MB86960 MB86701 MB86703 10BASE SD15-8 0900H FPT-100P MB86960APF 10BASE-T - Datasheet Archive

 

NETWORK INTERFACE CONTROLLER with ENCODER/DECODER (NICE) DATA SHEET FEATURES · Complies with international standards for

 

MB86960 MB86960 NETWORK INTERFACE CONTROLLER with ENCODER/DECODER (NICE) DATA SHEET FEATURES · Complies with international standards for Ethernet, ISO/ANSI/IEEE 8802-3 · Provides generic interface industry­standard microprocessor busses (x86, 680x0, RISC) · 20 Mbyte/second data transfer rate to/from the system bus · High-performance packet buffer architecture pipelines data for highest throughput · On-chip management control buffer pointers reduce software overhead and improve performance · Efficient, configurable two bank transmit buffer and ring receive buffer · High-speed burst and single transfer DMA · 64-element hash table for multicast address filtering · Power down mode reduces power dissipation for battery-powered equipment · High-speed, low-power CMOS technology Revised November 1997 multiple data packets to be "chained" together and transmitted to the network from a single transmit command, thus allowing greater design flexibility and throughput. Receive packets are captured in a ring buffer which can be configured in various sizes from 4 to 62 kilobytes, depending on the memory selected and amount allocated for the transmit buffer. Possible configurations for the system bus interface include I/O mapping, memory mapping and DMA access, or a combination of these. With a 20 Mbyte/sec bandwidth, the NICE system bus interface allows you to use the full throughput capacity of its unique packet buffering architecture. The NICE controller's selectable bus modes provide both big-and­little-endian byte ordering, permitting an efficient data interface with most microprocessors and higher-level protocols. Implemented in Fujitsu's high-speed, low-power CMOS process, the MB86960 MB86960 is supplied in a 100-pin plastic quad flat package for surface mounting. PIN CONFIGURATION · Available in 100-pin plastic quad flat package 100 GENERAL DESCRIPTION The MB86960 MB86960 Network Interface Controller with Encoder/Decoder (NICETM) is a high-performance, highly integrated monolithic device which incorporates both network controller, complete with buffer management, and Manchester encoder/decoder. The MB86960 MB86960 allows implementation of adapter solutions with a minimum of additional support chips. It can be combined with a Fujitsu Plug and Play ISA Controller (MB86701 MB86701 or MB86703 MB86703) and a Universal Interface to 10BASE 10BASE­T to form a highly integrated PnP ready Ethernet adapter card. The unique buffer management architecture of the MB86960 MB86960 allows packet data to access a buffer memory area from the host and from the network media simultaneously, with virtually no interaction. The network controller updates all receive and transmit pointers internally, thus reducing the software overhead required to control these operations and maximize performance. The NICE device has a partitionable 2, 4, 8, or 16 kilobyte, two-bank, transmit buffer which allows 81 1 80 100­PIN PLASTIC QUAD FLAT PACK (PQFP) 30 51 31 50 TOP VIEW MB86960 MB86960 controller presents a small foot-print to the board design, and is surface-mountable with its gull-wing leads. See Pin Configuration and Pin Assignments for the pin numbering. PIN ASSIGNMENTS AND DESCRIPTIONS Supplied in a 100-pin plastic quad flat pack, the NICE PIN ASSIGNMENTS PIN NO. PIN NAME 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 Note: SD11 SD10 VCC GND SD9 SD8 CS BHE SW/SB SA0 SA1 SA2 SA3 RDY(RDY) GND SD0 SD1 SD2 SD3 SD4 SD5 SD6 SD7 EOP(EOP) INT TYPE B B - - B B I I O I I I I O - B B B B B B B B I O B = Bidirectional I/O I = Standard Input O = Totem Pole Output PIN NO. PIN NAME 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 DREQ DACK VCC RD WE RESET BD0 BD1 BD2 BD3 BD4 BD5 BD6 BD7 GND BD8 BD9 BD10 BD11 BD12 BD13 BD14 BD15 BOE BWE PIN NO. PIN NAME TYPE O I - I I I B B B B B B B B - B B B B B B B B O O 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 Dual function pins have two names with the second in parentheses ( ). 2 BCS0 BCS1 VCC BA0 BA1 BA2 BA3 BA4 BA5 BA6 BA7 BA8 BA9 BA10 GND BA11 BA12 BA13 BA14 BA15 TEN TXD GND TXDATA­ TXDATA+ TYPE O O - O O O O O O O O O O O - O O O O O B B - O O PIN NO. PIN NAME 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 X1 X2 VCC GND TCK RXDATA­ RXDATA+ COL­ COL+ VCC LBC AC/DC RCK CKOUT GND RXD COL CRS RDYPOL CNTRL RMT SD15 SD14 SD13 SD12 TYPE I O - - B I I I I - B I B O - B B B I O O B B B B MB86960 MB86960 COL NETWORK CONTROLLER BWE BOE RMT SYSTEM INTERFACE BA0 ~ BA15 SW/SB BCS0 BSC1 BD0 ~ BD15 BLOCK DIAGRAM RCK CNTRL READ/WRITE Rx DATA RESET DMA RXD TRANSMITTER LBC RDYPOL TEN Tx DATA RDY (RDY) TCK BUFFER INT EOP (EOP) CRS BUFFER PORT REGISTERS CONTROLLLER CONTROL TXD CONTROL X1 DREQ RECEIVER DACK CS WE INTERNAL ADDRESS BUS HASH TABLE AC/DC COL+ RD COL BHE SA0 SA3 SD00 SD15 X2 CKOUT RXDATA+ STATUS & CONTROL REGISTERS MANCHESTER INTERNAL DATA BUS RXDATA ENCODER/ DECODER TXDATA+ TXDATA 3 MB86960 MB86960 PIN DESCRIPTIONS System Bus Interface Pins SYMBOL TYPE DESCRIPTION RESET I HARDWARE RESET: Active high. A minimum pulse of 300 nanoseconds in duration is required. This pin resets NICE's internal pointers and registers to the appropriate state. Note: NICE must be reset after power start before using. RDY (RDY) O READY: This output is asserted to indicate to the host that NICE is ready to complete the requested read of write operation. It will also be asserted if the device is unable to respond to the request for a read or write within 2.4 microsecond, In that case, NICE will also assert INT and the bus read error status bit, DLCR1, or bus write error status bit DLCR. RDY(RDY) may be an active low or active high signal as determined by RDYPOL, pin 94. If RDYPOL is a "1", RDY(RDY) will be active high. If RDYPOL is tied to a "0", RDY(RDY) will be an active low signal. RDYPOL I READY POLARITY SELECT: Control input to select the polarity of RDY(RDY), pin 14. When this pin is tied high, RDY(RDY) will be active high. If RDYPOL is tied low, RDY(RDY) will be an active low signal. WE I WRITE: The WE pin is an active low input that enables a write operation form the host system to the buffer memory port or to internal registers selected by system address inputs SA0-3. RD I READ: Active low input specifies that the current transfer between NICE and the host system is a read from one of NICE's internal registers or its data port as selected by SA0-3. CS I CHIP SELECT: This active low input signal is the chip select for NICE. BHE I BYTE HIGH ENABLE: Active Low. This is the byte/word control line. It is used only when NICE is configured for a 16-bit data bus by the SB/SW bit of DLCR6. It allows word, upper byte only or lower byte only transfers. The address select pin SA0 is used with BHE for byte or word transfers. as follows. SB/SW BHE SA0 FUNCTION 0 0 0 Word transfer 0 0 1 Byte transfer on upper half of data bus (SD15-8 SD15-8) 0 1 0 Byte transfer on lower half of data bus (SD7-0) 0 1 1 Reserved 1 X X Byte transfer (SD7-0) INT O INTERRUPT: Active low. Indicates that NICE requires host system attention after successful transmission or reception of a packet or if any error condition occurs, or if an EOP (end of process) signal from the host occurs after the completion of the DMA cycle. The Interrupt signal is maskable and can be disabled by writing a 0 to the appropriate mask bit. EOP(EOP) I END OF PROCESS: Indicates to NICE that the DMA transfer is finished. When the host DMA controller asserts EOP(EOP), further assertion of NICE's bus request output. DREQ, will be discontinued. Note: B = Bidirectional I/O I = Standard Input O = Totem Pole Output Dual function pins have two names with the second in parentheses ( ). 4 MB86960 MB86960 PIN DESCRIPTIONS System Bus Interface Pins (continued) SYMBOL TYPE DESCRIPTION CNTRL O CONTROL: This pin is the complement of the register bit CNTRL, DLCR4. It is used to control external functions. RMT O REMOTE CONTROL PACKET: When DLCR5 is set high, this pin follows the RMT 0900H 0900H bit (DCLR1) which indicates that a complete special packet with type field= 0900H 0900H has been received. This is intended for use as a remotely-controlled hardware function from other nodes in the network. DREQ O DMA REQUEST: Issued to the DMA controller to indicate that NICE has data available to be read in its receive buffer, or is ready to accept data into its transmit buffer. DACK I DMA ACKNOWLEDGE: Active low, indicates that the DMA controller is ready to transfer data between the host system and NICE's buffer memory through BMPR8. SA I SYSTEM ADDRESS LINES: Specify which of the internal registers of ports of NICE is selected for read/write operations. SD B SYSTEM DATA BUS: All data, command and status transfers between the host system and NICE take place over the bidirectional, 3-state, bus. The direction of the transfer is controlled by RD and WE. The register or buffer port being accessed is selected by a combination of DACK (if active, selecting the Buffer Port), or the address pins SA3-0 and register bank select bits REG BANK 1 and REG BANK 0, DLCR7. The portion of the data bus over which the transaction occurs is controlled by SB/SW, BHE, and SA0. SW/SB O SYSTEM WORD/SYSTEM BYTE CONFIGURATION: This signal output reflects the inverse of DCLR6, SB/SW. If SW/SB=1, the system interface is configured for word transfers, If SW/SB=0, the system interface is configured for byte-wide transfer on SD7-0, the lower byte. Note: B = Bidirectional I/O I = Standard Input O = Totem Pole Output Dual function pins have two names with the second in parentheses ( ). 5 MB86960 MB86960 PIN DESCRIPTIONS Buffer Memory Interface Pins SYMBOL TYPE DESCRIPTION BCS0 BSC1 O O BUFFER CHIP SELECT:Active low. BCS1 and BSC0 are the chip select lines, most significant chi byte and least significant byte respectively, of the dedicated buffer SRAM. BOE O BUFFER OUTPUT ENABLE: This active low signal is the output enable for the Buffer SRAM, and is asserted by NICE during buffer memory read cycles. BWE O BUFFER WRITE ENABLE: Active low. Used as a write strobe to the buffer SRAM memory during write operations. BD B BUFFER DATA: Data lines between the SRAM buffer memory and NICE. This SRAM data bus is configurable for an 8-bit or 16-bit data size by BUFFER BYTE/BUFFER WORD, BB/BW, in DLCR6. The transfer byte order within a word, most significant or least-significant byte first, is determined by DATA_ORDER, DLCR7. BA O BUFFER ADDRESS: These lines address up to 64 kilobytes of SRAM buffer memory. Network Interface Pins SYMBOL TYPE DESCRIPTION TXDATA+ TXDATA­ O O TRANSMIT INTERFACE PAIR: These are the differential outputs to the transceiver for transmitting. out uts RXDATA+ RXDATA­ I I RECEIVED DATA: These are the Manchester differential in uts from the transceiver to the receiver. inputs COL+ COL­ I I COLLISION: These differential inputs are driven with a 10 MHz signal when the transceiver detects a collision on the media. AC/DC I AC/DC COUPLING SELECT: AC/DC = 1 selects AC coupling; 0 selects DC coupling for the TXDATA ± outputs. When AC coupling is selected, both TXDATA+ and TXDATA­ are driven to the same output voltage level during the transmit idle period to prevent saturation of the isolation transformer. With DC coupling, these outputs remain at a 1 level during idle periods. System Clock Pins SYMBOL TYPE DESCRIPTION X1 I CRYSTAL INPUT: Connection for one side of the 20 MHz crystal, or input for an external 20 MHz clock source. X2 O CRYSTAL OUTPUT: Connection for the other side of the 20 MHz crystal. Leave unconnected if an external clock is used. CKOUT O CLOCK OUTPUT: 20 MHz free-running clock output provided by the crystal oscillator circuit. 