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| Quad Port PHY (Physical Layer) for 25.6 and 51.2 ATM Networks Features List Performs the PHY-Transmission Convergence (TC) and Physical Media Dependent (PMD) Sublayer functions for four 25.6 Mbps ATM channels Compliant to ATM Forum (af-phy-040.000) and ITU-T I.432.5 specifications for 25.6 Mbps physical interface Also operates at 51.2 Mbps data rate UTOPIA Level 1, UTOPIA Level 2, or DPI-4 Interface 3-Cell Transmit & Receive FIFOs LED Interface for status signalling Supports UTP Category 3 and 5 physical media Interfaces to standard magnetics Low-Power CMOS 3.3V supply with 5V tolerant inputs 144-pin PQFP Package (28 x 28 mm) Commercial and Industrial Temperature Ranges IDT77V1254L25 Description The IDT77V1254L25 is a member of IDT's family of products supporting Asynchronous Transfer Mode (ATM) data communications and networking. The IDT77V1254L25 implements the physical layer for 25.6 Mbps ATM, connecting four serial copper links (UTP Category 3 and 5) to one ATM layer device such as a SAR or a switch ASIC. The IDT77V1254L25 also operates at 51.2 Mbps, and is well suited to backplane driving applications. The 77V1254L25-to-ATM layer interface is selectable as one of three options: 16-bit UTOPIA Level 2, 8-bit UTOPIA Level 1 Multi-PHY, or quadruple 4-bit DPI (Data Path Interface). The IDT77V1254L25 is fabricated using IDT's state-of-the-art CMOS technology, providing the highest levels of integration, performance and reliability, with the low-power consumption characteristics of CMOS. Block Diagram TXREF T X C LK T X D A T A [15:0] T X P A R IT Y TX S O C TXEN T X C LA V T X A D D R [4:0] M O D E [1:0] P H Y -A T M Interface (U T O P IA or D P I) D ri ver T X /R X A T M C el IF O lF S cram bl er/ D escram bl er 5B /4B E ncodi ng/ D ecodi ng P /S and S /P N R ZI + Tx 1 + Rx1 - D ri ver T X /R X A T M C el IF O lF S cram bl er/ D escram bl er 5B /4B E ncodi ng/ D ecodi ng P /S and S /P N R ZI + TX 0 + RX 0 - C l R ecovery ock R X A D D R [4:0] R X C LK R X D A T A [15:0] R X P A R IT Y R XSO C RXEN R X C LA V C l R ecovery ock INT RST D ri ver T X /R X A T M C el IF O lF Mi croprocessor Interface S cram bl er/ D escram bl er 5B /4B E ncodi ng/ D ecodi ng P /S and S /P N R ZI C l R ecovery ock + - TX 2 + -RX 2 RD WR CS A D [7:0] A LE T X /R X A T M C el IF O lF O SC S cram bl er/ D escram bl er 5B /4B E ncodi ng/ D ecodi ng P /S and S /P N R ZI D ri ver + - TX 3 + -RX 3 C l R ecovery ock 4 4 RXREF R X LE D [3:0] T X LE D [3:0] 35 0 5 drw 0 1 . IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. 1 of 47 2001 Integrated Device Technology, Inc. September 21, 2001 DSC 6003 IDT77V1254L25 Applications Up to 204.8Mbps backplane transmission Rack-to-rack short links ATM Switches Operation AT 51.2 Mbps In addition to operation at the standard rate of 25.6 Mbps, the 77V1254L25 is also specified to operate at 51.2 Mbps. Except for the doubled bit rate, all other aspects of operation are identical to the 25.6 Mbps mode. The rate is determined by the frequency of the clock applied to the OSC input pin. OSC is 32 MHz for the 25.6 Mbps line rate, and 64 MHz for the 51.2 Mbps line rate. All ports operate at the same frequency. See Figure 36 for recommended line magnetics. Magnetics for 51.2 Mbps operation have a higher bandwidth than magnetics optimized for 25.6 Mbps. 77V1254L25 Overview The 77V1254L25 is a four port implementation of the physical layer standard for 25.6Mbps ATM network communications as defined by ATM Forum document af-phy-040.000 and ITU-T I.432.5. The physical layer is divided into a Physical Media Dependent sub layer (PMD) and Transmission Convergence (TC) sub layer. The PMD sub layer includes the functions for the transmitter, receiver and clock recovery for operation across 100 meters of category 3 and 5 unshielded twisted pair (UTP) cable. This is referred to as the Line Side Interface. The TC sub layer defines the line coding, scrambling, data framing and synchronization. On the other side, the 77V1254L25 interfaces to an ATM layer device (such as a switch core or SAR). This cell level interface is configurable as either 8-bit Utopia Level 1 Multi-PHY, 16-bit Utopia Level 2, or as four 4-bit DPI interfaces, as determined by two MODE pins. This is referred to as the PHY-ATM Interface. The pinout and front page block diagram are based on the Utopia 2 configuration. Table 2 shows the corresponding pin functions for the other two modes, and Figure 2 and Figure 3 show functional block diagrams. The 77V1254L25 is based on the 77105, and maintains significant register compatibility with it. The 77V1254L25, however, has additional register features, and also duplicates most of its registers to provide significant independence between the four ports. Access to these status and control registers is through the utility bus. This is an 8-bit muxed address and data bus, controlled by a conventional asynchronous read/write handshake. Additional pins permit insertion and extraction of an 8kHz timing marker, and provide LED indication of receive and transmit status. Auto-Synchronization and Good Signal Indication The 77V1254L25 features a new receiver synchronization algorithm that allow it to achieve 4b/5b symbol framing on any valid data stream. This is an improvement on earlier products which could frame only on the escape symbol, which occurs only in start-of-cell or 8kHz (X8) timing marker symbol pairs. ATM25 transceivers always transmit valid 4b/5b symbols, allowing the 77V1254L25 receive section to achieve symbol framing and properly indicate receive signal status, even in the absence of ATM cells or 8kHz (X8) timing markers in the receive data stream. A state maching monitors the received symbols and asserts the "Good Signal" status bit when a valid signal is being received. "Good Signal" is deasserted and the receive FIFO is disabled when the signal is lost. This is sometimes referred to as Loss of Signal (LOS). Functional Description Transmission Convergence (TC) Sub Layer Introduction The TC sub layer defines the line coding, scrambling, data framing and synchronization. Under control of a switch interface or Segmentation and Reassembly (SAR) unit, the 25.6Mbps ATM PHY accepts a 53byte ATM cell, scrambles the data, appends a command byte to the beginning of the cell, and encodes the entire 53 bytes before transmission. These data transformations ensure that the signal is evenly distributed across the frequency spectrum. In addition, the serialized bit stream is NRZI coded. An 8kHz timing sync pulse may be used for isochronous communications. Data Structure and Framing Each 53-byte ATM cell is preceded with a command byte. This byte is distinguished by an escape symbol followed by one of 17 encoded symbols. Together, this byte forms one of seventeen possible command bytes. Three command bytes are defined: 1. X_X (read: 'escape' symbol followed by another 'escape'): Startof-cell with scrambler/descrambler reset. 2. X_4 ('escape' followed by '4'): Start-of-cell without scrambler/ descrambler reset. 3. X_8 ('escape' followed by '8'): 8kHz timing marker. This command byte is generated when the 8kHz sync pulse is detected, and has priority over all line activity (data or command bytes). It is transmitted immediately when the sync pulse is detected. When this occurs during a cell transmission, the data transfer is temporarily interrupted on an octet boundary, and the X_8 command byte is inserted. This condition is the only allowed interrupt in an otherwise contiguous transfer. Below is an illustration of the cell structure and command byte usage: {X_X} {53-byte ATM cell} {X_4} {53-byte ATM {X_8} cell} ... In the above example, the first ATM cell is preceded by the X_X start-of-cell command byte which resets both the transmitter-scrambler and receiver-descrambler pseudo-random nibble generators (PRNG) to their initial states. The following cell illustrates the insertion of a start-ofcell command without scrambler/descrambler reset. During this cell's transmission, an 8kHz timing sync pulse triggers insertion of the X_8 8kHz timing marker command byte. 2 of 47 September 21, 2001 IDT77V1254L25 Transmission Description Refer to Figure 4. Cell transmission begins with the PHY-ATM Interface. An ATM layer device transfers a cell into the 77V1254L25 across the Utopia or DPI transmit bus. This cell enters a 3-cell deep transmit FIFO. Once a complete cell is in the FIFO, transmission begins by passing the cell, four bits (MSB first) at a time to the 'Scrambler'. The 'Scrambler' takes each nibble of data and exclusive-ORs them against the 4 high order bits (X(t), X(t-1), X(t-2), X(t-3)) of a 10 bit pseudo-random nibble generator (PRNG). Its function is to provide the appropriate frequency distribution for the signal across the line. The PRNG is clocked every time a nibble is processed, regardless of whether the processed nibble is part of a data or command byte. Note however that only data nibbles are scrambled. The entire command byte (X _C) is NOT scrambled before it's encoded (see diagram for illustration). The PRNG is based upon the following polynomial: X10 + X7 + 1 With this polynomial, the four output data bits (D3, D2, D1, D0) will be generated from the following equations: D3 = d3 xor X(t-3) D2 = d2 xor X(t-2) D1 = d1 xor X(t-1) D0 = d0 xor X(t) The following nibble is scrambled with X(t+4), X(t+3), X(t+2), and X(t+1). A scrambler lock between the transmitter and receiver occurs each time an X_X command is sent. An X_X command is initiated only at the beginning of a cell transfer after the PRNG has cycled through all of its states (210 - 1 = 1023 states). The first valid ATM data cell transmitted after power on will also be accompanied with an X_X command byte. Each time an X_X command byte is sent, the first nibble after the last escape (X) nibble is XOR'd with 1111b (PRNG = 3FFx). Because a timing marker command (X_8) may occur at any time, the possibility of a reset PRNG start-of-cell command and a timing marker command occurring consecutively does exist (e.g. X_X_X_8). In this case, the detection of the last two consecutive escape (X) nibbles will cause the PRNG to reset to its initial 3FFx state. Therefore, the PRNG is clocked only after the first nibble of the second consecutive escape pair. Once the data nibbles have been scrambled using the PRNG, the nibbles are further encoded using a 4b/5b process. The 4b/5b scheme ensures that an appropriate number of signal transitions occur on the line. A total of seventeen 5-bit symbols are used to represent the sixteen 4-bit data nibbles and the one escape (X) nibble. The table below lists the 4-bit data with their corresponding 5-bit symbols: 'DWD 6\PERO 'DWD 6\PERO 'DWD (6&; 6\PERO 'DWD 6\PERO GUZ D This encode/decode implementation has several very desirable properties. Among them is the fact that the output data bits can be represented by a set of relatively simple symbols; Run length is limited to <= 5; Disparity never exceeds +/- 1. On the receiver, the decoder determines from the received symbols whether a timing marker command (X_8) or a start-of-cell command was sent (X_X or X_4). If a start-of-cell command is detected, the next 53 bytes received are decoded and forwarded to the descrambler. (See TC Receive Block Diagram, Figure 5). 