CS8900A-CQ3

CS8900A Product Data Sheet FEATURES I Single-Chip IEEE 802.3 Ethernet Controller with Direct ISA-Bus Interface I Maximum Current Consumption = 55 mA (5V Supply) I 3 V Operation I Industrial Temperature Range I Comprehensive Suite of Software Drivers Available I Efficient PacketPage™ Architecture Operates in I/O and Memory Space, and as DMA Slave I Full Duplex Operation I On-Chip RAM Buffers Transmit and Receive Frames I 10BASE-T Port with Analog Filters, Provides: — Automatic Polarity Detection and Correction &U\VWDO /$1™ ISA Ethernet Controller DESCRIPTION The CS8900A is a low-cost Ethernet LAN Controller optimized for Industry Standard Architecture (ISA) Personal Computers. Its highly-integrated design eliminates the need for costly external components required by other Ethernet controllers. The CS8900A includes on-chip RAM, 10BASE-T transmit and receive filters, and a direct ISA-Bus interface with 24 mA Drivers. In addition to high integration, the CS8900A offers a broad range of performance features and configurationoptions. Its unique PacketPage architecture automatically adapts to changing network traffic patterns and available system resources. The result is increased system efficiency. The CS8900A is available in a 100-pin TQFP package ideally suited for small form-factor, cost-sensitive Ethernet applications. With the CS8900A, system engineers can design a complete Ethernet circuit that occupies less than 1.5 square inches (10 sq. cm) of board space. ORDERING INFORMATION CS8900A-CQ 0° to 70° C CS8900A-IQ -40° to 85° C CS8900A-CQ3 0° to 70° C CS8900A-IQ3 -40° to 85° C CRD8900A-1 5V TQFP-100 5V TQFP-100 3.3V TQFP-100 3.3V TQFP-100 Evaluation Kit I AUI Port for 10BASE2, 10BASE5 and 10BASE-F I Programmable Transmit Features: — Automatic Re-transmission on Collision — Automatic Padding and CRC Generation I Programmable Receive Features: — — — — Stream Transfer™ for Reduced CPU Overhead Auto-Switch Between DMA and On-Chip Memory Early Interrupts for Frame Pre-Processing Automatic Rejection of Erroneous Packets I EEPROM Support for Jumperless Configuration I Boot PROM Support for Diskless Systems I Boundary Scan and Loopback Test I LED Drivers for Link Status and LAN Activity I Standby and Suspend Sleep Modes EEPROM 20 MHz XTAL CS8900A ISA Ethernet Controller LED Control EEPROM Control RAM Clock 10BASE-T RX Filters & Receiver 10BASE-T TX Filters & Transmitter RJ-45 10BASE-T I S A ISA Bus Logic Encoder/ Decoder & PLL AUI Transmitter AUI Collision AUI Receiver Memory Manager 802.3 MAC Engine Boundary Power Scan Manager Test Logic Attachment Unit Interface (AUI) CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 Copyright  Cirrus Logic, Inc. 2001 (All Rights Reserved) APR ‘01 CS8900A Crystal LAN™ ISA Ethernet Controller TABLE OF CONTENTS 1.0 INTRODUCTION ......................................................................................................................7 1.1 General Description ............................................................................................................7 1.1.1 TDirect ISA-Bus Interface ......................................................................................7 1.1.2 TIntegrated Memory ..............................................................................................7 1.1.3 T802.3 Ethernet MAC Engine ................................................................................7 1.1.4 TEEPROM Interface ..............................................................................................7 1.1.5 TComplete Analog Front End ................................................................................7 1.2 System Applications ...........................................................................................................7 1.2.1 TMotherboard LANs ..............................................................................................7 1.2.2 TEthernet Adapter Cards .......................................................................................8 1.3 Key Features and Benefits .................................................................................................9 1.3.1 TVery Low Cost .....................................................................................................9 1.3.2 THigh Performance ................................................................................................9 1.3.3 TLow Power and Low Noise ..................................................................................9 1.3.4 TComplete Support ...............................................................................................9 2.0 PIN DESCRIPTION .............................................................................................................11 3.0 FUNCTIONAL DESCRIPTION ...............................................................................................16 3.1 Overview ..........................................................................................................................16 3.1.1 TConfiguration .....................................................................................................16 3.1.2 TPacket Transmission .........................................................................................16 3.1.3 TPacket Reception ..............................................................................................16 3.2 ISA Bus Interface .............................................................................................................17 3.2.1 TMemory Mode Operation ...................................................................................17 3.2.2 TI/O Mode Operation ...........................................................................................17 3.2.3 TInterrupt Request Signals ..................................................................................17 3.2.4 TDMA Signals ......................................................................................................17 