6 MB86960 MB86960 PIN DESCRIPTIONS modes are selected by setting DLCR7. Refer to the MEDIUM CONNECTION section under SYSTEM CONFIGURATION for a complete description of these modes. The following eight pins are provided for optional connection to an external encoder/decoder. They can also be used for test purposes, but are not used in a typical network interface application. Special encoder/decoder Controller - Encoder/Decoder Interface Pins SYMBOL TYPE DESCRIPTION TXD B TRANSMIT DATA: NRZ transmit serial data. Normally not used. In "Encoder/Decoder Bypass" mode and "NICE + Monitor" mode, an output which can be fed to an external encoder. In "Encoder/Decoder Test" mode, an input to the on-chip encoder. TCK B TRANSMIT DATA CLOCK: Clock synchronous with TXD serial data. Normally not used. In "Encoder/Decoder Bypass" mode, a 10 MHz data clock input used by the controller to synchronize the TXD data signal. In "NICE + Monitor" mode and "Encoder/Decoder Test" mode, an output from the on-chip encoder. TEN B TRANSMIT ENABLE: Normally not used. In "NICE + Monitor" mode and "Encoder/Decoder Bypass" mode, this pin is an output which can be used to control an external encoder. When asserted high, TEN enables the encoding of the transmitted data. In "Encoder/Decoder Test" mode, an input to the on-chip encoder. COL B COLLISION PRESENCE: Normally not used. In "Encoder/Decoder Bypass" mode, an active low input which indicates that the collision inputs COL are active, signifying that the transceiver has detected a collision on the media. In "NICE + Monitor" mode and "Encoder/Decoder Test" mode, this is an output from the on-chip encoder/decoder section. COL is a normally high input which changes to a 10 MHz pulse stream during collision detection. LBC B LOOPBACK CONTROL: Normally not used. In "Encoder/Decoder Bypass" mode and "NICE + Monitor" mode, this output should be connected to the loopback control pin of the external encoder/decoder. When this output is asserted high, the external encoder/decoder is placed in loopback mode. TEN enables the encoding of the transmitted data. In "Encoder/Decoder Test" mode, this is an input with the same function. RXD B RECEIVE SERIAL DATA: Normally not used. In "Encoder/Decoder Bypass" mode, "NICE + Monitor" mode and "Encoder/Decoder Test" mode, an NRZ serial bit stream from a decoder or demodulator to the data link controller. RCK B RECEIVE DATA CLOCK: Normally not used. In "Encoder/Decoder Bypass" mode, "NICE + Monitor" mode and "Encoder/Decoder Test" mode, this pin is an input for the serial data clock as recovered by the external decoder or demodulator. CRS B CARRIER SENSE: Normally not used. In "Encoder/Decoder Bypass" mode, an input indicating the presence of incoming data on the network. In "NICE + Monitor" mode and "Encoder/Decoder Test" mode, an output from the on-chip encoder/decoder. Assertion of this active high input indicates that a carrier has been sensed at the RXDATA inputs. 7 MB86960 MB86960 PIN DESCRIPTIONS Mode Configuration and Encoder/Decoder Pin Input/Output Table CNF1 CNF0 MODE 0 0 NORMAL NICE TXD O 0 E/D BYPASS RXD RCK CRS COL none none none none none none none 1 E/D TEST O O O O O O I O O I I I I O O Internal E/D is used only, NICE controller section is shutdown I O I I O O Device Power Pins SYMBOL O External E/D is used with NICE controller, internal E/D is shutdown O 1 LBC NICE + MONITOR Internal E/D is used with NICE controller, signal appears on output 1 1 TEN Internal E/D is used with NICE controller, no signal appears on pins none 0 TCK DESCRIPTION VCC POWER SUPPLY: A +5 VDC ±5% supply is required. GND SYSTEM GROUND: Ordering Code PACKAGE STYLE PACKAGE CODE ORDERING CODE 100-Pin Plastic Quad Flat Pack FPT-100P FPT-100P­M01 MB86960APF MB86960APF­G 8 MB86960 MB86960 Medium Connection SYSTEM CONFIGURATION Connection to the LAN medium can be accomplished with any of the popular connection methods: 1) on-board connection to unshielded twisted pair through a 10BASE-T 10BASE-T transceiver, 2) on-board connection to a thin 50-Ohm coaxial cable through a 10BASE2 10BASE2 transceiver or 3) off-board connection to any other type of medium, such as standard Ethernet coaxial cable (10BASE5 10BASE5), through an Attachment Unit Interface (AUI) connector. A highly integrated system configuration can be achieved with the NICE controller. Figure 1 illustrates a low chip count LAN controller with NICE, a Plug and Play ISA Controller bus interface chip such as Fujitsu's MB86701 MB86701 or MB86703 MB86703, and a 10BASE-T 10BASE-T twisted pair transceiver such as Fujitsu's MB86961A MB86961A. Because of its high integration and unique, innovative architecture, which handles all aspects of packet management and storage, a local microprocessor is not required. The NICE controller connects to the host system bus to provide command and status interfaces as well as packet data access. Command and status registers can be directly accessed by the host processor when mapped into the I/O or memory space of the host. Through a port on the device, data packets to be transmitted to the media are transferred first from host memory to a dedicated buffer memory for temporary storage until transmitted. Received data packets are first stored in the buffer memory, then later transferred to the host memory. NICE has an encoder/decoder (E/D) on chip. An external encoder/decoder can be used by making the NICE chip act like a controller alone (depending on customer's needs). This option can be changed by using bits 7 and 6 of DLCR7. Eight pins related to the on-chip E/D can be configured by DLCR7 (register DLCR7, bits 7 through 6) to operate in one of four modes. These pins are TXD, TCK, TEN, LBC, RXD, RCK, CRS, and COL. In the "Normal NICE" mode, an internal E/D is used. In this mode, the pins are all electrically isolated and no signals appear on the pins. In "NICE + Monitor" mode, all the pins listed above are outputs whose specific signals appear on the pins and can be monitored externally. In "Encoder/Decoder Bypass" mode, an external encoder/decoder is used with the NICE controller, its own internal E/D is shut down. In this mode, the pins are either outputs or inputs as needed to control the external encoder/decoder. In the "Encoder/Decoder Test" mode, only the E/D on NICE is active and accessible, the NICE controller section is shut down. In this mode, the pins are outputs or inputs for an encoder/decoder, with the opposite control direction of the outputs or inputs in the "Encoder/Decoder Bypass" mode. The various possibilities are shown in Figure 2 and the table below. MAIN MEMORY HOST CPU SYSTEM BUS MB86701 MB86701 or MB86703 MB86703 Plug and Play ISA Controller DLCR7 Bit 7 0 LAN NETWORK MEDIUM Figure 1.Typical System Configuration 9 1 NICE plus Monitor 0 Encoder/Decoder Bypass 1 BUFFER MEMORY Normal NICE 1 AUI 0 0 COAXIAL OR MB86961A MB86961A 10BASE 10BASE­T TRANSCEIVER MB86960 MB86960 NICE DLCR7 Bit 6 1 Encoder/Decoder Test Function MB86960 MB86960 CRYSTAL OSCILLATOR The ISO/ANSI/IEEE 8802­3 international LAN standard specifies a bit clock rate of 10 Mbit/sec. This is obtained from a 20 MHz clock generated by the on-chip oscillator, which operates from an external crystal connected between pins X1 and X2 on the NICE chip. Crystal capacitance as specified by the manufacturer should be connected from X1 and X2 to ground, considering any stray capacitance which can vary the crystal's frequency. See Figure 3 for typical values. A crystal with the following specifications is recommended: quartz (AT-cut; 20 MHz; frequency/accuracy of ±50 ppm at 25_C to 70_C; parallel resonant with 20 pF load in a fundamental mode. Possible vendors include: Ecliptek Corp. (Costa Mesa, CA), p/n ECSM 20.000M; and M-tron Industries, Inc. (Yankton, SD), p/n MP-1 & MP-2, with 20MHz, 50ppm over 0_C to 70_C, and 18 pF fundamental load. RXD, RXC CRS, TCK, COL ENCODER/ DECODER CONTROLLER TEN, TXD, LBC NICE CASE 00: NORMAL NICE MODE ENCODER/ DECODER CONTROLLER NICE CASE 01: NICE + MONITOR NICE X1 CONTROLLER TEST X2 20 MHz 20pF 20pF ENCODER/ DECODER CONTROLLER Figure 3. Crystal Connection NICE CASE 10: ENCODER/DECODER BYPASS The clock also serves as a reference for an internal phase locked loop which is used for clock recovery in the decoder section. Internal clocks are shut down when DLCR7 bit 5, PWRDN, is invoked for Power Down Mode. EED TEST SRAM CONFIGURATIONS ENCODER/ DECODER CONTROLLER Eight different configurations of SRAM for the packet buffer are possible as illustrated in Figure 4. First, the width of the SRAM data path can be 8 or 16 bits, selected by programming the Buffer Byte/Buffer Word (BB/BW) bit, bit 4 of DLCR6. If this bit is set to 1, byte-wide data is selected; if set to 0, the width is word-wide (16 bits). The SB/SW Bit, DLCR6 bit 5, selects the system bus width, while the BB/BW Bit, DLCR6 bit 4 selects the SRAM buffer width. Secondly, the depth of the SRAM is programmed by setting Buffer Size 1 and 0 (BS1 and BS0), bits 1 and 0 in DLCR6. Depth selections are 8, 16, 32 or 64 kilobytes. NICE CASE 01: NICE + MONITOR Figure 2. Encoder/Decoder Modes 10 MB86960 MB86960 BS1 DLCR6 BS0 DLCR 0 0 8­BIT BUFFER BUS 16­BIT BUFFER BUS BA BCS0 BA BCS1 BCS0 4Kx8 8Kx8 8 BD 0 8 BD BD BCS0 8Kx8 BD BA BCS1 BCS0 8Kx8 8Kx8 8 8 BD BD 8Kx8 8 BA 0 BCS0 BA 16Kx8 16Kx8 8 BD BCS1 BCS0 32Kx8 1 8 BA 1 BCS1 1 4Kx8 8 BD BD 8 BA 1 BCS1 BCS0 32Kx8 32Kx8 BD 8 BA BCS0 BCS1 32Kx8 32Kx8 8 BD BD Figure 4. SRAM Configuration 11 8 MB86960 MB86960 SB/SW BB/BW SYSTEM 0 0 word word 0 1 word byte 1 0 1 1 BUFFER CONTROLLER BUFFER The MB86960 MB86960 uses a dedicated buffer memory as shown in Figure 5 for intermediate storage of data packets to be transmitted, and of data packets received from the network. The buffer memory is connected directly to the controller rather than to a separate local microprocessor bus, thus eliminating the need for a local microprocessor. The buffer controller keeps track of buffer memory partitioning, allocation and updating of all receive and transmit pointers automatically, thus eliminating this task from software overhead. As a result of this automation and its high-performance packet buffering, the NICE controller can typically win benchmark performance tests over competing controllers. Do not use byte byte FUNCTIONAL DESCRIPTION The MB86960 MB86960 combines the functions of an Ethernet network controller with packet buffer management, and a 10 Mbit/s Manchester encoder/decoder. It consists of four major functional blocks: buffer controller, system interface, transmit controller with Manchester encoder, and receive controller with Manchester decoder. Access to the buffer memory is managed by NICE's on-chip buffer controller. As required, it updates internal address pointers for the tasks of transmit, retransmit, receive, rejection of packets with errors and data transfers to and from the host. Thus the host is relieved of buffer management functions, making NICE easy to operate and substantially reducing software requirements. Packets with errors, such as CRC errors, are auto­ matically rejected by NICE unless the host asserts the "accept bad packets" bit. When this bit is asserted, any packets received with alignment, CRC or short length errors are passed on to the host processor, and the appropriate error status bits are set to inform the host of the error. Similarly, by setting the "accept short packets" bit, reception of short packets down to 6 bytes in length is allowed. (Normal operation requires an IEEE minimum length packet of 60 bytes, excluding preamble and CRC.) The receive and transmit sections of the chip fully implement the ISO/ANSI/IEEE 8802-3 CSMA/CD specification for 10 Mbit/sec Ethernet. The transmitter assembles data packets for transmission and the receiver disassembles received data packets. Automatic generation and stripping of the 64-bit preamble, and generation and checking of the 32-bit CRC are provided on-chip. Other network functions provided on-chip include collision resolution by binary exponential backoff and re-transmission, several modes of address recognition, error detection and reporting, and serial/parallel and parallel/serial conversions. 