical MLP-28 Landing Diagram
Top View
0.20 mm 0.20 mm 0.50 mm 0.30 mm 0.85 mm
0.50 mm D2 0.35 mm
0.50 mm
0.20 mm
Optional GND Connection
b
0.10 mm
L E2
0.20 mm
0.30 mm
e
0.50 mm
0.35 mm
0.85 mm
0.10 mm
E
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D
Preliminary
C8051F310/1
Figure 4.6. Typical MLP-28 Solder Mask
Top View
0.20 mm 0.20 mm 0.50 mm 0.30 mm 0.85 mm
0.50 mm 0.60 mm 0.60 mm 0.70 mm 0.30 mm 0.20 mm 0.40 mm D2 0.35 mm
0.50 mm
0.20 mm
b
0.10 mm
L
e
E2
0.20 mm
0.30 mm
0.50 mm
0.35 mm
0.85 mm
0.10 mm
E
(c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
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D
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Preliminary
Notes
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5.
10-BIT ADC (ADC0)
The ADC0 subsystem for the C8051F310/1 consists of two analog multiplexers (referred to collectively as AMUX0) with 25 total input selections, and a 200 ksps, 10-bit successive-approximation-register ADC with integrated trackand-hold and programmable window detector. The AMUX0, data conversion modes, and window detector are all configurable under software control via the Special Function Registers shown in Figure 5.1. ADC0 operates in both Single-ended and Differential modes, and may be configured to measure P1.0-P3.4, the Temperature Sensor output, or VDD with respect to P1.0-P3.4 or GND. The ADC0 subsystem is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
Figure 5.1. ADC0 Functional Block Diagram
P1.0 AMX0P
AMX0P4 AMX0P3 AMX0P2 AMX0P1 AMX0P0
ADC0CN
AD0BUSY AD0WINT AD0CM2 AD0CM1 AD0CM0 000 001 010 011 100 101 AD0INT AD0TM AD0EN VDD Start Conversion
P1.7 P2.0 23-to-1 AMUX P3.1-3.4 available on C8051F310
Temp Sensor
P2.7 P3.0 P3.4
AD0BUSY (W) Timer 0 Overflow Timer 2 Overflow Timer 1 Overflow CNVSTR Input Timer 3 Overflow
(+)
10-Bit SAR
P1.0
(-)
P1.7 P2.0 23-to-1 AMUX P3.1-3.4 available on C8051F310 P2.7 P3.0 P3.4 VREF GND
SYSCLK
REF
ADC0H
ADC
ADC0L
VDD
AD0WINT Window Compare Logic
AD0LJST
AD0SC4
AD0SC3
AD0SC2
AD0SC1
AD0SC0
AMX0N
AMX0N4 AMX0N3 AMX0N2 AMX0N1 AMX0N0
32
ADC0LTH
ADC0LTL
ADC0CF
ADC0GTH ADC0GTL
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5.1. Analog Multiplexer
Preliminary
AMUX0 selects the positive and negative inputs to the ADC. Any of the following may be selected as the positive input: P1.0-P3.4, the on-chip temperature sensor, or the positive power supply (VDD). Any of the following may be selected as the negative input: P1.0-P3.4 or GND. When GND is selected as the negative input, ADC0 operates in Single-ended Mode; all other times, ADC0 operates in Differential Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in Figure 5.6 and Figure 5.7. The conversion code format differs between Single-ended and Differential modes. The registers ADC0H and ADC0L contain the high and low bytes of the output conversion code from the ADC at the completion of each conversion. Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit (ADC0CN.0). When in Single-ended Mode, conversion codes are represented as 10-bit unsigned integers. Inputs are measured from `0' to VREF * 1023/1024. Example codes are shown below for both right-justified and left-justified data. Unused bits in the ADC0H and ADC0L registers are set to `0'. Input Voltage VREF * 1023/1024 VREF * 512/1024 VREF * 256/1024 0 Right-Justified ADC0H:ADC0L (AD0LJST = 0) 0x03FF 0x0200 0x0100 0x0000 Left-Justified ADC0H:ADC0L (AD0LJST = 1) 0xFFC0 0x8000 0x4000 0x0000
When in Differential Mode, conversion codes are represented as 10-bit signed 2's complement numbers. Inputs are measured from -VREF to VREF * 511/512. Example codes are shown below for both right-justified and left-justified data. For right-justified data, the unused MSBs of ADC0H are a sign-extension of the data word. For left-justified data, the unused LSBs in the ADC0L register are set to `0'. Input Voltage VREF * 511/512 VREF * 256/512 0 -VREF * 256/512 - VREF Right-Justified ADC0H:ADC0L (AD0LJST = 0) 0x01FF 0x0100 0x0000 0xFF00 0xFE00 Left-Justified ADC0H:ADC0L (AD0LJST = 1) 0x7FC0 0x4000 0x0000 0xC000 0x8000
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be configured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog input, set to `0' the corresponding bit in register PnMDIN (for n = 0,1,2,3). To force the Crossbar to skip a Port pin, set to `1' the corresponding bit in register PnSKIP (for n = 0,1,2). See Section "13. Port Input/Output" on page 109 for more Port I/O configuration details.
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5.2.
Temperature Sensor
The typical temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the positive ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P.
Figure 5.2. Typical Temperature Sensor Transfer Function
(mV)
1200
1100
1000
900 VTEMP = 3.35*(TEMPC) + 897 mV 800
700 -50 0 50 100
(Celsius)
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature measurements (see Table 5.1 for linearity specifications). For absolute temperature measurements, gain and/or offset calibration is recommended. Typically a 1-point calibration includes the following steps: Step 1. Control/measure the ambient temperature (this temperature must be known). Step 2. Power the device, and delay for a few seconds to allow for self-heating. Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input and GND selected as the negative input. Step 4. Calculate the offset and/or gain characteristics, and store these values in non-volatile memory for use with subsequent temperature sensor measurements. Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 C. Note that parameters which affect ADC measurement, in particular the voltage reference value, will also affect temperature measurement.
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Preliminary
Figure 5.3. Temperature Sensor Error with 1-Point Calibration
5.00 5.00
4.00
4.00
3.00
3.00
2.00
2.00
Error (degrees C)
1.00
1.00
0.00 -40.00 -1.00
-20.00
0.00 20.00
40.00
60.00
0.00 80.00 -1.00
-2.00
-2.00
-3.00
-3.00
-4.00
-4.00
-5.00
-5.00
Temperature (degrees C)
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5.3.
Modes of Operation
ADC0 has a maximum conversion speed of 200 ksps. The ADC0 conversion clock is a divided version of the system clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by (AD0SC + 1) for 0 AD0SC 31).
5.3.1.
Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC0 Start of Conversion Mode bits (AD0CM2-0) in register ADC0CN. Conversions may be initiated by one of the following: 1. 2. 3. 4. 5. 6. Writing a `1' to the AD0BUSY bit of register ADC0CN A Timer 0 overflow (i.e., timed continuous conversions) A Timer 2 overflow A Timer 1 overflow A rising edge on the CNVSTR input signal (pin P0.6) A Timer 3 overflow
Writing a `1' to AD0BUSY provides software control of ADC0 whereby conversions are performed "on-demand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. See Section "17. Timers" on page 167 for timer configuration. Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port pin P0.6. When the CNVSTR input is used as the ADC0 conversion source, Port pin P0.6 should be skipped by the Digital Crossbar. To configure the Crossbar to skip P0.6, set to `1' Bit6 in register P0SKIP. See Section "13. Port Input/Output" on page 109 for details on Port I/O configuration.
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5.3.2. Tracking Modes
Preliminary
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked, except when a conversion is in progress. When the AD0TM bit is logic 1, ADC0 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR is low; conversion begins on the rising edge of CNVSTR (see Figure 5.4). Tracking can also be disabled (shutdown) when the device is in low power standby or sleep modes. Low-power trackand-hold mode is also useful when AMUX settings are frequently changed, due to the settling time requirements described in Section "5.3.3. Settling Time Requirements" on page 41.
Figure 5.4. 10-Bit ADC Track and Conversion Example Timing
A. ADC0 Timing for External Trigger Source
CNVSTR (AD0CM[2:0]=100)
1 2 3 4 5 6 7 8 9 10 11
SAR Clocks Low Power or Convert Low Power Mode
AD0TM=1
Track
Convert
AD0TM=0
Track or Convert
Convert
Track
Write '1' to AD0BUSY, Timer 0, Timer 2, Timer 1, Timer 3 Overflow (AD0CM[2:0]=000, 001,010 011, 101) SAR Clocks AD0TM=1
B. ADC0 Timing for Internal Trigger Source
1
2
3
4
5
6
7
8
9
10 11 12 13 14
Low Power or Convert
1
Track
2 3 4 5 6 7
Convert
8 9 10 11
Low Power Mode
SAR Clocks AD0TM=0 Track or Convert Convert Track
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5.3.3.
Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Note that in low-power tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the minimum tracking time requirements. Figure 5.5 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature Sensor output or VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum settling time requirements.
Equation 5.1. ADC0 Settling Time Requirements 2 t = ln ------ x R TOTAL C SAMPLE SA
Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds RTOTAL is the sum of the AMUX0 resistance and any external source resistance. n is the ADC resolution in bits (10).
n
Figure 5.5. ADC0 Equivalent Input Circuits
Differential Mode
MUX Select
Single-Ended Mode
MUX Select
Px.x RMUX = 5k CSAMPLE = 5pF RCInput= RMUX * CSAMPLE CSAMPLE = 5pF Px.x RMUX = 5k MUX Select
Px.x RMUX = 5k CSAMPLE = 5pF RCInput= RMUX * CSAMPLE
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Preliminary
Figure 5.6. AMX0P: AMUX0 Positive Channel Select Register
R R R R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
AMX0P4
Bit4
AMX0P3
Bit3
AMX0P2
Bit2
AMX0P1
Bit1
AMX0P0
Bit0
00000000
SFR Address:
0xBB Bits7-5: Bits4-0: UNUSED. Read = 000b; Write = don't care. AMX0P4-0: AMUX0 Positive Input Selection AMX0P4-0 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 - 11101 11110 11111 ADC0 Positive Input P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0 P3.1 P3.2 P3.3 P3.4 RESERVED Temp Sensor VDD
Only applies to C8051F310; selection RESERVED on C8051F311 devices.
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Figure 5.7. AMX0N: AMUX0 Negative Channel Select Register
R R R R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value SFR Address:
Bit7
Bit6
Bit5
AMX0N4 AMX0N3 AMX0N2 AMX0N1 AMX0N0 00000000 0xBA
Bits7-5: Bits4-0:
UNUSED. Read = 000b; Write = don't care. AMX0N4-0: AMUX0 Negative Input Selection. Note that when GND is selected as the Negative Input, ADC0 operates in Single-ended mode. For all other Negative Input selections, ADC0 operates in Differential mode. AMX0N4-0 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 - 11101 11110 11111 ADC0 Negative Input P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0 P3.1 P3.2 P3.3 P3.4 RESERVED VREF GND (ADC in Single-Ended Mode)
Only applies to C8051F310; selection RESERVED on C8051F311 devices.
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Preliminary
Figure 5.8. ADC0CF: ADC0 Configuration Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0SC4
Bit7
AD0SC3
Bit6
AD0SC2
Bit5
AD0SC1
Bit4
AD0SC0
Bit3
AD0LJST
Bit2
Bit1
Bit0
11111000
SFR Address:
0xBC Bits7-3: AD0SC4-0: ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in bits AD0SC4-0. SAR Conversion clock requirements are given in Table 5.1.
SYSCLK AD0SC = --------------------- - 1 CLK SAR
Bit2: AD0LJST: ADC0 Left Justify Select. 0: Data in ADC0H:ADC0L registers are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified. UNUSED. Read = 00b; Write = don't care.
Bits1-0:
Figure 5.9. ADC0H: ADC0 Data Word MSB Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xBE Bits7-0: ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7-2 are the sign extension of Bit1. Bits 1-0 are the upper 2 bits of the 10-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-0 are the most-significant bits of the 10-bit ADC0 Data Word.
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Figure 5.10. ADC0L: ADC0 Data Word LSB Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xBD Bits7-0: ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the 10-bit Data Word. For AD0LJST = 1: Bits 7-6 are the lower 2 bits of the 10-bit Data Word. Bits 5-0 will always read `0'.
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Preliminary
Figure 5.11. ADC0CN: ADC0 Control Register
R/W R/W R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W R/W Reset Value
AD0EN
Bit7
AD0TM
Bit6
AD0INT AD0BUSY AD0WINT AD0CM2
AD0CM1
Bit1
AD0CM0
Bit0 (bit addressable)
00000000
SFR Address:
0xE8
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bits2-0:
AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. AD0TM: ADC0 Track Mode Bit. 0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a conversion is in progress. 1: Low-power Track Mode: Tracking Defined by AD0CM2-0 bits (see below). AD0INT: ADC0 Conversion Complete Interrupt Flag. 0: ADC0 has not completed a data conversion since the last time AD0INT was cleared. 1: ADC0 has completed a data conversion. AD0BUSY: ADC0 Busy Bit. Read: 0: ADC0 conversion is complete or a conversion is not currently in progress. AD0INT is set to logic 1 on the falling edge of AD0BUSY. 1: ADC0 conversion is in progress. Write: 0: No Effect. 1: Initiates ADC0 Conversion if AD0CM2-0 = 000b AD0WINT: ADC0 Window Compare Interrupt Flag. 0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC0 Window Comparison Data match has occurred. AD0CM2-0: ADC0 Start of Conversion Mode Select. When AD0TM = 0: 000: ADC0 conversion initiated on every write of `1' to AD0BUSY. 001: ADC0 conversion initiated on overflow of Timer 0. 010: ADC0 conversion initiated on overflow of Timer 2. 011: ADC0 conversion initiated on overflow of Timer 1. 100: ADC0 conversion initiated on rising edge of external CNVSTR. 101: ADC0 conversion initiated on overflow of Timer 3. 11x: Reserved. When AD0TM = 1: 000: Tracking initiated on write of `1' to AD0BUSY and lasts 3 SAR clocks, followed by conversion. 001: Tracking initiated on overflow of Timer 0 and lasts 3 SAR clocks, followed by conversion. 010: Tracking initiated on overflow of Timer 2 and lasts 3 SAR clocks, followed by conversion. 011: Tracking initiated on overflow of Timer 1 and lasts 3 SAR clocks, followed by conversion. 100: ADC0 tracks only when CNVSTR input is logic low; conversion starts on rising CNVSTR edge. 101: Tracking initiated on overflow of Timer 3 and lasts 3 SAR clocks, followed by conversion. 11x: Reserved.
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5.4.
Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-programmed limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL) registers hold the comparison values. The window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0 Less-Than and ADC0 Greater-Than registers.
Figure 5.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
SFR Address:
0xC4 Bits7-0: High byte of ADC0 Greater-Than Data Word.
Figure 5.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
SFR Address:
0xC3 Bits7-0: Low byte of ADC0 Greater-Than Data Word.
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Preliminary
Figure 5.14. ADC0LTH: ADC0 Less-Than Data High Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xC6 Bits7-0: High byte of ADC0 Less-Than Data Word.
Figure 5.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xC5 Bits7-0: Low byte of ADC0 Less-Than Data Word.
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5.4.1.
Window Detector In Single-Ended Mode
Figure 5.16 shows two example window comparisons for right-justified, single-ended data, with ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). In single-ended mode, the input voltage can range from `0' to VREF * (1023/1024) with respect to GND, and is represented by a 10-bit unsigned integer value. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 5.17 shows an example using left-justified data with the same comparison values.
Figure 5.16. ADC Window Compare Example: Right-Justified Single-Ended Data
ADC0H:ADC0L Input Voltage (Px.x - GND) VREF x (1023/1024) 0x03FF AD0WINT not affected 0x0081 VREF x (128/1024) 0x0080 0x007F 0x0041 VREF x (64/1024) 0x0040 0x003F ADC0GTH:ADC0GTL VREF x (64/1024) ADC0LTH:ADC0LTL AD0WINT=1 0x0041 0x0040 0x003F VREF x (128/1024) 0x0081 0x0080 0x007F ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL Input Voltage (Px.x - GND) VREF x (1023/1024) 0x03FF ADC0H:ADC0L
AD0WINT=1
AD0WINT not affected 0 0x0000 0 0x0000
AD0WINT=1
Figure 5.17. ADC Window Compare Example: Left-Justified Single-Ended Data
ADC0H:ADC0L Input Voltage (Px.x - GND) VREF x (1023/1024) 0xFFC0 AD0WINT not affected 0x2040 VREF x (128/1024) 0x2000 0x1FC0 0x1040 VREF x (64/1024) 0x1000 0x0FC0 ADC0GTH:ADC0GTL VREF x (64/1024) ADC0LTH:ADC0LTL AD0WINT=1 0x1040 0x1000 0x0FC0 VREF x (128/1024) 0x2040 0x2000 0x1FC0 ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL Input Voltage (Px.x - GND) VREF x (1023/1024) 0xFFC0 ADC0H:ADC0L
AD0WINT=1
AD0WINT not affected 0 0x0000 0 0x0000
AD0WINT=1
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5.4.2.
Preliminary
Window Detector In Differential Mode
Figure 5.18 shows two example window comparisons for right-justified, differential data, with ADC0LTH:ADC0LTL = 0x0040 (+64d) and ADC0GTH:ADC0GTH = 0xFFFF (-1d). In differential mode, the measurable voltage between the input pins is between -VREF and VREF*(511/512). Output codes are represented as 10bit 2's complement signed integers. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0xFFFF (-1d) < ADC0H:ADC0L < 0x0040 (64d)). In the right example, an AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0xFFFF (-1d) or ADC0H:ADC0L > 0x0040 (+64d)). Figure 5.19 shows an example using left-justified data with the same comparison values.
Figure 5.18. ADC Window Compare Example: Right-Justified Differential Data
ADC0H:ADC0L Input Voltage (Px.x - Px.x) VREF x (511/512) 0x01FF AD0WINT not affected 0x0041 VREF x (64/512) 0x0040 0x003F 0x0000 0xFFFF 0xFFFE ADC0LTH:ADC0LTL AD0WINT=1 VREF x (-1/512) ADC0GTH:ADC0GTL VREF x (-1/512) 0x0000 0xFFFF 0xFFFE VREF x (64/512) 0x0041 0x0040 0x003F ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL Input Voltage (Px.x - Px.x) VREF x (511/512) 0x01FF ADC0H:ADC0L
AD0WINT=1
AD0WINT not affected -VREF 0x0200 -VREF 0x0200
AD0WINT=1
Figure 5.19. ADC Window Compare Example: Left-Justified Differential Data
ADC0H:ADC0L Input Voltage (Px.x - Px.x) VREF x (511/512) 0x7FC0 AD0WINT not affected 0x1040 VREF x (64/512) 0x1000 0x0FC0 0x0000 0xFFC0 0xFF80 ADC0LTH:ADC0LTL AD0WINT=1 VREF x (-1/512) ADC0GTH:ADC0GTL VREF x (-1/512) 0x0000 0xFFC0 0xFF80 VREF x (64/512) 0x1040 0x1000 0x0FC0 ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL Input Voltage (Px.x - Px.y) VREF x (511/512) 0x7FC0 ADC0H:ADC0L
AD0WINT=1
AD0WINT not affected -VREF 0x8000 -VREF 0x8000
AD0WINT=1
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Table 5.1. ADC0 Electrical Characteristics
VDD = 3.0 V, VREF = 2.40 V (REFSL=0), -40C to +85C unless otherwise specified PARAMETER DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Full Scale Error Offset Temperature Coefficient Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range CONVERSION RATE SAR Conversion Clock Conversion Time in SAR Clocks Track/Hold Acquisition Time Throughput Rate ANALOG INPUTS Input Voltage Range Input Capacitance TEMPERATURE SENSOR Linearity Gain Offset POWER SPECIFICATIONS Power Supply Current (VDD supplied to ADC0) Power Supply Rejection Note 1: Represents one standard deviation from the mean. Note 2: Includes ADC offset, gain, and linearity variations. Operating Mode, 200 ksps 400 0.3 900 A mV/V Notes 1, 2 Notes 1, 2 Notes 1, 2 (Temp = 0 C) 0.5 3350 110 89731 C V / C mV 0 5 VREF V pF 10 300 200 3 MHz clocks ns ksps Up to the 5 harmonic
th
CONDITIONS
MIN
TYP 10 0.5
MAX
UNITS bits
1 1 +12 +5
LSB LSB LSB LSB ppm/C dB dB dB
Guaranteed Monotonic -12 Differential mode -15
0.5 1 -5 3.6 53 55.5 -67 78
DYNAMIC PERFORMANCE (10 kHz sine-wave Single-ended input, 0 to 1 dB below Full Scale, 200 ksps)
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6.
VOLTAGE REFERENCE
The voltage reference MUX on C8051F310/1 devices is configurable to use an externally connected voltage reference or the power supply voltage or VDD (see Figure 6.1). The REFSL bit in the Reference Control register (REF0CN) selects the reference source. For an external source, REFSL should be set to `0'; For VDD as the reference source, REFSL should be set to `1'. The BIASE bit enables the internal voltage bias generator, which is used by the ADC, Temperature Sensor, and Internal Oscillator. This bit is forced to logic 1 when any of the aforementioned peripherals is enabled. The bias generator may be enabled manually by writing a `1' to the BIASE bit in register REF0CN; see Figure 6.2 for REF0CN register details. The electrical specifications for the voltage reference circuit are given in Table 6.1. Important Note About the VREF Input: Port pin P0.0 is used as the external VREF input. When using an external voltage reference, P0.0 should be configured as analog input and skipped by the Digital Crossbar. To configure P0.0 as analog input, set to `0' Bit0 in register P0MDIN. To configure the Crossbar to skip P0.0, set to `1' Bit0 in register P0SKIP. Refer to Section "13. Port Input/Output" on page 109 for complete Port I/O configuration details. The temperature sensor connects to the highest order input of the ADC0 positive input multiplexer (see Section "5.1. Analog Multiplexer" on page 36 for details). The TEMPE bit in register REF0CN enables/disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in meaningless data.
Figure 6.1. Voltage Reference Functional Block Diagram
REF0CN TEMPE REFSL BIASE
EN IOSCEN VDD External Voltage Reference Circuit VREF 0 EN
Bias Generator
To ADC, Internal Oscillator
Temp Sensor
To Analog Mux
R1
GND VDD 1
Internal VREF (to ADC)
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Figure 6.2. REF0CN: Reference Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
REFSL
Bit3
TEMPE
Bit2
BIASE
Bit1
Bit0
00000000
SFR Address:
0xD1 Bits7-3: Bit3: UNUSED. Read = 00000b; Write = don't care. REFSL: Voltage Reference Select. This bit selects the source for the internal voltage reference. 0: VREF input pin used as voltage reference. 1: VDD used as voltage reference. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor off. 1: Internal Temperature Sensor on. BIASE: Internal Analog Bias Generator Enable Bit. (Must be `1' if using ADC). 0: Internal Bias Generator off. 1: Internal Bias Generator on. UNUSED. Read = 0b. Write = don't care.
Bit2:
Bit1:
Bit0:
Table 6.1. External Voltage Reference Circuit Electrical Characteristics
VDD = 3.0 V; -40C to +85C unless otherwise specified PARAMETER Input Voltage Range Input Current Sample Rate = 200 ksps; VREF = 3.0 V CONDITIONS MIN 0 12 TYP MAX VDD UNITS V A
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7.
COMPARATORS
C8051F310/1 devices include two on-chip programmable voltage comparators: Comparator0 is shown in Figure 7.1; Comparator1 is shown in Figure 7.2. The two comparators operate identically with the following exceptions: (1) Their input selections differ as shown in Figure 7.1 and Figure 7.2; (2) Comparator0 can be used as a reset source. The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two outputs that are optionally available at the Port pins: a synchronous "latched" output (CP0, CP1), or an asynchronous "raw" output (CP0A, CP1A). The asynchronous CP0A signal is available even when in when the system clock is not active. This allows the Comparator to operate and generate an output with the device in STOP mode. When assigned to a Port pin, the Comparator output may be configured as open drain or push-pull (see Section "13.2. Port I/O Initialization" on page 113). Comparator0 may also be used as a reset source (see Section "9.5. Comparator0 Reset" on page 92). The Comparator0 inputs are selected in the CPT0MX register (Figure 7.5). The CMX0P1-CMX0P0 bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative input. The Comparator1 inputs are selected in the CPT1MX register (Figure 7.8). The CMX1P1-CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the Comparator1 negative input. Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be configured as analog inputs in their associated Port configuration register, and configured to be skipped by the Crossbar (for details on Port configuration, see Section "13.3. General Purpose Port I/O" on page 116).