3 of 47 September 21, 2001 IDT77V1254L25 9'' *1' 7; 7; 9'' 00 02'( 02'( RXREF TXREF *1' 7;/(' 7;/(' 7;/(' 7;/(' 9'' 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;'$7$ 7;3$5,7< TXEN 7;62& 7;$''5 7; 7; *1' $*1' $9'' 5; 5; $9'' $*1' $*1' $9'' 5; 5; $9'' $*1' $*1' $9'' $*1' 26& $9'' $*1' $*1' $9'' 5; 5; $9'' $*1' $*1' $9'' 5; 5; $9'' $*1' *1' 7; 7; 77V1254L25 9 34)3 9'' *1' 7; 7; 9'' '$ 6( $' $' $' $' *1' $' $' $' $' 9'' $/( CS RD WR RST *1' INT 9'' *1' 5;/(' 5;/(' 5;/(' 5;/(' 9'' *1' 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ . 7;$''5 9'' 7;$''5 7;$''5 7;$''5 7;&/$9 7;&/. *1' 9'' 5;&/. RXEN 5;$''5 5;$''5 *1' 5;$''5 5;$''5 5;$''5 5;&/$9 5;62& *1' 9'' 5;3$5,7< 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ *1' 9'' 5;'$7$ 5;'$7$ 5;'$7$ 5;'$7$ GUZ Figure 1 Pin Assignments 4 of 47 September 21, 2001 IDT77V1254L25 Signal Descriptions Line Side Signals Signal Name RX0+,RX1+,RX2+,RX3+,TX0+,TX1+,TX2+,TX3+,Pin Number 139, 138 133, 132 121, 120 115, 114 4, 3 144, 143 110, 109 106, 105 I/O In In In In Out Out Out Out Signal Description Port 0 positive and negative receive differential input pair. Port 1 positive and negative receive differential input pair. Port 2 positive and negative receive differential input pair. Port 3 positive and negative receive differential input pair. Port 0 positive and negative transmit differential output pair. Port 1 positive and negative transmit differential output pair. Port 2 positive and negative transmit differential output pair. Port 3 positive and negative transmit differential output pair. Utility Bus Signals Signal Name AD[7:0] ALE CS RD WR Pin Number I/O Signal Description 101, 100, 99, 98, 96, 95, 94, In/Out Utility bus address/data bus. The address input is sampled on the falling edge of ALE. Data is output on this 93 bus when a read is performed. Input data is sampled at the completion of a write operation. 91 90 89 88 In In In Utility bus address latch enable. Asynchronous input. An address on the AD bus is sampled on the falling edge of ALE. ALE must be low when the AD bus is being used for data. Utility bus asynchronous chip select. CS must be asserted to read or write an internal register. It may remain asserted at all times if desired Utility bus read enable. Active low asynchronous input. After latching an address, a read is performed by deasserting WR and asserting RD and CS. Utility bus write enable. Active low asynchronous input. After latching an address, a write is performed by deasserting RD, placing data on the AD bus, and asserting WR and CS. Data is sampled when WR or CS is deasserted. Miscellaneous Signals Signal Name DA INT Pin Number 103 85 I/O In Out Signal Description Reserved signal. This input must be connected to logic low. Interrupt. INT is an open-drain output, driven low to indicate an interrupt. Once low, INT remains low until the interrupt status in the appropriate interrupt Status Register is read. Interrupt sources are programmable via the interrupt Mask Registers. Reserved signal. This input must be connected to logic low. Mode Selects. They determine the configuration of the PHY/ATM interface. 00 = UTOPIA Level 2. 01 = UTOPIA Level 1. 10 = DPI. 11 is reserved. TTL line rate clock source, driven by a 100 ppm oscillator. 32 MHz for 25.6 Mbps; 64 MHz for 51.2 Mbps. Reset. Active low asynchronous input resets all control logic, counters and FIFOs. A reset must be performed after power up prior to normal operation of the part. Receive LED drivers. Driven low for 223 cycles of OSC, beginning with RXSOC when that port receives a good (non-null and non-errored) cell. Drives 8 mA both high and low. One per port. Receive Reference. Active low, synchronous to OSC. RXREF pulses low for a programmable number of clock cycles when an x_8 command byte is received. Register 0x40 is programmed to indicate which port is referenced. Reserved signal. This input must be connected to logic low. Table 1 Signal Descriptions (Part 1 of 3) MM MODE[1:0] OSC RST RXLED[3:0] RXREF 6 7, 8 126 87 82, 81, 80, 79 9 In In In In Out Out SE 102 In 5 of 47 September 21, 2001 IDT77V1254L25 TXLED[3:0] TXREF 12, 13, 14, 15 10 Out In Ports 3 thru 0 Transmit LED driver. Goes low for 223 cycles of OSC, beginning with TXSOC when this port receives a cell for transmission. 8 mA drive current both high and low. One per port. Transmit Reference. Synchronous to OSC. On the falling edge, an X_8 command byte is inserted into the transmit data stream. Logic for this signal is programmed in register 0x40. Typical application is WAN timing. Power Supply Signals Signal Name AGND AVDD GND VDD Pin Number I/O Signal Description Analog ground. AGND supply a ground reference to the analog portion of the ship, which sources a more constant current than the digital portion. Analog power supply 3.3 0.3V AVDD supply power to the analog portion of the chip, which draws a more constant current than the digital portion. Digital Ground. Digital power supply. 3.3 0.3V. 112, 117, 118, 123, 124, ____ 127, 129, 130, 135, 136, 141 113, 116, 119, 122, 125, 128, 131, 134, 137, 140 ____ 2, 11, 44, 50, 56, 67, 77, 83, ____ 86, 97, 107, 111, 142 1, 5, 16, 38, 45, 57, 68, 78, 84, 92, 104, 108 ____ 16-BIT UTOPIA 2 Signals (MODE[1:0] = 00) Signal Name RXADDR[4:0] RXCLAV Pin Number 53, 52, 51, 49, 48 54 I/O In Out Signal Description Utopia 2 Receive Address Bus. This bus is used in polling and selecting the receive port. The port addresses are defined in bits [4:0] of the Enhanced Control Registers. Utopia 2 Receive Cell Available. Indicates the cell available status of the addressed port. It is asserted when a full cell is available for retrieval from the receive FIFO. When non of the four ports is addressed. RXCLAV is high impedance. Utopia 2 Receive Clock. This is a free running clock input. Utopia 2 Receive Data. When one of the four ports is selected, the 77V1254L25 transfers received cells to an ATM device across this bus. Also see RXPARITY. Utopia 2 Receive Enable. Driven by an ATM device to indicate its ability to receive data across the RXDATA bus. Utopia 2 Receive Data Parity. Odd parity over RXDATA[15:0]. Utopia 2 Receive Start of Cell. Asserted coincident with the first word of data for each cell on RXDATA. Utopia 2 Transmit Address Bus. This bus is used in polling and selecting the transmit port. The port addresses are defined in bits [4:0] of the Enhanced Control Registers. Utopia 2 Transmit Cell Available. Indicates the availability of room in the transmit FIFO of the addressed port for a full cell. When none of the four ports is addressed, TXCLAV is high impedance. Utopia Transmit Clock. This is a free running clock input. Utopia 2 Transmit Data. An ATM device transfers cells across this bus to the 77V1254L25 for transmission. Also see TXPARITY. Utopia 2 Transmit Enable. Driven by an ATM device to indicate it is transmitting data across the TXDATA bus. Utopia 2 Transmit Data Parity. Odd parity across TXDATA[15:0]. Parity is checked and errors are indicated in the Interrupt Status Registers, as enabled in the Master Control Registers. No other action is taken in the event of an error. Tie high or low if unused. Utopia 2 Transmit Start of Cell. Asserted coincident with the first word of data for each cell on TXDATA. Table 1 Signal Descriptions (Part 2 of 3) RXCLK 46 In Out RXDATA[15:0] 59, 60, 61, 62, 63, 64, 65, 66, 69, 70, 71, 72, 73, 74, 75, 76 RXEN RXPARITY RXSOC TXADDR[4:0] TXCLAV TXCLK 47 58 55 36, 37, 39, 40, 41 42 43 In Out Out In Out In In TXDATA[15:0] 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17 TXEN TXPARITY 34 33 In In TXSOC 35 In 6 of 47 September 21, 2001 IDT77V1254L25 8-BIT UTOPIA Level 1 Signals (MODE[1:0] = 01) Signal Name RXCLAV[3:0] RXCLK RXDATA[7:0] Pin Number 64, 65, 66, 54 46 I/O Out In Signal Description Utopia 1 Receive Cell Available. Indicates the cell available status of the respective port. It is asserted when a full cell is available for retrieval from the receive FIFO. Utopia 1 Receive Clock. This is a free running clock input. Utopia 1 Receive Data. When one of the four ports is selected, the 77V1254L25 transfers received cells to an ATM device across this bus. Bit 5 in the Diagnostic Control Registers determines whether RXDATA tri-states when RXEN[3:0] are high. Also see RXPARITY. Utopia 1 Receive Enable. Driven by an ATM device to indicate its ability to receive data across the RXDATA bus. One for