3.3 Reset and Initialization .....................................................................................................18 3.3.1 TReset .................................................................................................................18 3.3.1.1 External Reset, or ISA Reset ...............................................................18 3.3.1.2 Power-Up Reset ..................................................................................18 3.3.1.3 Power-Down Reset ..............................................................................18 3.3.1.4 EEPROM Reset ...................................................................................18 3.3.1.5 Software Initiated Reset .......................................................................18 3.3.1.6 Hardware (HW) Standby or Suspend ..................................................18 3.3.1.7 Sof tware (SW) Suspend .....................................................................18 3.3.2 TAllowing Time for Reset Operation ....................................................................18 3.3.3 TBus Reset Considerations .................................................................................18 3.3.4 TInitialization ........................................................................................................19 3.4 Configurations with EEPROM ..........................................................................................20 3.4.1 TEEPROM Interface ............................................................................................20 3.4.2 TEEPROM Memory Organization ........................................................................20 3.4.3 TReset Configuration Block .................................................................................20 3.4.3.1 Reset Configuration Block Structure ....................................................20 3.4.3.2 Reset Configuration Block Header ......................................................20 3.4.3.3 Determining the EEPROM Type ..........................................................20 3.4.3.4 Checking EEPROM for presence of Reset Configuration Block ..........20 3.4.3.5 Determining Number of Bytes in the Reset Configuration Block .........21 3.4.4 TGroups of Configuration Data ............................................................................21 3.4.4.1 Group Header ......................................................................................22 3.4.5 TReset Configuration Block Checksum ...............................................................22 3.4.6 TEEPROM Example ............................................................................................22 3.4.7 TEEPROM Read-out ...........................................................................................22 CIRRUS LOGIC PRODUCT DATASHEET 2 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 3.4.7.1 Determining EEPROM Size .................................................................22 3.4.7.2 Loading Configuration Data .................................................................23 3.4.8 TEEPROM Read-out Completion ........................................................................23 3.5 Programming the EEPROM .............................................................................................23 3.5.1 TEEPROM Commands .......................................................................................23 3.5.2 TEEPROM Command Execution ........................................................................23 3.5.3 TEnabling Access to the EEPROM .....................................................................24 3.5.4 TWriting and Erasing the EEPROM ....................................................................24 3.6 Boot PROM Operation .....................................................................................................24 3.6.1 TAccessing the Boot PROM ................................................................................24 3.6.2 TConfiguring the CS8900A for Boot PROM Operation .......................................24 3.7 Low-Power Modes ..........................................................................................................25 3.7.1 THardware Standby ............................................................................................25 3.7.2 THardware Suspend ...........................................................................................25 3.7.3 TSoftware Suspend .............................................................................................26 3.8 LED Outputs .....................................................................................................................27 3.8.0.1 LANLED ..............................................................................................27 3.8.0.2 LINKLED or HC0 .................................................................................27 3.8.0.3 BSTATUS or HC1 ...............................................................................27 3.8.1 TLED Connection ................................................................................................27 3.9 Media Access Control ......................................................................................................27 3.9.1 TOverview ...........................................................................................................27 3.9.2 TFrame Encapsulation and Decapsulation .........................................................28 3.9.2.1 Transmission .......................................................................................28 3.9.2.2 Reception ............................................................................................28 3.9.2.3 Enforcing Minimum Frame Size ..........................................................28 3.9.3 TTransmit Error Detection and