Figure 7.1. Comparator0 Functional Block Diagram
CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0
CPT0CN
VDD
CPT0MX
CMX0N1 CMX0N0
CP0 Interrupt
CMX0P1 CMX0P0 P1.0 P1.4 P2.0 P2.4 CP0 +
CP0 Rising-edge
CP0 Falling-edge
Interrupt Logic
+
D
SET
CP0
Q D
SET
Q
P1.1 P1.5 P2.1 P2.5 CP0 GND Reset Decision Tree CP0RIE CP0FIE
CLR
Q
CLR
Q
Crossbar
(SYNCHRONIZER)
CP0A
CPT0MD
CP0MD1 CP0MD0
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The Comparator output can be polled in software, used as an interrupt source, and/or routed to a Port pin. When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system clock; the asynchronous output is available even in STOP mode (with no system clock active). When disabled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state, and its supply current falls to less than 100 nA. See Section "13.1. Priority Crossbar Decoder" on page 111 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be externally driven from -0.25 V to (VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in Table 7.1. The Comparator response time may be configured in software via the CPTnMD registers (see Figure 7.6 and Figure 7.9). Selecting a longer response time reduces the Comparator supply current. See Table 7.1 for complete timing and current consumption specifications.
Figure 7.2. Comparator1 Functional Block Diagram
CP1EN CP1OUT CP1RIF CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0
CPT1CN
VDD
CPT1MX
CMX1N1 CMX1N0
CP1 Interrupt
CMX1P1 CMX1P0
P1.2 P1.6 P2.2 P2.6 CP1 +
CP1 Rising-edge
CP1 Falling-edge
Interrupt Logic
+
D
SET
CP1
Q D
SET
Q
P1.3 P1.7 P2.3 P2.7 CP1 GND Reset Decision Tree CP1RIE CP1FIE
CL R
Q
CL R
Q
Crossbar
(SYNCHRONIZER)
CP1A
CPT1MD
CP1MD1 CP1MD0
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Figure 7.3. Comparator Hysteresis Plot
VIN+ VINCP0+ CP0+ CP0 _
OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage (Programmed with CP0HYP Bits)
VIN-
INPUTS
VIN+
Negative Hysteresis Voltage (Programmed by CP0HYN Bits)
VOH
OUTPUT
VOL
Negative Hysteresis Disabled Positive Hysteresis Disabled Maximum Positive Hysteresis Maximum Negative Hysteresis
The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN (for n = 0 or 1). The user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going symmetry of this hysteresis around the threshold voltage. The Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN (shown in Figure 7.4 and Figure 7.7). The amount of negative hysteresis voltage is determined by the settings of the CPnHYN bits. As shown in Figure 7.3, settings of 20, 10 or 5 mV of negative hysteresis can be programmed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is determined by the setting the CPnHYP bits. Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section "8.3. Interrupt Handler" on page 58). The CPnFIF flag is set to logic 1 upon a Comparator falling-edge interrupt, and the CPnRIF flag is set to logic 1 upon the Comparator rising-edge interrupt. Once set, these bits remain set until cleared by software. The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0. The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0. Note that false rising edges and falling edges can be detected when the comparator is first powered-on or if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the rising-edge and fallingedge flags be explicitly cleared to logic 0 a short time after the comparator is enabled or its mode bits have been changed. This Power Up Time is specified in Table 7.1 on page 64.
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Figure 7.4. CPT0CN: Comparator0 Control Register
R/W R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value SFR Address:
CP0EN
Bit7
CP0OUT
Bit6
CP0RIF
Bit5
CP0FIF
Bit4
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000 0x9B
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bits1-0:
CP0EN: Comparator0 Enable Bit. 0: Comparator0 Disabled. 1: Comparator0 Enabled. CP0OUT: Comparator0 Output State Flag. 0: Voltage on CP0+ < CP0-. 1: Voltage on CP0+ > CP0-. CP0RIF: Comparator0 Rising-Edge Interrupt Flag. 0: No Comparator0 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Rising Edge Interrupt has occurred. CP0FIF: Comparator0 Falling-Edge Interrupt Flag. 0: No Comparator0 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Falling-Edge Interrupt has occurred. CP0HYP1-0: Comparator0 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. CP0HYN1-0: Comparator0 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV.
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Figure 7.5. CPT0MX: Comparator0 MUX Selection Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
CMX0N1
Bit5
CMX0N0
Bit4
Bit3
Bit2
CMX0P1
Bit1
CMX0P0
Bit0
00000000
SFR Address:
0x9F Bits7-6: Bits5-4: UNUSED. Read = 00b, Write = don't care. CMX0N1-CMX0N0: Comparator0 Negative Input MUX Select. These bits select which Port pin is used as the Comparator0 negative input. CMX0N1 CMX0N0 0 0 0 1 1 0 1 1 Bits3-2: Bits1-0: Negative Input P1.1 P1.5 P2.1 P2.5
UNUSED. Read = 00b, Write = don't care. CMX0P1-CMX0P0: Comparator0 Positive Input MUX Select. These bits select which Port pin is used as the Comparator0 positive input. CMX0P1 CMX0P0 0 0 0 1 1 0 1 1 Positive Input P1.0 P1.4 P2.0 P2.4
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Figure 7.6. CPT0MD: Comparator0 Mode Selection Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
CP0RIE
Bit5
CP0FIE
Bit4
Bit3
Bit2
CP0MD1
Bit1
CP0MD0
Bit0
00000000
SFR Address:
0x9D Bits7-6: Bit5: UNUSED. Read = 00b. Write = don't care. CP0RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled. 1: Comparator rising-edge interrupt enabled. CP0FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator falling-edge interrupt enabled. CP0MD1-CP0MD0: Comparator0 Mode Select These bits select the response time for Comparator0. Mode 0 1 2 3 CP0MD1 0 0 1 1 CP0MD0 CP0 Response Time (TYP) 0 100 ns 1 175 ns 0 320 ns 1 1050 ns
Bit4:
Bits1-0:
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Figure 7.7. CPT1CN: Comparator1 Control Register
R/W R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value SFR Address:
CP1EN
Bit7
CP1OUT
Bit6
CP1RIF
Bit5
CP1FIF
Bit4
CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000 0x9A
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bits1-0:
CP1EN: Comparator1 Enable Bit. 0: Comparator1 Disabled. 1: Comparator1 Enabled. CP1OUT: Comparator1 Output State Flag. 0: Voltage on CP1+ < CP1-. 1: Voltage on CP1+ > CP1-. CP1RIF: Comparator1 Rising-Edge Interrupt Flag. 0: No Comparator1 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Rising Edge Interrupt has occurred. CP1FIF: Comparator1 Falling-Edge Interrupt Flag. 0: No Comparator1 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Falling-Edge Interrupt has occurred. CP1HYP1-0: Comparator1 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. CP1HYN1-0: Comparator1 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV.
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Figure 7.8. CPT1MX: Comparator1 MUX Selection Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
CMX1N1
Bit5
CMX1N0
Bit4
Bit3
Bit2
CMX1P1
Bit1
CMX1P0
Bit0
00000000
SFR Address:
0x9E Bits7-6: Bits5-4: UNUSED. Read = 00b, Write = don't care. CMX1N1-CMX1N0: Comparator1 Negative Input MUX Select. These bits select which Port pin is used as the Comparator1 negative input. CMX1N1 CMX1N0 0 0 0 1 1 0 1 1 Bits3-2: Bits1-0: Negative Input P1.3 P1.7 P2.3 P2.7
UNUSED. Read = 00b, Write = don't care. CMX1P1-CMX1P0: Comparator1 Positive Input MUX Select. These bits select which Port pin is used as the Comparator1 positive input. CMX1P1 CMX1P0 0 0 0 1 1 0 1 1 Positive Input P1.2 P1.6 P2.2 P2.6
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Figure 7.9. CPT1MD: Comparator1 Mode Selection Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
CP1RIE
Bit5
CP1FIE
Bit4
Bit3
Bit2
CP1MD1
Bit1
CP1MD0
Bit0
00000000
SFR Address:
0x9C Bits7-6: Bit5: UNUSED. Read = 00b, Write = don't care. CP1RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled 1: Comparator rising-edge interrupt enabled. CP1FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator falling-edge interrupt enabled. CP1MD1-CP1MD0: Comparator1 Mode Select. These bits select the response time for Comparator1. Mode 0 1 2 3 CP1MD1 0 0 1 1 CP1MD0 CP1 Response Time (TYP) 0 100 ns 1 175 ns 0 320 ns 1 1050 ns
Bit4:
Bits1-0:
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Table 7.1. Comparator Electrical Characteristics
VDD = 3.0 V, -40C to +85C unless otherwise noted. All specifications apply to both Comparator0 and Comparator1 unless otherwise noted. PARAMETER Response Time: Mode 0, Vcm = 1.5 V Response Time: Mode 1, Vcm = 1.5 V Response Time: Mode 2, Vcm = 1.5 V Response Time: Mode 3, Vcm = 1.5 V Common-Mode Rejection Ratio Positive Hysteresis 1 Positive Hysteresis 2 Positive Hysteresis 3 Positive Hysteresis 4 Negative Hysteresis 1 Negative Hysteresis 2 Negative Hysteresis 3 Negative Hysteresis 4 Inverting or Non-Inverting Input Voltage Range Input Capacitance Input Bias Current Input Offset Voltage POWER SUPPLY Power Supply Rejection Power-up Time Mode 0 Supply Current at DC Mode 1 Mode 2 Mode 3
Guaranteed
CONDITIONS CP0+ - CP0- = 100 mV CP0+ - CP0- = -100 mV CP0+ - CP0- = 100 mV CP0+ - CP0- = -100 mV CP0+ - CP0- = 100 mV CP0+ - CP0- = -100 mV CP0+ - CP0- = 100 mV CP0+ - CP0- = -100 mV CP0HYP1-0 = 00 CP0HYP1-0 = 01 CP0HYP1-0 = 10 CP0HYP1-0 = 11 CP0HYN1-0 = 00 CP0HYN1-0 = 01 CP0HYN1-0 = 10 CP0HYN1-0 = 11
MIN
TYP 100 250 175 500 320 1100 1050 5200 1.5 0
MAX
UNITS ns ns ns ns ns ns ns ns
4 1 7 13 25 1 7 13 25 VDD + 0.25
mV/V mV mV mV mV mV mV mV mV V pF nA
2 5 12 2 5 12 -0.25
5 10 20 0 5 10 20
7 0.001 -5 0.1 10 7.6 3.2 1.3 0.4 20 10 5 2.5 +5 1
mV mV/V s A A A A
Vcm is the common-mode voltage on CP0+ and CP0-. by design and/or characterization.
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8.
CIP-51 MICROCONTROLLER
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the MCS-51TM instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The MCU family has a superset of all the peripherals included with a standard 8051. Included are four 16-bit counter/timers (see description in Section 17), an enhanced full-duplex UART (see description in Section 15), an Enhanced SPI (see description in Section 16), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (Section 8.2.6), and 29 Port I/O (see description in Section 13). The CIP-51 also includes on-chip debug hardware (see description in Section 20), and interfaces directly with the analog and digital subsystems providing a complete data acquisition or control-system solution in a single integrated circuit. The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as additional custom peripherals and functions to extend its capability (see Figure 8.1 for a block diagram). The CIP-51 includes the following features: Fully Compatible with MCS-51 Instruction Set 25 MIPS Peak Throughput with 25 MHz Clock 0 to 25 MHz Clock Frequency 256 Bytes of Internal RAM 29 Port I/O Extended Interrupt Handler Reset Input Power Management Modes On-chip Debug Logic Program and Data Memory Security
Figure 8.1. CIP-51 Block Diagram
DATA BUS
D8 D8 D8 D8 D8
ACCUMULATOR
B REGISTER
STACK POINTER
DATA BUS
TMP1
TMP2
PSW
ALU
D8 D8
SRAM ADDRESS REGISTER
D8
SRAM (256 X 8)
D8
DATA BUS
SFR_ADDRESS BUFFER
D8
DATA POINTER
D8 D8
SFR BUS INTERFACE
SFR_CONTROL SFR_WRITE_DATA SFR_READ_DATA
PC INCREMENTER
DATA BUS
PROGRAM COUNTER (PC)
D8
MEM_ADDRESS MEM_CONTROL
PRGM. ADDRESS REG.
A16
MEMORY INTERFACE
MEM_WRITE_DATA MEM_READ_DATA
PIPELINE RESET CLOCK STOP IDLE POWER CONTROL REGISTER
D8
D8
CONTROL LOGIC INTERRUPT INTERFACE
SYSTEM_IRQs EMULATION_IRQ
D8
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Performance The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more than eight system clock cycles. With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute Number of Instructions 1 26 2 50 2/3 5 3 14 3/4 7 4 3 4/5 1 5 2 8 1
Programming and Debugging Support In-system programming of the FLASH program memory and communication with on-chip debug support logic is accomplished via the Cygnal 2-Wire Development Interface (C2). Note that the re-programmable FLASH can also be read and changed a single byte at a time by the application software using the MOVC and MOVX instructions. This feature allows program memory to be used for non-volatile data storage as well as updating program code under software control. The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware breakpoints, starting, stopping and single stepping through program execution (including interrupt service routines), examination of the program's call stack, and reading/writing the contents of registers and memory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or other on-chip resources. C2 details can be found in Section "20. C2 Interface" on page 201. The CIP-51 is supported by development tools from Cygnal Integrated Products and third party vendors. Cygnal provides an integrated development environment (IDE) including editor, macro assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient in-system device programming and debugging. Third party macro assemblers and C compilers are also available.
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8.1.
INSTRUCTION SET
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51TM instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51 instructions are the binary and functional equivalent of their MCS-51TM counterparts, including opcodes, addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051.
8.1.1.
Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based solely on clock cycle timing. All instruction timings are specified in terms of clock cycles. Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 8.1 is the CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock cycles for each instruction.
8.1.2.
MOVX Instruction and Program Memory
The MOVX instruction is typically used to access external data memory (Note: the C8051F310/1 does not support external data or program memory). In the CIP-51, the MOVX write instruction is used to accesses external RAM and the on-chip program memory space implemented as re-programmable FLASH memory. The FLASH access feature provides a mechanism for the CIP-51 to update program code and use the program memory space for non-volatile data storage. Refer to Section "10. FLASH Memory" on page 95 for further details.
Table 8.1. CIP-51 Instruction Set Summary
Mnemonic ADD A, Rn ADD A, direct ADD A, @Ri ADD A, #data ADDC A, Rn ADDC A, direct ADDC A, @Ri ADDC A, #data SUBB A, Rn SUBB A, direct SUBB A, @Ri SUBB A, #data INC A INC Rn INC direct INC @Ri DEC A DEC Rn DEC direct DEC @Ri INC DPTR Description ARITHMETIC OPERATIONS Add register to A Add direct byte to A Add indirect RAM to A Add immediate to A Add register to A with carry Add direct byte to A with carry Add indirect RAM to A with carry Add immediate to A with carry Subtract register from A with borrow Subtract direct byte from A with borrow Subtract indirect RAM from A with borrow Subtract immediate from A with borrow Increment A Increment register Increment direct byte Increment indirect RAM Decrement A Decrement register Decrement direct byte Decrement indirect RAM Increment Data Pointer Bytes 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 1 1 2 1 1 Clock Cycles 1 2 2 2 1 2 2 2 1 2 2 2 1 1 2 2 1 1 2 2 1
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Table 8.1. CIP-51 Instruction Set Summary
Mnemonic MUL AB DIV AB DA A ANL A, Rn ANL A, direct ANL A, @Ri ANL A, #data ANL direct, A ANL direct, #data ORL A, Rn ORL A, direct ORL A, @Ri ORL A, #data ORL direct, A ORL direct, #data XRL A, Rn XRL A, direct XRL A, @Ri XRL A, #data XRL direct, A XRL direct, #data CLR A CPL A RL A RLC A RR A RRC A SWAP A MOV A, Rn MOV A, direct MOV A, @Ri MOV A, #data MOV Rn, A MOV Rn, direct MOV Rn, #data MOV direct, A MOV direct, Rn MOV direct, direct MOV direct, @Ri MOV direct, #data MOV @Ri, A MOV @Ri, direct MOV @Ri, #data Description Multiply A and B Divide A by B Decimal adjust A LOGICAL OPERATIONS AND Register to A AND direct byte to A AND indirect RAM to A AND immediate to A AND A to direct byte AND immediate to direct byte OR Register to A OR direct byte to A OR indirect RAM to A OR immediate to A OR A to direct byte OR immediate to direct byte Exclusive-OR Register to A Exclusive-OR direct byte to A Exclusive-OR indirect RAM to A Exclusive-OR immediate to A Exclusive-OR A to direct byte Exclusive-OR immediate to direct byte Clear A Complement A Rotate A left Rotate A left through Carry Rotate A right Rotate A right through Carry Swap nibbles of A DATA TRANSFER Move Register to A Move direct byte to A Move indirect RAM to A Move immediate to A Move A to Register Move direct byte to Register Move immediate to Register Move A to direct byte Move Register to direct byte Move direct byte to direct byte Move indirect RAM to direct byte Move immediate to direct byte Move A to indirect RAM Move direct byte to indirect RAM Move immediate to indirect RAM Bytes 1 1 1 1 2 1 2 2 3 1 2 1 2 2 3 1 2 1 2 2 3 1 1 1 1 1 1 1 1 2 1 2 1 2 2 2 2 3 2 3 1 2 2 Clock Cycles 4 8 1 1 2 2 2 2 3 1 2 2 2 2 3 1 2 2 2 2 3 1 1 1 1 1 1 1 1 2 2 2 1 2 2 2 2 3 2 3 2 2 2
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Table 8.1. CIP-51 Instruction Set Summary
Mnemonic MOV DPTR, #data16 MOVC A, @A+DPTR MOVC A, @A+PC MOVX A, @Ri MOVX @Ri, A MOVX A, @DPTR MOVX @DPTR, A PUSH direct POP direct XCH A, Rn XCH A, direct XCH A, @Ri XCHD A, @Ri CLR C CLR bit SETB C SETB bit CPL C CPL bit ANL C, bit ANL C, /bit ORL C, bit ORL C, /bit MOV C, bit MOV bit, C JC rel JNC rel JB bit, rel JNB bit, rel JBC bit, rel ACALL addr11 LCALL addr16 RET RETI AJMP addr11 LJMP addr16 SJMP rel JMP @A+DPTR JZ rel JNZ rel CJNE A, direct, rel CJNE A, #data, rel CJNE Rn, #data, rel Description Load DPTR with 16-bit constant Move code byte relative DPTR to A Move code byte relative PC to A Move external data (8-bit address) to A Move A to external data (8-bit address) Move external data (16-bit address) to A Move A to external data (16-bit address) Push direct byte onto stack Pop direct byte from stack Exchange Register with A Exchange direct byte with A Exchange indirect RAM with A Exchange low nibble of indirect RAM with A BOOLEAN MANIPULATION Clear Carry Clear direct bit Set Carry Set direct bit Complement Carry Complement direct bit AND direct bit to Carry AND complement of direct bit to Carry OR direct bit to carry OR complement of direct bit to Carry Move direct bit to Carry Move Carry to direct bit Jump if Carry is set Jump if Carry is not set Jump if direct bit is set Jump if direct bit is not set Jump if direct bit is set and clear bit PROGRAM BRANCHING Absolute subroutine call Long subroutine call Return from subroutine Return from interrupt Absolute jump Long jump Short jump (relative address) Jump indirect relative to DPTR Jump if A equals zero Jump if A does not equal zero Compare direct byte to A and jump if not equal Compare immediate to A and jump if not equal Compare immediate to Register and jump if not equal Bytes 3 1 1 1 1 1 1 2 2 1 2 1 1 1 2 1 2 1 2 2 2 2 2 2 2 2 2 3 3 3 2 3 1 1 2 3 2 1 2 2 3 3 3 Clock Cycles 3 3 3 3 3 3 3 2 2 1 2 2 2 1 2 1 2 1 2 2 2 2 2 2 2 2/3 2/3 3/4 3/4 3/4 3 4 5 5 3 4 3 3 2/3 2/3 3/4 3/4 3/4
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Table 8.1. CIP-51 Instruction Set Summary
Mnemonic CJNE @Ri, #data, rel DJNZ Rn, rel DJNZ direct, rel NOP Description Compare immediate to indirect and jump if not equal Decrement Register and jump if not zero Decrement direct byte and jump if not zero No operation Bytes 3 2 3 1 Clock Cycles 4/5 2/3 3/4 1
Notes on Registers, Operands and Addressing Modes: Rn - Register R0-R7 of the currently selected register bank. @Ri - Data RAM location addressed indirectly through R0 or R1. rel - 8-bit, signed (two's complement) offset relative to the first byte of the following instruction. Used by SJMP and all conditional jumps. direct - 8-bit internal data location's address. This could be a direct-access Data RAM location (0x00-0x7F) or an SFR (0x80-0xFF). #data - 8-bit constant #data16 - 16-bit constant bit - Direct-accessed bit in Data RAM or SFR addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same 2K-byte page of program memory as the first byte of the following instruction. addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within the 8Kbyte program memory space. There is one unused opcode (0xA5) that performs the same function as NOP. All mnemonics copyrighted (c) Intel Corporation 1980.
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8.2.
MEMORY ORGANIZATION
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same address space but are accessed via different instruction types. The CIP-51 memory organization is shown in Figure 8.2.
Figure 8.2. Memory Map
PROGRAM/DATA MEMORY (FLASH)
0xFF 0x3E00 0x3DFF RESERVED 0x80 0x7F
DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE
Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) Special Function Register's (Direct Addressing Only)
16K FLASH (In-System Programmable in 512 Byte Sectors)
0x30 0x2F 0x20 0x1F 0x00
Bit Addressable General Purpose Registers
Lower 128 RAM (Direct and Indirect Addressing)
EXTERNAL DATA ADDRESS SPACE
0x0000 0xFFFF
Same 1024 bytes as from 0x0000 to 0x03FF, wrapped on 1K-byte boundaries
0x0400 0x03FF 0x0000
XRAM - 1024 Bytes
(accessable using MOVX instruction)
8.2.1.
Program Memory
The CIP-51 core has a 64k-byte program memory space. The C8051F310/1 implements 16k bytes of this program memory space as in-system, re-programmable FLASH memory, organized in a contiguous block from addresses 0x0000 to 0x3FFF. Addresses above 0x3E00 are reserved. Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for non-volatile data storage. Refer to Section "10. FLASH Memory" on page 95 for further details.
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8.2.2. Data Memory
Preliminary
The CIP-51 includes 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (SFR) but is physically separate from the SFR space. The addressing mode used by an instruction when accessing locations above 0x7F determines whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the upper 128 bytes of data memory. Figure 8.2 illustrates the data memory organization of the CIP-51.
8.2.3.
General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1 (PSW.4), select the active register bank (see description of the PSW in Figure 8.6). This allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes use registers R0 and R1 as index registers.
8.2.4.
Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20 through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from 0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or destination). The MCS-51TM assembly language allows an alternate notation for bit addressing of the form XX.B where XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
8.2.5.
Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be initialized to a location in the data memory not being used for data storage. The stack depth can extend up to 256 bytes.
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8.2.6.
Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers (SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new functionality while retaining compatibility with the MCS-51TM instruction set. Table 8.2 lists the SFRs implemented in the CIP-51 System Controller. The SFR registers are accessed anytime the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are bit-addressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 8.3, for a detailed description of each register.