each port Utopia 1 Receive Data Parity. Odd parity over RXDATA[7:0]. Utopia 1 Receive Start of Cell. Asserted coincident with the first word of data for each cell on RXDATA. Tristatable as determined by bit 5 in the Diagnostic Control Registers. Utopia 1 Transmit cell Available. Indicates the availability of room in the transmit FIFO of the respective port for a full cell. Utopia 1 Transmit Clock. This is a free running clock input. Utopia 1 Transmit Data. An ATM device transfers cells across the bus to the 77V1254L25 for transmission. Also see TXPARITY. Utopia 1 Transmit Enable. Driven by an ATM device to indicate it is transmitting data across the TXDATA bus. One for each port. Utopia 1 Transmit Data Parity. Odd parity across TXDATA[7:0]. Parity is checked and errors are indicated in the Interrupt Status Registers, as enabled in the Master Control Registers. No other action is taken in the event of an error. Tie high or low if unused. Utopia 1 Transmit Start of Cell. Asserted coincident with the first word of data for each cell on TXDATA. DPI Mode Signals (MODE[1:0] = 10) Signal Name DPICLK Pn_RCLK Pn_RD[3:0] Pin Number 43 52, 51, 49, 48 59, 60, 61, 62, 63, 64, 65, 66, 69, 70, 71, 72, 73, 74, 75, 76 53, 58, 54, 55 37, 39, 40, 41 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17 36, 33, 34, 35 I/O In In Out Signal Description DPI Source Clock for Transmit. This is the free-running clock used as the source to generate Pn_TCLK. DPI Port 'n' Receive Clock. Pn_RCLK is cycled to indicate that the interfacing device is ready to receive a nibble of data on Pn_RD[3:0] of port 'n'. DPI Port 'n' Receive Data. Cells received on port 'n' are passed to the interfacing device across this bus. Each port has its own dedicated bus. DPI Port 'n' Receive Frame. Pn_RFRM is asserted for one cycle immediately preceding the transfer of each cell on Pn_RD[3:0]. DPI Port 'n' Transmit Clock. Pn_TCLK is derived from DPICLK and is cycled when the respective port is ready to accept another 4 bits of data on Pn_TD[3:0]. DPI Port 'n' Transmit Data. Cells are passed across this bus to the PHY for transmission on port 'n'. Each port has its own dedicated bus. DPI Port 'n' Transmit Frame. Start of cell signal which is asserted for one cycle immediately preceding the first 4 bits of each cell on Pn_TD[3:0]. Table 1 Signal Descriptions (Part 3 of 3) 69, 70, 71, 72, 73, 74, 75, 76 Out RXEN[3:0] RXPARITY RXSOC TXCLAV[3:0] TXCLK TXDATA[7:0] TXEN[3:0] TXPARITY 51, 49, 48, 47 58 55 39, 40, 41, 42 43 In Out Out Out In 24, 23, 22, 21, 20, 19, 18, 17 In 27, 26, 25, 34 33 In In TXSOC 35 In Pn_RFRM Pn_TCLK Pn_TD[3:0] Out Out In Pn_TFRM In 7 of 47 September 21, 2001 IDT77V1254L25 Signal Assignment as a Function of PHY/ATM Interface Mode SIGNAL NAME VDD GND TX0TX0+ VDD MM MODE1 MODE0 RXREF TXREF GND TXLED3 TXLED2 TXLED1 TXLED0 VDD TXDATA0 TXDATA1 TXDATA2 TXDATA3 TXDATA4 TXDATA5 TXDATA6 TXDATA7 TXDATA8 TXDATA9 TXDATA10 TXDATA11 TXDATA12 TXDATA13 TXDATA14 TXDATA15 TXPARITY TXEN TXSOC TXADDR4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 TXDATA0 TXDATA1 TXDATA2 TXDATA3 TXDATA4 TXDATA5 TXDATA6 TXDATA7 TXDATA8 TXDATA9 TXDATA10 TXDATA11 TXDATA12 TXDATA13 TXDATA14 TXDATA15 TXPARITY TXEN TXSOC TXADDR4 TXDATA0 TXDATA1 TXDATA2 TXDATA3 TXDATA4 TXDATA5 TXDATA6 TXDATA7 TXEN[1] TXEN[2] TXEN[3] see note 2 see note 2 see note 2 see note 2 see note 2 TXPARITY TXEN[0] TXSOC see note 2 P0_TD[0] P0_TD[1] P0_TD[2] P0_TD[3] P1_TD[0] P1_TD[1] P1_TD[2] P1_TD[3] P2_TD[0] P2_TD[1] P2_TD[2] P2_TD[3] P3_TD[0] P3_TD[1] P3_TD[2] P3_TD[3] P2_TFRM P1_TFRM P0_TFRM P3_TFRM PIN NUMBER 16-BIT UTOPIA 2 MODE[1,0] = 00 8-BIT UTOPIA 1 MODE[1,0] = 01 DPI MODE[1,0] = 10 Table 2 Signal Assignment as a Function of PHY/ATM Interface Mode (Part 1 of 4) 8 of 47 September 21, 2001 IDT77V1254L25 SIGNAL NAME TXADDR3 VDD TXADDR2 TXADDR1 TXADDR0 TXCLAV TXCLK GND VDD RXCLK RXEN RXADDR0 RXADDR1 GND RXADDR2 RXADDR3 RXADDR4 RXCLAV RXSOC GND VDD RXPARITY RXDATA15 RXDATA14 RXDATA13 RXDATA12 RXDATA11 RXDATA10 RXDATA9 RXDATA8 GND VDD RXDATA7 RXDATA6 RXDATA5 RXDATA4 RXDATA3 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 RXDATA7 RXDATA6 RXDATA5 RXDATA4 RXDATA3 RXDATA7 RXDATA6 RXDATA5 RXDATA4 RXDATA3 P1_RD[3] P1_RD[2] P1_RD[1] P1_RD[0] P0_RD[3] RXPARITY RXDATA15 RXDATA14 RXDATA13 RXDATA12 RXDATA11 RXDATA10 RXDATA9 RXDATA8 RXPARITY see note 1 see note 1 see note 1 see note 1 see note 1 RXCLAV[3] RXCLAV[2] RXCLAV[1] P2_RFRM P3_RD[3] P3_RD[2] P3_RD[1] P3_RD[0] P2_RD[3] P2_RD[2] P2_RD[1] P2_RD[0] RXADDR2 RXADDR3 RXADDR4 RXCLAV RXSOC RXEN[3] see note 2 see note 2 RXCLAV[0] RXSOC P2_RCLK P3_RCLK P3_RFRM P1_RFRM P0_FRM RXCLK RXEN RXADDR0 RXADDR1 RXCLK RXEN[0] RXEN[1] RXEN[2] see note 2 see note 2 P0_RCLK P1_RCLK TXADDR2 TXADDR1 TXADDR0 TXCLAV TXCLK TXCLAV[3] TXCLAV[2] TXCLAV[1] TXCLAV[0] TXCLK P2_TCLK P1_TCLK P0_TCLK see note 1 DPICLK PIN NUMBER 16-BIT UTOPIA 2 MODE[1,0] = 00 TXADDR3 8-BIT UTOPIA 1 MODE[1,0] = 01 see note 2 DPI MODE[1,0] = 10 P3_TCLK Table 2 Signal Assignment as a Function of PHY/ATM Interface Mode (Part 2 of 4) 9 of 47 September 21, 2001 IDT77V1254L25 SIGNAL NAME RXDATA2 RXDATA1 RXDATA0 GND VDD RXLED0 RXLED1 RXLED2 RXLED3 GND VDD INT GND RST WR RD CS ALE VDD AD0 AD1 AD2 AD3 GND AD4 AD5 AD6 AD7 SE DA VDD TX3TX3+ GND VDD TX2TX2+ 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 Table 2 Signal Assignment as a Function of PHY/ATM Interface Mode (Part 3 of 4) PIN NUMBER 16-BIT UTOPIA 2 MODE[1,0] = 00 RXDATA2 RXDATA1 RXDATA0 8-BIT UTOPIA 1 MODE[1,0] = 01 RXDATA2 RXDATA1 RXDATA0 DPI MODE[1,0] = 10 P0_RD[2] P0_RD[1] P0_RD[0] 10 of 47 September 21, 2001 IDT77V1254L25 SIGNAL NAME GND AGND AVDD RX3RX3+ AVDD AGND AGND AVDD RX2RX2+ AVDD AGND AGND AVDD OSC AGND AVDD AGND AGND AVDD RX1RX1+ AVDD AGND AGND AVDD RX0RX0+ AVDD AGND GND TX1TX1+ PIN NUMBER 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 Table 2 Signal Assignment as a Function of PHY/ATM Interface Mode (Part 4 of 4) 16-BIT UTOPIA 2 MODE[1,0] = 00 8-BIT UTOPIA 1 MODE[1,0] = 01 DPI MODE[1,0] = 10 Note: 1.This output signal is unused in this mode. It must be left unconnected. 2.This input signal is unused in this mode. It must be connected to either logic high or logic low. 11 of 47 September 21, 2001 IDT77V1254L25 TXRef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ef 5;/('>@ 7;/('>@ GUZ Figure 2 Block Diagram for Utopia Level 1 Configuration (MODE[1:0] = 01) 12 of 47 September 21, 2001 IDT77V1254L25 '3,&/. 0RGH>@ 3B7&/. 3B7)50 3B7'>@ 3B5&/. 3B5)50 3B5'>@ TXRef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ef 5;/('>@ 7;/('>@ GUZ Figure 3 Block Diagram for DPI configuration (MODE[1:0] = 10) 13 of 47 September 21, 2001 IDT77V1254L25 The output of the 4b/5b encoder provides serial data to the NRZI encoder. The NRZI code transitions the wire voltage each time a '1' bit is sent. This, together with the previous encoding schemes guarantees that long run lengths of either '0' or '1's are prevented. Each symbol is shifted out with its most significant bit sent first. When no cells are available to transmit, the 77V1254L25 keeps the line active by continuing to transmit valid symbols. But it does not transmit another start-of-cell command until it has another cell for transmission. The 77V1254L25 never generates idle cells. Transmit HEC Byte Calculation/Insertion Byte #5 of each ATM cell, the HEC (Header Error Control) is calculated automatically across the first 4 bytes of the cell header, depending upon the setting of bit 5 of registers 0x03, 0x13, 0x23 and 0x33. This byte is then either inserted as a replacement of the fifth byte transferred to the PHY by the external system, or the cell is transmitted as received. A third operating mode provides for insertion of "Bad" HEC codes which may aid in communication diagnostics. These modes are controlled by the LED Driver and HEC Status/Control Registers. Receiver Description The receiver side of the TC sublayer operates like the transmitter, but in reverse. The data is NRZI decoded before each symbol is reassembled. The symbols are then sent to the 5b/4b decoder, followed by the Command Byte Interpreter, De-Scrambler, and finally through a FIFO to the UTOPIA or DPI interface to an ATM Layer device. ATM Cell Format %LW %LW +HDGHU %\WH +HDGHU %\WH +HDGHU %\WH +HDGHU %\WH 8') 3D\ORDG %\WH * * * set to 0 = Bad signal initially) which shows the status of the line per the following algorithm: To declare 'Good Signal' (from "Bad" to "Good") There is an updown counter that counts from 7 to 0 and is initially set to 7. When the clock ticks for 1,024 cycles (32MHz clock, 1,024 cycles = 204.8 symbols) and no "bad symbol" has been received, the counter decreases by one. However, if at least one "bad symbol" is detected during these 1,024 clocks, the counter is increased by one, to a maximum of 7. The Good Signal Bit is set to 1 when this counter reaches 0. The Good Signal Bit could be set to 1 as quickly as 1,433 symbols (204.8 x 7) if no bad symbols have been received. To declare 'Bad Signal' (from "Good" to "Bad") The same updown counter counts from 0 to 7 (being at 0 to provide a "Good" status). When the clock ticks for 1,024 cycles (32MHz clock, 1,024 cycles = 204.8 symbols) and there is at least one "bad symbol", the counter increases by one. If it detects all "good symbols" and no "bad symbols" in the next time period, the counter decreases by one. The "Bad Signal" is declared when the counter reaches 7. The Good Signal Bit could be set to 0 as quickly as 1,433 symbols (204.8 x 7) if at least one "bad symbol" is detected in each of seven consecutive groups of 204.8 symbols. 