12 MB86960 MB86960 TRANSMIT BUFFERS As shown in Figure 5, the buffer memory is divided into transmit and receive buffer areas. The partitioning of the memory is programmable, allowing the system to be configured with different proportions of space available for the transmitter and receiver functions. By programming the proportions, an optimum usage of the memory can be selected, according to the demands of a particular application. ONE OR TWO TRANSMIT BUFFERS T RECEIVED PACKET n+3 (LAST PART) The section of the memory used by the transmitter can be configured as a single buffer 2 kilobytes long, or as a pair of banks, each either 2, 4 or 8 kilobytes long. Within each buffer or bank, one or more packets can be written by the system until the available space is too small for another packet. Once started, the transmitter will transmit all packets in the buffer automatically before finishing with a status update, and an interrupt if so enabled. With the two-bank configurations, one bank can be transmitted while the other is being loaded. Using dual buffers and loading multiple packets for "packet chaining" gives the highest rate of transmission. This will boost performance for systems that require high throughput transmission. CURRENTLY AVAILABLE FREE BUFFER AREA RECEIVED PACKET n RECEIVE BUFFER RING 62 KBYTES MAX RECEIVED PACKET n + 1 NICE can be configured to operate with 8, 16, 32 or 64 kilobytes of total buffer memory size, including both transmit and receive spaces. This memory partitioning into transmit and receive sections is allocated by the system software. The total size of the transmit buffer space can be either 2, 4, 8 or 16 kilobytes. Immediately following the transmit buffer space is the receive buffer space, using the balance of the available memory. RECEIVED PACKET n + 2 RECEIVED PACKET n + 3 (FIRST PART) L NOTES 1. Length (L) = 8, 16, 32, or 64 Kbytes. 2. Transmit Size (T) = 2 (one bank), 4 (two banks), 8 (two banks), or 16 (two banks) Kbytes. 3. Receive packets are aligned on an eight byte boundary . 4. Each received packet is preceded by a four byte packet header as follows: Byte 0 ­ Packet Status Byte 1 ­ Not Used Byte 2 ­ Packet Size LSB's Byte 3 ­ Packet Size MSB's Figure 5. Buffer Memory Organization 13 MB86960 MB86960 BANK 0 2 KBYTES 2 KBYTES TRANSMIT SECTION BANK 0 4 KBYTES 8 KBYTES TRANSMIT SECTION BANK 1 62 KBYTES 4 KBYTES 62 KBYTES RECEIVE SECTION 56 KBYTES BANK 0 2 KBYTES BANK 1 2 KBYTES 56 KBYTES RECEIVE SECTION 4 KBYTES TRANSMIT SECTION BANK 0 8 KBYTES 16 KBYTES TRANSMIT SECTION 60 KBYTES BANK 1 60 KBYTES RECEIVE SECTION 8 KBYTES 48 KBYTES Figure 6. Transmit Buffer 14 48 KBYTES RECEIVE SECTION MB86960 MB86960 As shown in Figure 6, the remaining memory not used for the transmitter is used for the receiver, and is automatically configured as a "ring buffer" by the chip. Packets are stored head-to-toe in the receive buffer, as they are in the transmit buffer. As packets are being stored in the receive buffer, as the end of the linear addressing space is reached, the chip's receive-write pointer automatically wraps around to the top of the receive addressing range to make a seamless ring. The receive-read pointer does the same as the packets are read out to the system. The MB86960 MB86960 provides all the necessary buffer pointer management functions automatically, relieving the host system and its drivers of this time-consuming task. Since these tasks can be done faster in hardware than in software, this not only off-loads the host system, but it also speeds up the communication processes giving higher throughput. The buffer controller automatically prioritizes and services requests for access to the memory from the transmitter, the receiver, and the host system. It updates all buffer memory pointers, allocates memory space for incoming data packets, and controls pertinent bits within the status registers providing complete packet management functions. The NICE chip's arbitration mechanism provides packet management by interleaving packet data accesses to the buffer memory so that the operation appears to be "simultaneous": data can be written to or read from the buffer memory by the host via Buffer Memory Port Register 8 (BMPR8), while data packets are read out for transmission and/or written in for storage by the receiver. Each interface, whether host system or network access, appears to be served independently by the controller. Each interface has an associated FIFO to provide time for the buffer interleaving. Thus, packet data is "pipelined" through the system for highest performance and throughput, and the buffer controller supports all the cases of "simultaneous" access to the buffer memory, as illustrated in Figure 7 and as follows: 1. Data from the network is stored in the receive buffer. 2. The host retrieves packets from the receive buffer. 3. The host loads packet data into the transmit buffer. 4. The transmitter obtains data for transmission from the transmit buffer. 5. Any combination of the above can occur concurrently, including all four at once. System Access to Buffer NICE supports both programmed I/O, single cycle DMA and burst mode DMA transfers between the buffer memory and the host system. The host accesses the buffer memory by reading from or writing to NICE's Buffer Memory Port Register 8 (BMPR8). Data being read or written by the system passes through on-chip FIFO's to eliminate the effects of real-time interaction between the system, the transmitter and the receiver as they all access the buffer memory. All read and write operations to the external SRAM memory are controlled automatically by the NICE chip. HOST CPU SYSTEM INTERFACE READ AND/OR WRITE TRANSMIT AND SIMULTANEOUS RECEIVE NICE BUFFER CONTROLLER NETWORK MEDIA INTERLEAVE DATA DEDICATED BUFFER MEMORY Figure 7. Simultaneous Operations and Buffer Control Capability of NICE 15 MB86960 MB86960 Transmit Packet Data Formats Transmitter Access to Buffer The packets to be transmitted, less preamble and CRC fields, are first loaded into the transmit buffer along with a two-byte header indicating the packet length in bytes. See Figure 8 for details. Multiple packets can be loaded at the same time provided there is room in the buffer. After the packets are loaded, the host initiates transmission by writing the number of packets just loaded into a register for this purpose on the chip. If the two-bank buffer configuration has been selected, the second bank can now be loaded with additional packets. The size of each of the transmit banks can be changed by programming the Buffer Size control bits, BS0 and BS1. The transmit buffer size is thus allocatable by the software to be a single 2-kilobyte transmit buffer, two 2-kilobyte transmit buffers, two 4-kilobyte transmit buffers, or two 8 kilobyte transmit buffers. In all configurations, a single packet or multiple packets can be loaded into the buffer at one time for transmission. When a single transmit buffer is used, the system and the transmitter time-share the use of the buffer. When two buffers are used, the system can load packets into one of the buffers while the contents of the other are being transmitted. At reset, the pointers are initialized to point to the beginning of one of the transmit buffers. Each time the host writes data to the buffer via the Buffer Memory Port Register, an internal pointer is advanced to the next memory location within the transmit buffer. Once a data byte/word is written, it cannot be read and the internal pointer cannot be reversed. LENGTH LSB LENGTH MSB PACKET 1 DATA 1 LENGTH LSB LENGTH MSB Internal pointers managed by NICE control which of the two banks is selected for access by the host and which byte/word of the bank is accessed. NICE will switch banks as soon as the transmit start bit (TX START) of BMPR10 BMPR10 is written high by the host system. When this occurs, NICE will start transmitting at the earliest opportunity. Another automatically-managed pointer, the transmit-read pointer sequences through the bank being transmitted to read the packet data into the transmitter through its FIFO. If a collision occurs, the packet will be automatically retransmitted after a pseudo-random waiting interval called the backoff interval. If there are multiple packets in the bank, NICE will continue down the list, automatically transmitting them all. The details of this operation are described in the section on packet transmission. PACKET 2 DATA 2 LENGTH LSB LENGTH MSB DATA 3 LENGTH LSB LENGTH MSB DATA 4 NICE has the capability to transmit multiple back-toback packets of varying legal Ethernet sizes to the LAN network. These packets may vary in length from 60 bytes to 1,514 bytes, excluding preamble and CRC fields. As shown in Figure 8, multiple packets can reside within one transmit bank, separated by a non-transmitted, two-byte header which provides the length of the packet in bytes. Upon reaching the end of the "list" or "chain" of packets, the transmitter will stop, update it's status bits and, if enabled, generate an interrupt. DATA n UNUSED BUFFER AREA Figure 8. Transmit Buffer Detail 16 MB86960 MB86960 Receiver Access to Buffer packet is contained and reset its internal pointers so as to use that space for the next incoming packet. If this bit is set to a "1", the packet with a short length, alignment or CRC error will be accepted and the appropriate error bits in the status field of its header will be set. The same applies to DLCR5, ACPT SHORT PKTS, which when high allows retention of packets below 60 bytes in length, excluding preamble and CRC (shorter than IEEE 802.3 minimum size). Once initialized and enabled, the receiver will automatically load any error-free incoming packets which pass the address filter into the receive buffer through an on-chip FIFO, appending a four-byte header to the front end which provides packet length and status. An interrupt can be provided to alert the host processor that a packet is available in the buffer. The host processor can read out receive packets as they become available. Continuous reception can continue as long as the receive buffer does not become full. If the host processor reads the receive packets from the buffer promptly, the buffer will not fill up. But if overflow does occur, an interrupt will be generated to indicate the problem. If this occurs, data should be read from the buffer to free space. As soon as space becomes available in the receive buffer, the receiver will automatically continue reception. DATA STATUS RESERVED The receive buffer size can vary between a maximum of 62 kilobytes when 2 kilobytes is allocated for the transmit section and maximum memory size of 64 kilobytes is used, to a minimum of 4 kilobytes if 4 kilobytes is allocated for the transmit section and minimum memory size of 8 kilobytes is used. The receive section dynamically allocates space for each individual incoming data packet along an eight-byte "page" boundary. Each received packet is preceded by a four byte header which provides packet status and the length of that data packet. The