Table 8.2. Special Function Register (SFR) Memory Map
F8 F0 E8 E0 D8 D0 C8 C0 B8 B0 A8 A0 98 90 88 80 SPI0CN B ADC0CN ACC PCA0CN PSW TMR2CN SMB0CN IP P3 IE P2 SCON0 P1 TCON P0 0(8)
(bit addressable)
PCA0L PCA0H PCA0CPL0 P0MDIN P1MDIN P2MDIN PCA0CPL1 PCA0CPH1 PCA0CPL2 XBR0 XBR1 PCA0MD PCA0CPM0 PCA0CPM1 REF0CN TMR2RLL TMR2RLH SMB0CF SMB0DAT ADC0GTL AMX0N AMX0P OSCXCN OSCICN OSCICL CLKSEL EMI0CN SPI0CFG SPI0CKR SPI0DAT SBUF0 CPT1CN CPT0CN TMR3CN TMR3RLL TMR3RLH TMOD TL0 TL1 SP DPL DPH 1(9) 2(A) 3(B)
PCA0CPH0 P3MDIN PCA0CPH2 IT01CF PCA0CPM2 P0SKIP TMR2L ADC0GTH ADC0CF
PCA0CPL4 PCA0CPH4 EIP1 PCA0CPL3 PCA0CPH3 EIE1 PCA0CPM3 PCA0CPM4 P1SKIP P2SKIP TMR2H ADC0LTL ADC0LTH ADC0L ADC0H FLSCL
VDM0CN RSTSRC
FLKEY P3MDOUT CPT0MX PSCTL PCON 7(F)
P0MDOUT P1MDOUT P2MDOUT CPT1MD CPT0MD CPT1MX TMR3L TMR3H TH0 TH1 CKCON 4(C) 5(D) 6(E)
Table 8.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved Register Address Description ACC 0xE0 Accumulator ADC0CF 0xBC ADC0 Configuration ADC0CN 0xE8 ADC0 Control ADC0GTH 0xC4 ADC0 Greater-Than Compare High ADC0GTL 0xC3 ADC0 Greater-Than Compare Low ADC0H 0xBE ADC0 High ADC0L 0xBD ADC0 Low ADC0LTH 0xC6 ADC0 Less-Than Compare Word High Page 78 44 46 47 47 44 45 48
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Table 8.3. Special Function Registers
Register ADC0LTL AMX0N AMX0P B CKCON CLKSEL CPT0CN CPT0MD CPT0MX CPT1CN CPT1MD CPT1MX DPH DPL EIE1 EIP1 EMI0CN FLKEY FLSCL IE IP IT01CF OSCICL OSCICN OSCXCN P0 P0MDIN P0MDOUT P0SKIP P1 P1MDIN P1MDOUT P1SKIP P2 P2MDIN P2MDOUT P2SKIP P3 P3MDIN P3MDOUT PCA0CN PCA0CPH0 PCA0CPH1 PCA0CPH2 PCA0CPH3 PCA0CPH4 Address 0xC5 0xBA 0xBB 0xF0 0x8E 0xA9 0x9B 0x9D 0x9F 0x9A 0x9C 0x9E 0x83 0x82 0xE6 0xF6 0xAA 0xB7 0xB6 0xA8 0xB8 0xE4 0xB3 0xB2 0xB1 0x80 0xF1 0xA4 0xD4 0x90 0xF2 0xA5 0xD5 0xA0 0xF3 0xA6 0xD6 0xB0 0xF4 0xA7 0xD8 0xFC 0xEA 0xEC 0xEE 0xFE Description ADC0 Less-Than Compare Word Low AMUX0 Negative Channel Select AMUX0 Positive Channel Select B Register Clock Control Clock Select Comparator0 Control Comparator0 Mode Selection Comparator0 MUX Selection Comparator1 Control Comparator1 Mode Selection Comparator1 MUX Selection Data Pointer High Data Pointer Low Extended Interrupt Enable 1 Extended Interrupt Priority 1 External Memory Interface Control FLASH Lock and Key FLASH Scale Interrupt Enable Interrupt Priority INT0/INT1 Configuration Internal Oscillator Calibration Internal Oscillator Control External Oscillator Control Port 0 Latch Port 0 Input Mode Configuration Port 0 Output Mode Configuration Port 0 Skip Port 1 Latch Port 1 Input Mode Configuration Port 1 Output Mode Configuration Port 1 Skip Port 2 Latch Port 2 Input Mode Configuration Port 2 Output Mode Configuration Port 2 Skip Port 3 Latch Port 3 Input Mode Configuration Port 3 Output Mode Configuration PCA Control PCA Capture 0 High PCA Capture 1 High PCA Capture 2 High PCA Capture 3High PCA Capture 4 High Page No. 48 43 42 78 173 105 58 60 59 61 63 62 76 76 84 85 101 99 99 82 83 86 104 104 107 117 117 118 118 119 119 120 120 121 121 122 122 123 123 124 194 198 198 198 198 198
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Table 8.3. Special Function Registers
Register PCA0CPL0 PCA0CPL1 PCA0CPL2 PCA0CPL3 PCA0CPL4 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0H PCA0L PCA0MD PCON PSCTL PSW REF0CN RSTSRC SBUF0 SCON0 SMB0CF SMB0CN SMB0DAT SP SPI0CFG SPI0CKR SPI0CN SPI0DAT TCON TH0 TH1 TL0 TL1 TMOD TMR2CN TMR2H TMR2L TMR2RLH TMR2RLL TMR3CN TMR3H TMR3L TMR3RLH TMR3RLL VDM0CN Address 0xFB 0xE9 0xEB 0xED 0xFD 0xDA 0xDB 0xDC 0xDD 0xDE 0xFA 0xF9 0xD9 0x87 0x8F 0xD0 0xD1 0xEF 0x99 0x98 0xC1 0xC0 0xC2 0x81 0xA1 0xA2 0xF8 0xA3 0x88 0x8C 0x8D 0x8A 0x8B 0x89 0xC8 0xCD 0xCC 0xCB 0xCA 0x91 0x95 0x94 0x93 0x92 0xFF Description PCA Capture 0 Low PCA Capture 1 Low PCA Capture 2 Low PCA Capture 3Low PCA Capture 4 Low PCA Module 0 Mode Register PCA Module 1 Mode Register PCA Module 2 Mode Register PCA Module 3 Mode Register PCA Module 4 Mode Register PCA Counter High PCA Counter Low PCA Mode Power Control Program Store R/W Control Program Status Word Voltage Reference Control Reset Source Configuration/Status UART0 Data Buffer UART0 Control SMBus Configuration SMBus Control SMBus Data Stack Pointer SPI Configuration SPI Clock Rate Control SPI Control SPI Data Timer/Counter Control Timer/Counter 0 High Timer/Counter 1 High Timer/Counter 0 Low Timer/Counter 1 Low Timer/Counter Mode Timer/Counter 2 Control Timer/Counter 2 High Timer/Counter 2 Low Timer/Counter 2 Reload High Timer/Counter 2 Reload Low Timer/Counter 3Control Timer/Counter 3 High Timer/Counter 3Low Timer/Counter 3 Reload High Timer/Counter 3 Reload Low VDD Monitor Control Page No. 198 198 198 198 198 196 196 196 196 196 197 197 195 88 98 77 54 93 149 148 132 134 136 77 160 162 161 163 171 174 174 174 174 172 177 178 178 178 178 181 182 182 182 182 91
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Table 8.3. Special Function Registers
Register Address XBR1 0xE2 XBR0 0xE1 0x84-0x86, 0x96-0x97, 0xAB0xAF, 0xB4, 0xB9, 0xBF, 0xC7, 0xC9, 0xCE, 0xCF, 0xD2, 0xD3, 0xD7, 0xDF, 0xE3, 0xE5, 0xF5 Description Port I/O Crossbar Control 1 Port I/O Crossbar Control 0 Page No. 115 114
Reserved
8.2.7.
Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits should not be set to logic l. Future product versions may use these bits to implement new features in which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sections of the datasheet associated with their corresponding system function.
Figure 8.3. DPL: Data Pointer Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x82 Bits7-0: DPL: Data Pointer Low. The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly addressed FLASH memory.
Figure 8.4. DPH: Data Pointer High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x83 Bits7-0: DPH: Data Pointer High. The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly addressed FLASH memory.
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Figure 8.5. SP: Stack Pointer
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000111
SFR Address:
0x81 Bits7-0: SP: Stack Pointer. The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented before every PUSH operation. The SP register defaults to 0x07 after reset.
Figure 8.6. PSW: Program Status Word
R/W R/W R/W R/W R/W R/W R/W R Reset Value
CY
Bit7
AC
Bit6
F0
Bit5
RS1
Bit4
RS0
Bit3
OV
Bit2
F1
Bit1
PARITY
Bit0 (bit addressable)
00000000
SFR Address:
0xD0
Bit7:
Bit6:
Bit5: Bits4-3:
CY: Carry Flag. This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow (subtraction). It is cleared to logic 0 by all other arithmetic operations. AC: Auxiliary Carry Flag This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow from (subtraction) the high order nibble. It is cleared to logic 0 by all other arithmetic operations. F0: User Flag 0. This is a bit-addressable, general purpose flag for use under software control. RS1-RS0: Register Bank Select. These bits select which register bank is used during register accesses. RS1 0 0 1 1 RS0 0 1 0 1 Register Bank 0 1 2 3 Address 0x00 - 0x07 0x08 - 0x0F 0x10 - 0x17 0x18 - 0x1F
Bit2:
Bit1: Bit0:
OV: Overflow Flag. This bit is set to logic 1 if the last arithmetic operation resulted in a carry (addition), borrow (subtraction), or overflow (multiply or divide). It is cleared to logic 0 by all other arithmetic operations. F1: User Flag 1. This is a bit-addressable, general purpose flag for use under software control. PARITY: Parity Flag. This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum is even.
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Figure 8.7. ACC: Accumulator
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ACC.7
Bit7
ACC.6
Bit6
ACC.5
Bit5
ACC.4
Bit4
ACC.3
Bit3
ACC.2
Bit2
ACC.1
Bit1
ACC.0
Bit0 (bit addressable)
00000000
SFR Address:
0xE0
Bits7-0:
ACC: Accumulator. This register is the accumulator for arithmetic operations.
Figure 8.8. B: B Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
B.7
Bit7
B.6
Bit6
B.5
Bit5
B.4
Bit4
B.3
Bit3
B.2
Bit2
B.1
Bit1
B.0
Bit0 (bit addressable)
00000000
SFR Address:
0xF0
Bits7-0:
B: B Register. This register serves as a second accumulator for certain arithmetic operations.
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8.3.
Interrupt Handler
The CIP-51 includes an extended interrupt system supporting a total of 14 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1. If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI instruction, which returns program execution to the next instruction that would have been executed if the interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.) Each interrupt source can be individually enabled or disabled through the use of an associated interrupt enable bit in an SFR (IE-EIE1). However, interrupts must first be globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-enable settings. Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interruptpending flag remains set after the CPU completes the return-from-interrupt (RETI) instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction.
8.3.1.
MCU Interrupt Sources and Vectors
The MCUs support 14 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 8.4 on page 81. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
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8.3.2. External Interrupts
Preliminary
The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or active low; the IT0 and IT1 bits in TCON (Section "17.1. Timer 0 and Timer 1" on page 167) select level or edge sensitive. The table below lists the possible configurations. IT0 1 1 0 0 IN0PL 0 1 0 1 /INT0 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive IT1 1 1 0 0 IN1PL 0 1 0 1 /INT1 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive
/INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see Figure 8.13). Note that /INT0 and /INT0 Port pin assignments are independent of any Crossbar assignments. /INT0 and /INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section "13.1. Priority Crossbar Decoder" on page 111 for complete details on configuring the Crossbar). IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the /INT0 and /INT1 external interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interruptpending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It must then deactivate the interrupt request before execution of the ISR completes or another interrupt request will be generated.
8.3.3.
Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is used to arbitrate, given in Table 8.4.
8.3.4.
Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is 18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction.
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Table 8.4. Interrupt Summary
Cleared by HW? Bit addressable?
Interrupt Source
Interrupt Vector
Priority Pending Flag Order
Enable Flag
Priority Control
Reset External Interrupt 0 (/INT0) Timer 0 Overflow External Interrupt 1 (/INT1) Timer 1 Overflow UART0
0x0000 0x0003 0x000B 0x0013 0x001B 0x0023
Top 0 1 2 3 4
None IE0 (TCON.1) TF0 (TCON.5) IE1 (TCON.3) TF1 (TCON.7) RI0 (SCON0.0) TI0 (SCON0.1) TF2H (TMR2CN.7) TF2L (TMR2CN.6) SPIF (SPI0CN.7) WCOL (SPI0CN.6) MODF (SPI0CN.5) RXOVRN (SPI0CN.4) SI (SMB0CN.0)
N/A N/A Y Y Y Y Y Y Y Y Y N
Always Enabled EX0 (IE.0) ET0 (IE.1) EX1 (IE.2) ET1 (IE.3) ES0 (IE.4)
Always Highest PX0 (IP.0) PT0 (IP.1) PX1 (IP.2) PT1 (IP.3) PS0 (IP.4)
Timer 2 Overflow
0x002B
5
Y
N
ET2 (IE.5)
PT2 (IP.5)
SPI0
0x0033
6
Y
N
ESPI0 (IE.6)
PSPI0 (IP.6)
SMB0 RESERVED ADC0 Window Compare ADC0 Conversion Complete Programmable Counter Array
0x003B 0x0043 0x004B 0x0053 0x005B
7 8 9 10 11
Y
Comparator0
0x0063
12
Comparator1
0x006B
13
Timer 3 Overflow
0x0073
14
N/A N/A AD0WINT Y (ADC0CN.3) AD0INT Y (ADC0CN.5) CF (PCA0CN.7) Y CCFn (PCA0CN.n) CP0FIF (CPT0CN.4) N CP0RIF (CPT0CN.5) CP1FIF (CPT1CN.4) N CP1RIF (CPT1CN.5) TF3H (TMR3CN.7) N TF3L (TMR3CN.6)
ESMB0 (EIE1.0) N/A N/A EWADC0 N (EIE1.2) EADC0 N (EIE1.3) EPCA0 N (EIE1.4) N N ECP0 (EIE1.5)
PSMB0 (EIP1.0) N/A PWADC0 (EIP1.2) PADC0 (EIP1.3) PPCA0 (EIP1.4) PCP0 (EIP1.5)
N
ECP1 (EIE1.6)
PCP1 (EIP1.6)
N
ET3 (EIE1.7)
PT3 (EIP1.7)
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8.3.5. Interrupt Register Descriptions
Preliminary
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
Figure 8.9. IE: Interrupt Enable
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EA
Bit7
ESPI0
Bit6
ET2
Bit5
ES0
Bit4
ET1
Bit3
EX1
Bit2
ET0
Bit1
EX0
Bit0 (bit addressable)
00000000
SFR Address:
0xA8
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
EA: Enable All Interrupts. This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings. 0: Disable all interrupt sources. 1: Enable each interrupt according to its individual mask setting. ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of the SPI0 interrupts. 0: Disable all SPI0 interrupts. 1: Enable interrupt requests generated by SPI0. ET2: Enable Timer 2 Interrupt. This bit sets the masking of the Timer 2 interrupt. 0: Disable Timer 2 interrupt. 1: Enable interrupt requests generated by the TF2L or TF2H flags. ES0: Enable UART0 Interrupt. This bit sets the masking of the UART0 interrupt. 0: Disable UART0 interrupt. 1: Enable UART0 interrupt. ET1: Enable Timer 1 Interrupt. This bit sets the masking of the Timer 1 interrupt. 0: Disable all Timer 1 interrupt. 1: Enable interrupt requests generated by the TF1 flag. EX1: Enable External Interrupt 1. This bit sets the masking of External Interrupt 1. 0: Disable external interrupt 1. 1: Enable interrupt requests generated by the /INT1 input. ET0: Enable Timer 0 Interrupt. This bit sets the masking of the Timer 0 interrupt. 0: Disable all Timer 0 interrupt. 1: Enable interrupt requests generated by the TF0 flag. EX0: Enable External Interrupt 0. This bit sets the masking of External Interrupt 0. 0: Disable external interrupt 0. 1: Enable interrupt requests generated by the /INT0 input.
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Figure 8.10. IP: Interrupt Priority
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
PSPI0
Bit6
PT2
Bit5
PS0
Bit4
PT1
Bit3
PX1
Bit2
PT0
Bit1
PX0
Bit0 (bit addressable)
10000000
SFR Address:
0xB8
Bit7: Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 1, Write = don't care. PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control. This bit sets the priority of the SPI0 interrupt. 0: SPI0 interrupt set to low priority level. 1: SPI0 interrupt set to high priority level. PT2: Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupt priority determined by default priority order. 1: Timer 2 interrupts set to high priority level. PS0: UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupt priority determined by default priority order. 1: UART0 interrupts set to high priority level. PT1: Timer 1 Interrupt Priority Control. This bit sets the priority of the Timer 1 interrupt. 0: Timer 1 interrupt priority determined by default priority order. 1: Timer 1 interrupts set to high priority level. PX1: External Interrupt 1 Priority Control. This bit sets the priority of the External Interrupt 1 interrupt. 0: External Interrupt 1 priority determined by default priority order. 1: External Interrupt 1 set to high priority level. PT0: Timer 0 Interrupt Priority Control. This bit sets the priority of the Timer 0 interrupt. 0: Timer 0 interrupt priority determined by default priority order. 1: Timer 0 interrupt set to high priority level. PX0: External Interrupt 0 Priority Control. This bit sets the priority of the External Interrupt 0 interrupt. 0: External Interrupt 0 priority determined by default priority order. 1: External Interrupt 0 set to high priority level.
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Figure 8.11. EIE1: Extended Interrupt Enable 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ET3
Bit7
ECP1
Bit6
ECP0
Bit5
EPCA0
Bit4
EADC0
Bit3
EWADC0
Bit2
Reserved
Bit1
ESMB0
Bit0
00000000
SFR Address:
0xE6 Bit7: ET3: Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable Timer 3 interrupts. 1: Enable interrupt requests generated by the TF3L or TF3H flags. ECP1: Enable Comparator1 (CP1) Interrupt. This bit sets the masking of the CP1 interrupt. 0: Disable CP1 interrupts. 1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags. ECP0: Enable Comparator0 (CP0) Interrupt. This bit sets the masking of the CP0 interrupt. 0: Disable CP0 interrupts. 1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags. EPCA0: Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable all PCA0 interrupts. 1: Enable interrupt requests generated by PCA0. EADC0: Enable ADC0 Conversion Complete Interrupt. This bit sets the masking of the ADC0 Conversion Complete interrupt. 0: Disable ADC0 Conversion Complete interrupt. 1: Enable interrupt requests generated by the AD0INT flag. EWADC0: Enable Window Comparison ADC0 Interrupt. This bit sets the masking of ADC0 Window Comparison interrupt. 0: Disable ADC0 Window Comparison interrupt. 1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT). RESERVED. Read = 0. Must Write 0. ESMB0: Enable SMBus (SMB0) Interrupt. This bit sets the masking of the SMB0 interrupt. 0: Disable all SMB0 interrupts. 1: Enable interrupt requests generated by SMB0.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1: Bit0:
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Figure 8.12. EIP1: Extended Interrupt Priority 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PT3
Bit7
PCP1
Bit6
PCP0F
Bit5
PPCA0
Bit4
PADC0
Bit3
PWADC0
Bit2
Reserved
Bit1
PSMB0
Bit0
00000000
SFR Address:
0xF6 Bit7: PT3: Timer 3 Interrupt Priority Control. This bit sets the priority of the Timer 3 interrupt. 0: Timer 3 interrupts set to low priority level. 1: Timer 3 interrupts set to high priority level. PCP1: Comparator1 (CP1) Interrupt Priority Control. This bit sets the priority of the CP1 interrupt. 0: CP1 interrupt set to low priority level. 1: CP1 interrupt set to high priority level. PCP0: Comparator0 (CP0) Interrupt Priority Control. This bit sets the priority of the CP0 interrupt. 0: CP0 interrupt set to low priority level. 1: CP0 interrupt set to high priority level. PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control. This bit sets the priority of the PCA0 interrupt. 0: PCA0 interrupt set to low priority level. 1: PCA0 interrupt set to high priority level. PADC0 ADC0 Conversion Complete Interrupt Priority Control. This bit sets the priority of the ADC0 Conversion Complete interrupt. 0: ADC0 Conversion Complete interrupt set to low priority level. 1: ADC0 Conversion Complete interrupt set to high priority level. PWADC0: ADC0 Window Comparator Interrupt Priority Control. This bit sets the priority of the ADC0 Window interrupt. 0: ADC0 Window interrupt set to low priority level. 1: ADC0 Window interrupt set to high priority level. RESERVED. Read = 0. Must Write 0. PSMB0: SMBus (SMB0) Interrupt Priority Control. This bit sets the priority of the SMB0 interrupt. 0: SMB0 interrupt set to low priority level. 1: SMB0 interrupt set to high priority level.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1: Bit0:
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Figure 8.13. IT01CF: INT0/INT1 Configuration Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
IN1PL
Bit7
IN1SL2
Bit6
IN1SL1
Bit5
IN1SL0
Bit4
IN0PL
Bit3
IN0SL2
Bit2
IN0SL1
Bit1
IN0SL0
Bit0
00000001
SFR Address:
0xE4 Note: Refer to Figure 17.4 for INT0/1 edge- or level-sensitive interrupt selection. Bit7: IN1PL: /INT1 Polarity 0: /INT1 input is active low. 1: /INT1 input is active high. IN1SL2-0: /INT1 Port Pin Selection Bits These bits select which Port pin is assigned to /INT1. Note that this pin assignment is independent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to `1' the corresponding bit in register P0SKIP). IN1SL2-0 000 001 010 011 100 101 110 111 Bit3: /INT1 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7
Bits6-4:
Bits2-0:
IN0PL: /INT0 Polarity 0: /INT0 interrupt is active low. 1: /INT0 interrupt is active high. INT0SL2-0: /INT0 Port Pin Selection Bits These bits select which Port pin is assigned to /INT0. Note that this pin assignment is independent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to `1' the corresponding bit in register P0SKIP). IN0SL2-0 000 001 010 011 100 101 110 111 /INT0 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7
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8.4.
Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states; the external oscillator is not effected). Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the least power. Figure 1.15 describes the Power Control Register (PCON) used to control the CIP-51's power management modes. Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power management of the entire MCU is better accomplished by enabling/disabling individual peripherals as needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off the oscillators lowers power consumption considerably; however a reset is required to restart the MCU.
8.4.1.
Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon as the instruction that sets the bit completes execution. All internal registers and memory maintain their original data. All analog and digital peripherals can remain active during Idle mode. Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The pending interrupt will be serviced and the next instruction to be executed after the return from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. Refer to Section "9.6. PCA Watchdog Timer Reset" on page 92 for more information on the use and configuration of the WDT.
8.4.2.
Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset sequence and begins program execution at address 0x0000. If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode. The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the MCD timeout of 100 sec.
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Figure 8.14. PCON: Power Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
GF5
Bit7
GF4
Bit6
GF3
Bit5
GF2
Bit4
GF1
Bit3
GF0
Bit2
STOP
Bit1
IDLE
Bit0
00000000
SFR Address:
0x87 Bits7-2: Bit1: GF5-GF0: General Purpose Flags 5-0. These are general purpose flags for use under software control. STOP: Stop Mode Select. Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0. 1: CPU goes into Stop mode (internal oscillator stopped). IDLE: Idle Mode Select. Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0. 1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial Ports, and Analog Peripherals are still active.)
Bit0:
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9.
RESET SOURCES
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this reset state, the following occur: * * * * CIP-51 halts program execution Special Function Registers (SFRs) are initialized to their defined reset values External Port pins are forced to a known state Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal data memory are unaffected during a reset; any previously stored data is preserved. However, since the stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered. The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pull-ups are enabled during and after the reset. For VDD Monitor and power-on resets, the /RST pin is driven low until the device exits the reset state. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section "12. Oscillators" on page 103 for information on selecting and configuring the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock source (Section "18.3. Watchdog Timer Mode" on page 192 details the use of the Watchdog Timer). Program execution begins at location 0x0000.
Figure 9.1. Reset Sources
VDD
Power On Reset
Supply Monitor Px.x Px.x Comparator 0
+ C0RSEF
+ -
Enable
'0' (wired-OR)
/RST
Missing Clock Detector (oneshot)
EN
Reset Funnel
PCA WDT (Software Reset)
SWRSF
EN
System Clock
MCD Enable
CIP-51 Microcontroller Core
Extended Interrupt Handler
WDT Enable
Errant FLASH Operation
System Reset
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9.1. Power-On Reset
Preliminary
During power-up, the device is held in a reset state and the /RST pin is driven low until VDD settles above VRST. A delay occurs before the device is released from reset; the delay decreases as the VDD ramp time increases (VDD ramp time is defined as how fast VDD ramps from 0 V to VRST). Figure 9.2. plots the power-on and VDD monitor reset timing. The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to be released from reset before VDD reaches the VRST level. For ramp times less than 1 ms, the power-on reset delay (TPORDelay) is typically less than 0.3 ms. On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other resets). Since all resets cause program execution to begin at the same location (0x0000) software can read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data memory should be assumed to be undefined after a power-on reset. The VDD monitor is enabled following a power-on reset.