8kHz Timing Marker The 8kHz timing marker, described earlier, is a completely optional feature which is essential for some applications requiring synchronization for voice or video, and unnecessary for other applications. Figure 7 shows the options available for generating and receiving the 8kHz timing marker. The source of the marker is programmable in the RXREF and TXREF Control Register (0x40). Each port is individually programmable to either a local source or a looped remote source. The local source is TXREF, which is an 8kHz clock of virtually any duty cycle. When unused, TXREF should be tied high. Also note that it is not limited to 8kHz, should a different frequency be desired. When looped, a received X_8 command byte causes one to be generated on the transmit side. A received X_8 command byte causes the 77V1254L25 to issue a negative pulse on RXREF. The source channel of the marker is programmable. 3D\ORDG %\WH GUZ 8') 8VHU 'HILQHG )LHOG RU +(& . PHY-ATM Interface The 77V1254L25 PHY offers three choices in interfacing to ATM layer devices such as segmentation and reassembly (SAR) and switching chips. MODE[1:0] are used to select the configuration of this interface, as shown in the table below. UTOPIA is a Physical Layer to ATM Layer interface standardized by the ATM Forum. It has separate transmit and receive channels and specific handshaking protocols. UTOPIA Level 2 has dedicated address signals for both the transmit and receive directions that allow the ATM layer device to specify with which of the four PHY channels it is communicating. UTOPIA Level 1 does not have address signals. Note that although the IDT77V1254L25 can detect symbol and HEC errors, it does not attempt to correct them. Upon reset or the re-connect, each port's receiver is typically not symbol-synchronized. When not symbol-synchronized, the receiver will indicate a significant number of bad symbols, and will deassert the Good Signal Bit as described below. Synchronization is established immediately once that port receives an Escape symbol, usually as part of the start-of-cell command byte preceding the first received cell. The IDT77V1254L25 monitors line conditions and can provide an interrupt if the line is deemed 'bad'. The Interrupt Status Registers (registers 0x01, 0x11, 0x21 and 0x31) contain a Good Signal Bit (bit 6, 14 of 47 September 21, 2001 IDT77V1254L25 6WDUW RI &HOO &HOOV 3+<$70 ,QWHUIDFH &RQWURO +(& *HQ ,QVHUWLRQ TXRef N+] 6FUDPEOHU &RPPDQG %\WH ,QVHUWLRQ Reset 8723,$ RU Interface '3, ,QWHUIDFH 6FUDPEOH 1LEEOH 1H[W EE (QFRGLQJ Pseudo Random 351* Nibble Generator 26& &ORFN ,QSXW 15=, (QFRGLQJ 7; + 7; GUZ Figure 4 TC Transmit Block Diagram 351* RXRef 5HVHW 6FUDPEOH 1LEEOH 1H[W 5; 5; 15=, 'HFRGLQJ EE 'HFRGLQJ &RPPDQG %\WH 'HWHFWLRQ 5HPRYDO 'HFRGH 'H 6FUDPEOHU . 6WDUW RI &HOO &HOOV 0+] Clock &ORFN Recovery 6\QWKHVL]HU 3// 8723,$ RU Interface '3, ,QWHUIDFH 3+<$70 ,QWHUIDFH &RQWURO 5(&9 26& GUZ Figure 5 TC Receive Block Diagram 15 of 47 September 21, 2001 IDT77V1254L25 Instead, key handshaking signals are duplicated so that each channel has its own signals. In both versions of UTOPIA, all channels share a single transmit data bus and a single receive data bus for data transfer. DPI is a low-pin count Physical Layer to ATM Layer interface. The low-pin count characteristic allows the 77V1254L25 to incorporate four separate DPI 4-bit ports, one for each of the four serial ports. As with the UTOPIA interfaces, the transmit and receive directions have their own data paths and handshaking. UTOPIA Level 2 Interface option The 16-bit Utopia Level 2 interface operates as defined in ATM Forum document af-phy-0039. This PHY-ATM interface is selected by setting the MODE[1:0] pins both low. This mode is configured as a single 16-bit data bus in the transmit (ATM-to-PHY) direction, and a single 16-bit data bus in the receive (PHY-to-ATM) direction. In addition to the data bus, each direction also includes a single optional parity bit, an address bus, and several handshaking signals. The UTOPIA address of each channel is determined by bits 4 to 0 in the Enhanced Control Registers. Please note that the transmit bus and the receive bus operate completely independently. The Utopia 2 signals are summarized below: TXDATA[15:0] TXPARITY TXSOC TXADDR[4:0] TXEN TXCLAV TXCLK RXDATA[15:0] ATM to PHY ATM to PHY ATM to PHY ATM to PHY ATM to PHY PHY to ATM ATM to PHY PHY to ATM then driving TXEN or RXEN low. When TXEN is driven low, TXSOC (start of cell) is driven high to indicate that the first 16 bits of the cell are being driven on TXDATA. The ATM device may chose to temporarily suspend transfer of the cell by deasserting TXEN. Otherwise, TXEN remains asserted as the next 16 bits are driven onto TXDATA with each cycle of TXCLK. In the receive direction, the ATM device selects a port if it wished to receive the cell that the port is holding. It does this by asserting RXEN. The PHY then transfers the data 16 bits each clock cycle, as determined by RXEN. As in the transmit direction, the ATM device may suspend transfer by deasserting RXEN at any time. Note that the PHY asserts RXSOC coincident with the first 16 bits of each cell. TXPARITY and RXPARITY are parity bits for the corresponding 16bit data fields. Odd parity is used. Figure 9 through Figure 14 may be referenced for Utopia 2 bus examples. Because this interface transfers an even number of bytes, rather than the ATM standard of 53 bytes, a filler byte is inserted between the 5-byte header and the 48-byte payload. This is shown in Figure 8. UTOPIA Level 1 multi-phy interface Option The UTOPIA Level 1 MULTI-PHY interface is based on ATM Forum document af-phy-0017. Utopia Level 1 is essentially the same as Utopia Level 2, but without the addressing, polling and selection features. %LW )LUVW +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH %LW +HDGHU E\WH +HDGHU E\WH VWXII E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH RXPARITY RXSOC RXADDR[4:0] RXEN PHY to ATM PHY to ATM ATM to PHY ATM to PHY PHY to ATM ATM to PHY /DVW 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH RXCLAV RXCLK Figure 6 Utopia Level 2 Data Format and Sequence To determine if any of them has room to accept a cell for transmission (TXCLAV), or has a receive cell available to pass on to the ATM device (RXCLAV). To poll, the ATM device drives an address (TXADDR or RXADDR) then observes TXCLAV or RXCLAV on the next cycle of TXCLK or RXCLK. A port must tri-state TXCLAV and RXCLAV except when it is addressed. If TXCLAV or RXCLAV is asserted, the ATM device may select that port, then transfer a cell to or from it. Selection of a port is performed by driving the address of the desired port while TXEN or RXEN is high, Instead of addressing, this mode utilizes separate TXCLAV, TXEN, RXCLAV and RXEN signals for each channel of the 77V1254L25. There are just one each of the TXSOC and RXSOC signals, which are shared across all four channels. In addition to Utopia Level 2's cell mode transfer protocol, Utopia Level 1 also offers the option of a byte mode protocol. Bit 1 of the Master Control Registers is used to program whether the UTOPIA Level 1 bus is in cell mode or byte mode. In byte mode, the PHY is allowed to control data transfer on a byte-by-byte basis via the TXCLAV and RXCLAV signals. In cell mode, TXCLAV and RXCLAV are ignored once 16 of 47 September 21, 2001 IDT77V1254L25 the transfer of a cell has begun. In every other way the two modes are identical. Cell mode is the default configuration and is the one described later. The Utopia 1 signals are summarized below: TXDATA[7:0] TXPARITY TXSOC TXEN[3:0] ATM to PHY ATM to PHY ATM to PHY ATM to PHY PHY to ATM ATM to PHY PHY to ATM PHY to ATM PHY to ATM ATM to PHY PHY to ATM ATM to PHY TXCLAV[3:0] TXCLK RXDATA[7:0] RXPARITY RXSOC RXEN[3:0] RXCLAV[3:0] RXCLK Transmit and receive both utilize free running clocks, which are inputs to the 77V1254L25. All Utopia signals are timed to these clocks. In the transmit direction, the PHY first asserts TXCLAV (transmit cell available) to indicate that it has room in its transmit FIFO to accept at least one 53-byte ATM cell. When the ATM layer device is ready to begin passing the cell, it asserts TXEN (transmit enable) and TXSOC (start of cell), coincident with the first byte of the cell on TXDATA. TXEN remains asserted for the duration of the cell transfer, but the ATM device may deassert TXEN at any time once the cell transfer has begun, but data is transferred only when TXEN is asserted. In the receive direction, RXEN indicates when the ATM device is prepared to receive data. As with transmit, it may be asserted or deasserted at any time. Note, however, that not more than one RXEN should be asserted at a time. Also, once a given RX port is selected, that port's FIFO must be emptied of cells (as indicated by RXCLAV) before a different RX port may be enabled. In both transmit and receive, TXSOC and RXSOC (start of cell) is asserted for one clock, coincident with the first byte of each cell. Odd parity is utilized across each 8-bit data field. Figure 8 shows the data sequence for an ATM cell over Utopia Level 1, and Figures 15 to 21 are examples of the Utopia Level 1 handshake. 17 of 47 September 21, 2001 IDT77V1254L25 TXRef ,QSXW /76HO 5HJ %LW 5;5HI ;B UHFHLYHG 0X[ 7;5HI ;B JHQHUDWRU /76HO 5HJ %LW 5;5HI ;B UHFHLYHG 0X[ 7;5HI ;B JHQHUDWRU /76HO 5HJ %LW 5;5HI ;B UHFHLYHG 0X[ 7;5HI ;B JHQHUDWRU /76HO 5HJ %LW 5;5HI ;B UHFHLYHG 5;5HI 6HOHFW 'HFRGHU 0X[ 7;5HI ;B JHQHUDWRU . 5;5HI6HO>@ ,'79/ ,'79 Figure 7 RXREF and TXREF Block Diagram %LW )LUVW %LW RXRef 2XWSXW GUZ +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH /DVW 3D\ORDG E\WH GUZ Figure 8 Utopia 1 Data Format and Sequence 18 of 47 September 21, 2001 IDT77V1254L25 SROOLQJ SROOLQJ VHOHFWLRQ SROOLQJ 7;&/. 7;$''5>@ ) 1 +LJK= ) 1 ) 1 ) 1 ) 7;&/$9 1 1 1 1 1 TXEN 7;'DWD>@ 7;3$5,7< 7;62& FHOO WUDQVPLVVLRQ WR 3+< 1 3+< 1 GUZ 3 3 3 3 3 + + + XQGHILQHG 3 . Figure 9 Utopia 2 Transmit Handshake - Back to Back Cells SROOLQJ SROOLQJ VHOHFWLRQ SROOLQJ 7;&/. 7;$''5>@ ) 1 +LJK= ) 1 ) 1 ) 1 ) 7;&/$9 1 1 1 1 1 TXEN 7;'DWD>@ 7;3$5,7< 7;62& FHOO WUDQVPLVVLRQ WR 3+< 1 3+< 1 GUZ 3 3 3 + + + XQGHILQHG 3 . Figure 10 Utopia 2 Transmit Handshake - Delay Between Cells SROOLQJ SROOLQJ VHOHFWLRQ SROOLQJ 7;&/. 