data packets are linked or "chained" by internal pointers which use the length value in the packet header to calculate the length of the packet, and the starting address of the next packet. This buffer format is shown in Figure 9. Since NICE controls its dedicated buffer memory, FIFO size and depth are unimportant in this architecture, and need not be considered in system timing considerations. LENGTH LSB PACKET n1 LENGTH MSB DATA STATUS RESERVED LENGTH LSB PACKET n LENGTH MSB DATA UNUSED BUFFER AREA A status bit in one of NICE's internal registers (RX BUF EMPTY) informs the host when one or more packets are resident in the receive buffer and available to be read. The host retrieves these packets from the buffer memory by successive reads of BMPR8. Once a data byte/word is read from the buffer memory, internal pointers are advanced to the next byte/word. As data is thus read by the system, that memory becomes available for reception of new packets. NICE automatically rejects an incoming packet if there is not enough buffer space to fully receive that packet. Therefore, there is no chance for packets already received to be "overrun" by incoming packets. STATUS RESERVED LENGTH LSB LENGTH MSB DATA Figure 9. Receive Buffer Detail When DLCR5, the ACPT BAD PKTS ("accept bad packets") bit is set to a "0" (disabled), a bad incoming packet causes NICE to release buffer space in which that 17 MB86960 MB86960 Receive Packet Data Formats for buffer memory access. This third bank is normally selected most of the time, except during initialization or diagnostic routines, as access to the other registers is not needed during normal operation. Receive packets, less preamble and CRC fields, are stored in the buffer along with a four-byte header. The first byte gives status information, indicating errors, if any, that occurred during reception of the packet. Normally packets with errors are automatically discarded and eliminated from memory by the chip, but with a mode selection, the chip can allow reception of bad packets, with indication of their errors in the status byte of the header. The second byte of the header is reserved for possible future use. The last two bytes of the header give the byte count of the packet, less preamble and CRC. Refer to Figure 9. Buffer Access Buffer Memory Port Register 8 (BMPR) of the buffer memory port register set provides serial access to the receive and transmit buffers through on-chip FIFO's. This port can be accessed with 8-bit or 16-bit wide data. There is a separate FIFO for each direction of data transfer, so there is no complicated direction control needed. Writes to the transmit buffer can be interleaved with reads from the receive buffer if desired. All buffer memory pointers are automatically maintained by the chip, eliminating software overhead normally needed for this. SYSTEM INTERFACE The system interface block provides the connection between NICE and the host CPU. NICE supports both 8-bit and 16-bit bus widths and byte or word transfers as determined by DLCR6, SB/SW, the "system byte or system word" configuration bit. Depending on the type of host CPU, NICE will supply the data order, MSB or LSB first according to the setting of DCLR7 as described in the detailed register descriptions. NICE supports I/O-mapping, memory mapping, and burst or single transfer DMA modes. An interrupt output, INT, is provided which may be programmed by the user to inform the CPU of transmit and receive status conditions requiring host processing. This port can be accessed with I/O instructions using register address xxx8H, or by using DMA. In the latter case, assertion of the DACK input is sufficient to select the port. Thus data can be transferred from host memory to the transmit buffer, or from the receive buffer to host memory using CPU string moves, single-transfer programmed I/O moves, or DMA. The choice should be made according to which is most efficient at a system level, taking into account that a speedy transfer process will result in the best performance. A slow transfer process may not be satisfactory because it might result in poor throughput and performance, and might allow the receive buffer to overflow, losing packets. Three sets of user-accessible registers are contained within the MB86960 MB86960. All registers are accessible as bytes or words. DMA Operation The MB86960 MB86960 supports both single cycle and burst DMA operation for transfers of data between the host system and the dedicated buffer memory. The DREQ and DACK signals are used for handshaking between the external DMA and NICE. There is also an "end of process" input pin which, when asserted by the system DMA controller during a transfer cycle, will terminate the DMA activity after the current cycle completes. If enabled for DMA interrupt, upon completion of the DMA activity, the chip will generate an interrupt. Register Access All control and status registers on the NICE chip are accessible through its bus interface port, which can be I/O or memory mapped in the system. Eight of the registers in the set, whose addresses are xxx0H through xxx7H, are always directly accessible. For the remaining physical addresses, three different banks of registers can be accessed through indirect addressing of the banks (bank switching). The bank switching bits are part of the first eight registers which are permanently resident. Usually only one DMA operation will be run at a time, although the NICE chip could run two interleaving operations, one reading and one writing. There is only one DMA EOP bit, and only one DREQ pin and one DACK pin, so most hosts could not support more than one DMA operation at a time with NICE. The bank-switched register group consists of three sets or "banks" of registers. One of the sets is for Node ID (Ethernet Address) and TDR diagnostics, another is the Hash Table for multicast address filtering, and the third is 18 MB86960 MB86960 DMA Write (Transmit) DMA Read (Receive) Transmit DMA Enable, TX DMA EN, BMPR12 BMPR12, is set high to enable DMA operation for transfers of data packets from the host memory to NICE's transmit buffer. Burst transfers can also be enabled by invoking the DMA burst control register BMPR13 BMPR13. When NICE is ready to begin to accept data from the host, NICE will assert its DMA request output, DREQ. The host responds by asserting DMA Acknowledge, DACK, followed by write enable, WE, and placing the data on the data bus. NICE will assert its RDY(RDY) output when it is ready to complete the current data transfer cycle (polarity of RDY(RDY) and EOP(EOP) inputs are independently programmable). NICE accepts that data byte/word into its bus write FIFO, and later moves it into buffer memory. At the close of a transfer cycle, the host negates WE. In burst mode, NICE will negate DREQ two cycles before the end of the burst. The host DMA will then complete the last two transfer cycles, then negate DACK to close the burst. To start another burst, NICE will re-assert DREQ. The number of DMA write cycles within one burst can be 1, 4, 8, or 12 data transfers (bytes or words) depending on the burst control bits BURST1, BURST0, BMPR13 BMPR13. NICE will indicate when it has receive packets to be read with status bits and/or interrupts. Before attempting to read a packet, the host processor first reads the RX BUF EMPTY bit, DLCR5. If this bit is 0, there are one or more packets in the receive buffer to read. After reading each packet, the host will check this bit again to see if there are more. Prior to beginning the transfer of a packet from NICE's receive buffer to host memory via DMA, the host must first read the four-byte receive packet header from the buffer to obtain the packet status and the length of the packet in bytes. Calculating from the packet length the number of DMA cycles needed to read the packet, the host will load that number into the cycle counter of the host DMA controller. The starting address in system memory will also be loaded into the DMA controller. Next, RX DMA EN, BMPR12 BMPR12, is set high to enable DMA read operation to transfer the packet to host memory. When it is ready to begin, NICE asserts its DMA Request output, DREQ. The host responds by asserting DMA Acknowledge, DACK, followed by Read Enable, RD. NICE will assert its RDY output when it has placed the byte/word on the data bus and is ready to complete the data transfer cycle. The system memory will accept the data, then the host negates RD. NICE shifts the data down into its bus read FIFO, then moves its internal bus read pointer to point to the next byte/word in the buffer, moving it into the FIFO. The DMA controller may assert the end-of-process input, EOP(EOP), concurrently with the last data transfer cycle to indicate that the entire transfer process has been completed. This sets the DMA EOP bit in NICE which causes NICE to discontinue making further data requests. If enabled, the EOP(EOP) signal assertion can also generate an interrupt. When the DMA EOP bit, DLCR1, is set, the INT pin will assert if DLCR3, interrupt enable for DMA EOP , is high. This interrupt can be used by the host to initiate the actions for closing the process. Upon servicing the interrupt, if DMA EOP is high, the host should close the DMA process, reset the NICE chip's DMA logic and clear the interrupt by writing 00H to BMPR12 BMPR12. Note: Clearing TX DMA EN must be done to close the transmit DMA process before attempting another DMA process. This is accomplished by writing 00H to BMPR12 BMPR12. When this is done, the DMA EOP bit will clear automatically, clearing the EOP status and interrupt, so it is not necessary to clear the interrupt separately. NICE will negate DREQ two cycles before the end of the burst. After the host negates DACK, if NICE can transfer more data, NICE will re-assert DREQ to repeat the process. The number of DMA read cycles in a burst can be 1, 4, 8, or 12 transfer cycles of data (bytes or words), depending on the burst control bits BURST1, BURST0, BMPR13 BMPR13. The DMA controller may assert the end-of-process input, EOP(EOP), concurrently with the last byte/word data transfer to indicate that the entire process has completed. NICE will then discontinue making further data requests. RX DMA EN must be cleared when the DMA process is completed, and set again when the host desires to begin reading another packet from the receive buffer using DMA. When EOP(EOP) is asserted by the host DMA controller, the DMA EOP bit, DLCR1, will be set high, and an interrupt will also be generated, provided it is enabled by a high, DLCR3. This interrupt can be used by the host to initiate the final actions to close the DMA process. The interrupt is cleared and the DMA is disabled and reset by writing 00H to the DMA Enable Register, BMPR12 BMPR12. Note: Clearing RX DMA EN must be done to close the After finishing the loading of packets into the buffer, the host initiates packet transmission. This is done by loading the number of packets to be transmitted into the Transmit Packet Count Register, BMPR10 BMPR10, and asserting the Transmit Start bit, TX START, of the same register, BMPR10 BMPR10. 