Figure 9.2. Power-On and VDD Monitor Reset Timing
volts VDD VRST
2.70 2.55 2.0
1.0
VD D
t
Logic HIGH
/RST
Logic LOW
TPORDelay VDD Monitor Reset
Power-On Reset
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9.2.
Power-Fail Reset / VDD Monitor
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply monitor will drive the /RST pin low and hold the CIP-51 in a reset state (see Figure 9.2). When VDD returns to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below the level required for data retention. If the PORSF flag reads `1', the data may no longer be valid. The VDD monitor is disabled after power-on resets; however its defined state (enabled/disabled) is not altered by any other reset source. For example, if the VDD monitor is enabled and a software reset is performed, the VDD monitor will still be enabled after the reset. Important Note: The VDD monitor must be enabled before it is selected as a reset source. Selecting the VDD monitor as a reset source before it is enabled and stabilized may cause a system reset. The procedure for configuring the VDD monitor as a reset source is shown below: Step 1. Enable the VDD monitor (VDMEN bit in VDM0CN = `1'). Step 2. Wait for the VDD monitor to stabilize (see Table 9.1 for the VDD Monitor turn-on time). Step 3. Select the VDD monitor as a reset source (PORSF bit in RSTSRC = `1'). See Figure 9.2 for VDD monitor timing; note that the reset delay is not incurred after a VDD monitor reset. See Table 9.1 for complete electrical characteristics of the VDD monitor.
Figure 9.3. VDM0CN: VDD Monitor Control
R/W Bit7 R Bit6 R Bit5 R R R R R Reset Value
VDMEN VDDSTAT Reserved
Reserved
Bit4
Reserved
Bit3
Reserved
Bit2
Reserved
Bit1
Reserved
Bit0
Variable
SFR Address: 0xFF
Bit7:
Bit6:
Bits5-0:
VDMEN: VDD Monitor Enable. This bit is turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system resets until it is also selected as a reset source in register RSTSRC (Figure 9.4). The VDD Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the VDD monitor as a reset source before it has stabilized may generate a system reset. See Table 9.1 for the minimum VDD Monitor turn-on time. 0: VDD Monitor Disabled. 1: VDD Monitor Enabled. VDD STAT: VDD Status. This bit indicates the current power supply status (VDD Monitor output). 0: VDD is at or below the VDD monitor threshold. 1: VDD is above the VDD monitor threshold. Reserved. Read = Variable. Write = don't care.
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9.3. External Reset
Preliminary
The external /RST pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the /RST pin generates a reset; an external pull-up and/or decoupling of the /RST pin may be necessary to avoid erroneous noise-induced resets. See Table 9.1 for complete /RST pin specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
9.4.
Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system clock remains high or low for more than 100 s, the one-shot will time out and generate a reset. After a MCD reset, the MCDRSF flag (RSTSRC.2) will read `1', signifying the MCD as the reset source; otherwise, this bit reads `0'. Writing a `1' to the MCDRSF bit enables the Missing Clock Detector; writing a `0' disables it. The state of the /RST pin is unaffected by this reset.
9.5.
Comparator0 Reset
Comparator0 can be configured as a reset source by writing a `1' to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read `1' signifying Comparator0 as the reset source; otherwise, this bit reads `0'. The state of the /RST pin is unaffected by this reset.
9.6.
PCA Watchdog Timer Reset
The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be used to prevent software from running out of control during a system malfunction. The PCA WDT function can be enabled or disabled by software as described in Section "18.3. Watchdog Timer Mode" on page 192; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to `1'. The state of the /RST pin is unaffected by this reset.
9.7.
FLASH Error Reset
If a FLASH read/write/erase or program read targets an illegal address, a system reset is generated. This may occur due to any of the following: * * * * A FLASH write or erase is attempted above user code space. This occurs when PSWE is set to `1' and a MOVX write operation targets an address above address 0x3DFF. A FLASH read is attempted above user code space. This occurs when a MOVC operation targets an address above address 0x3DFF. A Program read is attempted above user code space. This occurs when user code attempts to branch to an address above 0x3DFF. A FLASH read, write or erase attempt is restricted due to a FLASH security setting (see Section "10.3. Security Options" on page 97).
The FERROR bit (RSTSRC.6) is set following a FLASH error reset. The state of the /RST pin is unaffected by this reset.
9.8.
Software Reset
Software may force a reset by writing a `1' to the SWRSF bit (RSTSRC.4). The SWRSF bit will read `1' following a software forced reset. The state of the /RST pin is unaffected by this reset.
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Figure 9.4. RSTSRC: Reset Source Register
R R R/W R/W R Bit3 R/W Bit2 R/W R Reset Value
Bit7
FERROR
Bit6
C0RSEF
Bit5
SWRSF
Bit4
WDTRSF MCDRSF
PORSF
Bit1
PINRSF
Bit0
Variable
SFR Address: 0xEF
Bit7: Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0. Write = don't care. FERROR: FLASH Error Indicator. 0: Source of last reset was not a FLASH read/write/erase error. 1: Source of last reset was a FLASH read/write/erase error. C0RSEF: Comparator0 Reset Enable and Flag. 0: Read: Source of last reset was not Comparator0. Write: Comparator0 is not a reset source. 1: Read: Source of last reset was Comparator0. Write: Comparator0 is a reset source (active-low). SWRSF: Software Reset Force and Flag. 0: Read: Source of last reset was not a write to the SWRSF bit. Write: No Effect. 1: Read: Source of last was a write to the SWRSF bit. Write: Forces a system reset. WDTRSF: Watchdog Timer Reset Flag. 0: Source of last reset was not a WDT timeout. 1: Source of last reset was a WDT timeout. MCDRSF: Missing Clock Detector Flag. 0: Read: Source of last reset was not a Missing Clock Detector timeout. Write: Missing Clock Detector disabled. 1: Read: Source of last reset was a Missing Clock Detector timeout. Write: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected. PORSF: Power-On Reset Force and Flag. This bit is set anytime a power-on reset occurs. Writing this bit enables/disables the VDD monitor as a reset source. Note: writing `1' to this bit before the VDD monitor is enabled and stabilized may cause a system reset. See register VDM0CN (Figure 9.3) 0: Read: Last reset was not a power-on or VDD monitor reset. Write: VDD monitor is not a reset source. 1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate. Write: VDD monitor is a reset source. PINRSF: HW Pin Reset Flag. 0: Source of last reset was not /RST pin. 1: Source of last reset was /RST pin.
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Table 9.1. Reset Electrical Characteristics
-40C to +85C unless otherwise specified. PARAMETER CONDITIONS IOL = 8.5 mA, VDD = 2.7 V to 3.6 V /RST Output Low Voltage /RST Input High Voltage /RST Input Low Voltage /RST Input Pullup Current VDD POR Threshold (VRST) Missing Clock Detector Timeout Reset Time Delay Minimum /RST Low Time to Generate a System Reset VDD Monitor Turn-on Time VDD Monitor Supply Current /RST = 0.0 V 2.40 Time from last system clock rising edge to reset initiation Delay between release of any reset source and code execution at location 0x0000 100 5.0 15 100 20 50 25 2.55 220 MIN 0.7 x VDD 0.3 x VDD 40 2.70 600 TYP MAX 0.6 UNITS V V
A V s s s s A
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10.
FLASH MEMORY
On-chip, re-programmable FLASH memory is included for program code and non-volatile data storage. The FLASH memory can be programmed in-system, a single byte at a time, through the C2 interface or by software using the MOVX instruction. Once cleared to logic 0, a FLASH bit must be erased to set it back to logic 1. FLASH bytes would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. Code execution is stalled during a FLASH write/erase operation. Refer to Table 10.1 for complete FLASH memory electrical characteristics.
10.1.
Programming The FLASH Memory
The simplest means of programming the FLASH memory is through the C2 interface using programming tools provided by Cygnal or a third party vendor. This is the only means for programming a non-initialized device. For details on the C2 commands to program FLASH memory, see Section "20. C2 Interface" on page 201. To ensure the integrity of FLASH contents, it is strongly recommended that the on-chip VDD Monitor be enabled in any system that includes code that writes and/or erases FLASH memory from software.
10.1.1. FLASH Lock and Key Functions
FLASH writes and erases by user software are protected with a lock and key function. The FLASH Lock and Key Register (FLKEY) must be written with the correct key codes, in sequence, before FLASH operations may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be written in order. If the key codes are written out of order, or the wrong codes are written, FLASH writes and erases will be disabled until the next system reset. FLASH writes and erases will also be disabled if a FLASH write or erase is attempted before the key codes have been written properly. The FLASH lock resets after each write or erase; the key codes must be written again before a following FLASH operation can be performed. The FLKEY register is detailed in Figure 10.3.
10.1.2. FLASH Erase Procedure
The FLASH memory can be programmed from software using the MOVX write instruction with the address and data byte to be programmed provided as normal operands. Before writing to FLASH memory using MOVX, FLASH write operations must be enabled by: (1) setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1 (this directs the MOVX writes to target FLASH memory); and (2) Writing the FLASH key codes in sequence to the FLASH Lock register (FLKEY). The PSWE bit remains set until cleared by software. A write to FLASH memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits to logic 1 in FLASH. A byte location to be programmed should be erased before a new value is written. The FLASH memory is organized in 512-byte pages. The erase operation applies to an entire page (setting all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps: Step 1. Disable interrupts (recommended). Step 2. Set thePSEE bit (register PSCTL). Step 3. Set the PSWE bit (register PSCTL). Step 4. Write the first key code to FLKEY: 0xA5. Step 5. Write the second key code to FLKEY: 0xF1. Step 6. Using the MOVX instruction, write a data byte to any location within the 512-byte page to be erased.
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10.1.3. FLASH Write Procedure
Preliminary
FLASH bytes are programmed by software with the following sequence: Step 1. Disable interrupts (recommended). Step 2. Erase the 512-byte FLASH page containing the target location, as described in Section 10.1.2. Step 3. Set the PSWE bit (register PSCTL). Step 4. Clear the PSEE bit (register PSCTL). Step 5. Write the first key code to FLKEY: 0xA5. Step 6. Write the second key code to FLKEY: 0xF1. Step 7. Using the MOVX instruction, write a single data byte to the desired location within the 512-byte sector. Steps 5-7 must be repeated for each byte to be written. After FLASH writes are complete, PSWE should be cleared so that MOVX instructions do not target program memory.
Table 10.1. FLASH Electrical Characteristics
VDD = 2.7 V to 3.6 V; -40C to +85C unless otherwise specified. PARAMETER CONDITIONS MIN FLASH Size C8051F310/1 16384 Endurance 20k Erase Cycle Time 25 MHz System Clock 10 Write Cycle Time 25 MHz System Clock 40
TYP 100k 15 55
MAX
20 70
UNITS bytes Erase/Write ms s
Note: 512 bytes at location 0x3E00 to 0x3FFF are reserved.
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10.2.
Non-volatile Data Storage
The FLASH memory can be used for non-volatile data storage as well as program code. This allows data such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM.
10.3.
Security Options
The CIP-51 provides security options to protect the FLASH memory from inadvertent modification by software as well as to prevent the viewing of proprietary program code and constants. The Program Store Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register PSCTL) bits protect the FLASH memory from accidental modification by software. PSWE must be explicitly set to `1' before software can modify the FLASH memory; both PSWE and PSEE must be set to `1' before software can erase FLASH memory. Additional security features prevent proprietary program code and data constants from being read or altered across the C2 interface. A Security Lock Byte located at the last byte of FLASH user space offers protection of the FLASH program memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The FLASH security mechanism allows the user to lock n 512-byte FLASH pages, starting at page 0 (addresses 0x0000 to 0x01FF), where n is the 1's compliment number represented by the Security Lock Byte. See example below. Security Lock Byte: 1's Compliment: FLASH pages locked: Addresses locked: 11111101b 00000010b 2 0x0000 to 0x03FF
Important Notes About the FLASH Security: 1. Clearing any bit of the Lock Byte to `0' will lock the FLASH page containing the Lock Byte (in addition to the selected pages); reads of any byte within the locked pages (including the Lock Byte) will return 0x00. 2. Locked pages cannot be read, written, or erased via the C2 interface. 3. Locked pages cannot be read, written, or erased by user firmware executing from unlocked memory space. 4. User firmware executing in a locked page may read and write FLASH memory in any locked or unlocked page excluding the reserved area. 5. User firmware executing in a locked page may erase FLASH memory in any locked or unlocked page excluding the reserved area and the page containing the Lock Byte. 6. Locked pages can only be unlocked by a C2 Device Erase command. 7. If a user firmware FLASH access attempt is denied (per restrictions #3, #4, and #5 above), a FLASH Error system reset will be generated.
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Figure 10.1. FLASH Program Memory Map and Security Byte
C8051F310/1 Reserved
0x3E00
Locked when any other FLASH pages are locked
Lock Byte
0x3DFF 0x3DFE 0x3C00
Unlocked FLASH Pages Access limit set according to the FLASH security lock byte
FLASH memory organized in 512-byte pages
0x0000
Figure 10.2. PSCTL: Program Store R/W Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
PSEE
Bit1
PSWE
Bit0
00000000
SFR Address:
0x8F Bits7-2: Bit1: UNUSED: Read = 000000b, Write = don't care. PSEE: Program Store Erase Enable Setting this bit (in combination with PSWE) allows an entire page of FLASH program memory to be erased. If this bit is logic 1 and FLASH writes are enabled (PSWE is logic 1), a write to FLASH memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter. 0: FLASH program memory erasure disabled. 1: FLASH program memory erasure enabled. PSWE: Program Store Write Enable Setting this bit allows writing a byte of data to the FLASH program memory using the MOVX write instruction. The FLASH location should be erased before writing data. 0: Writes to FLASH program memory disabled. 1: Writes to FLASH program memory enabled; the MOVX write instruction targets FLASH memory.
Bit0:
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Figure 10.3. FLKEY: FLASH Lock and Key Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xB7 Bits7-0: FLKEY: FLASH Lock and Key Register Write: This register must be written to before FLASH writes or erases can be performed. FLASH remains locked until this register is written to with the following key codes: 0xA5, 0xF1. The timing of the writes does not matter, as long as the codes are written in order. The key codes must be written for each FLASH write or erase operation. FLASH will be locked until the next system reset if the wrong codes are written or if a FLASH operation is attempted before the codes have been written correctly. Read: When read, bits 1-0 indicate the current FLASH lock state. 00: FLASH is write/erase locked. 01: The first key code has been written (0xA5). 10: FLASH is unlocked (writes/erases allowed). 11: FLASH writes/erases disabled until the next reset.
Figure 10.4. FLSCL: FLASH Scale Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
FOSE
Bit7
Reserved
Bit6
Reserved
Bit5
Reserved
Bit4
Reserved
Bit3
Reserved
Bit2
Reserved
Bit1
Reserved
Bit0
10000000
SFR Address:
0xB6 Bits7: FOSE: FLASH One-shot Enable This bit enables the FLASH read one-shot. When the FLASH one-shot disabled, the FLASH sense amps are enabled for a full clock cycle during FLASH reads. At system clock frequencies below 10 MHz, disabling the FLASH one-shot will increase system power consumption. 0: FLASH one-shot disabled. 1: FLASH one-shot enabled. RESERVED. Read = 0. Must Write 0.
Bits6-0:
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11.
EXTERNAL RAM
The C8051F310/1 devices include 1024 bytes of RAM mapped into the external data memory space. All of these address locations may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in Figure 11.1). Note: the MOVX instruction is also used for writes to the FLASH memory. See Section "10. FLASH Memory" on page 95 for details. The MOVX instruction accesses XRAM by default. For a 16-bit MOVX operation (@DPTR), the upper 6-bits of the 16-bit external data memory address word are "don't cares". As a result, the 1024-byte RAM is mapped modulo style over the entire 64 k external data memory address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses 0x0400, 0x0800, 0x0C00, 0x1000, etc. This is a useful feature when performing a linear memory fill, as the address pointer doesn't have to be reset when reaching the RAM block boundary.
Figure 11.1. EMI0CN: External Memory Interface Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2 Bit1
PGSEL
Bit0
00000000
SFR Address: 0xAA
Bits 7-2: Bits 1-0:
UNUSED. Read = 000000b. Write = don't care. PGSEL: XRAM Page Select. The EMI0CN register provides the high byte of the 16-bit external data memory address when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. Since the upper (unused) bits of the register are always zero, the PGSEL determines which page of XRAM is accessed. For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed.
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12.
OSCILLATORS
C8051F310/1 devices include a programmable internal oscillator and an external oscillator drive circuit. The internal oscillator can be enabled/disabled and calibrated using the OSCICN and OSCICL registers, as shown in Figure 12.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or a scaled version of the internal oscillator. The internal oscillator's electrical specifications are given in Table 12.1 on page 105.
Figure 12.1. Oscillator Diagram
OSCICL
IOSCEN IFRDY
OSCICN
IFCN1 IFCN0
CLKSEL
CLKSL0 SYSCLK
Option 3 XTAL2
Option 4 XTAL2
EN
Programmable Internal Clock Generator
n
Option 2 VDD
Option 1 XTAL1 10M Input Circuit XTAL2 OSC
XTAL2
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
OSCXCN
12.1.
Programmable Internal Oscillator
All C8051F310/1 devices include a programmable internal oscillator that defaults as the system clock after a system reset. The internal oscillator period can be programmed via the OSCICL register as defined by Figure 12.2. OSCICL is factor calibrated to obtain a 24.5 MHz frequency. Electrical specifications for the precision internal oscillator are given in Table 12.1 on page 105. Note that the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
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XFCN2 XFCN1 XFCN0
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Figure 12.2. OSCICL: Internal Oscillator Calibration Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Variable
SFR Address:
0xB3 Bit7: Bits 6-0: UNUSED. Read = 0. Write = don't care. OSCICL: Internal Oscillator Calibration Register. This register determines the internal oscillator period. This reset value for OSCICL determines the oscillator base frequency. The reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz.
Figure 12.3. OSCICN: Internal Oscillator Control Register
R/W R R/W R/W R/W R/W R/W R/W Reset Value
IOSCEN
Bit7
IFRDY
Bit6
Bit5
Bit4
Bit3
Bit2
IFCN1
Bit1
IFCN0
Bit0
11000000
SFR Address:
0xB2 Bit7: IOSCEN: Internal Oscillator Enable Bit. 0: Internal Oscillator Disabled. 1: Internal Oscillator Enabled. IFRDY: Internal Oscillator Frequency Ready Flag. 0: Internal Oscillator is not running at programmed frequency. 1: Internal Oscillator is running at programmed frequency. UNUSED. Read = 0000b, Write = don't care. IFCN1-0: Internal Oscillator Frequency Control Bits. 00: SYSCLK derived from Internal Oscillator divided by 8. 01: SYSCLK derived from Internal Oscillator divided by 4. 10: SYSCLK derived from Internal Oscillator divided by 2. 11: SYSCLK derived from Internal Oscillator divided by 1.
Bit6:
Bits5-2: Bits1-0:
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Figure 12.4. CLKSEL: Clock Select Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Reserved
Bit7
Reserved
Bit6
Reserved
Bit5
Reserved
Bit4
Reserved
Bit3
Reserved
Bit2
Reserved
Bit1
SEL0
Bit0
00000000
SFR Address:
0xA9 Bits7-1: Bit0: Reserved. Read = 0000000b, Must Write = 0000000. SEL0: System Clock Source Select Bit. 0: SYSCLK derived from the Internal Oscillator, and scales per the IFCN bits in register OSCICN. 1: SYSCLK derived from the External Oscillator circuit.
Table 12.1. Internal Oscillator Electrical Characteristics
VDD = 2.7 V to 3.6 V; -40C to +85C unless otherwise specified. PARAMETER CONDITIONS Internal Oscillator Frequency Internal Oscillator Supply Current OSCICN.7 = 1 (from VDD) MIN 24 TYP 24.5 450 MAX 25 1000 UNITS MHz A
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12.2.
Preliminary
External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 12.1. A 10 M resistor also must be wired across the XTAL2 and XTAL1 pins for the crystal/resonator configuration. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown in Option 2, 3, or 4 of Figure 12.1. The type of external oscillator must be selected in the OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see Figure 12.5). Important Note on External Oscillator Usage: Port pins must be configured when using the external oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar should be configured to skip the Port pins used by the oscillator circuit; see Section "13.1. Priority Crossbar Decoder" on page 111 for Crossbar configuration. Additionally, when using the external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs. In CMOS clock mode, the associated pin should be configured as a digital input. See Section "13.2. Port I/O Initialization" on page 113 for details on Port input mode selection.
12.3.
System Clock Selection
The CLKSL0 bit in register OSCICN selects which oscillator is used as the system clock. CLKSL0 must be set to `1' for the system clock to run from the external oscillator; however the external oscillator may still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The system clock may be switched on-the-fly between the internal and external oscillator, so long as the selected oscillator is enabled and has settled. The internal oscillator requires little start-up time and may be selected as the system clock immediately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use as the system clock. The Crystal Valid Flag (XTLVLD in register OSCXCN) is set to `1' by hardware when the external oscillator is settled. To avoid reading a false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external oscillator and checking XTLVLD. RC and C modes typically require no startup time.
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Figure 12.5. OSCXCN: External Oscillator Control Register
R Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R R/W R/W R/W Reset Value
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit3
XFCN2
Bit2
XFCN1
Bit1
XFCN0
Bit0
00000000
SFR Address:
0xB1 Bit7: XTLVLD: Crystal Oscillator Valid Flag. (Read only when XOSCMD = 11x.) 0: Crystal Oscillator is unused or not yet stable. 1: Crystal Oscillator is running and stable. XOSCMD2-0: External Oscillator Mode Bits. 00x: External Oscillator circuit off. 010: External CMOS Clock Mode. 011: External CMOS Clock Mode with divide by 2 stage. 100: RC Oscillator Mode. 101: Capacitor Oscillator Mode. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. RESERVED. Read = 0, Write = don't care. XFCN2-0: External Oscillator Frequency Control Bits. 000-111: See table below: XFCN 000 001 010 011 100 101 110 111 Crystal (XOSCMD = 11x) f 32kHz 32kHz < f 84kHz 84kHz < f 225kHz 225kHz < f 590kHz 590kHz < f 1.5MHz 1.5MHz < f 4MHz 4MHz < f 10MHz 10MHz < f 30MHz RC (XOSCMD = 10x) f 25kHz 25kHz < f 50kHz 50kHz < f 100kHz 100kHz < f 200kHz 200kHz < f 400kHz 400kHz < f 800kHz 800kHz < f 1.6MHz 1.6MHz < f 3.2MHz C (XOSCMD = 10x) K Factor = 0.87 K Factor = 2.6 K Factor = 7.7 K Factor = 22 K Factor = 65 K Factor = 180 K Factor = 664 K Factor = 1590
Bits6-4:
Bit3: Bits2-0:
CRYSTAL MODE (Circuit from Figure 12.1, Option 1; XOSCMD = 11x) Choose XFCN value to match crystal frequency. RC MODE (Circuit from Figure 12.1, Option 2; XOSCMD = 10x) Choose XFCN value to match frequency range: f = 1.23(103) / (R * C), where f = frequency of clock in MHz C = capacitor value in pF R = Pull-up resistor value in k C MODE (Circuit from Figure 12.1, Option 3; XOSCMD = 10x) Choose K Factor (KF) for the oscillation frequency desired: f = KF / (C * VDD), where f = frequency of clock in MHz C = capacitor value the XTAL2 pin in pF VDD = Power Supply on MCU in volts
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12.4. External Crystal Example
Preliminary
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 12.1, Option 1. The External Oscillator Frequency Control value (XFCN) should be chosen from the Crystal column of the table in Figure 12.5 (OSCXCN register). For example, an 11.0592 MHz crystal requires an XFCN setting of 111b. When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Enable the external oscillator. Wait at least 1 ms. Poll for XTLVLD => `1'. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as short as possible and shielded with ground plane from any other traces which could introduce noise or interference.
12.5.
External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 12.1, Option 2. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first select the RC network value to produce the desired frequency of oscillation. If the frequency desired is 100 kHz, let R = 246 k and C = 50 pF: f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 * 50 ] = 0.1 MHz = 100 kHz Referring to the table in Figure 12.5, the required XFCN setting is 010b.
12.6.
External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in Figure 12.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and C = 50 pF: f = KF / ( C * VDD ) = KF / ( 50 * 3 ) MHz f = KF / 150 MHz If a frequency of roughly 150 kHz is desired, select the K Factor from the table in Figure 12.5 as KF = 22: f = 22 / 150 = 0.146 MHz, or 146 kHz Therefore, the XFCN value to use in this example is 011b.