Handling .............................................................29 3.9.3.1 Loss of Carrier .....................................................................................29 3.9.3.2 SQE Error ............................................................................................29 3.9.3.3 Out-of-Window (Late) Collision ............................................................29 3.9.3.4 Jabber Error ........................................................................................29 3.9.3.5 Transmit Collision ................................................................................29 3.9.3.6 Transmit Underrun ..............................................................................29 3.9.4 TReceive Error Detection and Handling ..............................................................30 3.9.4.1 CRC Error ............................................................................................30 3.9.4.2 Runt Frame .........................................................................................30 3.9.4.3 Extra Data ...........................................................................................30 3.9.4.4 Dribble Bits and Alignment Error .........................................................30 3.9.5 TMedia Access Management ..............................................................................30 3.9.5.1 Collision Avoidance .............................................................................30 3.9.5.2 Two-Part Deferral ................................................................................30 3.9.5.3 Simple Deferral ....................................................................................31 3.9.5.4 Collision Resolution .............................................................................31 3.9.5.5 Normal Collisions ................................................................................31 3.9.5.6 Late Collisions .....................................................................................32 3.9.5.7 Backoff ................................................................................................32 3.9.5.8 Standard Backoff .................................................................................32 3.9.5.9 Modified Backoff ..................................................................................32 3.9.5.10 SQE Test ...........................................................................................32 3.10 Encoder/Decoder (ENDEC) ...........................................................................................33 3.10.1 TEncoder ...........................................................................................................33 3.10.2 TCarrier Detection .............................................................................................33 3.10.3 TClock and Data Recovery ...............................................................................33 CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 3 CS8900A Crystal LAN™ ISA Ethernet Controller 3.10.4 TInterface Selection ...........................................................................................34 3.10.4.1 10BASE-T Only .................................................................................34 3.10.4.2 AUI Only ............................................................................................34 3.10.4.3 Auto-Select ........................................................................................34 3.11 10BASE-T Transceiver ...................................................................................................34 3.11.1 T10BASE-T Filters .............................................................................................34 3.11.2 TTransmitter ......................................................................................................35 3.11.3 TReceiver ..........................................................................................................35 3.11.3.1 Squelch Circuit ...................................................................................35 3.11.3.2 Extended Range ................................................................................35 3.11.4 TLink Pulse Detection ........................................................................................35 3.11.5 TReceive Polarity Detection and Correction ......................................................36 3.11.6 TCollision Detection ...........................................................................................36 3.12 Attachment Unit Interface (AUI) .....................................................................................36 3.12.1 TAUI Transmitter ...............................................................................................36 3.12.2 TAUI Receiver ...................................................................................................37 3.12.3 TCollision Detection ...........................................................................................37 3.13 External Clock Oscillator ................................................................................................37 4.0 PACKETPAGE ARCHITECTURE ..........................................................................................38 4.1 PacketPage Overview ......................................................................................................38 4.1.1 TIntegrated Memory ............................................................................................38 4.1.2 TBus Interface Registers .....................................................................................38 4.1.3 TStatus and Control Registers .............................................................................38 4.1.4 TInitiate Transmit Registers .................................................................................38 4.1.5 TAddress Filter