19 MB86960 MB86960 control and status bits. In system word mode, data can be transferred 16-bits at a time on the system bus, or 8-bits at a time by using the byte lane controls of NICE. When transferring in 16-bit mode to/from the registers, even direct addresses are used to select the registers. For example, to access the Transmit/Receive Status Registers, address xxx0H would be used. The transmit status would be on the low byte and the receive status on the high byte. Separate access of high and low bytes is achieved by using the appropriate byte-access processor instructions. receive DMA process before attempting another DMA process. This is accomplished by writing 00H to BMPR12 BMPR12. When this is done, the DMA EOP bit will clear automatically, clearing the EOP status and interrupt, so it is not necessary to clear the interrupt separately. CONTROL AND STATUS REGISTERS The control and status registers on the NICE chip are accessed through direct register addresses xxx0H through xxxFH, and indirect or bank-switching address bits RBS1, RBS0, DLCR7. Table 1 summarizes the addressing scheme while tables 2 and 3 summarize the Table 1. Internal Register Address Map RBS1,RBS0 SA3 SA2 SA1 SA0 ADDRESS XX XX XX XX XX XX XX XX 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 DLCR0[1] DLCR1 DLCR2 DLCR3 DLCR4 DLCR5 DLCR6 DLCR7 TRANSMIT STATUS RECEIVE STATUS TRANSMIT INT ENABLE RECEIVE INT ENABLE TRANSMIT MODE RECEIVE MODE CONFIG 0 CONFIG 1 00 00 00 00 00 00 00 00 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 DLCR8 DLCR9 DLCR10 DLCR10 DLCR11 DLCR11 DLCR12 DLCR12 DLCR13 DLCR13 DLCR14 DLCR14 DLCR15 DLCR15 NODE ID 0 NODE ID 1 NODE ID 2 NODE ID 3 NODE ID 4 NODE ID 5 TDR 0 (LSB) TDR 1 (MSB) 01 01 01 01 01 01 01 01 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 HT8 HT9 HT10 HT11 HT12 HT13 HT14 HT15 HASH TABLE 0 HASH TABLE 1 HASH TABLE 2 HASH TABLE 3 HASH TABLE 4 HASH TABLE 5 HASH TABLE 6 HASH TABLE 7 10 10 10 10 10 10 10 10 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 BMPR8[2] BMPR9 BMPR10 BMPR10 BMPR11 BMPR11 BMPR12 BMPR12 BMPR13 BMPR13 BMPR14 BMPR14 BMPR15 BMPR15 BUFFER MEMORY PORT RESERVED TRANSMIT START 16 COLLISIONS DMA ENABLE DMA BURST SKIP PACKET RESERVED 11 X X X X - RESERVED DESCRIPTION 1. All registers are both word and byte accessible. In word mode, register bytes are paired to form words starting with registers 0 and 1. The odd-addressed byte becomes the high byte of the word 2. In word mode, BMPR8 is a 16-bit port. In byte mode, it is an 8-bit port. The byte ordering Is determined by DLCR7 20 MB86960 MB86960 Table 2. Summary of Control and Status Bits: DLCR0-7, BMPR8-15 BMPR8-15 Register BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 TX STATUS DLCR0 TX DONE NET BSY TX-RX CR LOST 0 COL 16 COL 0 RX STATUS DLCR1 RX PKT BUS RD ERR DMA EOP RMT 0900H 0900H SHORT ERR ALIGN ERR CRC ERR RX BUF OVERFLO TX INT ENABLE DLCR2 INT EN 0 0 0 0 INT EN INT EN 0 RX INT ENABLE DLCR3 INT EN INT EN INT EN INT EN INT EN INT EN INT EN INT EN TX MODE DLCR 4 COL CTR 3 COL CTR 2 COL CTR 1 COL CTR 0 0 CNTRL LBC EN TX DEFER RX MODE DLCR5 0 RX BUF EMPTY ACPT BAD PKTS 40 BIT ADDR ACPT SHORT PKTS 1 AF1 AF0 CONFIG0 DLCR6 DLC EN 1 SB/SW BB/BW TBS 1 TBS 0 BS 1 BS 0 PWRDN RDYPOL RBS 1 RBS 0 EOPPOL M.L/ L.M CONFIG1 DLCR7 E/D CNF 1 E/D CNF 0 BUF MEM PORT BMPR8 7 6 5 4 3 2 1 0 BUF MEM PORT BMPR9 15 14 13 12 11 10 9 8 TX START TX PKT CNT 6 TX PKT CNT 5 TX PKT CNT 4 TX PKT CNT 3 TX PKT CNT 2 TX PKT CNT 1 TX PKT CNT 0 16 COLLISIONS BMPR11 BMPR11 0 0 0 0 0 16 COL CNTRL 2 16 COL CNTRL 1 16 COL CNTRL 0 DMA ENABLE BMPR12 BMPR12 0 0 0 0 0 0 RX DMA ENABLE TX DMA ENABLE DMA BURST BMPR13 BMPR13 0 0 0 0 0 0 BURST 1 BURST 0 SKIP PACKET BMPR14 BMPR14 0 0 0 0 0 SKIP PKT 0 0 RESERVED BMPR15 BMPR15 0 0 0 0 0 0 0 0 TX START BMPR10 BMPR10 21 MB86960 MB86960 Table 3. Summary of Control and Status Bits:DLCR8-15 DLCR8-15, HT8-15 HT8-15, Packet Buffer Headers Register Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 7 6 5 4 3 2 1 0 . . . . . . . . . . . . . . . . . . . . . . . . NODE ID 5 DLCR13 DLCR13 47 46 45 44 43 42 41 40 TDR 0 DLCR14 DLCR14 7 6 5 4 3 2 1 0 TDR1 DLCR15 DLCR15 N/A (0) N/A (0) 13 12 11 10 9 8 7 6 5 4 3 2 1 0 . . . . . . . . . . . . . . . . . . . . . . . . HASH TABLE 7 HT15 63 62 61 60 59 58 57 56 TX LENGTH LSB (TX HEADER 0) 7 6 5 4 3 2 1 0 TX LENGTH MSB (TX HEADER 1) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) 10 9 8 PKT STATUS (RX HEADER 0) N/A (0) N/A (0) GOOD PKT RMT 0900H 0900H SHORT ERR ALIGN ERR CRC ERR RBUF OVRFLO RESERVED (RX HEADER 1) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) RX LENGTH LSB (RX HEADER 2) 7 6 5 4 3 2 1 0 RX LENGTH MSB (RX HEADER 3) N/A (0) N/A (0) N/A (0) N/A (0) N/A (0) 10 9 8 NODE ID 0 DLCR8 . . . HASH TABLE 0 HT8 . . . 22 MB86960 MB86960 Type Descriptions (TYPE) by setting the corresponding enable bits in the Transmit Interrupt Enable register. See Table 4. The following legend of descriptions applies to the type column of the register bit description tables: Bits 7, 2 and 1 in this register, the bits that can generate interrupts, are cleared by writing 1 to the bit. Writing 0 to the bit has no effect, only the NICE chip control logic can set these bits. Clearing the bit that caused the interrupt will clear both the bit itself and the interrupt. Since two or more status conditions can occur at one time, the interrupt routine must read all of them and act on all of those that are set. R: Readable bit W: Writeable bit C: Clears associated status bit and/or interrupt when 1 is written; no effect when 0 is written N: Not used; reserved; write only 0 when written 0/1:Initial state after hardware reset One method for clearing interrupts is to read the contents of the status register, then write the same value back to the register, thus clearing all bits which were set. Another technique is to clear each status bit separately by writing its mask to the register. This might be done as the corresponding interrupt service is performed. Note: Wholesale clearing of all status bits by writing FFH to the register is not recommended, since this may clear status which has just been set and not yet read by the system. The transmitter must be idle and TX DONE, DLCR0, must be cleared by writing 1 to it before starting the transmitter (by writing 1 to TX START, BMPR10 BMPR10). DATA LINK CONTROL REGISTERS Status and control bits for the transmitter and receiver sections of the NICE chip are located in the first eight data link control registers, DLCR0­7. See Tables 4­11 for details. Transmit Status Register This register provides transmit status for the host processor. The system can enable interrupts based on the assertion (going high) of bits 7, 2, and/or 1 of this register Table 4. DLCR0 - Transmit Status Register BIT SYMBOL TYPE DESCRIPTION 7 TX DONE R C 0 TRANSMIT DONE: This bit is set high when all packets in the active transmit buffer have been successfully transmitted to the LAN media, or skipped due to excessive collisions. Can generate interrupt if enabled by DLCR2. 6 NET BSY R NET BUSY: This is a real-time image of the Carrier Sense signal of the receiver. 5 TX-RX R 0 TRANSMIT PACKET RECEIVED: Indicates that a good packet was received by NICE shortly after transmission was completed. This is used to indicate self-reception of the packet. This bit is cleared as each transmission begins. 4 CR LOST R 0 CARRIER LOST: This bit is set if the receive carrier sense input is negated during a packet transmission. This can be caused by a collision or a shorted LAN medium. It is automatically cleared as each transmission begins. 3 0 N 0 RESERVED: Write 0. 2 COL R C 0 COLLISION: This bit will assert during transmission of a data packet if a collision occurs on the network. The buffer controller will automatically retransmit the current packet after collisions up to 15 times. The user may read the number of consecutive collisions in the collision counter, DLCR4. Can generate interrupt if enabled by DLCR2. 1 16 COL R C 0 16 COLLISIONS: This bit is set after the sixteenth unsuccessful transmission of the same packet. Can generate interrupt if enabled by DLCR2. 0 0 R 0 RESERVED: Write 0. 23 MB86960 MB86960 Receive Status Register the buffer. The bits in this register are cleared by writing 1 to the bit. Writing 0 to the bit has no effect. Only the NICE chip control logic can set these bits. Clearing the bit that caused the interrupt will clear both the bit itself and the interrupt. Since two or more status conditions can occur at one time, the interrupt routine must read all of them and act on all of those that are set. See Table 5. One method for clearing interrupts is to read the contents of the Transmit and Receive Status Registers, then write the same value back to the registers, thus clearing all bits which were set. Another technique is to clear each status bit separately by writing its mask to the register as the corresponding interrupt service is performed. Note: Wholesale clearing of all status bits by writing FFH to the register is not recommended, since this may clear status which has just been set and not yet read by the system. This register contains eight status bits which can generate interrupts if enabled by the corresponding bit in DLCR3. Five of these bits report the status of the most recently received packet that was accepted for storage in the receive buffer. Bit 7, RX PKT, is set whenever a new packet is successfully received and stored in the buffer. One bit reports reception of a special packet with 0900H 0900H in its `type' field. Other bits in this register report buffer overflow, DMA end-of-process and bus read error. Bits 1, 2 and 3 indicate errors, if any, detected in the packet. If ACPT BAD PKTS, DCLR5 and/or ACPT SHORT PKTS, DLCR5 are set to 1 allowing acceptance of a bad packet, these error bits will be stored in the status byte of the receive packet header. If DLCR5 and DLCR5 are both 0, all packets with detected errors will be discarded automatically, and removed from Table 5. DLCR1 - Receive Status Register BIT SYMBOL TYPE DESCRIPTION 7 RX PKT R C 0 RECEIVE PACKET: Set when a new receive packet is stored in the Receive Buffer. Can generate interrupt if enabled by DLCR3. 6 BUS RD ERR R C 0 BUS READ ERROR: Set when a ready response cannot be issued within 2.4 µs after the RD signal is asserted. Occurs when reading an empty buffer. Can generate interrupt if enabled by DLCR3. 5 DMA EOP R C 0 DMA END OF PROCESS: Set when the host DMA asserts the EOP pin indicating that the process is finished. When set, inhibits further assertion of DREQ. Cleared by writing 00H to BMPR12 BMPR12. Do not clear by writing 1 to this bit as this may result in unwanted DREQ. Can generate interrupt if enabled by DLCR3. 4 RMT 0900H 0900H R C 0 REMOTE CONTROL PACKET RECEIVED: This bit is set if a packet is received with 0900H 0900H in its Length/Type Field (two bytes following the source address, received MSB first). Can generate interrupt if enabled by DLCR3. 3 SHORT ERR R C 0 SHORT PACKET ERROR: Set when a packet is received with less than 60 bytes, excluding its Preamble and CRC fields. Such a packet usually indicates a collision has truncated its original length, since IEEE 802.3 minimum length is 60 bytes. Can generate interrupt if enabled by DLCR3. See also Table 8. 2 ALIGN ERR R C 0 ALIGNMENT PACKET ERROR: This bit will assert if a packet is received with an alignment error, meaning there were 1 to 7 extra bits at the end of the packet. Such an occurrence usually indicates a collision, or a faulty transceiver. Can generate interrupt if enabled by DLCR3. See also Table 8. 1 CRC ERR R C 0 CRC PACKET ERROR: This bit is set if a packet is received with a CRC error. This usually indicates a collision has corrupted the packet. Can generate interrupt if enabled by DLCR3. See also Table 8. 0 RX BUF OVRFLO R C 0 RECEIVE BUFFER OVERFLOW: This bit will be set if the receive buffer becomes full and must reject a packet for lack of space. Can generate interrupt if enabled by DLCR3. Does not get set in loopback mode. 24 MB86960 MB86960 Transmit Interrupt Enable Register This register contains the bits which enable or mask the status bits in DLCR0 from generating interrupts. Only bits 7, 2 and 1 can generate interrupts. The other bits are not used. See Table 6. Table 6. DLCR2 - Transmit Interrupt Enable Register BIT SYMBOL TYPE DESCRIPTION 7 INT EN R W 0 INTERRUPT ENABLE: When high, enables TX DONE to generate interrupt. See also DLCR0. 