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13.
PORT INPUT/OUTPUT
Digital and analog resources are available through 29 I/O pins (C8051F310) or 25 I/O pins (C8051F311). Port pins are organized as three byte-wide Ports and one 5-bit (C8051F310) or 1-bit (C8051F311) Port. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog input; Port pins P0.0-P2.3 can be assigned to one of the internal digital resources as shown in Figure 13.3. The designer has complete control over which functions are assigned, limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corresponding Port latch, regardless of the Crossbar settings. The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder (Figure 13.3 and Figure 13.4). The registers XBR0 and XBR1, defined in Figure 13.5 and Figure 13.6, are used to select internal digital functions. All Port I/Os are 5 V tolerant (refer to Figure 13.2 for the Port cell circuit). The Port I/O cells are configured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2,3). Complete Electrical Specifications for Port I/O are given in Table 13.1 on page 124.
Figure 13.1. Port I/O Functional Block Diagram
XBR0, XBR1, PnSKIP Registers PnMDOUT, PnMDIN Registers
Priority Decoder
Highest Priority UART SPI (Internal Digital Signals) SMBus CP0 Outputs CP1 Outputs SYSCLK 4 PCA Lowest Priority T0, T1 6 5 2 8 P0 (P0.0-P0.7) 8 (Port Latches) P1 (P1.0-P1.7) 4 (P2.0-P2.3) P2 4 (P2.4-P2.7) 5 P3 (P3.0-P3.4) P3 I/O Cells P3.0 P3.4 2 4 2 2 2 4 8 P2 I/O Cells P2.0 P2.7 8 P0 I/O Cells P0.0 P0.7 P1.0 P1.7
Digital Crossbar
8
P1 I/O Cells
Note: P3.1-P3.4 only available on the C8051F310
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Figure 13.2. Port I/O Cell Block Diagram
/WEAK-PULLUP
PUSH-PULL /PORT-OUTENABLE
VDD
VDD
(WEAK) PORT PAD
PORT-OUTPUT
Analog Select ANALOG INPUT PORT-INPUT
GND
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13.1.
Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 13.3) assigns a priority to each I/O function, starting at the top with UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that are to be used for analog input, dedicated functions, or GPIO. Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.3 and/or P0.2 if the external oscillator circuit is enabled, P0.6 if the ADC is configured to use the external conversion start signal (CNVSTR), and any selected ADC or Comparator inputs. The Crossbar skips selected pins as if they were already assigned, and moves to the next unassigned pin. Figure 13.3 shows the Crossbar Decoder priority with no Port pins skipped (P0SKIP, P1SKIP, P2SKIP = 0x00); Figure 13.4 shows the Crossbar Decoder priority with the XTAL1 (P0.2) and XTAL2 (P0.3) pins skipped (P0SKIP = 0xC0 to skip P0.2 and P0.3 for XTAL use).
Figure 13.3. Crossbar Priority Decoder with No Pins Skipped
P0 CNVSTR XTAL1 XTAL2 VREF P1 P2
SF Signals PIN I/O TX0 RX0 SCK MISO MOSI NSS SDA SCL CP0
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 ECI T0 T1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 P0SKIP[7:0] Port pin potentially available to peripheral SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must be manually configured to skip their corresponding port pins. P1SKIP[7:0] P2SKIP[3:0]
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Figure 13.4. Crossbar Priority Decoder with Crystal Pins Skipped
P0 CNVSTR XTAL1 XTAL2 VREF P1 P2
SF Signals PIN I/O TX0 RX0 SCK MISO MOSI NSS SDA SCL CP0
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 ECI T0 T1 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 P0SKIP[0:7] Port pin potentially available to peripheral SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must be manually configured to skip their corresponding port pins. P1SKIP[0:7] P2SKIP[0:3]
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and SCL); when the UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized functions have been assigned. Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the NSSMD1NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be routed to a Port pin.
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13.2. Port I/O Initialization
Port I/O initialization consists of the following steps: Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode register (PnMDIN). Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output Mode register (PnMDOUT). Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP). Step 4. Assign Port pins to desired peripherals. Step 5. Enable the Crossbar (XBARE = `1'). All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its weak pull-up, digital driver, and digital receiver are disabled. This process saves power and reduces noise on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this practice is not recommended. Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a `1' indicates a digital input, and a `0' indicates an analog input. All pins default to digital inputs on reset. See Figure 13.8 for the PnMDIN register details. The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the PnMDOUT settings. When the WEAKPUD bit in XBR1 is `0', a weak pull-up is enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pull-up is turned off on an output that is driving a `0' to avoid unnecessary power dissipation. Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions required by the design. Setting the XBARE bit in XBR1 to `1' enables the Crossbar. Until the Crossbar is enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode Table; as an alternative, the Configuration Wizard utility of the Cygnal IDE software will determine the Port I/O pin-assignments based on the XBRn Register settings. The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers are disabled while the Crossbar is disabled.
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Figure 13.5. XBR0: Port I/O Crossbar Register 0
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CP1AE
Bit7
CP1E
Bit6
CP0AE
Bit5
CP0E
Bit4
SYSCKE
Bit3
SMB0E
Bit2
SPI0E
Bit1
URT0E
Bit0
00000000
SFR Address:
0xE1 Bit7: CP1AE: Comparator1 Asynchronous Output Enable 0: Asynchronous CP1 unavailable at Port pin. 1: Asynchronous CP1 routed to Port pin. CP1E: Comparator1 Output Enable 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin. CP0AE: Comparator0 Asynchronous Output Enable 0: Asynchronous CP0 unavailable at Port pin. 1: Asynchronous CP0 routed to Port pin. CP0E: Comparator0 Output Enable 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. SYSCKE: /SYSCLK Output Enable 0: /SYSCLK unavailable at Port pin. 1: /SYSCLK output routed to Port pin. SMB0E: SMBus I/O Enable 0: SMBus I/O unavailable at Port pins. 1: SMBus I/O routed to Port pins. SPI0E: SPI I/O Enable 0: SPI I/O unavailable at Port pins. 1: SPI I/O routed to Port pins. URT0E: UART I/O Output Enable 0: UART I/O unavailable at Port pin. 1: UART TX0, RX0 routed to Port pins P0.4 and P0.5.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
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Figure 13.6. XBR1: Port I/O Crossbar Register 1
R/W R/W R/W R/W R/W R/W Bit2 R/W R/W Bit0 Reset Value
WEAKPUD
Bit7
XBARE
Bit6
T1E
Bit5
T0E
Bit4
ECIE
Bit3
PCA0ME
Bit1
00000000
SFR Address:
0xE2 Bit7: WEAKPUD: Port I/O Weak Pull-up Disable. 0: Weak Pull-ups enabled (except for Ports whose I/O are configured as analog input). 1: Weak Pull-ups disabled. XBARE: Crossbar Enable. 0: Crossbar disabled. 1: Crossbar enabled. T1E: T1 Enable 0: T1 unavailable at Port pin. 1: T1 routed to Port pin. T0E: T0 Enable 0: T0 unavailable at Port pin. 1: T0 routed to Port pin. ECIE: PCA0 External Counter Input Enable 0: ECI unavailable at Port pin. 1: ECI routed to Port pin. PCA0ME: PCA Module I/O Enable Bits. 000: All PCA I/O unavailable at Port pins. 001: CEX0 routed to Port pin. 010: CEX0, CEX1 routed to Port pins. 011: CEX0, CEX1, CEX2 routed to Port pins. 100: CEX0, CEX1, CEX2, CEX3 routed to Port pins. 101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins.
Bit6:
Bit5:
Bit4:
Bit3:
Bits2-0:
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13.3. General Purpose Port I/O
Preliminary
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for general purpose I/O. Ports3-0 are accessed through corresponding special function registers (SFRs) that are both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is latched to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write instructions. The read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SET, when the destination is an individual bit in a Port SFR. For these instructions, the value of the register (not the pin) is read, modified, and written back to the SFR.
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Figure 13.7. P0: Port0 Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P0.7
Bit7
P0.6
Bit6
P0.5
Bit5
P0.4
Bit4
P0.3
Bit3
P0.2
Bit2
P0.1
Bit1
P0.0
Bit0 (bit addressable)
11111111
SFR Address:
0x80
Bits7-0:
P0.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0). Read - Always reads `1' if selected as analog input in register P0MDIN. Directly reads Port pin when configured as digital input. 0: P0.n pin is logic low. 1: P0.n pin is logic high.
Figure 13.8. P0MDIN: Port0 Input Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
SFR Address:
0xF1 Bits7-0: Analog Input Configuration Bits for P0.7-P0.0 (respectively). Port pins configured as analog inputs have their weak pull-up, digital driver, and digital receiver disabled. 0: Corresponding P0.n pin is configured as an analog input. 1: Corresponding P0.n pin is not configured as an analog input.
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Figure 13.9. P0MDOUT: Port0 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xA4 Bits7-0: Output Configuration Bits for P0.7-P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0. 0: Corresponding P0.n Output is open-drain. 1: Corresponding P0.n Output is push-pull. (Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless of the value of P0MDOUT).
Figure 13.10. P0SKIP: Port0 Skip Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xD4 Bits7-0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P0.n pin is not skipped by the Crossbar. 1: Corresponding P0.n pin is skipped by the Crossbar.
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Figure 13.11. P1: Port1 Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P1.7
Bit7
P1.6
Bit6
P1.5
Bit5
P1.4
Bit4
P1.3
Bit3
P1.2
Bit2
P1.1
Bit1
P1.0
Bit0 (bit addressable)
11111111
SFR Address:
0x90
Bits7-0:
P1.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0). Read - Always reads `1' if selected as analog input in register P1MDIN. Directly reads Port pin when configured as digital input. 0: P1.n pin is logic low. 1: P1.n pin is logic high.
Figure 13.12. P1MDIN: Port1 Input Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
SFR Address:
0xF2 Bits7-0: Analog Input Configuration Bits for P1.7-P1.0 (respectively). Port pins configured as analog inputs have their weak pull-up, digital driver, and digital receiver disabled. 0: Corresponding P1.n pin is configured as an analog input. 1: Corresponding P1.n pin is not configured as an analog input.
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Figure 13.13. P1MDOUT: Port1 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xA5 Bits7-0: Output Configuration Bits for P1.7-P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0. 0: Corresponding P1.n Output is open-drain. 1: Corresponding P1.n Output is push-pull.
Figure 13.14. P1SKIP: Port1 Skip Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xD5 Bits7-0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P1.n pin is not skipped by the Crossbar. 1: Corresponding P1.n pin is skipped by the Crossbar.
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Figure 13.15. P2: Port2 Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P2.7
Bit7
P2.6
Bit6
P2.5
Bit5
P2.4
Bit4
P2.3
Bit3
P2.2
Bit2
P2.1
Bit1
P2.0
Bit0 (bit addressable)
11111111
SFR Address:
0xA0
Bits7-0:
P2.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0). Read - Always reads `1' if selected as analog input in register P2MDIN. Directly reads Port pin when configured as digital input. 0: P2.n pin is logic low. 1: P2.n pin is logic high.
Figure 13.16. P2MDIN: Port2 Input Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
SFR Address:
0xF3 Bits7-0: Analog Input Configuration Bits for P2.7-P2.0 (respectively). Port pins configured as analog inputs have their weak pull-up, digital driver, and digital receiver disabled. 0: Corresponding P2.n pin is configured as an analog input. 1: Corresponding P2.n pin is not configured as an analog input.
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Figure 13.17. P2MDOUT: Port2 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xA6 Bits7-0: Output Configuration Bits for P2.7-P2.0 (respectively): ignored if corresponding bit in register P2MDIN is logic 0. 0: Corresponding P2.n Output is open-drain. 1: Corresponding P2.n Output is push-pull.
Figure 13.18. P2SKIP: Port2 Skip Register
R/W R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
Bit4
00000000
SFR Address:
0xD6 Bits7-0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P2.n pin is not skipped by the Crossbar. 1: Corresponding P2.n pin is skipped by the Crossbar. Note: Only P2.0-P2.3 are associated with the Crossbar.
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Figure 13.19. P3: Port3 Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P3.7
Bit7
P3.6
Bit6
P3.5
Bit5
P3.4
Bit4
P3.3
Bit3
P3.2
Bit2
P3.1
Bit1
P3.0
Bit0 (bit addressable)
11111111
SFR Address:
0xB0
Bits7-0:
P3.[7:0] Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P3MDOUT.n bit = 0). Read - Always reads `1' if selected as analog input in register P3MDIN. Directly reads Port pin when configured as digital input. 0: P3.n pin is logic low. 1: P3.n pin is logic high. Note: Only P3.0-P3.4 are associated with Port pins on C8051F310 devices; Only P3.0 is associated with a Port pin on C8051F311 devices.
Figure 13.20. P3MDIN: Port3 Input Mode Register
R/W R/W R/W R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
11111111
SFR Address:
0xF4 Bits7-5: Bits4-0: UNUSED. Read = 000b; Write = don't care. Input Configuration Bits for P3.4-P3.0 (respectively). Port pins configured as analog inputs have their weak pull-up, digital driver, and digital receiver disabled. 0: Corresponding P3.n pin is configured as an analog input. 1: Corresponding P3.n pin is not configured as an analog input. Note: Only P3.0-P3.4 are associated with Port pins on C8051F310 devices; Only P3.0 is associated with a Port pin on C8051F311 devices.
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Figure 13.21. P3MDOUT: Port3 Output Mode Register
R/W R/W R/W R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
00000000
SFR Address:
0xA7 Bits7-5: Bits4-0: UNUSED. Read = 000b; Write - don't care. Output Configuration Bits for P3.4-P3.0 (respectively): ignored if corresponding bit in register P3MDIN is logic 0. 0: Corresponding P3.n Output is open-drain. 1: Corresponding P3.n Output is push-pull. Note: Only P3.0-P3.4 are associated with Port pins on C8051F310 devices; Only P3.0 is associated with a Port pin on C8051F311 devices.
Table 13.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6V, -40C to +85C unless otherwise specified PARAMETERS CONDITIONS IOH = -3mA, Port I/O push-pull Output High Voltage IOH = -10A, Port I/O push-pull IOH = -10mA, Port I/O push-pull IOL = 8.5mA Output Low Voltage Input High Voltage Input Low Voltage Input Leakage Current Weak Pull-up Off Weak Pull-up On, VIN = 0 V 25 IOL = 10A IOL = 25mA 2.0 0.8 1 40 1.0 V V A MIN VDD-0.7 VDD-0.1 VDD-0.8 0.6 0.1 V V TYP MAX UNITS
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14.
SMBUS
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to the interface by the system controller are byte oriented with the SMBus interface autonomously controlling the serial transfer of the data. Data can be transferred at up to 1/10th of the system clock as a master or slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus: SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data register, used for both transmitting and receiving SMBus data and slave addresses.
Figure 14.1. SMBus Block Diagram
SMB0CN MT SSAAAS AXTTCRC I SMAOKBK TO RL ED QO RE S T SMB0CF E I BESSSS N N U XMMMM SHSTBBBB M YHTFCC B OOT S S LEE10 D
00 01 10 11 SMBUS CONTROL LOGIC Arbitration SCL Synchronization SCL Generation (Master Mode) SDA Control Data Path IRQ Generation Control
T0 Overflow T1 Overflow TMR2H Overflow TMR2L Overflow SCL
FILTER
Interrupt Request
SCL Control SDA Control
N
C R O S S B A R SDA
Port I/O
SMB0DAT 76543210
FILTER
N
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14.1. Supporting Documents
Preliminary
It is assumed the reader is familiar with or has access to the following supporting documents: 1. 2. 3. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
14.2.
SMBus Configuration
Figure 14.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage through a pull-up resistor or similar circuit. Every device connected to the bus must have an open-drain or open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
Figure 14.2. Typical SMBus Configuration
VDD = 5V VDD = 3V VDD = 5V VDD = 3V
Master Device
Slave Device 1
Slave Device 2
SDA SCL
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14.3.
SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ). The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitration. Note that it is not necessary to specify one device as the Master in a system; any device who transmits a START and a slave address becomes the master for the duration of that transfer. A typical SMBus transaction consists of a START condition followed by an address byte (Bits7-1: 7-bit slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see Figure 14.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation. All transactions are initiated by a master, with one or more addressed slave devices as the target. The master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master generates a STOP condition to terminate the transaction and free the bus. Figure 14.3 illustrates a typical SMBus transaction.
Figure 14.3. SMBus Transaction
SCL
SDA SLA6 SLA5-0 R/W D7 D6-0
START
Slave Address + R/W
ACK
Data Byte
NACK
STOP
14.3.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section "14.3.4. SCL High (SMBus Free) Timeout" on page 128). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer if addressed. This arbitration scheme is nondestructive: one device always wins, and no data is lost.
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14.3.2. Clock Low Extension
Preliminary
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line LOW to extend the clock low period, effectively decreasing the serial clock frequency.
14.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a "timeout" condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition. When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable and re-enable) the SMBus in the event of an SCL low timeout.
14.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 s, the bus is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a Master START, the START will be generated following this timeout. Note that a clock source is required for free timeout detection, even in a slaveonly implementation.
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14.4.
Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides the following application-independent features: * * * * * * * Byte-wise serial data transfers Clock signal generation on SCL (Master Mode only) and SDA data synchronization Timeout/bus error recognition, as defined by the SMB0CF configuration register START/STOP timing, detection, and generation Bus arbitration Interrupt generation Status information
SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting, this interrupt is generated after the ACK cycle so that software may read the received ACK value; when receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing ACK value. See Section "14.5. SMBus Transfer Modes" on page 137 for more details on transmission sequences. Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section "14.4.2. SMB0CN Control Register" on page 133; Table 14.4 provides a quick SMB0CN decoding reference. SMBus configuration options include: * * * * Timeout detection (SCL Low Timeout and/or Bus Free Timeout) SDA setup and hold time extensions Slave event enable/disable Clock source selection
These options are selected in the SMB0CF register, as described in Section "14.4.1. SMBus Configuration Register" on page 130.
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14.4.1. SMBus Configuration Register
Preliminary
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes, select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however, the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of the current transfer).
Table 14.1. SMBus Clock Source Selection
SMBCS1 SMBCS0 SMBus Clock Source 0 0 Timer 0 Overflow 0 1 Timer 1 Overflow 1 0 Timer 2 High Byte Overflow 1 1 Timer 2 Low Byte Overflow The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or when the Free Timeout detection is enabled. When operating as a master, overflows from the selected source determine the absolute minimum SCL low and high times as defined in Equation 14.1. Note that the selected clock source may be shared by other peripherals so long as the timer is left running at all times. For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer configuration is covered in Section "17. Timers" on page 167.
Equation 14.1. Minimum SCL High and Low Times 1 T HighMin = T LowMin = --------------------------------------------f ClockSourceOverflow
The selected clock source should be configured to establish the minimum SCL High and Low times as per Equation 14.1. When the interface is operating as a master (and SCL is not driven or extended by any other devices on the bus), the typical SMBus bit rate is approximated by Equation 14.2.
Equation 14.2. Typical SMBus Bit Rate f ClockSourceOverflow BitRate = --------------------------------------------3
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Figure 14.4 shows the typical SCL generation described by Equation 14.2. Notice that THIGH is typically twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be extended low by slower slave devices, or driven low by contending master devices). The bit rate when operating as a master will never exceed the limits defined by equation Equation 14.1.
Figure 14.4. Typical SMBus SCL Generation
Timer Source Overflows SCL
TLow
THigh
SCL High Timeout
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high. The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 14.2 shows the minimum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically necessary when SYSCLK is above 10 MHz.
Table 14.2. Minimum SDA Setup and Hold Times
EXTHOLD 0 1
Minimum SDA Setup Time Tlow - 4 system clocks OR 1 system clock + s/w delay 11 system clocks
Minimum SDA Hold Time 3 system clocks 12 system clocks
Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w delay occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w delay is zero.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low timeouts (see Section "14.3.3. SCL Low Timeout" on page 128). The SMBus interface will force Timer 3 to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus. SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see Figure 14.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an interrupt will be generated, and STO will be set).
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Figure 14.5. SMB0CF: SMBus Clock/Configuration Register
R/W R/W R R/W Bit4 R/W Bit3 R/W R/W R/W Reset Value
ENSMB
Bit7
INH
Bit6
BUSY
Bit5
EXTHOLD SMBTOE
SMBFTE
Bit2
SMBCS1
Bit1
SMBCS0
Bit0
00000000
SFR Address: 0xC1
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bits1-0:
ENSMB: SMBus Enable. This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins. 0: SMBus interface disabled. 1: SMBus interface enabled. INH: SMBus Slave Inhibit. When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are not affected. 0: SMBus Slave Mode enabled. 1: SMBus Slave Mode inhibited. BUSY: SMBus Busy Indicator. This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0 when a STOP or free-timeout is sensed. EXTHOLD: SMBus Setup and Hold Time Extension Enable. This bit controls the SDA setup and hold times according to Table 14.2. 0: SDA Extended Setup and Hold Times disabled. 1: SDA Extended Setup and Hold Times enabled. SMBTOE: SMBus SCL Timeout Detection Enable. This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low. Timer 3 should be programmed to generate interrupts at 25 ms, and the Timer 3 interrupt service routine should reset SMBus communication. SMBFTE: SMBus Free Timeout Detection Enable. When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. SMBCS1-SMBCS0: SMBus Clock Source Selection. These two bits select the SMBus clock source, which is used to generate the SMBus bit rate. The selected device should be configured according to Equation 14.1. SMBCS1 0 0 1 1 SMBCS0 0 1 0 1 SMBus Clock Source Timer 0 Overflow Timer 1 Overflow Timer 2 High Byte Overflow Timer 2 Low Byte Overflow
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14.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see Figure 14.6). The higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive modes, respectively. STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a `1' to STA will cause the SMBus interface to enter Master Mode and generate a START when the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a `1' to STO while in Master Mode will cause the interface to generate a STOP and end the current transfer after the next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be generated. As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be ignored until the next START is detected. The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared. The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or when an arbitration is lost; see Table 14.3 for more details. Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and the bus is stalled until software clears SI. Table 14.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 14.4 for SMBus status decoding using the SMB0CN register.
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Figure 14.6. SMB0CN: SMBus Control Register
R R R/W R/W R R R/W R/W Reset Value
MASTER TXMODE
Bit7 Bit6
STA
Bit5
STO
Bit4
ACKRQ ARBLOST
Bit3 Bit2
ACK
Bit1
SI
Bit0
00000000
Bit Addressable
SFR Address: 0xC0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
MASTER: SMBus Master/Slave Indicator. This read-only bit indicates when the SMBus is operating as a master. 0: SMBus operating in Slave Mode. 1: SMBus operating in Master Mode. TXMODE: SMBus Transmit Mode Indicator. This read-only bit indicates when the SMBus is operating as a transmitter. 0: SMBus in Receiver Mode. 1: SMBus in Transmitter Mode. STA: SMBus Start Flag. Write: 0: No Start generated. 1: When operating as a master, a START condition is transmitted if the bus is free (If the bus is not free, the START is transmitted after a STOP is received or a timeout is detected). If STA is set by software as an active Master, a repeated START will be generated after the next ACK cycle. Read: 0: No Start or repeated Start detected. 1: Start or repeated Start detected. STO: SMBus Stop Flag. Write: 0: No STOP condition is transmitted. 1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA and STO are set, a STOP condition is transmitted followed by a START condition. Read: 0: No Stop condition detected. 1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode). ACKRQ: SMBus Acknowledge Request This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK bit to be written with the correct ACK response value. ARBLOST: SMBus Arbitration Lost Indicator. This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a transmitter. A lost arbitration while a slave indicates a bus error condition. ACK: SMBus Acknowledge Flag. This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted. 0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). 1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). SI: SMBus Interrupt Flag. This bit is set by hardware under the conditions listed in Table 14.3. SI must be cleared by software. While SI is set, SCL is held low and the SMBus is stalled.