Registers ....................................................................................38 4.1.6 TReceive and Transmit Frame Locations ............................................................38 4.2 PacketPage Memory Map ................................................................................................39 4.3 Bus Interface Registers ....................................................................................................41 4.4 Status and Control Registers ...........................................................................................46 4.4.1 TConfiguration and Control Registers .................................................................46 4.4.2 TStatus and Event Registers ...............................................................................46 4.4.3 TStatus and Control Bit Definitions ......................................................................46 4.4.3.1 Act-Once Bits .......................................................................................47 4.4.3.2 Temporal Bits .......................................................................................47 4.4.3.3 Interrupt Enable Bits and Events .........................................................47 4.4.3.4 Accept Bits ...........................................................................................47 4.4.4 TStatus and Control Register Summary ..............................................................48 4.5 Initiate Transmit Registers ................................................................................................70 4.6 Address Filter Registers ...................................................................................................71 4.7 Receive and Transmit Frame Locations ...........................................................................72 4.7.1 TReceive PacketPage Locations .........................................................................72 4.7.2 TTransmit Locations ............................................................................................72 4.8 Eight and Sixteen Bit Transfers ........................................................................................72 4.8.1 TTransferring Odd-Byte-Aligned Data .................................................................73 4.8.2 TRandom Access to CS8900A Memory ..............................................................73 4.9 Memory Mode Operation ..................................................................................................73 4.9.1 TAccesses in Memory Mode ...............................................................................73 4.9.2 TConfiguring the CS8900A for Memory Mode .....................................................73 4.9.3 TBasic Memory Mode Transmit ...........................................................................74 4.9.4 TBasic Memory Mode Receive ............................................................................74 4.9.5 TPolling the CS8900A in Memory Mode ..............................................................75 4.10 I/O Space Operation ......................................................................................................75 4.10.1 TReceive/Transmit Data Ports 0 and 1 ..............................................................75 CIRRUS LOGIC PRODUCT DATASHEET 4 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.10.2 TTxCMD Port ....................................................................................................75 4.10.3 TTxLength Port ..................................................................................................75 4.10.4 TInterrupt Status Queue Port ............................................................................75 4.10.5 TPacketPage Pointer Port .................................................................................75 4.10.6 TPacketPage Data Ports 0 and 1 ......................................................................76 4.10.7 TI/O Mode Operation .........................................................................................76 4.10.8 TBasic I/O Mode Transmit .................................................................................76 4.10.9 TBasic I/O Mode Receive ..................................................................................76 4.10.10 TAccessing Internal Registers .........................................................................77 4.10.11 TPolling the CS8900A in I/O Mode .................................................................77 5.0 OPERATION ..........................................................................................................................78 5.1 Managing Interrupts and Servicing the Interrupt Status Queue .......................................78 5.2 Basic Receive Operation ..................................................................................................78 5.2.0.1 Overview .............................................................................................78 5.2.1 TTerminology: Packet, Frame, and Transfer .......................................................80 5.2.1.1 Packet .................................................................................................80 5.2.1.2 Frame ..................................................................................................80 5.2.1.3 Transfer ...............................................................................................80 5.2.2 TReceive Configuration .......................................................................................80 5.2.2.1 Configuring the Physical Interface .......................................................80 5.2.2.2 Choosing which Frame Types to Accept .............................................80 5.2.2.3 Selecting which Events Cause Interrupts ............................................81 5.2.2.4 Choosing How to Transfer Frames ......................................................81 5.2.3 TReceive Frame Pre-Processing ........................................................................81 5.2.3.1 Destination Address Filtering ..............................................................82 5.2.3.2 Early Interrupt Generation ...................................................................83 5.2.3.3 Acceptance Filtering ............................................................................83 5.2.3.4 Normal Interrupt Generation ................................................................83 5.2.4 THeld vs. DMAed Receive Frames .....................................................................83 5.2.5 TBuffering Held Receive Frames ........................................................................83 5.2.6 TTransferring Held Receive Frames ...................................................................85 5.2.7 TReceive Frame Visibility ....................................................................................85 5.2.8 TExample of Memory Mode Receive Operation .................................................85 5.2.9 TReceive Frame Byte Counter ............................................................................86 5.3 Receive Frame Address Filtering .....................................................................................86 5.3.0.1 Individual Address Frames ..................................................................87 5.3.0.2 Multicast Frames .................................................................................87 5.3.0.3 Broadcast Frames ...............................................................................87 5.3.1 TConfiguring the Destination Address Filter ........................................................87 5.3.2 THash Filter .........................................................................................................88 5.3.2.1 Hash Filter Operation ..........................................................................88 5.3.3 TBroadcast Frame Hashing Exception ................................................................88 5.4 Receive DMA ...................................................................................................................89 5.4.1 TOverview ...........................................................................................................89 5.4.2 TConfiguring the CS8900A for DMA Operation ..................................................89 5.4.3 TDMA Receive Buffer Size ..................................................................................89 5.4.4 TReceive-DMA-Only Operation ...........................................................................90 5.4.5 TCommitting Buffer Space to a DMAed Frame ...................................................91 5.4.6 TDMA Buffer Organization ..................................................................................91 5.4.7 TRxDMAFrame Bit ..............................................................................................91 5.4.8 TReceive DMA Example Without Wrap-Around ..................................................91 5.4.9 TReceive DMA Operation for RxDMA-Only Mode ..............................................91 5.5 Auto-Switch DMA .............................................................................................................92 CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 5 CS8900A Crystal LAN™ ISA Ethernet Controller 5.5.1 TOverview ...........................................................................................................92 5.5.2 TConfiguring the CS8900A for Auto-Switch DMA ...............................................93 5.5.3 TAuto-Switch DMA Operation ..............................................................................93 5.5.4 TDMA Channel Speed vs. Missed Frames ..........................................................94 5.5.5 TExit From DMA ..................................................................................................94 5.5.6 TAuto-Switch DMA Example ...............................................................................95 5.6 StreamTransfer ................................................................................................................95 5.6.1 TOverview ...........................................................................................................95 5.6.2 TConfiguring the CS8900A for StreamTransfer ...................................................95 5.6.3 TStreamTransfer Operation .................................................................................95 5.6.4 TKeeping StreamTransfer Mode Active ...............................................................95 5.6.5 TExample of StreamTransfer ...............................................................................97 5.6.6 TReceive DMA Summary ....................................................................................97 5.7 Transmit Operation ...........................................................................................................98 5.7.1 TOverview ...........................................................................................................98 5.7.2 TTransmit Configuration ......................................................................................98 5.7.2.1 Configuring the Physical Interface .......................................................98 5.7.2.2 Selecting which Events Cause Interrupts ............................................98 5.7.3 TChanging the Configuration ...............................................................................98 5.7.4 TEnabling CRC Generation and Padding ............................................................99 5.7.5 TIndividual Packet Transmission .........................................................................99 5.7.6 TTransmit in Poll Mode ......................................................................................100 5.7.7 TTransmit in Interrupt Mode ..............................................................................100 5.7.8 TCompleting Transmission ................................................................................101 5.7.9 TRdy4TxNOW vs. Rdy4Tx ................................................................................101 5.7.10 TCommitting Buffer Space to a Transmit Frame .............................................101 5.7.11 TTransmit Frame Length .................................................................................104 5.8 Full duplex Considerations .............................................................................................104 5.9 Auto-Negotiation Considerations ....................................................................................104 6.0 TEST MODES ......................................................................................................................105 6.0.1 TLoopback & Collision Diagnostic Tests ...........................................................105 6.0.2 TInternal Tests ...................................................................................................105 6.0.3 TExternal Tests .................................................................................................105 6.0.4 TLoopback Tests ...............................................................................................105 6.0.5 T10BASE-T Loopback and Collision Tests ........................................................105 6.0.6 TAUI Loopback and Collision Tests ...................................................................105 6.1 Boundary Scan ...............................................................................................................106 6.1.1 TOutput Cycle ....................................................................................................106 6.1.2 TInput Cycle ......................................................................................................106 6.1.3 TContinuity Cycle ...............................................................................................107 7.0 T CHARACTERISTICS/SPECIFICATIONS - COMMERCIAL .............................................110 8.0 T CHARACTERISTICS/SPECIFICATIONS - INDUSTRIAL ................................................121 9.0 PHYSICAL DIMENSIONS ....................................................................................................132 10.0 GLOSSARY OF TERMS ....................................................................................................133 10.1 Acronyms .....................................................................................................................133 10.2 Definitions .....................................................................................................................134 10.3 Acronyms Specific to the CS8900A .............................................................................135 10.4 Terms Specific to the CS8900A ...................................................................................135 10.5 Suffixes Specific to the CS8900A. ................................................................................136 11.0 REVISION HISTORY ..........................................................................................................137 CIRRUS LOGIC PRODUCT DATASHEET 6 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 1.0 INTRODUCTION 1.1 General Description The CS8900A is a true single-chip, full-duplex, Ethernet solution, incorporating all of the analog and digital circuitry needed for a complete Ethernet circuit. Major functional blocks include: a direct ISA-bus interface; an 802.3 MAC engine; integrated buffer memory; a serial EEPROM interface; and a complete analog front end with both 10BASE-T and AUI. 1.1.1 Direct ISA-Bus Interface Included in the CS8900A is a direct ISA-bus interface with full 24 mA drive capability. Its configuration options include a choice of four interrupts and three DMA channels (one of each selected during initialization). In Memory Mode, it supports Standard or Ready Bus cycles without introducing additional wait states. 1.1.2 Integrated Memory The CS8900A incorporates a 4-Kbyte page of onchip memory, eliminating the cost and board area associated with external memory chips. Unlike most other Ethernet controllers, the CS8900A buffers entire transmit and receive frames on chip, eliminating the need for complex, inefficient memory management schemes. In addition, the CS8900A operates in either Memory space, I/O space, or with external DMA controllers, providing maximum design flexibility. 1.1.3 802.3 Ethernet MAC Engine The CS8900A’s Ethernet Media Access Control (MAC) engine is fully compliant with the IEEE 802.3 Ethernet standard (ISO/IEC 8802-3, 1993), and supports full-duplex operation. It handles all aspects of Ethernet frame transmission and reception, including: collision detection, preamble generation and detection, and CRC generation and test. Programmable MAC features include automatic retransmission on collision, and automatic padding of transmitted frames. 1.1.4 EEPROM Interface The CS8900A provides a simple and efficient serial EEPROM interface that allows configuration information to be stored in an optional EEPROM, and then loaded automatically at power-up. This eliminates the need for costly and cumbersome switches and jumpers. 1.1.5 Complete Analog Front End The CS8900A’s analog front end incorporates a Manchester encoder/decoder, clock recovery circuit, 10BASE-T transceiver, and complete Attachment Unit Interface (AUI). It provides manual and automatic selection of either 10BASE-T or AUI, and offers three on-chip LED drivers for link status, bus status, and Ethernet line activity. The 10BASE-T transceiver includes drivers, receivers, and analog filters, allowing direct connection to low-cost isolation transformers. It supports 100, 120, and 150 Ω shielded and unshielded cables, extended cable lengths, and automatic receive polarity reversal detection and correction. The AUI port provides a direct interface to 10BASE-2, 10BASE-5 and 10BASE-FL networks, and is capable of driving a full 50-meter AUI cable. 