7;$''5>@ ) 1 +LJK= ) 1 ) 0 ) 1 ) 7;&/$9 1 1 1 0 1 TXEN 7;'DWD>@ 7;3$5,7< 7;62& FHOO WUDQVPLVVLRQ WR 3 3 3 +LJK= 3 3 3 . GUZ +LJK= 3+< 0 3+< 0 Figure 11 Utopia 2 Transmit Handshake - Transmission Suspended 19 of 47 September 21, 2001 IDT77V1254L25 SROOLQJ SROOLQJ VHOHFWLRQ SROOLQJ 5;&/. 5;$''5>@ 1 ) 1 ) 1 +LJK= ) 1 ) 1 ) 5;&/$9 1 1 1 1 RXEN 5;'DWD>@ 5;3$5,7< 5;62& FHOO WUDQVPLVVLRQ WR 3 3 3 3 3 +LJK= + + + XQGHILQHG 3 . +LJK= 3+< 1 3+< 1 GUZ Figure 12 Utopia 2 Receive Handshake - Back to Back Cells SROOLQJ SROOLQJ VHOHFWLRQ SROOLQJ 5;&/. 5;$''5>@ 1 ) 1 +LJK= ) 1 ) 1 ) 1 ) 5;&/$9 1 1 1 1 RXEN +LJK= 5;'DWD>@ 5;3$5,7< 5;62& 3 3 XQGHILQHG + + . +LJK= FHOO WUDQVPLVVLRQ WR 3+< 1 3+< 1 GUZ Figure 13 Utopia 2 Receive Handshake - Delay Between Cells 20 of 47 September 21, 2001 IDT77V1254L25 SROOLQJ SROOLQJ UHVHOHFWLRQ SROOLQJ 5;&/. 5;$''5>@ 1 ) 1 +LJK= ) 0 ) 1 ) 1 5;&/$9 1 1 0 1 RXEN 5;'DWD>@ 5;3$5,7< 5;62& FHOO WUDQVPLVVLRQ IURP 3 3 3 +LJK= 3 3 3 +LJK= 3+< 0 3+< 0 GUZ Figure 14 Utopia 2 Receive Handshake - Suspended Transfer of Data . 7;&/. 7;&/$9>@ TXEN>@ 7;'$7$>@ 7;3$5,7< 7;62& ; + + 3 3 3 3 3 ; GUZ . Figure 15 Utopia 1 Transmit Handshake - Single Cell 7;&/. 7;&/$9>@ TXEN>@ 7;'$7$>@ 7;3$5,7< 7;62& 3 3 3 + + + + ; + GUZ GUZ Figure 16 Utopia 1 Transmit Handshake - Back-to-Back Cells, and TXEN Suspended Transmission 21 of 47 September 21, 2001 IDT77V1254L25 7;&/. 7;&/$9>@ TXEN>@ 7;'$7$>@ 7;3$5,7< 7;62& 3 3 3 3 3 ; ; ; 3 3 + GUZ . Figure 17 Utopia 1 Transmit Handshake - TXEN Suspended Transmission and Back-to-Back Cells (Byte Mode Only) 5;&/. 5;&/$9>@ RXEN>@ +LJK= 5;'$7$>@ 5;3$5,7< 5;62& 3 3 + + + +LJK= GUZ . Figure 18 Utopia 1 Receive Handshake - Delay Between Cells 5;&/. 5;&/$9>@ RXEN>@ 5;'$7$>@ 5;3$5,7< 5;62& 3 3 +LJK= + 3 3 ; ; + + +LJK= GUZ . Figure 19 Utopia 1 Receive Handshake - RXEN and RXCLAV Control 22 of 47 September 21, 2001 IDT77V1254L25 5;&/. 5;&/$9>@ (DUO\ 5[&/$9 RSWLRQ ELW UHJLVWHUV [ [ [ [ RXEN>@ 5;'$7$>@ 5;3$5,7< 5;62& 3 +LJK= 3 3 3 3 3 3 ; ; +LJK= +LJK= +LJK= . GUZ Figure 20 Utopia 1 Receive Handshake - RXCLAV Deassertion 5;&/. 5;&/$9>@ RXEN>@ +LJK= 5;'$7$>@ 5;3$5,7< 5;62& + + ; + + + 3 +LJK= GUZ Figure 21 Utopia 1 Receive Handshake - RXCLAV Suspended Transfer (Byte Mode Only) Control and Status Interface . DPI Interface Option The DPI interface is relatively new and worth additional description. The biggest difference between the DPI configurations and the UTOPIA configurations is that each channel has its own DPI interface. Each interface has a 4-bit data path, a clock and a start-of-cell signal, for both the transmit direction and the receive direction. Therefore, each signal is point-to-point, and none of these signals has high-Z capability. Additionally, there is one master DPI clock input (DPICLK) into the 77V1254L25 which is used as a source for the DPI transmit clock outputs. DPI is a cell-based transfer scheme like Utopia Level 2, whereas UTOPIA Level 1 transfers can be either byte- or cell-based. Another unique aspect of DPI is that it is a symmetrical interface. It is as easy to connect two PHYs back-to-back as it is to connect a PHY to a switch fabric chip. In contrast, Utopia is asymmetrical. Note that for the 77V1254L25 the nomenclature "transmit" and "receive" is used in the naming of the DPI signals, whereas other devices may use more generic "in" and "out" nomenclature for their DPI signals. The DPI signals are summarized below, where "Pn_" refers to the signals for channel number "n": DPICLK Pn_TCLK Pn_TD[3:0] Pn_TFRM Pn_RCLK Pn_RD[3:0] Pn_RFRM input to PHY PHY to ATM ATM to PHY ATM to PHY ATM to PHY PHY to ATM PHY to ATM 23 of 47 September 21, 2001 IDT77V1254L25 In the transmit direction (ATM to PHY), the ATM layer device asserts start-of-cell signal (Pn_TFRM) for one clock cycle, one clock prior to driving the first nibble of the cell on Pn_TD[3:0]. Once the ATM side has begun sending a cell, it is prepared to send the entire cell without interruption. The 77V1254L25 drives the transmit DPI clocks (Pn_TCLK) back to the ATM device, and can modulate (gap) it to control the flow of data. Specifically, if it cannot accept another nibble, the 77V1254L25 disables Pn_TCLK and does not generate another rising edge until it has room for the nibble. Pn_TCLK are derived from the DPICLK free running clock source. The DPI protocol is exactly symmetrical in the receive direction, with the 77V1254L25 driving the data and start-of-cell signals while receiving Pn_RCLK as an input. The DPI data interface is four bits, so the 53 bytes of an ATM cell are transferred in 106 cycles. Figure 22 shows the sequence of that data transfer. igures 23 through 30 show how the handshake operates. %LW )LUVW %LW +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH +HDGHU E\WH 3D\ORDG E\WH 3D\ORDG E\WH /DVW 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH 3D\ORDG E\WH Figure 22 DPI Data Format and Sequence 3B5&/. LQ 3B5)50 RXW 3B5' RXW ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH ; ; GUZ Figure 23 DPI Receive Handshake - One Cell Received 3B5&/. LQ 3B5)50 RXW 3B5' RXW ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH GUZ Figure 24 DPI Receive Handshake - Back-to-Back Cells . 24 of 47 September 21, 2001 IDT77V1254L25 3B5&/. LQ 3B5)50 RXW 3B5' RXW &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH GUZ Figure 25 DPI Receive Handshake - ATM Layer Device Suspends Transfer $70 /D\HU 'HYLFH 1RW 5HDG\ 9 1RW 5HDG\ . 3B5&/. LQ 3B5)50 RXW 3B5' RXW &HOO 1LEEOH &HOO 1LEEOH ; ; ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH GUZ Figure 26 DPI Receive Handshake - Neither Device Ready 3B7&/. RXW . 3B7)50 LQ 3B7' LQ ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH ; ; Figure 27 DPI Transmit Handshake - One Cell for Transmission 3B7&/. RXW 3B7)50 LQ 3B7' LQ ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH Figure 28 DPI Transmit Handshake - Back-to-Back Cells for Transmission 3B7&/. RXW 3B7)50 LQ 3B7' LQ &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH Figure 29 DPI Transmit Handshake - 77V1254L25 Transmit FIFO Full 25 of 47 September 21, 2001 IDT77V1254L25 9 1RW 5HDG\ $70 /D\HU 'HYLFH 1RW 5HDG\ 3B7&/. RXW 3B7)50 LQ 3B7' LQ &HOO 1LEEOH &HOO 1LEEOH ; ; ; ; &HOO 1LEEOH &HOO 1LEEOH &HOO 1LEEOH GUZ . Figure 30 DPI Transmit Handshake - Neither Device Ready Control and Status Interface Utility Bus The Utility Bus is a byte-wide interface that provides access to the registers within the IDT77V1254L25. These registers are used to select desired operating characteristics and functions, and to communicate status to external systems. The Utility Bus is implemented using a multiplexed address and data bus (AD[7:0]) where the register address is latched via the Address Latch Enable (ALE) signal. The Utility Bus interface is comprised of the following pins: AD[7:0], ALE, CS, RD, WR Read Operation Refer to the Utility Bus timing waveforms in Figures 43 and 44. A register read is performed as follows: 1. Initial condition: - RD, WR, CS not asserted (logic 1) - ALE not asserted (logic 0) 2. Set up register address: - place desired register address on AD[7:0] - set ALE to logic 1; - latch this address by setting ALE to logic 0. 3. Read register data: - Remove register address data from AD[7:0] - assert CS by setting to logic 0; - assert RD by setting to logic 0 - wait minimum pulse width time (see AC specifications) Write Operation A register write is performed as described below: 1. Initial condition: - RD, WR, CS not asserted (logic 1) - ALE not asserted (logic 0) 2. Set up register address: - place desired register address on AD[7:0] - set ALE to logic 1; - latch this address by setting ALE to logic 0. 3. Write data: - place data on AD[7:0] - assert CS by setting to logic 0; - assert WR (logic 0) for minimum time (according to timing specification); reset WR to logic 1 to complete register write cycle. Interrupt Operations The IDT77V1254L25 provides a variety of selectable interrupt and signalling conditions which are useful both during `normal' operation, and as diagnostic aids. Refer to the Status and Control Register List section. 26 of 47 September 21, 2001 IDT77V1254L25 Overall interrupt control is provided via bit 0 of the Master Control Registers. When this bit is cleared (set to 0), interrupt signalling is prevented on the respective port. The Interrupt Mask Registers allow individual masking of different interrupt sources. Additional interrupt signal control is provided by bit 5 of the Master Control Registers. When this bit is set (=1), receive cell errors will be flagged via interrupt signalling and all other interrupt conditions are masked. These errors include: Bad receive HEC Short (fewer than 53 bytes) cells Received cell symbol error Normal interrupt operations are performed by setting bit 0 and clearing bit 5 in the Master Control Registers. INT (pin 85) will go to a low state when an interrupt condition is detected. The external system should then interrogate the 77V1254L25 to determine which one (or more) conditions caused this flag, and reset the interrupt for further occurrences. This is accomplished by reading the Interrupt Status Registers. Decoding the bits in these bytes will tell which error condition caused the interrupt. Reading these registers also: clears the (sticky) interrupt status bits in the registers that are read resets INT This leaves the interrupt system ready to signal an alarm for further problems. LED Control and Signaling The LED outputs provide bi-directional LED drive capability of 8 mA. As an example, the RXLED outputs are described in the truth table: State Cells being received Cells not being received Pin Voltage Low High As illustrated in the following drawing (Figure 31), this could be connected to provide for a two-LED condition