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Table 14.3. Sources for Hardware Changes to SMB0CN
Bit MASTER Cleared by Hardware When: * A STOP is generated. * Arbitration is lost. * START is generated. * A START is detected. * SMB0DAT is written before the start of an SMBus * Arbitration is lost. frame. * SMB0DAT is not written before the start of an SMBus frame. * A START followed by an address byte is received. * Must be cleared by software. * A STOP is detected while addressed as a slave. * A pending STOP is generated. * Arbitration is lost due to a detected STOP. * A byte has been received and an ACK response * After each ACK cycle. value is needed. * A repeated START is detected as a MASTER when * Each time SI is cleared. STA is low (unwanted repeated START). * SCL is sensed low while attempting to generate a STOP or repeated START condition. * SDA is sensed low while transmitting a `1' (excluding ACK bits). * The incoming ACK value is low (ACKNOWL* The incoming ACK value is high (NOT EDGE). ACKNOWLEDGE). * A START has been generated. * Must be cleared by software. * Lost arbitration. * A byte has been transmitted and an ACK/NACK received. * A byte has been received. * A START or repeated START followed by a slave address + R/W has been received. * A STOP has been received. Set by Hardware When: * A START is generated.
TXMODE STA STO ACKRQ
ARBLOST
ACK
SI
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14.4.3. Data Register
Preliminary
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software may safely read or write to the data register when the SI flag is set. Software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0, as the interface may be in the process of shifting a byte of data into or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in SMB0DAT.
Figure 14.7. SMB0DAT: SMBus Data Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xC2 Reset Value
00000000
Bits7-0:
SMB0DAT: SMBus Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long as the SI flag is set. When the SI flag is not set, the system may be in the process of shifting data in/out and the CPU should not attempt to access this register.
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14.5.
SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter.
14.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt. Figure 14.8 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any number of bytes may be transmitted. Notice that the `data byte transferred' interrupts occur after the ACK cycle in this mode.
Figure 14.8. Typical Master Transmitter Sequence
S SLA W A Data Byte A Data Byte A P
Interrupt
Interrupt
Interrupt
Interrupt
Received by SMBus Interface Transmitted by SMBus Interface
S = START P = STOP A = ACK W = WRITE SLA = Slave Address
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14.5.2. Master Receiver Mode
Preliminary
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial data. After each byte is received, ACKRQ is set to `1' and an interrupt is generated. Software must write the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a `1' to the ACK bit generates an ACK; writing a `0' generates a NACK). Software should write a `0' to the ACK bit after the last byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written while an active Master Receiver. Figure 14.9 shows a typical Master Receiver sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the `data byte transferred' interrupts occur before the ACK cycle in this mode.
Figure 14.9. Typical Master Receiver Sequence
S SLA R A Data Byte A Data Byte N P
Interrupt
Interrupt
Interrupt
Interrupt S = START P = STOP A = ACK N = NACK R = READ SLA = Slave Address
Received by SMBus Interface Transmitted by SMBus Interface
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14.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit (WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 14.10 shows a typical Slave Receiver sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the `data byte transferred' interrupts occur before the ACK cycle in this mode.
Figure 14.10. Typical Slave Receiver Sequence
Interrupt
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt Received by SMBus Interface Transmitted by SMBus Interface
Interrupt
Interrupt S = START P = STOP A = ACK W = WRITE SLA = Slave Address
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14.5.4. Slave Transmitter Mode
Preliminary
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a slave address and direction bit (READ in this case) is received. Upon entering Slave Transmitter Mode, an interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 14.11 shows a typical Slave Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the `data byte transferred' interrupts occur after the ACK cycle in this mode.
Figure 14.11. Typical Slave Transmitter Sequence
Interrupt
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt Received by SMBus Interface Transmitted by SMBus Interface
Interrupt
Interrupt
S = START P = STOP N = NACK R = READ SLA = Slave Address
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14.6.
SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the shown response options are only the typical responses; application-specific procedures are allowed as long as they conform to the SMBus specification. Highlighted responses are allowed but do not conform to the SMBus specification.
Table 14.4. SMBus Status Decoding
VALUES READ MODE ARBLOST STATUS VECTOR ACKRQ CURRENT SMBUS STATE TYPICAL RESPONSE OPTIONS VALUES WRITTEN ACK X X X X X X X X 1 0 0 1 0 1 0 STO 0 0 1 0 1 1 0 0 0 1 1 0 0 0 0 STA 0 1 0 0 0 1 1 0 0 0 1 1 1 0 0
ACK
1110
0 0
0 0
X
A master START was generated.
Load slave address + R/W into SMB0DAT. Set STA to restart transfer. Abort transfer. Load next data byte into SMB0DAT. End transfer with STOP. End transfer with STOP and start another transfer. Send repeated START. Switch to Master Receiver Mode (clear SI without writing new data to SMB0DAT).
A master data or address byte was 0 transmitted; NACK received. A master data or address byte was transmitted; ACK received.
Master Transmitter
1100 0 0 1
A master data byte was received; ACK requested.
Acknowledge received byte; Read SMB0DAT. Send NACK to indicate last byte, and send STOP. Send NACK to indicate last byte, and send STOP followed by START.
Master Receiver
1000
1
0
X
Send ACK followed by repeated START. Send NACK to indicate last byte, and send repeated START. Send ACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). Send NACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI).
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Table 14.4. SMBus Status Decoding
VALUES READ MODE ARBLOST STATUS VECTOR ACKRQ CURRENT SMBUS STATE TYPICAL RESPONSE OPTIONS VALUES WRITTEN ACK X X X X 1 0 1 0 0 X X 0 X X X 1 0 0 0 STO 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 STA 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 0 0 0 1
ACK 0 1 X X
0 Slave Transmitter 0100 0 0 0101 0
0 0 1 X
A slave byte was transmitted; NACK No action required (expecting received. STOP condition). A slave byte was transmitted; ACK received. A Slave byte was transmitted; error detected. A STOP was detected while an addressed Slave Transmitter. Load SMB0DAT with next data byte to transmit. No action required (expecting Master to end transfer). No action required (transfer complete).
1
0
A slave address was received; ACK Acknowledge received address. X requested. Do not acknowledge received address. Lost arbitration as master; slave address received; ACK requested. Acknowledge received address. Do not acknowledge received address. Reschedule failed transfer; do not acknowledge received address.
0010 1 1 X
Slave Receiver
0010
0 1
1 1 0 1
Lost arbitration while attempting a X repeated START. X X Lost arbitration while attempting a STOP. A STOP was detected while an addressed slave receiver.
Abort failed transfer. Reschedule failed transfer. No action required (transfer complete/aborted). No action required (transfer complete). Abort transfer. Reschedule failed transfer. Acknowledge received byte; Read SMB0DAT. Do not acknowledge received byte.
0001
0 0
Lost arbitration due to a detected X STOP. A slave byte was received; ACK requested.
1 0000 1
0
X
1
Lost arbitration while transmitting a Abort failed transfer. X data byte as master. Reschedule failed transfer.
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15.
UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART. Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details in Section "15.1. Enhanced Baud Rate Generation" on page 144). Received data buffering allows UART0 to start reception of a second incoming data byte before software has finished reading the previous data byte. UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0). The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0 always access the Transmit register. Reads of SBUF0 always access the buffered Receive register; it is not possible to read data from the Transmit register. With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive complete).
Figure 15.1. UART0 Block Diagram
SFR Bus
Write to SBUF TB8
SET D CLR Q
SBUF (TX Shift)
TX
Crossbar
Zero Detector
Stop Bit Start Tx Clock
Shift
Data
Tx Control
Tx IRQ Send
SCON SMODE MCE REN TB8 RB8 TI RI UART Baud Rate Generator
TI Serial Port Interrupt RI
Port I/O
Rx IRQ Rx Clock
Rx Control
Start Shift 0x1FF RB8 Load SBUF
Input Shift Register (9 bits)
Load SBUF
SBUF (RX Latch)
Read SBUF
SFR Bus
RX
Crossbar
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15.1.
Preliminary
Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 15.2), which is not user-accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates. The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to begin any time a START is detected, independent of the TX Timer state.
Figure 15.2. UART0 Baud Rate Logic
Timer 1 TL1
Overflow
UART
2
TX Clock
TH1
Start Detected
RX Timer
Overflow
2
RX Clock
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section "17.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload" on page 169). The Timer 1 reload value should be set so that overflows will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an external input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 15.1.
Equation 15.1. UART0 Baud Rate T1 CLK 1 -UartBaudRate = ------------------------------ x -( 256 - T1H ) 2
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload value). Timer 1 clock frequency is selected as described in Section "17. Timers" on page 167. A quick reference for typical baud rates and system clock frequencies is given in Table 15.1 through Table 15.6. Note that the internal oscillator may still generate the system clock when the external oscillator is driving Timer 1.
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15.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown below.
Figure 15.3. UART Interconnect Diagram
RS-232
RS-232 LEVEL XLTR
TX RX
C8051Fxxx
OR
TX TX
MCU
RX RX
C8051Fxxx
15.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2). Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits are lost. If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
Figure 15.4. 8-Bit UART Timing Diagram
MARK SPACE BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT
BIT SAMPLING
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15.2.2. 9-Bit UART
Preliminary
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80 (SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the stop bit is ignored. Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to `1'. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: (1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to `1'. If the above conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to `1'. A UART0 interrupt will occur if enabled when either TI0 or RI0 is set to `1'.
Figure 15.5. 9-Bit UART Timing Diagram
MARK SPACE BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 D8 STOP BIT
BIT SAMPLING
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15.3.
Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address byte has been received. In the UART interrupt handler, software will compare the received address with the slave's own assigned 8bit address. If the addresses match, the slave will clear its MCE0 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte. Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s).
Figure 15.6. UART Multi-Processor Mode Interconnect Diagram
Master Device
RX TX
Slave Device
RX TX
Slave Device
RX TX
Slave Device
V+ RX TX
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Preliminary
Figure 15.7. SCON0: Serial Port 0 Control Register
R/W R R/W R/W R/W R/W R/W R/W Reset Value
S0MODE
Bit7
Bit6
MCE0
Bit5
REN0
Bit4
TB80
Bit3
RB80
Bit2
TI0
Bit1
RI0
Bit0
01000000
Bit Addressable
SFR Address: 0x98
Bit7:
Bit6: Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
S0MODE: Serial Port 0 Operation Mode. This bit selects the UART0 Operation Mode. 0: 8-bit UART with Variable Baud Rate. 1: 9-bit UART with Variable Baud Rate. UNUSED. Read = 1b. Write = don't care. MCE0: Multiprocessor Communication Enable. The function of this bit is dependent on the Serial Port 0 Operation Mode. S0MODE = 0: Checks for valid stop bit. 0: Logic level of stop bit is ignored. 1: RI0 will only be activated if stop bit is logic level 1. S0MODE = 1: Multiprocessor Communications Enable. 0: Logic level of ninth bit is ignored. 1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1. REN0: Receive Enable. This bit enables/disables the UART receiver. 0: UART0 reception disabled. 1: UART0 reception enabled. TB80: Ninth Transmission Bit. The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It is not used in 8-bit UART Mode. Set or cleared by software as required. RB80: Ninth Receive Bit. RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th data bit in Mode 1. TI0: Transmit Interrupt Flag. Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8-bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. RI0: Receive Interrupt Flag. Set to `1' by hardware when a byte of data has been received by UART0 (set at the STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to `1' causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software.
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Figure 15.8. SBUF0: Serial (UART0) Port Data Buffer Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x99 Reset Value
00000000
Bits7-0:
SBUF0[7:0]: Serial Data Buffer Bits 7-0 (MSB-LSB) This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch.
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Table 15.1. Timer Settings for Standard Baud Rates Using The Internal Oscillator
Frequency: 24.5 MHz Target Baud Rate Baud Rate % Error (bps) 230400 -0.32% 115200 -0.32% 57600 0.15% 28800 -0.32% 14400 0.15% 9600 -0.32% 2400 -0.32% 1200 0.15% Oscillator Divide Factor 106 212 426 848 1704 2544 10176 20448 Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK XX SYSCLK XX SYSCLK XX SYSCLK / 4 01 SYSCLK / 12 00 SYSCLK / 12 00 SYSCLK / 48 10 SYSCLK / 48 10 X = Don't care T1M Timer 1 Reload Value (hex) 1 0xCB 1 0x96 1 0x2B 0 0x96 0 0xB9 0 0x96 0 0x96 0 0x2B
SYSCLK from Internal Osc.
SCA1-SCA0
and T1M bit definitions can be found in Section 17.1.
Table 15.2. Timer Settings for Standard Baud Rates Using an External Oscillator
Frequency: 25.0 MHz Target Baud Rate Baud Rate % Error (bps) 230400 -0.47% 115200 0.45% 57600 -0.01% 28800 0.45% 14400 -0.01% 9600 0.15% 2400 0.45% 1200 -0.01% 57600 -0.47% 28800 -0.47% 14400 0.45% 9600 0.15% Oscillator Divide Factor 108 218 434 872 1736 2608 10464 20832 432 864 1744 2608 Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK / 4 SYSCLK / 4 EXTCLK / 8 SYSCLK / 48 SYSCLK / 48 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 X = Don't care
SYSCLK from Internal Osc.
XX XX XX 01 01 11 10 10 11 11 11 11
T1M Timer 1 Reload Value (hex) 1 0xCA 1 0x93 1 0x27 0 0x93 0 0x27 0 0x5D 0 0x93 0 0x27 0 0xE5 0 0xCA 0 0x93 0 0x5D
SYSCLK from External Osc.
SCA1-SCA0 and T1M bit definitions can be found in Section 17.1.
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Table 15.3. Timer Settings for Standard Baud Rates Using an External Oscillator
Frequency: 22.1184 MHz Target Baud Rate Baud Rate % Error (bps) 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00% 2400 0.00% 1200 0.00% 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00% Oscillator Divide Factor 96 192 384 768 1536 2304 9216 18432 96 192 384 768 1536 2304 Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK XX SYSCLK XX SYSCLK XX SYSCLK / 12 00 SYSCLK / 12 00 SYSCLK / 12 00 SYSCLK / 48 10 SYSCLK / 48 10 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 X = Don't care T1M Timer 1 Reload Value (hex) 1 0xD0 1 0xA0 1 0x40 0 0xE0 0 0xC0 0 0xA0 0 0xA0 0 0x40 0 0xFA 0 0xF4 0 0xE8 0 0xD0 0 0xA0 0 0x70
SYSCLK from Internal Osc.
SYSCLK from External Osc.
SCA1-SCA0
and T1M bit definitions can be found in Section 17.1.
Table 15.4. Timer Settings for Standard Baud Rates Using an External Oscillator
Frequency: 18.432 MHz Target Baud Rate Baud Rate % Error (bps) 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00% 2400 0.00% 1200 0.00% 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00%
Oscillator Divide Factor 80 160 320 640 1280 1920 7680 15360 80 160 320 640 1280 1920
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK XX SYSCLK XX SYSCLK XX SYSCLK / 4 01 SYSCLK / 4 01 SYSCLK / 12 00 SYSCLK / 48 10 SYSCLK / 48 10 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 EXTCLK / 8 11 X = Don't care
T1M Timer 1 Reload Value (hex) 1 0xD8 1 0xB0 1 0x60 0 0xB0 0 0x60 0 0xB0 0 0xB0 0 0x60 0 0xFB 0 0xF6 0 0xEC 0 0xD8 0 0xB0 0 0x88
SYSCLK from Internal Osc.
SYSCLK from External Osc.
SCA1-SCA0 and T1M bit definitions can be found in Section 17.1.
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Preliminary
Table 15.5. Timer Settings for Standard Baud Rates Using an External Oscillator
Frequency: 11.0592 MHz Target Baud Rate Baud Rate % Error (bps) 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00% 2400 0.00% 1200 0.00% 230400 0.00% 115200 0.00% 57600 0.00% 28800 0.00% 14400 0.00% 9600 0.00% Oscillator Divide Factor 48 96 192 384 768 1152 4608 9216 48 96 192 384 768 1152 Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK SYSCLK / 12 SYSCLK / 12 SYSCLK / 12 SYSCLK / 48 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 X = Don't care XX XX XX XX 00 00 00 10 11 11 11 11 11 11 T1M Timer 1 Reload Value (hex) 1 0xE8 1 0xD0 1 0xA0 1 0x40 0 0xE0 0 0xD0 0 0x40 0 0xA0 0 0xFD 0 0xFA 0 0xF4 0 0xE8 0 0xD0 0 0xB8
SYSCLK from Internal Osc.
SYSCLK from External Osc.
SCA1-SCA0
and T1M bit definitions can be found in Section 17.1.
Table 15.6. Timer Settings for Standard Baud Rates Using an External Oscillator
Frequency: 3.6864 MHz Target Baud Rate% Oscillator Baud Rate Error Divide (bps) Factor 230400 0.00% 16 115200 0.00% 32 57600 0.00% 64 28800 0.00% 128 14400 0.00% 256 9600 0.00% 384 2400 0.00% 1536 1200 0.00% 3072 230400 0.00% 16 115200 0.00% 32 57600 0.00% 64 28800 0.00% 128 14400 0.00% 256 9600 0.00% 384
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK SYSCLK SYSCLK SYSCLK / 12 SYSCLK / 12 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 X = Don't care XX XX XX XX XX XX 00 00 11 11 11 11 11 11
T1M Timer 1 Reload Value (hex) 1 0xF8 1 0xF0 1 0xE0 1 0xC0 1 0x80 1 0x40 0 0xC0 0 0x80 0 0xFF 0 0xFE 0 0xFC 0 0xF8 0 0xF0 0 0xE8
SYSCLK from Internal Osc.
SYSCLK from External Osc.
SCA1-SCA0 and T1M bit definitions can be found in Section 17.1.
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16.
ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode.
Figure 16.1. SPI Block Diagram
SFR Bus
SPI0CKR
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0
SPI0CFG
SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT
SPI0CN
SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN
SYSCLK
Clock Divide Logic
SPI CONTROL LOGIC
Data Path Control Pin Interface Control
SPI IRQ
Tx Data
MOSI
SPI0DAT Transmit Data Buffer Pin Control Logic
SCK
Shift Register
76543210
Rx Data
MISO
C R O S S B A R
Port I/O
Receive Data Buffer
NSS
Write SPI0DAT
Read SPI0DAT
SFR Bus
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16.1. Signal Descriptions
Preliminary
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
16.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire mode.
16.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device. It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register.
16.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is not selected (NSS = 1) in 4-wire slave mode.
16.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0 bits in the SPI0CN register. There are three possible modes that can be selected with these bits: 1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-to-point communication between a master and one slave. 2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple master devices can be used on the same SPI bus. 3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration should only be used when operating SPI0 as a master device.
See Figure 16.2, Figure 16.3, and Figure 16.4 for typical connection diagrams of the various operational modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or 3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will be mapped to a pin on the device. See Section "13. Port Input/Output" on page 109 for general purpose port I/O and crossbar information.
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16.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire singlemaster mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0 must be manually re-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using generalpurpose I/O pins. Figure 16.2 shows a connection diagram between two master devices in multiple-master mode. 3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 16.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 16.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices.
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Figure 16.2. Multiple-Master Mode Connection Diagram
NSS GPIO MISO MOSI SCK NSS
Master Device 1
MISO MOSI SCK GPIO
Master Device 2
Figure 16.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram
Master Device
MISO MOSI SCK
MISO MOSI SCK
Slave Device
Figure 16.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram
Master Device
GPIO
MISO MOSI SCK NSS
MISO MOSI SCK NSS
Slave Device
MISO MOSI SCK NSS
Slave Device
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16.3.
SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will load the shift register with the transmit buffer's contents after the last SCK edge of the next (or current) SPI transfer. When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0, and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer. Figure 16.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master device. 3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and re-enabling SPI0 with the SPIEN bit. Figure 16.3 shows a connection diagram between a slave device in 3-wire slave mode and a master device.
16.4.
SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: Note that all of the following bits must be cleared by software. 1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can occur in all SPI0 modes. 2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0 modes. 3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost.
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16.5. Serial Clock Timing
Preliminary
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0 should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The clock and data line relationships for master mode are shown in Figure 16.5. For slave mode, the clock and data relationships are shown in Figure 16.6 and Figure 16.7. Note that CKPHA must be set to `0' on both the master and slave SPI when communicating between two of the following devices: C8051F04x, C8051F06x, C8051F12x, C8051F31x, C8051F32x, and C8051F33x The SPI0 Clock Rate Register (SPI0CKR) as shown in Figure 16.10 controls the master mode serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz, whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-wire slave mode), and the serial input data synchronously with the slave's system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less than 1/10 the system clock frequency. In the special case where the master only wants to transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency. This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave's system clock.
Figure 16.5. Master Mode Data/Clock Timing
SCK (CKPOL=0, CKPHA=0)
SCK (CKPOL=0, CKPHA=1)
SCK (CKPOL=1, CKPHA=0)
SCK (CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (Must Remain High in Multi-Master Mode)
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Figure 16.6. Slave Mode Data/Clock Timing (CKPHA = 0)
SCK (CKPOL=0, CKPHA=0)
SCK (CKPOL=1, CKPHA=0)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (4-Wire Mode)
Figure 16.7. Slave Mode Data/Clock Timing (CKPHA = 1)
SCK (CKPOL=0, CKPHA=1)
SCK (CKPOL=1, CKPHA=1)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (4-Wire Mode)
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16.6.
Preliminary
SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate Register. The four special function registers related to the operation of the SPI0 Bus are described in the following figures.
Figure 16.8. SPI0CFG: SPI0 Configuration Register
R R/W R/W R/W R R R R Reset Value
SPIBSY
Bit7
MSTEN
Bit6
CKPHA
Bit5
CKPOL
Bit4
SLVSEL
Bit3
NSSIN
Bit2
SRMT
Bit1
RXBMT
Bit0
00000111
SFR Address: 0xA1
Bit 7: Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
SPIBSY: SPI Busy (read only). This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode). MSTEN: Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. CKPHA: SPI0 Clock Phase. This bit controls the SPI0 clock phase. 0: Data centered on first edge of SCK period. 1: Data centered on second edge of SCK period. CKPOL: SPI0 Clock Polarity. This bit controls the SPI0 clock polarity. 0: SCK line low in idle state. 1: SCK line high in idle state. SLVSEL: Slave Selected Flag (read only). This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the instantaneous value at the NSS pin, but rather a de-glitched version of the pin input. NSSIN: NSS Instantaneous Pin Input (read only). This bit mimics the instantaneous value that is present on the NSS port pin at the time that the register is read. This input is not de-glitched. SRMT: Shift Register Empty (Valid in Slave Mode, read only). This bit will be set to logic 1 when all data has been transferred in/out of the shift register, and there is no new information available to read from the transmit buffer or write to the receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from the transmit buffer or by a transition on SCK. NOTE: SRMT = 1 when in Master Mode. RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only). This bit will be set to logic 1 when the receive buffer has been read and contains no new information. If there is new information available in the receive buffer that has not been read, this bit will return to logic 0. NOTE: RXBMT = 1 when in Master Mode.
In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device. See Table 16.1 for timing parameters.
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Figure 16.9. SPI0CN: SPI0 Control Register
R/W R/W R/W R/W R/W R/W R R/W Reset Value
SPIF
Bit7
WCOL
Bit6
MODF
Bit5
RXOVRN NSSMD1
Bit4 Bit3
NSSMD0
Bit2
TXBMT
Bit1
SPIEN
Bit0
00000110
Bit Addressable
SFR Address: 0xF8
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bits 3-2:
Bit 1:
Bit 0:
SPIF: SPI0 Interrupt Flag. This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled, setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not automatically cleared by hardware. It must be cleared by software. WCOL: Write Collision Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to the SPI0 data register was attempted while a data transfer was in progress. It must be cleared by software. MODF: Mode Fault Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software. RXOVRN: Receive Overrun Flag (Slave Mode only). This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must be cleared by software. NSSMD1-NSSMD0: Slave Select Mode. Selects between the following NSS operation modes: (See Section "16.2. SPI0 Master Mode Operation" on page 155 and Section "16.3. SPI0 Slave Mode Operation" on page 157). 00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin. 01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device. 1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will assume the value of NSSMD0. TXBMT: Transmit Buffer Empty. This bit will be set to logic 0 when new data has been written to the transmit buffer. When data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer. SPIEN: SPI0 Enable. This bit enables/disables the SPI. 0: SPI disabled. 1: SPI enabled.
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Figure 16.10. SPI0CKR: SPI0 Clock Rate Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7
Bit7
SCR6
Bit6
SCR5
Bit5
SCR4
Bit4
SCR3
Bit3
SCR2
Bit2
SCR1
Bit1
SCR0
Bit0
00000000
SFR Address: 0xA2
Bits 7-0:
SCR7-SCR0: SPI0 Clock Rate. These bits determine the frequency of the SCK output when the SPI0 module is configured for master mode operation. The SCK clock frequency is a divided version of the system clock, and is given in the following equation, where SYSCLK is the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK f SCK = -----------------------------------------------2 x ( SPI0CKR + 1 )
for 0 <= SPI0CKR <= 255 Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000 f SCK = ------------------------2 x (4 + 1)
f SCK = 200kHz
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Figure 16.11. SPI0DAT: SPI0 Data Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA3 Reset Value
00000000
Bits 7-0:
SPI0DAT: SPI0 Transmit and Receive Data. The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT places the data into the transmit buffer and initiates a transfer when in Master Mode. A read of SPI0DAT returns the contents of the receive buffer.