6 0 N 0 RESERVED: Write 0. 5 INT EN N 0 RESERVED: Write 0. 4 0 N 0 RESERVED: Write 0. 3 0 N 0 RESERVED: Write 0. 2 INT EN R W 0 INTERRUPT ENABLE: When high, enables COL to generate interrupt. See also DLCR0. 1 INT EN R W 0 INTERRUPT ENABLE: When high, enables 16 COL to generate interrupt. See also DLCR0. 0 0 N 0 RESERVED: Write 0. 25 MB86960 MB86960 Receive Interrupt Enable Register Transmit Mode Register This register provides control for enabling or masking interrupts based on the assertion of status bits in DCLR1, the Receive Status Register. See Table 7. This register contains two control bits associated with transmission, a general-purpose control bit which drives a pin on the chip, and a collision counter. See Table 9. Table 7. DLCR3 - Receive Interrupt Enable Register BIT SYMBOL TYPE DESCRIPTION 7 INT EN R W 0 INTERRUPT ENABLE: When high, enables RX PKT to generate interrupt. See also DLCR1. 6 INT EN R W 0 INTERRUPT ENABLE: When high, enables BUS RD ERR to generate interrupt. See also DLCR1. 5 INT EN R W 0 INTERRUPT ENABLE: When high, enables DMA EOP to generate interrupt. See also DLCR1. 4 INT EN R W 0 INTERRUPT ENABLE: When high, enables RMT 0900H 0900H to generate interrupt. See also DLCR1. 3 INT EN R W 0 INTERRUPT ENABLE: When high, enables SHORT ERR to generate interrupt. See also DLCR1 and Table 8. 2 INT EN R W 0 INTERRUPT ENABLE: When high, enables ALIGN ERR to generate interrupt. See also DLCR1 and Table 8. 1 INT EN R W 0 INTERRUPT ENABLE: When high, enables CRC ERR to generate interrupt. See also DLCR1 and Table 8. 0 INT EN R W 0 INTERRUPT ENABLE: When high, enables RBUF OVRFLO to generate interrupt. See also DLCR1. Table 8. Network Error Monitoring Modes ACPT BAD PKTS DLCR5 ACPT SHORT PKTS DLCR5 INT EN SHORT ERRORS DLCR3 INT EN INT EN CRC ALIGN ERRORS ERRORS DLCR3 DLCR3 0 0 0 0 0 0 0 1/0 1/0 1/0 Error interrupts only, if enabled. 0 1 0 1/0 1/0 Save short packets if otherwise error free in buffer; interrupts only for alignment and CRC errors, if enabled. RX PKT will be set high if short packet received. 1 0 0 0 0 All others Mode Description Normal non-monitor mode. Save packets with short, alignment and/or CRC errors in buffer; RX PKT will be set high if packet with error received. Do Not Use. Note: Packet acceptance requires both error filter acceptance and address filter acceptance. 26 MB86960 MB86960 Table 9. DLCR4 - Transmit Mode Register BIT SYMBOL TYPE DESCRIPTION 7 COL CTR 3 R 1 COLLISION COUNT 3: DLCR4 plus 1 indicates the number of consecutive collisions encountered by the current transmit packet. (Read only). See Table 10. 6 COL CTR 2 R 1 COLLISION COUNT 2: DLCR4 plus 1 indicates the number of consecutive collisions encountered by the current transmit packet. (Read only). See Table 10. 5 COL CTR 1 R 1 COLLISION COUNT 1: DLCR4 plus 1 indicates the number of consecutive collisions encountered by the current transmit packet. (Read only). See Table 10. 4 COL CTR 0 R 1 COLLISION COUNT 0: DLCR4 plus 1 indicates the number of consecutive collisions encountered by the current transmit packet. (Read only). See Table 10 3 0 N 0 REVERSED: Write 0. 2 CNTRL R W 1 CONTROL OUTPUT: The inverse of this is bit is output for general use on pin 95. 1 LBC R W 1 LOOPBACK CONTROL: This bit controls the loopback function of the NICE encoder/decoder. A 0 in this bit places the chip in internal loopback mode. 0 EN TX DEFER R W 0 ENABLE TRANSMIT DEFER: Program this bit low for normal network operation. When high, the transmitter will not defer to traffic on the network. Table 10. Collision Count Collision Count 16 COL DLCR0 DLCR4 DLCR4 DLCR4 DLCR4 COL DLCR0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 2 0 0 0 1 0 1 3 0 0 0 1 1 1 . . . . . . . . . . . . . . . . . . . . . 15 0 1 1 1 1 1 16 1 0 0 0 0 1 Receive Mode Register start the routine which reads packets from the buffer. As this routine begins, the interrupt on RX PKT can be disabled to prevent unneeded interrupts. After the first packet is read from the buffer, the RX BUF EMPTY bit would be read to see if any more packets have come in (packets may, at times, arrive in bursts). If the buffer is not empty, another packet would be read out, and this procedure repeated until the buffer is empty. After emptying the buffer, the host clears RX PKT, then re-enables interrupts on RX PKT, checks the buffer status one more time (since a packet can come in at any time), then exits to do other tasks. This register contains six bits which control receiver function, and one receive buffer status bit. See Table 11. The status bit, RX BUF EMPTY (Receive Buffer Empty), is very important to the software routine which reads receive packets from the buffer. It tells the host routine whether there are any packets in the receive buffer which are complete and ready to read. In a multi-tasking system, this indicator would be used in conjunction with an interrupt when RX PKT asserts, which means a packet has arrived in memory. The interrupt would be used to 27 MB86960 MB86960 during reception and no alignment or CRC error. Under normal operation, packets with less than 60 bytes, the IEEE 802.3 lower limit, would be discarded. These functions are provided for diagnostic purposes. Packets are accepted only if both the address filter and the error filter are passed. Packets with no content errors, i.e., short, alignment or CRC, are accepted without regard to collision indicators. Two of the control bits allow reception of packets with certain types of errors. The ACPT BAD PKTS bit, when set, causes the receiver to retain and store in the buffer packets with CRC, alignment and/or short length errors provided there was no indication of collision during reception. Likewise, the ACPT SHORT PKTS bit, when set, allows the retention of short packets down to and including only six bytes in length, excluding preamble and CRC, provided there was no indication of collision Table 11. DLCR5 - Receive Mode Register BIT SYMBOL TYPE DESCRIPTION 7 0 N 0 RESERVED: Write 0. 6 RX BUF EMTY R 1 RECEIVE BUFFER EMPTY: Status bit which indicates that the receive buffer does not have any complete packets to read. (Read only). 5 ACPT BAD PKTS R W 0 ACCEPT PACKETS WITH ERRORS: When set high, allows packets with CRC, alignment and/or short length errors to be saved into the receive buffer for analysis, provided there was no indication of collision during reception. Otherwise such packets would be discarded automatically by the receiver and removed from the buffer. See also Table 8. 4 40 BIT ADDR R W 0 40 BIT ADDRESS: When set high, instead of the customary 48-bit NODE ID address filter, only the first 40 bits of the NODE ID are compared (NODE ID 0­4). 3 ACPT SHORT PKTS R W 0 ACCEPT SHORT PACKETS: When set high, allows short packets (packets with less than 60 bytes, excluding Preamble and CRC, i.e. below IEEE minimum length) down to 6 bytes, excluding preamble and CRC, to be saved into the receive buffer, provided there was no CRC or alignment error and no indication of collision during reception. Otherwise such packets would be discarded automatically by the receiver and removed from the buffer. See also Table 8. 2 1 N 0 RESERVED: Write 1. 1 AF1 R W 0 ADDRESS FILTER MODE: AF1 and AF0, DLCR5, control the address filtering on incoming packets. See table below under AF0. 0 AF0 R W 1 ADDRESS FILTER MODE: AF1 and AF0, DLCR5, control the address filtering on incoming packets: AF1 AF0 Description of Address Accepted 0 1 NODE ID, Broadcast, Multicast & 2nd-24th bits of NODE ID 1 0 NODE ID, Broadcast, Multicast & Hash Table 0 0 Reject all packets 1 1 Accept all packet Note: Self reception of broadcast and multicast packets prohibited except in "Accept all packets" mode. When LBC is low (loopback mode) broadcast packets can be self-received, except in "Reject all packets" mode. 28 MB86960 MB86960 Configuration Registers 0 and 1 Basic system configuration bits are found in these two registers. Among the configuration controls found here are physical packet buffer memory size, partitioning between transmit and receive buffers, widths of memory and system buses, byte lane control, chip configuration and power down control. Most of these configuration parameters will be programmed only during initialization after power start and hardware reset. See Tables 12 and 13. Table 12. DLCR6 - Configuration Register 0 BIT SYMBOL TYPE DESCRIPTION 7 DLC EN R W 1 ENABLE DATA LINK CONTROLLER: When low, enables the receiver and transmitter sections of the NICE chip. This bit must be set high during initialization and later set low to enable loopback testing and operation of the network. Program NODE ID only when this bit is high. 6 1 N 0 RESERVED: Write 1. 5 SB/SW R W 1 SYSTEM BYTE/WORD BUS WIDTH: When high, system bus will operate in 8-bit data mode; when low, 16-bit data mode is selected. See also BB/BW below. 4 BB/BW R W 1 BUFFER BYTE/WORK WIDTH: When high, buffer memory will operate in 8-bit data mode; when low, 16-bit data mode is selected. See table for allowable combinations with SB/SW: SB/SW 0 word word 1 word byte 1 0 1 R W 01 BUFFER 0 TBS 1, 0 SYSTEM 0 3, 2 BB/BW 1 Do not use byte byte TRANSMIT BUFFER SIZE: Selects size of Transmit Buffer(s). See table: Total Size TX BUF 1 2KB 2KB 2 2KB 4KB 10 2 4KB 8KB 11 R W 10 Size each TX BUF 01 BS1, 0 No. TX BUFS 00 1, 0 TBS 1,0 2 8KB 16KB BUFFER SIZE: Selects physical size of total SRAM buffer memory for both transmit and receive functions. See table: BS1 BS0 SRAM Size 0 0 8KB 0 1 16KB 1 0 32KB 1 1 64KB 29 MB86960 MB86960 Table 13. DLCR7 - Configuration Register 1 BIT SYMBOL TYPE DESCRIPTION 7, 6 E/D CNF 1,0 R W 00 ENCODER/DECODER CONFIGURATION: Selects the operating mode of the controller-encoder/decoder functions and their interface. See table below and pin descriptions for the monitor pins, TXD, TCK, TEN, LBC, RXD, RCK, CRS and COL: E/D CNF 1 E/D CNF 0 Registers 0 0 Normal NICE: Internal encoder/decoder active. Monitor pins inactive. 0 1 NICE + Monitor: Internal encoder/decoder active. Monitor pins outputting all controller/encoder/ decoder interface signals 1 0 Encoder/Decoder Bypass: Internal encoder/ decoder not used. Monitor pins can be used to interface controller to external encoder/decoder. 1 1 Encoder/Decoder Test: Controller inactive, encoder/decoder active. Monitor pins used to test encoder/decoder. 5 PWRDN R W 1 POWER DOWN: When set high, enables power to the chip for all functions; when set low, places chip in power down mode for power conservation. 4 RDYPOL R 0/1 READY PIN POLARITY: Reads the state of the RDY POL pin 94. 3, 2 RBS 1, 0 R W 00 REGISTER BANK SELECT: Provides the indirect address for selection of one of the three sets of registers to access when the physical register address is xxx8H­xxxFH. The lower 7 registers are not bank-selectable. See table: RBS1 RBS0 0 0 DLCR0-7, DLCR8-F Registers 0 1 DLCR0-7, HT8-F 1 0 DLCR0-7, BMR8-F 1 1 RESERVED 1 EOPPOL R W 0 EOP PIN SIGNAL POLARITY: When high, the EOP pin is active-high; when low, EOP is active-low. 0 M.L/ L.M R W 0 BYTE ORDER CONTROL: Selects byte lane ordering for packet data in the buffer (applies only in System Word Mode). In both Most.Least and Least.Most modes, the first and second bytes of the packet will appear in the same word on the system bus. When this bit is high (M.L mode), the first and all odd-numbered bytes of a packet and its header will appear on the high byte of the system bus. Note that header bytes are also swapped. 