indicator. These could also be different colors to provide simple status indication at a glance. (The minimum value for R should be 330). TXLED Truth Table State Cells being transmitted Pin Voltage Low Cells not being transmitted High Diagnostic Function 9 5 5[/(' 7[/(' ,QGLFDWHV &HOOV EHLQJ UHFHLYHG RU WUDQVPLWWHG 5 ,QGLFDWHV &HOOV DUH QRW EHLQJ UHFHLYHG RU WUDQVPLWWHG GUZ Figure 31 LED Indicator 27 of 47 September 21, 2001 IDT77V1254L25 Loopback There are two loopback modes supported by the 77V1254L25. The loopback mode is controlled via bits 1 and 0 of the Diagnostic Control Registers: Bit 1 0 1 1 Bit 0 0 0 1 Mode Normal operating mode PHY Loopback Line Loopback Normal Mode This mode, Figure 32, supports normal operating conditions: data to be transmitted is transferred to the TC, where it is queued and formatted for transmission by the PMD. Receive data from the PMD is decoded along with its clock for transfer to the receiving "upstream system". PHY Loopback As Figure 33 illustrates below, this loopback mode provides a connection within the PHY from the transmit PHY-ATM interface to the PHY-ATM receive interface. Note that while this mode is operating, no data is forwarded to or received from the line interface. Line Loopback Line Loopback Figure 34 might also be called "remote loopback" since it provides for a means to test the overall system, including the line. Since this mode will probably be entered under direction from another system (at a remote location), receive data is also decoded and transferred to the upstream system to allow it to listen for commands. A common example would be a command asking the upstream system to direct the TC to leave this loopback state, and resume normal operations. $70 /D\HU 'HYLFH 77V1254L25 ,'79 7& VXEOD\HU 30' VXEOD\HU /LQH ,QWHUIDFH GUZ Figure 32 Normal Mode $70 /D\HU 'HYLFH ,'79 77V1254L25 7& VXEOD\HU 30' VXEOD\HU /LQH ,QWHUIDFH GUZ Figure 33 PHY Loopback 28 of 47 September 21, 2001 IDT77V1254L25 77V1254L25 ,'79 $70 /D\HU 'HYLFH 7& VXEOD\HU 30' VXEOD\HU /LQH ,QWHUIDFH GUZ Figure 34 Line Loopback Counters Several condition counters are provided to assist external systems (e.g., software drivers) in evaluating communications conditions. It is anticipated that these counters will be polled from time to time (user selectable) to evaluate performance. A separate set of registers exists for each channel of the PHY. Symbol Error Counters - 8 bits - counts all invalid 5-bit symbols received Transmit Cell Counters - 16 bits - counts all transmitted cells Receive Cell Counters - 16 bits - counts all received cells, excluding idle cells and HEC errored cells Receive HEC Error Counters - 5 bits - counts all HEC errors received The TXCell and RXCell counters are sized (16 bits) to provide a full cell count (without roll over) if the counter is read once/second. The Symbol Error counter and HEC Error counter were given sufficient size to indicate exact counts for low error-rate conditions. If these counters overflow, a gross condition is occurring, where additional counter resolution does not provide additional diagnostic benefit. Reading Counters 1. Decide which counter value is desired. Write to the Counter Select Register(s) (0x06, 0x16, 0x26 and 0x36) to the bit location corresponding to the desired counter. This loads the High and Low Byte Counter Registers with the selected counter's value, and resets this counter to zero. 2. Note: Only one counter may be enabled at any time in each of the Counter Select Registers. Read the Counter Registers (0x04, 0x14, 0x24 or 0x34 (low byte)) and (0x05, 0x15, 0x25 or 0x35 (high byte)) to get the value. Note: The PHY takes some time to set up the low and high byte counters after a specific counter has been selected in the Counter Selector register. This time delay (in S) varies with the line rate and can be calculated as follows: Time delay (S) = 12.5___ line rate (Mbps) Loop Timing Feature The 77V1254L25 also offers a loop timing feature for specific applications where data needs to be repeated / transmitted using the recovered clock. If the loop timing mode is enabled in the Enhanced Control Register 1 bit 6, the recovered receive clock is used as to clock out data on transmit side. This mode is port specific, i.e., the user can select one or more ports to be in loop timing mode. In normal mode, the transmitter transmits data using the multiplied oscillator clock. Further reads may be accomplished in the same manner by writing to the Counter Select Registers. 29 of 47 September 21, 2001 IDT77V1254L25 Jitter in Loop Timing Mode One of the primary concerns when using loop timing mode is the amount of jitter that gets added each time data is transmitted. Table 3 shows the jitter measured at various data rates. The set-up shown in Figure 35 was used to perform these tests. The maximum jitter seen was at TX point 5 and the minimum jitter was at point 2. The loop timing jitter is defined as the amount of jitter generated by each TX node. In other words, the loop timing jitter or the jitter added by a loop-timed port in the set-up below is the difference between the Total Output Jitter and the Total Input Jitter. OSC 1 2 TX P0 Normal Mode RX RX TX CLK P1 Loop Timing Mode Data Data 3 RX TX CLK P2 Loop Timing Mode Data Data 4 RX TX 5 CLK P3 Loop Timing Mode Data Data SWITCH Figure 35 Test Setup for Loop Timing Jitter Measurements Loop Timing Jitter Specification Line Rate Mbps 32 64 Data Rate Mbps 25.6 51.2 Min. --- Typ. 100 ps 100 ps Max. --- Note Using 32Mhz OSC Using 64Mhz OSC Table 3 Loop Timing Jitter The waveforms below show some of the measurements taken with the set-up in Figure 35. Using the formula above, the jitter specification was derived. For example, at data rate of 25.6Mbps, jitter added going through Line Card 3 is 1.5ns -1.4ns (as shown in the waveforms below). 30 of 47 September 21, 2001 IDT77V1254L25 Jitter at 25.6Mbps at point 4 with respect to point 1 Jitter at 25.6Mbps at point 5 with respect to point 1 Jitter at 51.2Mbps at point 4 with respect to point 1 Jitter at 51.2Mbps at point 5 with respect to point 1 From the above measurements taken, the amount of jitter being added at each TX point is not significant. These tests were also run for extended periods of time (64 hours) and no bit errors were seen. VPI/VCI Swapping For compatibility with IDT's SwitchStar products (77V400 and 77V500), the 77V1254L25 has the ability to swap parts of the VPI/VCI address space in the header of receive cells. This function is controlled by the VPI/VCI Swap bits, which are bit 5 of the Enhanced Control Registers (0x08, 0x18, 0x28 and 0x38). The portions of the VPI/VCI that are swapped are shown below. Bits X(7:0) are swapped with Y(7:0) when the VPI/VCI Swap bit is set and the chip is in DPI mode. *)&93, 93, 9&, 9&, +(& 37, 93, 9&, %\WH %\WH %\WH &/3 %\WH %\WH < < < < ; ; ; ; ; < ; < ; < ; < %\WH %\WH %\WH %\WH %\WH 31 of 47 September 21, 2001 IDT77V1254L25 Line Side (Serial) Interface Each of the four ports has two pins for differential serial transmission, and two pins for differential serial receiving. PHY to Magnetics Interface A standard connection to 100 and 120 unshielded twisted pair cabling is shown in Figure 36. Note that the transmit signal is somewhat attenuated in order to meet the launch amplitude specified by the standards. The external receive circuitry is designed to attenuate low frequencies in order to compensate for the high frequency attenuation of the cable. Also, the receive circuitry biases the positive and negative RX inputs to slightly different voltages. This is done so that the receiver does not receive false signals in the absence of a real signal. This can be important because the 77V1254L25 does not disable error detection or interrupts when an input signal is not present. When connecting to UTP at 51.2 Mbps, it is necessary to use magnetics with sufficient bandwidth. Such a device can also operate satisfactorily at 25.6 Mbps. Refer to Table 5 for the recommended magnetics. $*1' 0DJQHWLFV & 5 & 5 5 5 ,'79 ,'79 7[' 7[' 5- &RQQHFWRU 5 $9'' 5 5[' 5 5 / 5[' 5 $*1' GUZ . $*1' Figure 36 Recommended Connection to Magnetics Component R1 R2 R3 R4 R5 R6 R7 R8 R9 Value 47 47 620 110 2700 2700 82 33 33 Tolerance 5% 5% 5% 5% 5% 5% 5% 5% 5% Table 4 Analog Component Values (Part 1 of 2) 32 of 47 September 21, 2001 IDT77V1254L25 Component C1 C2 L1 Value 470pF 470pF 3.3H Tolerance 20% 20% 20% Table 4 Analog Component Values (Part 2 of 2) Magnetics Modules for 25.6 Mbps Pulse PE-67583 or R4005 TDK TLA-6M103 Pulse R4005 www.pulseeng.com www.component.tdk.com www.pulseeng.com Magnetics Module for 51.2 Mbps Table 5 Magnetics Modules Status and Control Register List The 77V1254L25 has 37 registers that are accessible through the utility bus. Each of the four ports has 9 registers dedicated to that port. There is only one register (0x40) which is not port specific. For those register bits which control operation of the Utopia interface, the operation of the Utopia interface is determined by the registers corresponding to the port which is selected at that particular time. For consistent operation, the Utopia control bits should be programmed the same for all four ports, except for the Utopia 2 port addresses in the Enhanced Control Registers. Register Name Master Control Registers Interrupt Status Registers Diagnostic Control Registers LED Driver and HEC Status/control Low Byte Counter Register [7:0] High Byte Counter Register [15:8] Counter Registers Read Select Interrupt Mask Registers Enhanced Control 1 Registers RXREF and TXREF Control Register Nomenclature "Reserved" register bits, if written, should always be written "0" R-only or W-only = register is read-only or write-only "0" = `cleared' or `not set' Register Address Port 0 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 Port 1 0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 