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Preliminary
Figure 16.12. SPI Master Timing (CKPHA = 0)
SCK* T T
MCKH
MCKL
T
MIS
T
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 16.13. SPI Master Timing (CKPHA = 1)
SCK* T T
MCKH
MCKL
T
MIS
T
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
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Figure 16.14. SPI Slave Timing (CKPHA = 0)
NSS T T T
SE
CKL
SD
SCK* T
CKH
T
SIS
T
SIH
MOSI
T
SEZ
T
SOH
T
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 16.15. SPI Slave Timing (CKPHA = 1)
NSS T T T
SE
CKL
SD
SCK* T
CKH
T
SIS
T
SIH
MOSI
T
T
SEZ
SOH
T
SLH
T
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
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Preliminary
Table 16.1. SPI Slave Timing Parameters
PARAMETER DESCRIPTION MIN MAX UNITS MASTER MODE TIMING (See Figure 16.12 and Figure 16.13) TMCKH TMCKL TMIS TMIH SCK High Time SCK Low Time MISO Valid to SCK Shift Edge SCK Shift Edge to MISO Change 1*TSYSCLK 1*TSYSCLK 1*TSYSCLK + 20 0 ns ns ns ns
SLAVE MODE TIMING (See Figure 16.14 and Figure 16.15) TSE TSD TSEZ TSDZ TCKH TCKL TSIS TSIH TSOH TSLH
NSS Falling to First SCK Edge Last SCK Edge to NSS Rising NSS Falling to MISO Valid NSS Rising to MISO High-Z SCK High Time SCK Low Time MOSI Valid to SCK Sample Edge SCK Sample Edge to MOSI Change SCK Shift Edge to MISO Change Last SCK Edge to MISO Change (CKPHA = 1 ONLY)
2*TSYSCLK 2*TSYSCLK 4*TSYSCLK 4*TSYSCLK 5*TSYSCLK 5*TSYSCLK 2*TSYSCLK 2*TSYSCLK 4*TSYSCLK 6*TSYSCLK 8*TSYSCLK
ns ns ns ns ns ns ns ns ns ns
TSYSCLK is equal to one period of the device system clock (SYSCLK).
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17.
TIMERS
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the standard 8051, and two are 16-bit auto-reload timer for use with the ADC, SMBus, or for general purpose use. These timers can be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0 and Timer 1 are nearly identical and have four primary modes of operation. Timer 2 and Timer 3 offer 16-bit and split 8bit timer functionality with auto-reload. Timer 0 and Timer 1 Modes: Timer 2 Modes: 13-bit counter/timer 16-bit timer with auto-reload 16-bit counter/timer 8-bit counter/timer with auto-reload Two 8-bit timers with auto-reload Two 8-bit counter/timers (Timer 0 only) Timer 3 Modes: 16-bit timer with auto-reload Two 8-bit timers with auto-reload
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M-T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock from which Timer 0 and/or Timer 1 may be clocked (See Figure 17.6 for pre-scaled clock selection). Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator clock source divided by 8. Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer register is incremented on each high-to-low transition at the selected input pin (T0 or T1). Events with a frequency of up to onefourth the system clock's frequency can be counted. The input signal need not be periodic, but it should be held at a given level for at least two full system clock cycles to ensure the level is properly sampled.
17.1.
Timer 0 and Timer 1
Each timer is implemented as 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1) and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0 and Timer 1 as well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register (Section "8.3.5. Interrupt Register Descriptions" on page 61); Timer 1 interrupts can be enabled by setting the ET1 bit in the IE register (Section 8.3.5). Both counter/timers operate in one of four primary modes selected by setting the Mode Select bits T1M1T0M0 in the Counter/Timer Mode register (TMOD). Each timer can be configured independently. Each operating mode is described below.
17.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same manner as described for Timer 0. The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions TL0.4TL0.0. The three upper bits of TL0 (TL0.7-TL0.5) are indeterminate and should be masked out or ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to 0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are enabled. The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section "13.1. Priority Crossbar Decoder" on page 111 for information on selecting and configuring external I/O pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock Scale bits in CKCON (see Figure 17.6). (c) 2003 Cygnal Integrated Products, Inc. DS009-1.3b MAY03
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Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal /INT0 is active as defined by bit IN0PL in register INT01CF (see Figure 8.13). Setting GATE0 to `1' allows the timer to be controlled by the external input signal /INT0 (see Section "8.3.5. Interrupt Register Descriptions" on page 61), facilitating pulse width measurements. TR0 GATE0 0 X 1 0 1 1 1 1 X = Don't Care /INT0 X X 0 1 Counter/Timer Disabled Enabled Disabled Enabled
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial value before the timer is enabled. TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0. Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The input signal /INT1 is used with Timer 1; the /INT1 polarity is defined by bit IN1PL in register INT01CF (see Figure 8.13).
Figure 17.1. T0 Mode 0 Block Diagram
CKCON
TTTTTTSS 3 3 2 2 1 0 CC MMMMMM A A HLHL 10
G A T E 1 C / T 1
TMOD
TTG 11A MM T 10E 0 C / T 0 TT 00 MM 10 I N 1 P L
INT01CF
I N 1 S L 2 I N 1 S L 1 I N 1 S L 0 I N 0 P L I N 0 S L 2 I N 0 S L 1 I N 0 S L 0
Pre-scaled Clock
0 0
SYSCLK
1 1
T0 TR0 GATE0 Crossbar
TCLK
/INT0
IN0PL
XOR
17.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
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TCON
TL0 (5 bits)
TH0 (8 bits)
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt
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17.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from all ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be correct. When in Mode 2, Timer 1 operates identically to Timer 0. Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0 is active as defined by bit IN0PL in register INT01CF (see Section "8.3.2. External Interrupts" on page 59 for details on the external input signals /INT0 and /INT1).
Figure 17.2. T0 Mode 2 Block Diagram
CKCON
TTTTTTSS 3 3 2 2 1 0CC MMMMMM A A HLHL 10
G A T E 1 C / T 1
TMOD
TTG 11A MM T 10E 0 C / T 0 TT 00 MM 10 I N 1 P L
INT01CF
I N 1 S L 2 I N 1 S L 1 I N 1 S L 0 I N 0 P L I N 0 S L 2 I N 0 S L 1 I N 0 S L 0
Pre-scaled Clock
0 0
SYSCLK
1 1
T0
TCLK
TL0 (8 bits) TCON
TR0 Crossbar GATE0 TH0 (8 bits) /INT0 IN0PL
XOR
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt
Reload
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17.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the Timer 1 interrupt. Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0, 1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However, the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode settings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1, configure it for Mode 3.
Figure 17.3. T0 Mode 3 Block Diagram
CKCON
TTTTTTS 332210C MMMMMM A HLHL 1 S C A 0
G A T E 1 C / T 1
TMOD
T 1 M 1 T 1 M 0 G A T E 0 C / T 0 TT 00 MM 10
Pre-scaled Clock
0 TR1 TH0 (8 bits) TCON
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt Interrupt
SYSCLK
1 0
1 T0 TL0 (8 bits) TR0 Crossbar GATE0
/INT0
IN0PL
XOR
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Figure 17.4. TCON: Timer Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF1
Bit7
TR1
Bit6
TF0
Bit5
TR0
Bit4
IE1
Bit3
IT1
Bit2
IE0
Bit1
IT0
Bit0 (bit addressable)
00000000
SFR Address:
0x88
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF1: Timer 1 Overflow Flag. Set by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine. 0: No Timer 1 overflow detected. 1: Timer 1 has overflowed. TR1: Timer 1 Run Control. 0: Timer 1 disabled. 1: Timer 1 enabled. TF0: Timer 0 Overflow Flag. Set by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine. 0: No Timer 0 overflow detected. 1: Timer 0 has overflowed. TR0: Timer 0 Run Control. 0: Timer 0 disabled. 1: Timer 0 enabled. IE1: External Interrupt 1. This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine if IT1 = 1. When IT1 = 0, this flag is set to `1' when /INT1 is active as defined by bit IN1PL in register INT01CF (see Figure 8.13). IT1: Interrupt 1 Type Select. This bit selects whether the configured /INT1 interrupt will be edge or level sensitive. /INT1 is configured active low or high by the IN1PL bit in the IT01CF register (see Figure 8.13). 0: /INT1 is level triggered. 1: /INT1 is edge triggered. IE0: External Interrupt 0. This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine if IT0 = 1. When IT0 = 0, this flag is set to `1' when /INT0 is active as defined by bit IN0PL in register INT01CF (see Figure 8.13). IT0: Interrupt 0 Type Select. This bit selects whether the configured /INT0 interrupt will be edge or level sensitive. /INT0 is configured active low or high by the IN0PL bit in register IT01CF (see Figure 8.13). 0: /INT0 is level triggered. 1: /INT0 is edge triggered.
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Figure 17.5. TMOD: Timer Mode Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
GATE1
Bit7
C/T1
Bit6
T1M1
Bit5
T1M0
Bit4
GATE0
Bit3
C/T0
Bit2
T0M1
Bit1
T0M0
Bit0
00000000
SFR Address:
0x89 Bit7: GATE1: Timer 1 Gate Control. 0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level. 1: Timer 1 enabled only when TR1 = 1 AND /INT1 is active as defined by bit IN1PL in register INT01CF (see Figure 8.13). C/T1: Counter/Timer 1 Select. 0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4). 1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin (T1). T1M1-T1M0: Timer 1 Mode Select. These bits select the Timer 1 operation mode. T1M1 0 0 1 1 Bit3: T1M0 0 1 0 1 Mode Mode 0: 13-bit counter/timer Mode 1: 16-bit counter/timer Mode 2: 8-bit counter/timer with auto-reload Mode 3: Timer 1 inactive
Bit6:
Bits5-4:
Bit2:
Bits1-0:
GATE0: Timer 0 Gate Control. 0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level. 1: Timer 0 enabled only when TR0 = 1 AND /INT0 is active as defined by bit IN0PL in register INT01CF (see Figure 8.13). C/T0: Counter/Timer Select. 0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3). 1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin (T0). T0M1-T0M0: Timer 0 Mode Select. These bits select the Timer 0 operation mode. T0M1 0 0 1 1 T0M0 0 1 0 1 Mode Mode 0: 13-bit counter/timer Mode 1: 16-bit counter/timer Mode 2: 8-bit counter/timer with auto-reload Mode 3: Two 8-bit counter/timers
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Figure 17.6. CKCON: Clock Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
T3MH
Bit7
T3ML
Bit6
T2MH
Bit5
T2ML
Bit4
T1M
Bit3
T0M
Bit2
SCA1
Bit1
SCA0
Bit0
00000000
SFR Address:
0x8E Bit7: T3MH: Timer 3 High Byte Clock Select. This bit selects the clock supplied to the Timer 3 high byte if Timer 3 is configured in split 8-bit timer mode. T3MH is ignored if Timer 3 is in any other mode. 0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN. 1: Timer 3 high byte uses the system clock. T3ML: Timer 3 Low Byte Clock Select. This bit selects the clock supplied to Timer 3. If Timer 3 is configured in split 8-bit timer mode, this bit selects the clock supplied to the lower 8-bit timer. 0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN. 1: Timer 3 low byte uses the system clock. T2MH: Timer 2 High Byte Clock Select. This bit selects the clock supplied to the Timer 2 high byte if Timer 2 is configured in split 8-bit timer mode. T2MH is ignored if Timer 2 is in any other mode. 0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN. 1: Timer 2 high byte uses the system clock. T2ML: Timer 2 Low Byte Clock Select. This bit selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer mode, this bit selects the clock supplied to the lower 8-bit timer. 0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN. 1: Timer 2 low byte uses the system clock. T1M: Timer 1 Clock Select. This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1. 0: Timer 1 uses the clock defined by the prescale bits, SCA1-SCA0. 1: Timer 1 uses the system clock. T0M: Timer 0 Clock Select. This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to logic 1. 0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0. 1: Counter/Timer 0 uses the system clock. SCA1-SCA0: Timer 0/1 Prescale Bits. These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured to use prescaled clock inputs. SCA1 SCA0 Prescaled Clock 0 0 System clock divided by 12 0 1 System clock divided by 4 1 0 System clock divided by 48 1 1 External clock divided by 8 Note: External clock divided by 8 is synchronized with the system clock, and the external clock must be less than or equal to the system clock to operate in this mode.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bits1-0:
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Figure 17.7. TL0: Timer 0 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x8A Bits 7-0: TL0: Timer 0 Low Byte. The TL0 register is the low byte of the 16-bit Timer 0.
Figure 17.8. TL1: Timer 1 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x8B Bits 7-0: TL1: Timer 1 Low Byte. The TL1 register is the low byte of the 16-bit Timer 1.
Figure 17.9. TH0: Timer 0 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x8C Bits 7-0: TH0: Timer 0 High Byte. The TH0 register is the high byte of the 16-bit Timer 0.
Figure 17.10. TH1: Timer 1 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x8D Bits 7-0: TH1: Timer 1 High Byte. The TH1 register is the high byte of the 16-bit Timer 1.
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17.2.
Timer 2
Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TL2 (low byte) and TH2 (high byte). Timer 2 may operate in 16bit auto-reload mode or (split) 8-bit auto-reload mode. The T2SPLIT bit (TMR2CN.3) defines the Timer 2 operation mode. Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
17.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT (TMR2CN.3) is zero, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2 reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 17.11, and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TL2) overflow from 0xFF to 0x00.
Figure 17.11. Timer 2 16-Bit Mode Block Diagram
CKCON
TTTTTTSS 3 3 2 2 1 0 CC T2XCLK M M M M M M A A HLHL 10
SYSCLK / 12
0 0
TR2 TCLK
To SMBus TL2 Overflow
To ADC, SMBus
External Clock / 8 SYSCLK
1
TMR2CN
1
TL2
TH2
TF2H TF2L TF2LEN T2SPLIT TR2 T2XCLK
Interrupt
TMR2RLL TMR2RLH
Reload
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17.2.2. 8-bit Timers with Auto-Reload
Preliminary
When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TH2 and TL2). Both 8-bit timers operate in auto-reload mode as shown in Figure 17.12. TMR2RLL holds the reload value for TL2; TMR2RLH holds the reload value for TH2. The TR2 bit in TMR2CN handles the run control TH2. TL2 is always running when configured for 8-bit Mode. Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows: T2MH 0 0 1 T2XCLK 0 1 X TH2 Clock Source SYSCLK / 12 External Clock / 8 SYSCLK T2ML 0 0 1 T2XCLK 0 1 X TL2 Clock Source SYSCLK / 12 External Clock / 8 SYSCLK
Note: External clock divided by 8 is synchronized with the system clock, and the external clock must be less than or equal to the system clock to operate in this mode. The TF2H bit is set when TH2 overflows from 0xFF to 0x00; the TF2L bit is set when TL2 overflows from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time TH2 overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is generated each time either TL2 or TH2 overflows. When TF2LEN is enabled, software must check the TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags are not cleared by hardware and must be manually cleared by software.
Figure 17.12. Timer 2 8-Bit Mode Block Diagram
CKCON T2XCLK
TTTTTTSS 3 3 2 2 1 0 CC MMMMMMA A HLHL 10
TMR2RLH
Reload
To SMBus
SYSCLK / 12
0 0
External Clock / 8
1 TR2 1
TCLK
TH2 TMR2CN
TF2H TF2L TF2LEN T2SPLIT TR2 T2XCLK
Interrupt
TMR2RLL SYSCLK
Reload
1 TCLK 0 TL2 To ADC, SMBus
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Figure 17.13. TMR2CN: Timer 2 Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF2H
Bit7
TF2L
Bit6
TF2LEN
Bit5
Bit4
T2SPLIT
Bit3
TR2
Bit2
Bit1
T2XCLK
Bit0 (bit addressable)
00000000
SFR Address:
0xC8
Bit7:
Bit6:
Bit5:
Bit4: Bit3:
Bit2:
Bit1: Bit0:
TF2H: Timer 2 High Byte Overflow Flag. Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode, this will occur when Timer 2 overflows from 0xFFFF to 0x0000. When the Timer 2 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine. TF2H is not automatically cleared by hardware and must be cleared by software. TF2L: Timer 2 Low Byte Overflow Flag. Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. When this bit is set, an interrupt will be generated if TF2LEN is set and Timer 2 interrupts are enabled. TF2L will set when the low byte overflows regardless of the Timer 2 mode. This bit is not automatically cleared by hardware. TF2LEN: Timer 2 Low Byte Interrupt Enable. This bit enables/disables Timer 2 Low Byte interrupts. If TF2LEN is set and Timer 2 interrupts are enabled, an interrupt will be generated when the low byte of Timer 2 overflows. This bit should be cleared when operating Timer 2 in 16-bit mode. 0: Timer 2 Low Byte interrupts disabled. 1: Timer 2 Low Byte interrupts enabled. UNUSED. Read = 0b. Write = don't care. T2SPLIT: Timer 2 Split Mode Enable. When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload. 0: Timer 2 operates in 16-bit auto-reload mode. 1: Timer 2 operates as two 8-bit auto-reload timers. TR2: Timer 2 Run Control. This bit enables/disables Timer 2. In 8-bit mode, this bit enables/disables TH2 only; TL2 is always enabled in this mode. 0: Timer 2 disabled. 1: Timer 2 enabled. UNUSED. Read = 0b. Write = don't care. T2XCLK: Timer 2 External Clock Select. This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this bit selects the external oscillator clock source for both timer bytes. However, the Timer 2 Clock Select bits (T2MH and T2ML in register CKCON) may still be used to select between the external clock and the system clock for either timer. 0: Timer 2 external clock selection is the system clock divided by 12. 1: Timer 2 external clock selection is the external clock divided by 8. Note that the external oscillator source divided by 8 is synchronized with the system clock.
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Figure 17.14. TMR2RLL: Timer 2 Reload Register Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xCA Bits 7-0: TMR2RLL: Timer 2 Reload Register Low Byte. TMR2RLL holds the low byte of the reload value for Timer 2.
Figure 17.15. TMR2RLH: Timer 2 Reload Register High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xCB Bits 7-0: TMR2RLH: Timer 2 Reload Register High Byte. The TMR2RLH holds the high byte of the reload value for Timer 2.
Figure 17.16. TMR2L: Timer 2 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xCC Bits 7-0: TMR2L: Timer 2 Low Byte. In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8-bit mode, TMR2L contains the 8-bit low byte timer value.
Figure 17.17. TMR2H Timer 2 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xCD Bits 7-0: TMR2H: Timer 2 High Byte. In 16-bit mode, the TMR2H register contains the high byte of the 16-bit Timer 2. In 8-bit mode, TMR2H contains the 8-bit high byte timer value.
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17.3.
Timer 3
Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3SPLIT bit (TMR3CN.3) defines the Timer 3 operation mode. Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
17.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3 reload registers (TMR3RLH and TM32RLL) is loaded into the Timer 3 register as shown in Figure 17.11, and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled (if IE.5 is set), an interrupt will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and the TF3LEN bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TL3) overflow from 0xFF to 0x00.
Figure 17.18. Timer 3 16-Bit Mode Block Diagram
CKCON
TTTTTTSS 3 3 2 2 1 0 CC T3XCLK M M M M M M A A HLHL 10
SYSCLK / 12
0 0
TR3 TCLK
To ADC
External Clock / 8 SYSCLK
1
TMR3CN
1
TL3
TH3
TF3H TF3L TF3LEN T3SPLIT TR3 T3XCLK
Interrupt
TMR3RLL TMR3RLH
Reload
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17.3.2. 8-bit Timers with Auto-Reload
Preliminary
When T3SPLIT is set, Timer 3 operates as two 8-bit timers (TH3 and TL3). Both 8-bit timers operate in auto-reload mode as shown in Figure 17.12. TMR3RLL holds the reload value for TL3; TMR3RLH holds the reload value for TH3. The TR3 bit in TMR3CN handles the run control TH3. TL3 is always running when configured for 8-bit Mode. Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows: T3MH 0 0 1 T3XCLK 0 1 X TH3 Clock Source SYSCLK / 12 External Clock / 8 SYSCLK T3ML 0 0 1 T3XCLK 0 1 X TL3 Clock Source SYSCLK / 12 External Clock / 8 SYSCLK
Note: External clock divided by 8 is synchronized with the system clock, and the external clock must be less than or equal to the system clock to operate in this mode. The TF3H bit is set when TH3 overflows from 0xFF to 0x00; the TF3L bit is set when TL3 overflows from 0xFF to 0x00. When Timer 3 interrupts are enabled (IE.5), an interrupt is generated each time TH3 overflows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each time either TL3 or TH3 overflows. When TF3LEN is enabled, software must check the TF3H and TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not cleared by hardware and must be manually cleared by software.
Figure 17.19. Timer 3 8-Bit Mode Block Diagram
CKCON T3XCLK
TTTTTTSS 3 3 2 2 1 0 CC MMMMMM A A HLHL 10
TMR3RLH
Reload
SYSCLK / 12
0 0
External Clock / 8
1 TR3 1
TCLK
TH3 TMR3CN
TF3H TF3L TF3LEN T3SPLIT TR3 T3XCLK
Interrupt
TMR3RLL SYSCLK
Reload
1 TCLK 0 TL3 To ADC
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Figure 17.20. TMR3CN: Timer 3 Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF3H
Bit7
TF3L
Bit6
TF3LEN
Bit5
Bit4
T3SPLIT
Bit3
TR3
Bit2
Bit1
T3XCLK
Bit0
00000000
SFR Address:
0x91 Bit7: TF3H: Timer 3 High Byte Overflow Flag. Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode, this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the Timer 3 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine. TF3H is not automatically cleared by hardware and must be cleared by software. TF3L: Timer 3 Low Byte Overflow Flag. Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. When this bit is set, an interrupt will be generated if TF3LEN is set and Timer 3 interrupts are enabled. TF3L will set when the low byte overflows regardless of the Timer 3 mode. This bit is not automatically cleared by hardware. TF3LEN: Timer 3 Low Byte Interrupt Enable. This bit enables/disables Timer 3 Low Byte interrupts. If TF3LEN is set and Timer 3 interrupts are enabled, an interrupt will be generated when the low byte of Timer 3 overflows. This bit should be cleared when operating Timer 3 in 16-bit mode. 0: Timer 3 Low Byte interrupts disabled. 1: Timer 3 Low Byte interrupts enabled. UNUSED. Read = 0b. Write = don't care. T3SPLIT: Timer 3 Split Mode Enable. When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload. 0: Timer 3 operates in 16-bit auto-reload mode. 1: Timer 3 operates as two 8-bit auto-reload timers. TR3: Timer 3 Run Control. This bit enables/disables Timer 3. In 8-bit mode, this bit enables/disables TH3 only; TL3 is always enabled in this mode. 0: Timer 3 disabled. 1: Timer 3 enabled. UNUSED. Read = 0b. Write = don't care. T3XCLK: Timer 3 External Clock Select. This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock Select bits (T3MH and T3ML in register CKCON) may still be used to select between the external clock and the system clock for either timer. 0: Timer 3 external clock selection is the system clock divided by 12. 1: Timer 3 external clock selection is the external clock divided by 8. Note that the external oscillator source divided by 8 is synchronized with the system clock.
Bit6:
Bit5:
Bit4: Bit3:
Bit2:
Bit1: Bit0:
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Preliminary
Figure 17.21. TMR3RLL: Timer 3 Reload Register Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x92 Bits 7-0: TMR3RLL: Timer 3 Reload Register Low Byte. TMR3RLL holds the low byte of the reload value for Timer 3.
Figure 17.22. TMR3RLH: Timer 3 Reload Register High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x93 Bits 7-0: TMR3RLH: Timer 3 Reload Register High Byte. The TMR3RLH holds the high byte of the reload value for Timer 3.
Figure 17.23. TMR3L: Timer 3 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x94 Bits 7-0: TMR3L: Timer 3 Low Byte. In 16-bit mode, the TMR3L register contains the low byte of the 16-bit Timer 3. In 8-bit mode, TMR3L contains the 8-bit low byte timer value.