30 MB86960 MB86960 Example of using Least.Most Byte Ordering: Note to software engineers regarding NICE/EtherStarTM compatibility: If you desire to use the same node driver for Fujitsu's NICE and EtherStar controllers, the driver can determine which chip is being used by reading DLCR7 and/or DLCR6 after hardware reset. NICE will read 30B6H 30B6H or 20BGH 20BGH (30 or 20 for DLCR7 and B6 for DLCR6); EtherStar will read 0000H 0000H. System Bus Transmit Packet: High Byte TX Length, high byte Destination Addr, 2nd byte Power-down mode saves power when the device is not in use. When ready to place the NICE chip in Power Down Mode, first write 1 to DLCR6, DLC EN, to turn the receiver and transmitter off, then write 0 to DLCR7, PWRDN. To exit the power-down mode, write 1 to PWRDN. Register contents will be preserved, unless a hardware reset is issued. Hardware reset will also terminate the power-down mode. Source Addr, 2nd byte Length Field, low byte* Data Field, 2nd byte Low Byte TX Length, low byte Destination Addr, 1st byte. Source Addr, 1st byte. Length Field, high byte* Data Field, 1st byte. Receive Packet: High Byte Unused; reserved RX Length, high byte Destination Addr, 2nd byte Byte order control provided by the Most.Least/ Least.Most bit, DLCR7, provides compatibility with various higher-level protocols, such as TCP/IP and XNS. These protocols may have different transmission order of the bytes within a word. When M.L/L.M is low, the least significant byte of the word is transmitted first, followed by the most significant. When M.L/L.M is set high, the byte order is reversed. This feature applies only when the system bus is operated in 16-bit (word) mode. Source Addr, 2nd byte Length Field, low byte* Data Field, 2nd byte Low Byte Receive Packet Status RX Length, low byte Destination Addr, 1st byte. Source Addr, 1st byte. Length Field, high byte* Data Field, 1st byte. Example of using Most.Least Byte Ordering: The byte order control works by reversing or not reversing the bytes of all words as they pass between the buffer memory and the system bus. Thus all data stored in the transmit buffer or retrieved from the receive buffer is affected, including the nontransmitted headers. The NICE registers, other than the Buffer Memory Port, BMPR8:9, are not affected by this control bit. Care must be taken in the software driver code to reverse the header information as well as the packet data when using this feature. Examples follow. System Bus Transmit Packet: High Byte TX Length, low byte * Destination Addr, 1st byte Source Addr, 1st byte Length Field, high byte Data Field, 1st byte Low Byte TX Length, high byte* Destination Addr, 2nd byte. Source Addr, 2nd byte. Length Field, low byte Data Field, 2nd byte. Receive Packet: High Byte Receive Packet Status RX Length, low byte * Destination Addr, 1st byte Source Addr, 1st byte Length Field, high byte Data Field, 1st byte Low Byte Unused; reserved RX Length, high byte* Destination Addr, 2nd byte. Source Addr, 2nd byte. Length Field, low byte Data Field, 2nd byte. Note: Asterisk indicates numerically reversed byte ordering. 31 MB86960 MB86960 NODE ID REGISTERS The amount of elapsed time this represents is two (2) times the signal delay from the node to the fault. An open on the network will usually cause a false collision, whereas a short is more likely to cause loss of carrier sense. The Node ID Registers are accessed in register bank "0" at register addresses xxx8H­xxxDH. During initialization of the node, the unique Ethernet address assigned to the node is loaded into these registers. The first register at xxx8H corresponds to the first byte of the Node ID, which corresponds to the first address byte to be received as a packet arrives from the network. If the chip is configured to do so in its Address Filter mode bits, DLCR5, the destination address field of an incoming packet will be compared to the Node ID stored in these registers. If there is a match, provided the packet passes the error filter, it will be accepted. The TDR Count comes from DLCR14 DLCR14 and 15. DLCR14 DLCR14 is the least-significant byte, DLCR15 DLCR15 the most-significant. Only the lower 14 bits of the counter are equipped, which is more than is needed for an IEEE or Ethernet LAN. (The top two bits, DLCR15 DLCR15, are always 0.) To perform the TDR test for a fault, first enable interrupts for transmitter done (TX DONE). This is done by setting DLCR2 high. (An alternative to using the interrupt would be polling the TX DONE bit looking for a high level.) Set the 16 Collisions Register, BMPR11 BMPR11, to 07H for this test (no halt, skip failed packet). Clear all status bits by writing FF86H FF86H to the Receive and Transmit Status Registers. Next, transmit, or attempt to transmit, a packet of 600 bits or more in length. Up to 16 attempts may be made automatically if collisions are being indicated. Upon completion of the transmission attempt(s) TX DONE will go high, generating an interrupt if enabled. When this occurs, read the Transmit Status Register and the TDR Register. These registers are readable as well as writable, but they should not be accessed while the receiver is enabled. To avoid interaction with the receiver, access these registers only when DLC EN is 1. It is recommended that they be written and read only during initialization before enabling the receiver, i.e. before writing 0 to DLC EN, DLCR6. The address contained in these registers is used only for receive (destination) address filtering, not for the source address of outgoing packets. Outgoing packet addresses must be provided by the system as part of the packet data. Interpreting the results: If the count is zero, no fault was detected. If the count is greater than zero but smaller than the packet length, it may indicate a cable fault. If the count is less than 525, there may have been a real collision occurring during the test. Real collisions normally occur within the first 65 bytes of the packet, including preamble. Take note of the error messages, COL and CR LOST. COL high suggests a cable open, whereas CR LOST suggests a short. It is best to repeat the measurement several times, then throw out the anomalous values, if any, and average the rest. A cluster of readings at about the same value is a strong indicator of a valid fault measurement. If such a cluster of readings occurs, multiply the average of the cluster by 39 feet to estimate the distance from the node to the fault. (39 ft. = (100 ns x .8 x 186,282 mi/s x 5280 ft/mi)/2 . this assumes the network is mostly coaxial cable with signal propagation speed of approximately .8 x C, the speed of light.) Within each byte, the bits are transmitted and received on the network least-significant bit first. See Table 3 for the transmission bit order, which follows the bit numbering in this table. Time Domain Reflectometry (TDR) Counter The TDR Counter can be used to get a rough indication of the location of a fault on the network, if one exists. When a node transmits, a short or open on the network would cause a reflected signal to the node's receiver which can sometimes be detected. The reflection will cause the carrier sense to fail and/or a false collision to be detected. This affect, time domain reflectometry, can be used to estimate the distance along the network cable from the node to the fault. The TDR Counter counts the number of bits transmitted before either a collision occurs, or carrier sense is lost, whichever comes first. If neither occur during transmission of the packet, the count is cleared. 32 MB86960 MB86960 HASH TABLE Whereas some controllers share a single such core between transmitter and receiver, NICE has two of these, one for the generator and one for the checker, allowing both to operate concurrently for self-receive. To begin the calculation, the register is first set to all 1's. For the generator case, as the packet is transmitted, the data is clocked serially into the left-hand end of the register starting with the 48 bits of the destination address (the preamble is skipped). After the last bit of the `data' field is clocked into the register, the CRC calculation is finished. The feedback line is then forced low and the register becomes a simple shift-right register. Its contents are then shifted out serially and transmitted, appending the CRC to the end of the packet. For the CRC checker, the calculation starts out the same way as for CRC generation feeding the incoming data into the register. But in this case, the CRC field of the packet is also fed into the calculation. The result is a fixed constant in the register if no CRC error has occurred. The Hash Table provides a means for filtering incoming multicast packets so that the host processor does not have to process ones that are not of interest. The principle employed in this filtering scheme was originally developed by computer science to arrange a large number of elements of an array or database in such a way that facilitates searching for elements associated with a given key or datum. The `hash function' is a mathematical or logical function which maps all possible elements in a domain onto a smaller domain called the `hash table'. As an example, suppose the following hashing function is used: "Treating the multicast address as a non-negative 48-bit integer, divide this number by 64 and take the remainder." This function will map all multicast addresses into a 64-element hash table since the remainder can be only the integer values 0 through 63. Applying this hashing function results in taking the least-significant 6 bits of the multicast address as an integer. In the hash table, for each element, 0 through 63, a single bit is stored which indicates whether the address is to be accepted (1) or rejected (0). If, for example, the node belongs to three multicast groups, only three or fewer of the hash table elements will store 1's, the rest 0's. The scheme allows the acceptance of any number of the addresses, including all of them. The limitation is that there may be addresses not of interest used on the network which also fall into the `accept' elements, so in this case the filtering is imperfect. But in any case, most of the nonapplying addresses can be filtered out in this way. For the Hash Filter, after the last bit of the destination address has been clocked into the register, the left-hand six register bits are stored in another register used to address the Hash Table elements. The left-most bit is most significant. The left-most three bits are used as the Hash Table register address and the right-most three as the bit address within a register byte. Having selected a Hash Table element in this way, a 1 in the table will indicate the packet is to be accepted, provided it is a multicast packet (first bit of destination address must be 1), and passes the error filters. The hash filter is only employed when the address filter mode select bits, AF1, AF0 are 0, 1, selecting the "NODE ID, Broadcast, Multicast + Hash Table" mode. Like the NODE ID registers, the Hash Table registers should only be accessed when the receiver is disabled, i.e. when DLC EN is high, to avoid interaction with the receiver. There are eight bytes of registers in the Hash Table containing the 64 1-bit elements (refer to Table 1 for location). Source code software examples showing how to calculate entries for the Hash Table are available from the Fujitsu Microelectronics Customer Response Center (CRC), phone: 1­800­866­8608 The actual hashing function used in the NICE chip is this: "Calculate the CRC on the multicast address and take the high-order 6 bits of this calculation". The six bits are used to address the elements of the hash table. If a 1 is