Port 2 0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 Port 3 0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x40 R/W = register may be read and written via the utility bus sticky = register bit is cleared after the register containing it is read; all sticky bits are read-only "1" = `set' All Ports 33 of 47 September 21, 2001 IDT77V1254L25 Master Control Registers Addresses: 0x00, 0x10, 0x20, 0x30 Bit 7 6 5 4 3 2 1 0 Type R/W R/W R/W R/W R/W R/W R/W R/W 0 Initial State Reserved Function 1 = discard errored cells Discard Receive Error Cells - On receipt of any cell with an error (e.g. short cell, invalid command mnemonic, receive HEC error (if enabled), this cell will be discarded and will not enter the receive FIFO. 0 = all interrupts 0 = disabled 1 = discard idle cells 0 = not halted 0 = cell mode 1 = enable interrupts Enable Cell Error Interrupts Only - If Bit 0 in this register is set (Interrupts Enabled), setting of this bit enables only "Received Cell Error" (as defined in bit 6) to trigger interrupt line. Transmit Data Parity Check - Directs TC to check parity of TXDATA against parity bit located in TXPARITY. Discard Received Idle Cells - Directs TC to discard received idle (VPI/VCI = 0) cells from PMD without signalling external systems. Halt Transmit - Halts transmission of data from TC to PMD and forces the TXD outputs to the "0" state UTOPIA Level 1 mode select: - 0 = cell mode, 1 = byte mode. Not applicable for Utopia 2 or DPI modes. Enable Interrupt Pin (Interrupt Mask Bit) - Enables interrupt output pin (pin 85). If cleared, pin is always high and interrupt is masked. If set, an interrupt will be signaled by setting the interrupt pin to "0". It doesn't affect the Interrupt Status Registers. Interrupt Status Registers Addresses: 0x01, 0x11, 0x21, 0x31 Bit 7 6 R Type Initial State Reserved 0 = Bad Signal Good Signal Bit - See definition on page 13. 1 - Good Signal 0 - Bad Signal HEC error cell received - Set when a HEC error is detected on received cell. "Short Cell" Received - Interrupt signal which flags received cells with fewer than 53 bytes. This condition is detected when receiving Start-of-Cell command bytes with fewer than 53 bytes between them. Transmit Parity Error - If Bit 4 of Register 0x00 / 0x10 / 0x20 / 0x30 is set (Transmit Data Parity Check), this interrupt flags a transmit data parity error condition. Odd parity is used. Receive Signal Condition change - This interrupt is set when the received 'signal' changes either from 'bad to good' or from 'good to bad'. Received Symbol Error - Set when an undefined 5-bit symbol is received. Receive FIFO Overflow - Interrupt which indicates when the receive FIFO has filled and cannot accept additional data. Function 5 4 3 2 1 0 sticky sticky sticky sticky sticky sticky 0 0 0 0 0 0 Diagnostic Control Registers Addresses: 0x02, 0x12, 0x22, 0x32 Bit 7 Type R/W Initial State 0 = normal Function Force TXCLAV deassert - (applicable only in Utopia 1 and 2 modes) Used during line loopback mode to prevent upstream system from continuing to send data to the 77V1254L25. 34 of 47 September 21, 2001 IDT77V1254L25 Addresses: 0x02, 0x12, 0x22, 0x32 Bit 6 Type R/W Initial State 0 = UTOPIA Function RXCLAV Operation Select - (for Utopia 1 mode) The UTOPIA standard dictates that during cell mode operation, if the receive FIFO no longer has a complete cell available for transfer from PHY, RXCLAV is deasserted following transfer of the last byte out of the PHY to the upstream system. With this bit set, early deassertion of this signal will occur coincident with the end of Payload byte 44 (as in octet mode for TXCLAV). This provides early indication to the upstream system of this impending condition. 0 = "Standard UTOPIA RXCLAV' 1 = "Cell mode = Byte mode" Single/Multi-PHY configuration select - (applicable and writable only in Utopia 1 mode) 0 = single: Never tri-state RXDATA, RXPARITY and RXSOC 1 = Multi-PHY mode: Tri-state RXDATA, RXPARITY and RXSOC when RXEN = 1 RFLUSH = Clear Receive FIFO - This signal is used to tell the TC to flush (clear) all data in the receive FIFO. The TC signals this completion by clearing this bit. Insert Transmit Payload Error - Tells TC to insert cell payload errors in transmitted cells. This can be used to test error detection and recovery systems at destination station, or, under loopback control, at the local receiving station. This payload error is accomplished by flipping bit 0 of the last cell payload byte. Insert Transmit HEC Error - Tells TC to insert HEC error in Byte 5 of cell. This can be used to test error detection and recovery systems in downstream switches, or, under loopback control, the local receiving station. The HEC error is accomplished by flipping bit 0 of the HEC byte. Loopback Control bit # 1 0 0 0 Normal mode (receive from network) 1 0 PHY Loopback 1 1 Line Loopback 5 R/W 1 = tri-state 4 3 R/W R/W 0 = normal 0 = normal 2 R/W 0 = normal 1,0 R/W 00 = normal LED Driver and HEC Status/Control Registers Addresses: 0x03, 0x13, 0x23, 0x33 Bit 7 6 5 4, 3 R/W R/W R/W Type 0 0 = enable checking 0 = enable calculate & replace 00 = 1 cycle Initial State Reserved Disable Receive HEC Checking (HEC Enable) - When not set, the HEC is calculated on first 4 bytes of received cell, and compared against the 5th byte. When set (= 1), the HEC byte is not checked. Disable Transmit HEC Calculate & Replace - When set, the 5th header byte of cells queued for transmit is not replaced with the HEC calculated across the first four bytes of that cell. RXREF Pulse Width Select bit # 4 3 0 0 RXREF active for 1 OSC cycle 0 1 RXREF active for 2 OSC cycles 1 0 RXREF active for 4 OSC cycles 1 1 RXREF active for 8 OSC cycles FIFO Status TXLED Status RXLED Status 1 = TxFIFO empty 0 = Cell Transmitted 0 = Cell Received 0 = TxFIFO not empty 1 = Cell Not Transmitted 1 = Cell Not Received Function 2 1 0 R R R 1 = empty 1 1 35 of 47 September 21, 2001 IDT77V1254L25 Low Byte Counter Registers [7:0] Addresses: 0x04, 0x14, 0x24, 0x34 Bit [7:0] Type R Initial State 0x00 Function Provides low byte of counter value selected via registers 0x06, 0x16, 0x26, and 0x36 High Byte Counter Registers [15:8] Addresses: 0x05, 0x15, 0x25, 0x35 Bit [7:0] Type R Initial State 0x00 Function Provides high-byte of counter value selected via registers 0x06, 0x16, 0x26, and 0x36 Counter Select Registers Addresses: 0x06, 0x16, 0x26, 0x36 Bit 7 6 5 4 3 2 1 0 Type -- -- -- -- W W W W -- -- -- -- 0 0 0 0 Initial State Reserved. Reserved. Reserved. Reserved. Symbol Error Counter. TXCell Counter. RXCell Counter. Cells with HEC errors are never counted. Receive HEC Error Counter. Function Note: For proper operation, only one bit may be set in a Counter Select Register at any time. Interrupt Mask Registers Addresses: 0x07, 0x17, 0x27, 0x37 Bit 7 6 5 4 3 2 1 0 R/W R/W R/W R/W R/W R/W Type 0 0 0 = interrupt enabled 0 = interrupt enabled 0 = interrupt enabled 0 = interrupt enabled 0 = interrupt enabled 0 = interrupt enabled Initial State Reserved. Reserved. HEC Error Cell. Short Cell Error. Transmit Parity Error. Receive Signal Condition Change. Receive Cell Symbol Error. Receive FIFO Overflow. Function Note: When set to "1", these bits mask the corresponding interrupts going to the interrupt pin (INT). When set to "0", the interrupts are unmasked. These interrupts correspond to the interrupt status bits in the Interrupt Status Registers. 36 of 47 September 21, 2001 IDT77V1254L25 Enhanced Control 1 Registers Addresses: 0x08, 0x18, 0x28, 0x38 Bit 7 6 5 4-0 Type W R/W R/W R/W Initial State 0 = not reset 0 = OSC 0 Port 0 (Reg 0x08) 00000 Port 1 (Reg 0x18) 00001 Port 2 (Reg 0x28) 00010 Port 3 (Reg 0x38) 00011 Function Individual Port Software Reset 1= Reset. This bit is self-cleaning; It isn't necessary to write "0" to exit reset. Transmit Line Clock (or Loop Timing Mode). When set to 0, the OSC input is used as the transmit line clock. When set to 1, the recovered receive clock is used as the transmit line clock. Reserved Utopia 2 Port Address When operating in Utopia 2 Mode, these register bits determine the Utopia 2 port address RXREF and TXREF Control Register Addresses: 0x40 Bit 7-6 5 4 3-0 R/W Type R/W W Initial State Function 0 = RXREF0 (Port 0) RXREF Source Select Selects which of the four ports (0-3) is the source of RXREF. 0 = not reset 0 0000 = not looped Master Software Reset 1 = Reset. This bit is self-cleaning; it isn't necessary to write "0" to exit reset. Reserved RXREF to TXREF Loop Select When set to 0, TXREF is used to generate X_8 timing marker commands. When set to 1, TXREF input is ignored, and received X_8 timing commands. are looped back and added to the transmit stream of that same port. See Figure 7. bit 3: port 3 bit 2: port 2 bit 1: port 1 bit 0: port 0 Absolute Maximum Ratings Symbol VTERM TBIAS TSTG IOUT Rating Terminal Voltage with Respect to GND Temperature Under Bias Storage Temperature DC Output Current Value -0.5 to +5.5 -55 to +125 -55 to +120 50 V C C mA Unit Note: Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. 37 of 47 September 21, 2001 IDT77V1254L25 Recommended DC Operating Conditions Symbol VDD GND VIH VIL AVDD AGND VDIF Parameter Digital Supply Voltage Digital Ground Voltage Input High Voltage Input Low Voltage Analog Supply Voltage Analog Ground Voltage VDD - AVDD Min. 3.0 0 2.0 -0.3 3.0 0 -0.5 Typ. 3.3 0 ____ ____ 3.3 0 0 Max. 3.6 0 5.25 0.8 3.6 0 0.5 V V V V V V V Unit Capacitance (TA = +25C, F = 1MHz) Symbol CIN1 CIO1 Parameter Input Capacitance I/O Capacitance Conditions VIN = 0V VOUT = 0V Max. 10 10 Unit pF pF 1. Characterized values, not tested. DC Electrical Characteristics (All Pins except TX+/- and RX+/-) Symbol ILI ILO VOH1 VOH2 VOL3 IDD1 4, 5 1 2 Parameter Input Leakage Current /O (as input) Leakage Current Output Logic "1" Voltage Output Logic "1" Voltage Output Logic "0" Voltage Digital Power Supply Current - VDD Test Conditions Gnd VIN VDD Gnd VIN VDD IOH = -2mA, VDD = min. IOH = -8mA, VDD = min. IOL = -8mA, VDD = min. OSC = 32 MHz, all outputs unloaded OSC = 64 MHz, all outputs unloaded Min. -5 -10 2.4 2.4 -- -- -- -- -- 5 Max. Unit A A V V V mA mA mA mA 10 -- -- 0.4 90 170 55 60 IDD2 1. 