Figure 17.24. TMR3H Timer 3 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0x95 Bits 7-0: TMR3H: Timer 3 High Byte. In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In 8-bit mode, TMR3H contains the 8-bit high byte timer value.
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18.
PROGRAMMABLE COUNTER ARRAY
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer and five 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line (CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section "13.1. Priority Crossbar Decoder" on page 111 for details on configuring the Crossbar). The counter/timer is driven by a programmable timebase that can select between six sources: system clock, system clock divided by four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an external clock signal on the ECI input pin. Each capture/compare module may be configured to operate independently in one of six modes: Edge-Triggered Capture, Software Timer, HighSpeed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM (each mode is described in Section "18.2. Capture/ Compare Modules" on page 185). The external oscillator clock option is ideal for real-time clock (RTC) functionality, allowing the PCA to be clocked by a precision external oscillator while the internal oscillator drives the system clock. The PCA is configured and controlled through the system controller's Special Function Registers. The PCA block diagram is shown in Figure 18.1 Important Note: The PCA Module 4 may be used as a watchdog timer (WDT), and is enabled in this mode following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled. See Section 18.3 for details.
Figure 18.1. PCA Block Diagram
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 PCA CLOCK MUX 16-Bit Counter/Timer
Capture/Compare Module 0
Capture/Compare Module 1
Capture/Compare Module 2
Capture/Compare Module 3
Capture/Compare Module 4 / WDT
CEX0
CEX1
CEX2
CEX3
CEX4
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ECI
Crossbar
Port I/O
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18.1. PCA Counter/Timer
Preliminary
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte (MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches the value of PCA0H into a "snapshot" register; the following PCA0H read accesses this "snapshot" register. Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter. Reading PCA0H or PCA0L does not disturb the counter operation. The CPS2-CPS0 bits in the PCA0MD register select the timebase for the counter/timer as shown in Table 18.1. Note that in `External oscillator source divided by 8' mode, the external oscillator source is synchronized with the system clock, and must have a frequency less than or equal to the system clock. When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle mode.
Table 18.1. PCA Timebase Input Options
CPS2 0 0 0 0 1 1
CPS1 0 0 1 1 0 0
CPS0 0 1 0 1 0 1
Timebase System clock divided by 12 System clock divided by 4 Timer 0 overflow High-to-low transitions on ECI (max rate = system clock divided by 4) System clock External oscillator source divided by 8
External oscillator source divided by 8 is synchronized with the system clock.
Figure 18.2. PCA Counter/Timer Block Diagram
IDLE
PCA0MD
CWW I DD DT L LEC K C P S 2 CCE PPC SSF 10
PCA0CN
CC FR C C F 4 CC CC FF 32 CC CC FF 10
PCA0L read
To SFR Bus
Snapshot Register
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 000 001 010 011 100 101 0 1
PCA0H
PCA0L
Overflow CF To PCA Modules
To PCA Interrupt System
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18.2.
Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 system controller. These registers are used to exchange data with a module and configure the module's mode of operation. Table 18.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA capture/compare module's operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1. See Figure 18.3 for details on the PCA interrupt configuration.
Table 18.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM X X X X X X 0 1 X X X CAPP CAPN 1 0 1 0 1 1 0 0 0 0 0 MAT 0 0 0 1 1 X X X TOG 0 0 0 0 1 1 0 0 PWM ECCF 0 0 0 0 0 1 1 1 X X X X X X X X Operation Mode Capture triggered by positive edge on CEXn Capture triggered by negative edge on CEXn Capture triggered by transition on CEXn Software Timer High Speed Output Frequency Output 8-Bit Pulse Width Modulator 16-Bit Pulse Width Modulator
1 0 1 0 1 0 1 0 1 0 X = Don't Care
Figure 18.3. PCA Interrupt Block Diagram
(for n = 0 to 4)
PCA0CPMn
P ECCMT P E WC A A A OWC MOPP TGMC 1 MP N n n n F 6nnn n n PCA Counter/ Timer Overflow
PCA0CN
CC FR CCCCC CCCCC FFFFF 43210
PCA0MD
C WW I DD DTL L EC K CCCE PPPC SSSF 210
0 1
ECCF0
PCA Module 0 (CCF0)
ECCF1
0 1
EPCA0
0 1
EA
0 1
Interrupt Priority Decoder
PCA Module 1 (CCF1)
ECCF2
0 1
PCA Module 2 (CCF2)
ECCF3
0 1
PCA Module 3 (CCF3)
ECCF4
0 1
PCA Module 4 (CCF4)
0 1
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18.2.1. Edge-triggered Capture Mode
Preliminary
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA counter/timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transition that triggers the capture: low-tohigh transition (positive edge), high-to-low transition (negative edge), or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the state of the Port pin associated with CEXn can be read directly to determine whether a rising-edge or falling-edge caused the capture.
Figure 18.4. PCA Capture Mode Diagram
PCA Interrupt
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MPN n n n F 6nnn n n
x0 x00x
PCA0CN
CC FR CCCCC CCCCC FFFFF 43210
(to CCFn)
PCA0CPLn
PCA0CPHn
0
Port I/O
Crossbar
CEXn
1 0 1 PCA Timebase
Capture
PCA0L
PCA0H
Note: The CEXn input signal must remain high or low for at least 2 system clock cycles in order to be valid.
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18.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software Timer mode. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to `0'; writing to PCA0CPHn sets ECOMn to `1'.
Figure 18.5. PCA Software Timer Mode Diagram
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
ENB
PCA Interrupt
1
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MP N n n n F 6nnn n n
x 00 00x Enable Match 0 1
PCA0CN PCA0CPLn PCA0CPHn
CC FR CCCCC CCCCC FFFFF 43210
16-bit Comparator
PCA Timebase
PCA0L
PCA0H
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18.2.3. High Speed Output Mode
Preliminary
In High Speed Output mode, a module's associated CEXn pin is toggled each time a match occurs between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-Speed Output mode. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to `0'; writing to PCA0CPHn sets ECOMn to `1'.
Figure 18.6. PCA High Speed Output Mode Diagram
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
PCA0CPMn
ENB
1
P ECCMT P E WC A A AOWC MOPP TGMC 1 MP N n n n F n 6nnn n
x 00 0x PCA Interrupt
PCA0CN PCA0CPLn PCA0CPHn
CC FR CCCCC CCCCC FFFFF 43210
Enable
16-bit Comparator
Match
0 1
TOGn
Toggle
0 CEXn 1
Crossbar
Port I/O
PCA Timebase
PCA0L
PCA0H
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18.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module's associated CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the output is toggled. The frequency of the square wave is then defined by Equation 18.1.
Equation 18.1. Square Wave Frequency Output F PCA F CEXn = ---------------------------------------2 x PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation. Where FPCA is the frequency of the clock selected by the CPS2-0 bits in the PCA mode register, PCA0MD. The lower byte of the capture/compare module is compared to the PCA counter low byte; on a match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn register.
Figure 18.7. PCA Frequency Output Mode
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
PCA0CPMn
ENB
1
P ECCMT P E WC A A A OWC MOPP TGMC 1 MP N n n n F 6nnn n n
x 000 x Enable
PCA0CPLn
8-bit Adder
Adder Enable
PCA0CPHn
TOGn
Toggle 8-bit Comparator
match
0 CEXn 1
Crossbar
Port I/O
PCA Timebase
PCA0L
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18.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate a pulse width modulated (PWM) output on its associated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register. When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be reset (see Figure 18.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00, PCA0CPLn is reloaded automatically with the value stored in the module's capture/compare high byte (PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register enables 8-Bit Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 18.2. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to `0'; writing to PCA0CPHn sets ECOMn to `1'.
Equation 18.2. 8-Bit PWM Duty Cycle ( 256 - PCA0CPHn ) DutyCycle = -------------------------------------------------256
Using Equation 18.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is 0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to `0'.
Figure 18.8. PCA 8-Bit PWM Mode Diagram
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
PCA0CPHn
ENB
1
PCA0CPMn
P ECCMT P E WC A A A OWC MOPP TGMC 1 MP N n n n F 6nnn n n
0 00x0 x Enable
PCA0CPLn
8-bit Comparator
match
S
SET
Q
CEXn
Crossbar
Port I/O
R
PCA Timebase
CLR
Q
PCA0L
Overflow
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18.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare module defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by Equation 18.3. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to `0'; writing to PCA0CPHn sets ECOMn to `1'.
Equation 18.3. 16-Bit PWM Duty Cycle ( 65536 - PCA0CPn ) DutyCycle = ---------------------------------------------------65536
Using Equation 18.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is 0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to `0'.
Figure 18.9. PCA 16-Bit PWM Mode
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
ENB
1
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MPN n n n F 6nnn n n
1 00x0 x Enable
PCA0CPHn
PCA0CPLn
16-bit Comparator
match
S
SET
Q
CEXn
Crossbar
Port I/O
R
PCA Timebase
CLR
Q
PCA0H
PCA0L
Overflow
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18.3. Watchdog Timer Mode
Preliminary
A programmable watchdog timer (WDT) function is available through the PCA Module 4. The WDT is used to generate a reset if the time between writes to the WDT update register (PCA0CPH4) exceed a specified limit. The WDT can be configured and enabled/disabled as needed by software. With the WDTE bit set in the PCA0MD register, Module 4 operates as a watchdog timer (WDT). The Module 4 high byte is compared to the PCA counter high byte; the Module 4 low byte holds the offset to be used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some PCA registers are restricted while the Watchdog Timer is enabled.
18.3.1. Watchdog Timer Operation
While the WDT is enabled: * * * * * * PCA counter is forced on. Writes to PCA0L and PCA0H are not allowed. PCA clock source bits (CPS2-CPS0) are frozen. PCA Idle control bit (CIDL) is frozen. Module 4 is forced into software timer mode. Writes to the Module 4 mode register (PCA0CPM4) are disabled.
While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run until the WDT is disabled. The PCA counter run control (CR) will read zero if the WDT is enabled but user software has not enabled the PCA counter. If a match occurs between PCA0CPH4 and PCA0H while the WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a write of any value to PCA0CPH4. Upon a PCA0CPH4 write, PCA0H plus the offset held in PCA0CPL4 is loaded into PCA0CPH4 (See Figure 18.10).
Figure 18.10. PCA Module 4 with Watchdog Timer Enabled
PCA0MD
CWW I DD DT L LEC K CCCE PPPC SSSF 210
PCA0CPH4
Enable
8-bit Comparator
Match
Reset
PCA0CPL4
8-bit Adder
Adder Enable
PCA0H
PCA0L Overflow
Write to PCA0CPH4
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Note that the 8-bit offset held in PCA0CPH4 is compared to the upper byte of the 16-bit PCA counter. This offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The total offset is then given (in PCA clocks) by Equation 18.4, where PCA0L is the value of the PCA0L register at the time of the update.
Equation 18.4. Watchdog Timer Offset in PCA Clocks Offset = ( 256 x PCA0CPL4 ) + ( 256 - PCA0L )
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH4 and PCA0H. Software may force a WDT reset by writing a `1' to the CCF4 flag (PCA0CN.4) while the WDT is enabled.
18.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks: * * * * * Disable the WDT by writing a `0' to the WDTE bit. Select the desired PCA clock source (with the CPS2-CPS0 bits). Load PCA0CPL4 with the desired WDT update offset value. Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle mode). Enable the WDT by setting the WDTE bit to `1'.
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing the WDTE bit. The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by 12, PCA0L defaults to 0x00, and PCA0CPL4 defaults to 0x00. Using Equation 18.4, this results in a WDT timeout interval of 256 system clock cycles. Table 18.3 lists some example timeout intervals for typical system clocks.
Table 18.3. Watchdog Timer Timeout Intervals
System Clock (Hz) 24,500,000 24,500,000 24,500,000 18,432,000 18,432,000 18,432,000 11,059,200 11,059,200 11,059,200 3,060,000 3,060,000 3,060,000 32,000 32,000 32,000
PCA0CPL4 255 128 32 255 128 32 255 128 32 255 128 32 255 128 32
Timeout Interval (ms) 32.1 16.2 4.1 42.7 21.5 5.5 71.1 35.8 9.2 257 129.5 33.1 24576 12384 3168
Assumes SYSCLK / 12 as the PCA clock source, and a PCA0L value of 0x00 at the update time. Internal oscillator reset frequency.
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18.4.
Preliminary
Register Descriptions for PCA Figure 18.11. PCA0CN: PCA Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Following are detailed descriptions of the special function registers related to the operation of the PCA.
CF
Bit7
CR
Bit6
Bit5
CCF4
Bit4
CCF3
Bit3
CCF2
Bit2
CCF1
Bit1
CCF0
Bit0 (bit addressable)
00000000
SFR Address:
0xD8
Bit7:
Bit6:
Bit5: Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
CF: PCA Counter/Timer Overflow Flag. Set by hardware when the PCA Counter/Timer overflows from 0xFFFF to 0x0000. When the Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CR: PCA Counter/Timer Run Control. This bit enables/disables the PCA Counter/Timer. 0: PCA Counter/Timer disabled. 1: PCA Counter/Timer enabled. UNUSED. Read = 0b, Write = don't care. CCF4: PCA Module 4 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF3: PCA Module 3 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF2: PCA Module 2 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF1: PCA Module 1 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF0: PCA Module 0 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software.
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Figure 18.12. PCA0MD: PCA Mode Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CIDL
Bit7
WDTE
Bit6
WDLCK
Bit5
Bit4
CPS2
Bit3
CPS1
Bit2
CPS0
Bit1
ECF
Bit0
01000000
SFR Address:
0xD9 Bit7: CIDL: PCA Counter/Timer Idle Control. Specifies PCA behavior when CPU is in Idle Mode. 0: PCA continues to function normally while the system controller is in Idle Mode. 1: PCA operation is suspended while the system controller is in Idle Mode. WDTE: Watchdog Timer Enable If this bit is set, PCA Module 4 is used as the watchdog timer. 0: Watchdog Timer disabled. 1: PCA Module 4 enabled as Watchdog Timer. WDLCK: Watchdog Timer Lock This bit locks/unlocks the Watchdog Timer Enable. When WDLCK is set, the Watchdog Timer may not be disabled until the next system reset. 0: Watchdog Timer Enable unlocked. 1: Watchdog Timer Enable locked. UNUSED. Read = 0b, Write = don't care. CPS2-CPS0: PCA Counter/Timer Pulse Select. These bits select the timebase source for the PCA counter. CPS2 0 0 0 0 1 1 1 1
Bit6:
Bit5:
Bit4: Bits3-1:
CPS1 0 0 1 1 0 0 1 1
CPS0 0 1 0 1 0 1 0 1
Timebase System clock divided by 12 System clock divided by 4 Timer 0 overflow High-to-low transitions on ECI (max rate = system clock divided by 4) System clock External clock divided by 8 Reserved Reserved
External oscillator source divided by 8 is synchronized with the system clock.
Bit0:
ECF: PCA Counter/Timer Overflow Interrupt Enable. This bit sets the masking of the PCA Counter/Timer Overflow (CF) interrupt. 0: Disable the CF interrupt. 1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to `1', the PCA0MD register cannot be modified. To change the contents of the PCA0MD register, the Watchdog Timer must first be disabled.
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Figure 18.13. PCA0CPMn: PCA Capture/Compare Mode Registers
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PWM16n
Bit7
ECOMn
Bit6
CAPPn
Bit5
CAPNn
Bit4
MATn
Bit3
TOGn
Bit2
PWMn
Bit1
ECCFn
Bit0
00000000
SFR Address:
0xDA, 0xDB, 0xDC, 0xDD, 0xDE
PCA0CPMn Address:
PCA0CPM0 = 0xDA (n = 0), PCA0CPM1 = 0xDB (n = 1), PCA0CPM2 = 0xDC (n = 2), PCA0CPM3 = 0xDD (n = 3), PCA0CPM4 = 0xDE (n = 4)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PWM16n: 16-bit Pulse Width Modulation Enable. This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1). 0: 8-bit PWM selected. 1: 16-bit PWM selected. ECOMn: Comparator Function Enable. This bit enables/disables the comparator function for PCA module n. 0: Disabled. 1: Enabled. CAPPn: Capture Positive Function Enable. This bit enables/disables the positive edge capture for PCA module n. 0: Disabled. 1: Enabled. CAPNn: Capture Negative Function Enable. This bit enables/disables the negative edge capture for PCA module n. 0: Disabled. 1: Enabled. MATn: Match Function Enable. This bit enables/disables the match function for PCA module n. When enabled, matches of the PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD register to be set to logic 1. 0: Disabled. 1: Enabled. TOGn: Toggle Function Enable. This bit enables/disables the toggle function for PCA module n. When enabled, matches of the PCA counter with a module's capture/compare register cause the logic level on the CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module operates in Frequency Output Mode. 0: Disabled. 1: Enabled. PWMn: Pulse Width Modulation Mode Enable. This bit enables/disables the PWM function for PCA module n. When enabled, a pulse width modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is cleared; 16-bit mode is used if PWM16n is set to logic 1. If the TOGn bit is also set, the module operates in Frequency Output Mode. 0: Disabled. 1: Enabled. ECCFn: Capture/Compare Flag Interrupt Enable. This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt. 0: Disable CCFn interrupts. 1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
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Figure 18.14. PCA0L: PCA Counter/Timer Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xF9 Bits 7-0: PCA0L: PCA Counter/Timer Low Byte. The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
Figure 18.15. PCA0H: PCA Counter/Timer High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xFA Bits 7-0: PCA0H: PCA Counter/Timer High Byte. The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
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Figure 18.16. PCA0CPLn: PCA Capture Module Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xFB, 0xE9, 0xEB, 0xED, 0xFD
PCA0CPLn Address:
PCA0CPL0 = 0xFB (n = 0), PCA0CPL1 = 0xE9 (n = 1), PCA0CPL2 = 0xEB (n = 2), PCA0CPL3 = 0xED (n = 3), PCA0CPL4 = 0xFD (n = 4)
Bits7-0:
PCA0CPLn: PCA Capture Module Low Byte. The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
Figure 18.17. PCA0CPHn: PCA Capture Module High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address:
0xFC, 0xEA, 0xEC,0xEE, 0xFE
PCA0CPHn Address:
PCA0CPH0 = 0xFC (n = 0), PCA0CPH1 = 0xEA (n = 1), PCA0CPH2 = 0xEC (n = 2), PCA0CPH3 = 0xEE (n = 3), PCA0CPH4 = 0xFE (n = 4)
Bits7-0:
PCA0CPHn: PCA Capture Module High Byte. The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
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19.
REVISION SPECIFIC BEHAVIOR
This chapter contains behavioral differences between C8051F310/1 "REV A" and "REV B" or later devices. These differences do not affect the functionality or performance of most systems and are described below.
19.1.
Revision Identification
The Lot ID Code on the top side of the device package can be used for decoding device revision information. On C8051F310 devices, the revision letter is the second-to-last letter of the Lot ID Code. On C8051F311 devices, the revision letter is the last letter of the Lot ID Code. Figure 19.1 shows how to find the Lot ID Code on the top side of the device package.
Figure 19.1. Reading Package Marking
C8051F310 Package Marking C8051F311 Package Marking
C8051F310 T2ABGFAC ^ indicates REV A 0227 EP
CYG F311 ABGFA ^ indicates REV A
19.2.
Reset Behavior
The reset behavior of C8051F310/1 "REV A" devices is different than "REV B" and later devices. The differences affect the state of the /RST pin during a VDD Monitor reset and GPIO pins during any device reset.
19.2.1. Weak Pull-ups on GPIO Pins
On "REV A" devices, GPIO pins are tri-stated with weak pull-ups disabled during the assertion phase of any reset. The pull-ups are enabled immediately following reset de-assertion. On "REV B" and later devices, GPIO pins are tri-stated with weak pull-ups enabled during and after the assertion phase of any reset.
19.2.2. VDD Monitor and the /RST Pin
On "REV A" devices, a VDD Monitor reset does not affect the state of the /RST pin. On "REV B" and later devices, a VDD Monitor reset will pull the /RST pin low for the duration of the brownout conditon.
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19.3. PCA Counter
Preliminary
On "REV A" devices, if the main PCA counter (PCA0H : PCA0L) overflows during the execution phase of a readmodify-write instruction (bit-wise SETB or CLR, ANL, ORL, XRL) that targets the PCA0CN register, the CF (Counter Overflow) bit will not be set. An example software work-around is as follows: Disable global interrupts (EA = 0). Read PCA0L. This will latch the value of PCA0H. Read PCA0H, saving the value. Execute the bit-wise operation on CCFn (for example, CLR CCF0, or CCF0 = 0;). Read PCA0L. Read PCA0H, saving the value. If the value of PCA0H read in Step 3 is 0xFF and the value for PCA0H read in Step 6 is 0x00, then manually set the CF bit in software (for example, SETB CF, or CF = 1;). Step 8. Re-enable interrupts (EA = 1). Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7.
This behavior is not present on "REV B" and later devices. Software written for "REV A" devices will run on "REV B" and later devices without modification.
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20.
C2 INTERFACE
C8051F310/1 devices include an on-chip Cygnal 2-Wire (C2) debug interface to allow FLASH programming, boundary scan functions, and in-system debugging with the production part installed in the end application. The C2 interface uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information between the device and a host system. See the C2 Interface Specification for details on the C2 protocol.
20.1.
C2 Interface Registers
The following describes the C2 registers necessary to perform FLASH programming and boundary scan functions through the C2 interface. All C2 registers are accessed through the C2 interface as described in the C2 Interface Specification.
Figure 20.1. C2ADD: C2 Address Register
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7-0:
The C2ADD register is accessed via the C2 interface to select the target Data register for C2 Data Read and Data Write commands. Address 0x00 0x01 0x02 0xB4 Description Selects the Device ID register for Data Read instructions Selects the Revision ID register for Data Read instructions Selects the C2 FLASH Programming Control register for Data Read/Write instructions Selects the C2 FLASH Programming Data register for Data Read/Write instructions
Figure 20.2. DEVICEID: C2 Device ID Register
Reset Value
00001001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
This read-only register returns the 8-bit device ID: 0x09 (C8051F310/1).
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Preliminary
Figure 20.3. REVID: C2 Revision ID Register
Reset Value
Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
This read-only register returns the 8-bit revision ID.
Figure 20.4. FPCTL: C2 FLASH Programming Control Register
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7-0
FPCTL: FLASH Programming Control Register. This register is used to enable FLASH programming via the C2 interface. To enable C2 FLASH programming, the following codes must be written in order: 0x02, 0x01. Note that once C2 FLASH programming is enabled, a system reset must be issued to resume normal operation.
Figure 20.5. FPDAT: C2 FLASH Programming Data Register
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7-0:
FPDAT: C2 FLASH Programming Data Register. This register is used to pass FLASH commands, addresses, and data during C2 FLASH accesses. Valid commands are listed below. Code 0x06 FLASH Block Read 0x07 FLASH Block Write 0x08 FLASH Page Erase 0x03 Device Erase Command
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Preliminary
C8051F310/1
20.2.
C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging, FLASH programming, and boundary scan functions may be performed. This is possible because C2 communication is typically performed when the device is in the halt state, where all on-chip peripherals and user software are stalled. In this halted state, the C2 interface can safely `borrow' the C2CK (/RST) and C2D (P3.0) pins. In most applications, external resistors are required to isolate C2 interface traffic from the user application. A typical isolation configuration is shown in Figure 20.6.
Figure 20.6. Typical C2 Pin Sharing
C8051Fxxx
/Reset (a) Input (b) Output (c)
C2CK C2D
C2 Interface Master
The configuration in Figure 20.6 assumes the following: 1. 2. The user input (b) cannot change state while the target device is halted. The /RST pin on the target device is used as an input only.
Additional resistors may be necessary depending on the specific application.
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Disclaimers
Preliminary
Life support: These products are not designed for use in life support appliances or systems where malfunction of these products can reasonably be expected to result in personal injury. Cygnal Integrated Products customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Cygnal Integrated Products for any damages resulting from such applications. Right to make changes: Cygnal Integrated Products reserves the right to make changes, without notice, in the products, including circuits and/or software, described or contained herein in order to improve design and/or performance. Cygnal Integrated Products assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work infringement, unless otherwise specified. CIP-51 is a trademark of Cygnal Integrated Products, Inc. MCS-51 and SMBus are trademarks of Intel Corporation. I2C is a trademark of Philips Semiconductor. SPI is a trademark of Motorola, Inc.
CYGNAL INTEGRATED PRODUCTS 4301 Westbank Drive Suite B-100 Austin, TX 78746 www.cygnal.com
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