stored in an element of the table, associated packets are accepted. The hash filter criterium is only used on multicast addresses, which all start with a 1. Node ID's, which start with a 0, are not filtered by the hash filter. The broadcast address, a special case of the multicast set wherein all the bits are 1's, will be accepted anyway unless the "Reject all packets" mode is selected. Figure 10 shows the register core, a modified shift-right register, used in generating and checking CRC's. 33 MB86960 MB86960 DATA D Q + D Q D Q D Q D Q D Q + D Q D Q + D Q D Q D Q + D Q + D Q Q D Q D Q D Q + D Q D Q + D Q + D Q D Q D Q D Q D Q D Q Q D Q D Q + = Exclusive OR Figure 10. CRC Register Core 34 + D Q D Q + D Q D Q + D Q D Q Q + + MB86960 MB86960 TRANSMIT AND RECEIVE PACKET HEADERS data. See Table 3 for location of the bits, and description for DLCR7, M.L/L.M. Both transmit and receive packets have headers stored with them in the buffer memory which are not part of the transmitted packet. These headers precede the packet data. BUFFER MEMORY PORT REGISTERS The Buffer Memory Port Registers, BMPR8­15, provide the host access to the buffer memory and certain control functions. It is recommended that this bank be selected most of the time the chip is on the network for convenience in accessing the buffer memory and the control bits (Register Bank Select = 10 binary). Refer to Table 1 for location of these registers. Transmit Packet Length An 11-bit integer indicating the number of bytes in the packet to be transmitted, excluding preamble and CRC fields which are generated by the NICE chip. See Table 3 for bit locations, and description for DLCR7, M.L/L.M. Receive Packet Status Writing a byte/word to BMPR8, the buffer port, transfers that data to the currently addressed location in the transmit buffer and increments the transmit buffer pointer to point to the next byte/word. Reading a byte/word from this port transfers the contents of the currently addressed location in the receive buffer to the host and increments the receive buffer pointer to point to the next byte/word. BMPR9 is used only in word mode as the high byte of the word. In word mode, all transfers must be 16-bits wide, as the Buffer Port does not support byte-wide transfers in this mode. All other registers can be accessed word-wide, high byte only or low byte only as desired. The receive packet header consists of one byte of packet status, an unused byte and two bytes (11 bits) for packet length in bytes. See Table 3 for location of the bits, and description for DLCR7, M.L/L.M. Bits 1, 2, 3 and 4 of the status byte are an image of the same bits in the Receive Status Register, DLCR1, with respect to the packet that follows. Bit 5 is the GOOD PKT bit. A 1 in this bit location indicates no errors were detected in the packet. Bits 0, 6 and 7 are unused and are always 0. Receive Packet Length The third and fourth bytes of the receive packet header indicate the total number of bytes in the stored packet Table 14. BMPR10 BMPR10 - Transmit Start Register BIT SYMBOL TYPE DESCRIPTION 7 TX START W 0 TRANSMITTER START: Writing 1 to this bit commands transmitter to start transmitting the packet(s) loaded into the transmit buffer. Before doing so, the transmitter must be idle (not busy with another buffer). The TX DONE bit is used to determine the required transmitter status, idle or busy. 6­0 TX PKT CNT R W 0 TRANSMIT PACKET COUNT: A binary integer written by the system to indicate the number of packets contained in the transmit buffer for transmission. This information can be loaded at the same time the TX START bit is set high. As the transmitter finishes transmitting each packet, this counter is decremented. The value can be read by the system to see how many packets remain to be transmitted. 35 MB86960 MB86960 Transmit Start Register a halt by writing any action code listed in Table 15 to this register. The Transmit Start Register, BMPR10 BMPR10, contains the TX START bit and the TX PKT CNT. Writing 1 to the TX START bit immediately starts the transmitter. The Transmit Packet Count is a 7-bit binary integer written by the host to indicate the number of packets in the transmit buffer to be transmitted. See Table 14. This register should only be written when the transmitter is idle. It can be read at any time. TX START will always read as 1. DMA Enable Register This is a write-only register which is used to enable and clear either Receive Read DMA or Transmit Write DMA. Refer to Table 16 for the codes. DMA Burst Register (BMPR13 BMPR13) This register is used to select the burst length for DMA operation. The burst length can be 1, 4, 8 or 12 transfers. Each transfer is one byte or one word, depending on the mode selected, System Byte or System Word (see SB/SW in DLCR6). 16 Collisions Control Register This is a command register to control the actions taken when 16 consecutive attempts to transmit a packet are all met with collision. Table 15 summarizes the use of this register. It serves as both a mode setup register and an action command register. As a mode select register, two functions are selectable. Firstly, automatic continuation or halt after 16 collisions can be selected. If automatic continuation is selected, there is an option to continue attempting to transmit the same packet, or skip to the next packet. If halt is enabled, the Transmitter is restarted after CODE No. of Transfers 00H 1 01H 4 02H 8 03H 12 Table 15. 16 Collision Action Codes (written to BMPR11 BMPR11) ACTION CODE 02H or 03H DESCRIPTION MODE SETUP: Halt after 16 Collisions. 02H COMMAND: Resume transmitting, repeat failed packet (for use following a halt). Terminates the halt. Instructs transmitter to resume transmitting by repeating the failed packet. The collision counter is reset, allowing up to 16 additional attempts to be made. Halt after 16 collisions. 03H COMMAND: Resume transmitting, skip failed packet (for use following a halt). Terminates the halt. Instructs transmitter to skip the failed packet and resume transmitting with the next packet in the buffer. The collision counter is reset, allowing up to 16 additional attempts to be made. If there is no next packet, the transmitter will deactivate, setting TX DONE as it does so. Halt after 16 collisions. 06H MODE SETUP: Continue automatically after 16 collisions, repeat failed packet. Warning: If the network medium is disconnected, transmission attempts will usually result in false collision detection. Under this condition, this mode will cause the transmitter to continue re-attempting transmission of the same packet indefinitely. Interrupt or periodic polling of the status bits should be used to detect this condition. 07H MODE SETUP: Continue automatically after 16 collisions, skip failed packet. Warning: This mode will result in failure to transmit some packets, since it skips a packet which has had 16 collisions. This condition is rare on a healthy network, but it does happen. To avoid this, use mode 06H. Table 16. DMA Enable Register (BMPR12 BMPR12) ACTION CODE DESCRIPTION 01H Enables Transmit Write DMA 02H Enables Receive Read DMA 00H Clear or terminate DMA activity, DMA EOP status bit and associated interrupt, if any. Normally used as response to End of Process (DMA EOP) interrupt. 36 MB86960 MB86960 Skip Packet Register (BMPR14 BMPR14) Mode Register are set in case of a collision-terminating transmission. Another status bit (16 COL) indicates that sixteen consecutive attempts to transmit a packet have been made and all have been terminated by collision. This case may indicate a network problem. For example, a disconnected cable or terminator will produce false collisions. But 16 collisions can occur normally, although rarely. A pseudo-random number generator provides the collision backoff function. This is clocked at the bit rate, 10 MHz, so that distances between stations become part of the randomizing function. It is sampled at the time of collision, masking all but the appropriate number of bits specified by the 8802­3 backoff algorithm. This value is then counted down at the slot-time rate (512 bits) to generate the backoff interval. For a first collision, only one bit is used, giving a backoff of either 51.2 microseconds or 0. For a second consecutive collision, two bits are used, and so forth, up to ten bits. From the tenth to the 16th collision, 10 bits are used. This gives a pseudo-random backoff interval of from 0 to 52.38 ms, the so-called `binary exponential backoff' for collisions per 8802-3. Only one bit in this register is active, bit 2, the rest are 0. Writing 04H to this register commands the buffer controller to skip the balance of the current receive packet in memory. The bit can then be read to see when the skip process is complete (within 300 ns). The bit returns to 0 when the chip is ready to read the next packet, if there is another packet, or stop reading if there is not. Limitation of use: Do not use this feature before reading at least four (4) times from the beginning of the packet, nor if there are only eight (8) or fewer bytes left of the packet in the buffer. Doing so may corrupt the receive buffer pointers. BMPR15 BMPR15 is unused and reserved for possible future use. Write only 0's to this register. TRANSMITTER CIRCUITS Circuits within the transmitter include a transmitter state machine, a small FIFO for pipe-lining the packet data, preamble generator, CRC generator, parallel to serial converter, backoff generator, inter-packet gap timer and a time domain reflectometer (TDR) counter. Time Domain Reflectometry The TDR function provided counts the actual number of bits transmitted for each packet before an indication of either collision or carrier loss occurs, or the transmission completes. If a transmission completes without error indications, the TDR counter is cleared. See also the register description for DLCR14 DLCR14 and DLCR15 DLCR15. The transmitter state machine provides sequencing of events for the transmitter, including idle, preamble, data, CRC, inter-packet gap, jam and backoff. It detects various transmit error conditions and sets appropriate bits within the DLCR registers. The pipeline FIFO provides elastic buffering that the buffer controller can load with data to be transmitted. NICE's CRC generator calculates the Ethernet 32-bit CRC on the destination and source address, the length field and the data field as specified by the ISO/ANSI/ IEEE 8802-3 specification for Ethernet. This value is appended to the end of the packet. Media Access Control NICE's transmitter state machine implements the media access protocol for 8802-3 networks called CSMA/CD, Carrier Sense, Multiple Access with Collision Detection. The `carrier sense' part means that the controller monitors the network for carrier from other nodes, and defers transmission while other nodes are transmitting (collision avoidance). But collisions can still occur when two nodes, perhaps separated on the network by several microseconds, start to transmit at nearly the same time. This is handled by the `collision detection' part. All nodes are required to monitor the network for collisions and, when involved in one, transmit a 32-bit `Jam' to reinforce the collision, then terminate transmission. Later, after waiting a pseudo-random backoff interval, the node automatically re-attempts to transmit the packet. Transmit Error Processing NICE has four transmit error status bits in its Transmit Status Register (DLCR0) for reporting the three possible transmit errors. The errors are: 1) loss of carrier during transmission, which usually indicates a medium fault or a collision, 2) collision, and 3) 16 consecutive collisions. The latter two