2. 3. 4. 5. 5 Analog Power Supply Current - AVDD OSC = 32 MHz, all outputs unloaded OSC = 64 MHz, all outputs unloaded For AD[7:0] pins only. For all output pins except AD[7:0], INT and TX+/-. For all output pins except TX+/-. Add 15mA for each TX+/- pair that is driving a load. Total supply current is the sum of IDD1 and IDD2 38 of 47 September 21, 2001 IDT77V1254L25 DC Electrical Characteristics (TX+/- Output Pins Only) Symbol VOH1 VOL Parameter Output Logic High Voltage Output Logic Low Voltage Test Conditions IOH = -20mA IOL = -20mA Min. VDD - 0.5V -- Max. -- 0.5 Unit V V DC Electrical Characteristics (RXD+/- Input Pins Only) Symbol VIR VIP VICM Parameter RXD+/- input voltage range RXD+/- input peak-to-peak differential voltage RXD+/- input common mode voltage 0 0.6 1.0 Min. -- -- VDD/2 Typ Max. VDD 2*VDD VDD-0.5 Unit V V V UTOPIA Level 2 Bus Timing Parameters Symbol t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t12 t13 t14 t15 t16 t17 t18 t19 t20 t21 t22 t23 TXCLK Frequency TXCLK Duty Cycle (% of t1) TXDATA[15:0], TXPARITY Setup Time to TXCLK TXDATA[15:0], TXPARITY Hold Time to TXCLK TXADDR[4:0], Setup Time to TXCLK TXADDR[4:0], Hold Time to TXCLK TXSOC, TXEN Setup Time to TXCLK TXSOC, TXEN Hold Time to TXCLK TXCLK to TXCLAV High-Z TXCLK to TXCLAV Low-Z (min) and Valid (max) RXCLK Frequency RXCLK Duty Cycle (% of t12) RXEN Setup Time to RXCLK RXCLK Hold Time to RXCLK RXADDR[4:0] Setup Time to RXCLK RXADDR[4:0] Hold Time to RXCLK RXCLK to RXCLAV High-Z RXCLK to RXCLAV Low-Z (min) and Valid (max) RXCLK to RXSOC High-Z RXCLK to RXSOC Low-Z (min) and Valid (max) RXCLK to RXDATA, RXPARITY High-Z RXCLK to RXDATA, RXPARITY Low-Z (min) and Valid (max) Parameter 0.2 40 4 1.5 4 1.5 4 1.5 2 2 0.2 40 4 1.5 4 1.5 2 2 2 2 2 2 Min. Max. 50 60 -- -- -- -- -- -- 10 10 50 60 -- -- -- -- 10 10 10 10 10 10 Unit MHz % ns ns ns ns ns ns ns ns MHz % ns ns ns ns ns ns ns ns ns ns 39 of 47 September 21, 2001 IDT77V1254L25 W 7;&/. 7;'$7$>@ 7;3$5,7< W 7;$''5>@ W 7;62& W W W W 2FWHW W 2FWHW W W W TXEN 7;&/$9 +LJK= +LJK= GUZ Figure 37 UTOPIA Level 2 Transmit W 5;&/. W W W W 5;&/$9 5;62& 5;'$7$>@ 5;3$5,7< +LJK= +LJK= +LJK= W RXEN W 5;$''5>@ W W W W W W W W +LJK= +LJK= +LJK= GUZ Figure 38 UTOPIA Level 2 Receive . UTOPIA Level 1 Bus Timing Parameters Symbol t31 t32 t33 t34 t35 t36 t37 t39 t40 t41 TXCLK Frequency TXCLK Duty Cycle (% of t31) TXDATA[7:0], TXPARITY Setup Time to TXCLK TXDATA[7:0], TXPARITY Hold Time to TXCLK TXSOC, TXEN[3:0] Setup Time to TXCLK TXSOC, TXEN[3:0] Hold Time to TXCLK TXCLK to TXCLAV[3:0] Invalid (min) and Valid (max) RXCLK Frequency RXCLK Duty Cycle (% of t39) RXEN[3:0] Setup Time to RXCLK Parameter 0.2 40 4 1.5 4 1.5 2 0.2 40 4 Min. Max. 50 60 -- -- -- -- 10 50 60 -- Unit MHz % ns ns ns ns ns MHz % ns 40 of 47 September 21, 2001 IDT77V1254L25 Symbol t42 t43 t44 t45 t46 t47 Parameter RXEN[3:0] Hold Time to RXCLK RXCLK to RXCLAV[3:0] Invalid (min) and Valid (max) RXCLK to RXSOC High-Z RXCLK to RXSOC Low-Z (min) and Valid (max) RXCLK to RXDATA, RXPARITY High-Z RXCLK to RXDATA, RXPARITY Low-Z (min) and Valid (max) W 7;&/. 7;'$7$>@ 7;3$5,7< 7;62& 2FWHW W W 2FWHW W W Min. 1.5 2 2 2 2 2 W W Max. -- 10 10 10 10 10 Unit ns ns ns ns ns ns TXEN[3:0] 7;&/$9>@ GUZ Figure 39 UTOPIA Level 1 Transmit W 5;&/. W W W W W W W W W W RXEN[3:0] 5;&/$9>@ 5;62& 5;'$7$>@ 5;3$5,7< +LJK= +LJK= +LJK= +LJK= GUZ Figure 40 UTOPIA Level 1 Receive DPI Bus Timing Parameters Symbol t51 t52 t53 t54 t55 t56 t57 DPICLK Frequency DPICLK Duty Cycle (% of t51) DPICLK to Pn_TCLK Propagation Delay Pn_TFRM Setup Time to Pn_TCLK Pn_TFRM Hold Time to Pn_TCLK Pn_TD[3:0] Setup Time to Pn_TCLK Pn_TD[3:0] Hold Time to Pn_TCLK Parameter 0.2 40 2 4 1 4 1 Min. Max. 50 60 14 -- -- -- -- Unit MHz % ns ns ns ns ns 41 of 47 September 21, 2001 IDT77V1254L25 Symbol t61 t62 t63 t64 t65 Pn_RCLK Period Pn_RCLK High Time Pn_RCLK Low Time Pn_RCLK to Pn_TFRM Invalid (min) and Valid (max) Pn_RCLK to Pn_RD Invalid (min) and Valid (max) Parameter 25 10 10 2 2 Min. Max. -- -- -- 12 12 Unit ns ns ns ns ns W '3,&/. W 3QB7&/. W 3QB7)50 W W W 3QB7'>@ W GUZ . Figure 41 DPI Transmit W 3QB5&/. W W W 3QB5)50 W 3QB5'>@ GUZ . Figure 42 DPI Receive Utility Bus Read Cycle Name Tas Tcsrd Tah Tapw Ttria Min. 10 0 5 10 0 Max. -- -- -- -- -- Unit MHz % ns ns ns Description Address setup to ALE Chip select to read enable Address hold to ALE ALE min pulse width Address tri-state to RD assert 42 of 47 September 21, 2001 IDT77V1254L25 Name Trdpw Tdh Tch Ttrid Trd Tar Trdd Min. 20 0 0 -- -- 5 0 Max. -- -- -- 10 18 -- -- Unit ns ns ns ns ns ns ns Description Min. RD pulse width Data Valid hold time RD deassert to CS deassert RD deassert to data tri-state Read Data access ALE low to start of read Start of read to Data low-Z Utility Bus Write Cycle Name Tapw Tas Tah Tcswr Twrpw Tdws Tdwh Tch Taw Min. 10 10 5 0 20 20 10 0 20 7DV $GGUHVV 7DSZ $/( 7FVUG 7FK Max. -- -- -- -- -- -- -- -- -- 7DK Unit ns ns ns ns ns ns ns ns ns Description ALE min pulse widt Address set up to ALE Address hold time to ALE CS Assert to WR Min. WR pulse width Write Data set up Write Data hold time WR deassert to CS deassert ALE low to end of write $'>@ LQSXW CS 7DU 7UGSZ 7WULG 7GK 'DWD GUZ RD 7UG 7UGG $'>@ RXWSXW Figure 43 Utility Bus Read Cycle 43 of 47 September 21, 2001 IDT77V1254L25 7DV $'>@ $GGUHVV 7DSZ $/( 7DK 7GZV 'DWD LQSXW 7GZK 7DZ 7FK CS 7FVZU 7ZUSZ WR GUZ . Figure 44 Utility Bus Write Cycle OSC, RXREF, TXREF and Reset Timing Symbol Tcyc Tch Tcl Tcc Trrpd Ttrh Ttrl Trspw 1 Parameter OSC cycle period OSC high tim OSC low time OSC cycle to cycle period variation OSC to RXREF Propagation Delay TXREF High Time TXREF Low Time Minimum RST Pulse Width 30 15 40 40 -- 1 35 35 Min. Typ. 31.25 15.625 -- -- -- -- -- -- -- Max. 33 16.5 60 60 1 30 -- -- -- Unit ns ns % % % ns ns ns -- two OSC cycles 1. The width of the RXREF pulse is programmable in the LED Driver and HEC Status/Control Registers. 7F\F 26& 7FK 7FO 7UUSG RXREF 7UUSG 7WUO TXREF 7WUK 7UVSZ RST GUZ . Figure 45 OSC, RXREF, TXREF and Reset Timing 44 of 47 September 21, 2001 IDT77V1254L25 AC Test Conditions Input Pulse Levels Input Rise/Fall Times Input Timing Reference Levels Output Reference Levels Output Load GND to 3.0V 3ns 1.5V 1.5V See Figure 46 3.3V 1.2K D.U.T. 900 30pF* * Includes jig and scope capacitances. Figure 46 Output Load A note about Figures 47 and 48: The ATM Forum and ITU-T standards for 25 Mbps ATM define "Network" and "User" interfaces. They are identical except that transmit and receive are switched between the two. A Network device can be connected directly to a User device with a straight-through cable. User-to-User or Network-to-Network connections require a cable with 1-to-7 and 2-to-8 crossovers. 1RWH 1RWH $*1' 1RWH 5- &RQQHFWRU 7[ 5- 5- 5- 5[ 0DJQHWLFV $*1' 5[ )LOWHU 7[ )LOWHU 5; 5; 7; 7; 0DJQHWLFV 0DJQHWLFV 0DJQHWLFV 1RWH ,'7 77V1254L25 9 GUZ . Figure 47 PC Board Layout for ATM Network Note: 1.No power or ground plane inside this area. 2.Analog power plane inside this area. 3.Digital power plane inside this area. 4.A single ground plane should extend over the area covered by the analog and digital power planes, without breaks. 5.All analog signal traces should avoid 90 corners. 45 of 47 September 21, 2001 IDT77V1254L25 1RWH 1RWH $*1' 5- &RQQHFWRU 5[ 5- 5- 5- 7[ 0DJQHWLFV $*1' 7[ )LOWHU 5[ )LOWHU 1RWH 7; 7; 5; 5; 0DJQHWLFV 0DJQHWLFV 0DJQHWLFV 1RWH ,'7 9 77V1254L25 GUZ . Figure 48 PC Board Layout for ATM User Note: 1.No power or ground plane inside this area. 2.Analog power plane inside this area. 3.Digital power plane inside this area. 4.A single ground plane should extend over the area covered by the analog and digital power planes, without breaks. 5.All analog signal traces should avoid 90 corners. Package Dimensions $ $ H 3LQ 34)3 . 4.3514 '5.4035 ' ( ( ' ' 2.4792 ' $ 4.4319 ' 5.5125 ' / E 6<0%2/ $ $ $ ' ' ( ( / H E 0,1 120 0$; GUZ 'LPHQVLRQV DUH LQ PLOOLPHWHUV PSC-4053 is a more comprehensive package outline drawing and is available from the packaging section of the IDT web site. 46 of 47 September 21, 2001 IDT77V1254L25 Ordering Information ,'7 11111 'HYLFH 7\SH $ 3RZHU 111 6SHHG $ 3DFNDJH $ 3URFHVV 7HPS 5DQJH %ODQN , 3* &RPPHUFLDO & WR & ,QGXVWULDO & WR & 3LQ 34)3 38 / 0EV 77V1254L25 9 4XDG 0EV $70 3+< 7UDQVPLVVLRQ &RQYHUJHQFH 7& DQG 30' 6XEOD\HUV GUZ . Revision History 3/2/98: 10/5/98 11/30/98 3/23/99: 3/8/01 ADVANCE INFORMATION. Initial Draft. PRELIMINARY. TXOSC pin name changed to OSC. Missing information added. Package code corrected in ordering code. PRELIMINARY. Numerous minor edits. Corrections to Figures 26 and 30. Elimination of Line Rate Selection bit in the Master Control Registers. IDD1 and IDD2 values updated. Addition of VPI/VCI Swap feature. Improvements to Utopia bus timing parameters. Update to new format, revisions to Utopia 1 text. Changed from Preliminary to Final. Various typographic corrections. Corrected default values for UTOPIA 2 Port Address in the Enhanced Control 1 Registers. Added IDD values for 51 Mbps.Removed Trd minimum spec. IDD Values for 25 Mbps and 51 Mbps updated. Changed values in the Max. column for IDD1 and IDD2 in the DC Electrical Characteristics (All pins except TX and RX) table. Changed value in Max. column for t23 in Utopia Level 2 Bus Timing Parameters table. Added Loop Timing Feature section. 9/21/2001 CORPORATE HEADQUARTERS 2975 Stender Way Santa Clara, CA 95054 for SALES: 800-345-7015 or 408-727-6116 fax: 408-330-1748 www.idt.com 47 of 47 for Tech Support: email: phyhelp@idt.com phone: 408-330-1752 September 21, 2001 |
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