1.2 System Applications The CS8900A is designed to work well in either motherboard or adapter applications. 1.2.1 Motherboard LANs The CS8900A requires the minimum number of external components needed for a full Ethernet node. Its small-footprint package and high level of integration allow System Engineers to design a complete Ethernet circuit that occupies as little as 1.5 square inches of PCB area (Figure 1). In addition, the CS8900A’s power-saving features and CMOS design make it a perfect fit for power-sensi- CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 7 CS8900A Crystal LAN™ ISA Ethernet Controller EEPROM 20 MHz XTAL (2.0 sq. in.) I S A CS8900A RJ-45 10BASE-T Figure 1. Complete Ethernet Motherboard Solution tive portable and desktop PCs. Motherboard design options include: • An EEPROM can be used to store node-specific information, such as the Ethernet Individual Address and node configuration. The 20 MHz crystal oscillator may be replaced by a 20 MHz clock signal. gineers to design Ethernet solutions that meet their particular system requirements. Adapter card design options include: • • A Boot PROM can be added to support diskless applications. The 10BASE-T transmitter and receiver impedance can be adjusted to support 100, 120, or 150 Ohm twisted pair cables. An external Latchable-Address-bus decode circuit can be added to operate the CS8900A in Upper-Memory space. On-chip LED ports can be used for either optional LEDs, or as programmable outputs. • 1.2.2 Ethernet Adapter Cards The CS8900A’s highly efficient PacketPage architecture, with StreamTransfer™ and Auto-Switch DMA options, make it an excellent choice for highperformance, low-cost ISA adapter cards (Figure 2). The CS8900A’s wide range of configuration options and performance features allow en- • • LED RJ-45 EEPROM 20 MHz XTAL ’245 CS8900A Boot PROM Attachment Unit Interface (AUI) Figure 2. Full-Featured ISA Adapter Solution CIRRUS LOGIC PRODUCT DATASHEET 8 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 1.3 Key Features and Benefits 1.3.1 Very Low Cost The CS8900A is designed to provide the lowestcost Ethernet solution available for embedded applications, portable motherboards, non-ISA bus systems and adapter cards. Cost-saving features include: • • Integrated RAM eliminates the need for expensive external memory chips. On-chip 10BASE-T filters allow designers to use simple isolation transformers instead of more costly filter/transformer packages. The serial EEPROM port, used for configuration and initialization, eliminates the need for expensive switches and jumpers. The CS8900A is designed to be used on a 2layer circuit board instead of a more expensive multilayer board. The 8900A-based solution offers the smallest footprint available, saving valuable printed circuit board area. A set of certified software drivers is available at no charge, eliminating the need for costly software development. older I/O-space designs, PacketPage is faster, simpler and more efficient. To boost performance further, the CS8900A includes several key features that increase throughput and lower CPU overhead, including: • • StreamTransfer cuts up to 87% of interrupts to the host CPU during large block transfers. Auto-Switch DMA allows the CS8900A to maximize throughput while minimizing missed frames. Early interrupts allow the host to preprocess incoming frames. On-chip buffering of full frames cuts the amount of host bandwidth needed to manage Ethernet traffic. • • • • • • 1.3.3 Low Power and Low Noise For low power needs, the CS8900A offers three power-down options: Hardware Standby, Hardware Suspend, and Software Suspend. In Standby mode, the chip is powered down with the exception of the 10BASE-T receiver, which is enabled to listen for link activity. In either Hardware or Software Suspend mode, the receiver is disabled and power consumption drops to the micro-ampere range. In addition, the CS8900A has been designed for very low noise emission, thus shortening the time required for EMI testing and qualification. 1.3.4 Complete Support The CS8900A comes with a suite of software drivers for immediate use with most industry standard network operating systems. In addition, complete evaluation kits and manufacturing packages are available, significantly reducing the cost and time required to produce new Ethernet products. 1.3.2 High Performance The CS8900A is a full 16-bit Ethernet controller designed to provide optimal system performance by minimizing time on the ISA bus and CPU overhead per frame. It offers equal or superior performance for less money when compared to other Ethernet controllers. The CS8900A’s PacketPage architecture allows software to select whichever access method is best suited to each particular CPU/ISA-bus configuration. When compared to CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 9 CS8900A Crystal LAN™ ISA Ethernet Controller 20 MHz 5V 4.99 k Ω, 1% 10 BASE T Isolation 1 Transformer 16 1:1 14 11 1: 2 9 EEPROM 93C46 1 CS 4 DO 3 DI 2 CLK 4.7 kΩ 97 98 77 XTAL1 XTAL2 SLEEP 3 6 5 4 EECS EEDATAIN EEDATAOUT EESK 76 93 TEST RES RXD92 91 6 3 2 1 12 V RJ45 100 Ω, 1% 3 RXD+ 24.3 Ω, 1% 88 6 TXD68 pF 7 TXD+ 87 24.3 Ω, 1% 8 0.1 µF ISA BUS LA[20:23] BALE SA[0:19] Address Decoder 4 PAL 20 7 CHIPSEL ELCS SA[0:19] CS8900A DO- 84 DO+ 83 CI- 82 81 CI+ DI- 80 DI+ 79 39.2 Ω, 1% 28 29 62 61 49 36 63 75 34 33 64 MEMW MEMR IOW IOR REFRESH SBHE AUI Isolation 1 Transformer 16 1:1 2 15 13 15 pin D 10 3 9 2 12 5 4, 6 4 5 7 8 39.2 Ω, 1% 39.2 Ω, 1% 0.1 µF 13 1:1 1:1 12 10 9 39.2 Ω, 1% 0.1 µF AEN RESET MEMCS16 IOCS16 IOCHRDY BSTATUS/HCI 78 5V 16 IRQ10 IRQ11 IRQ12 IRQ5 DRQ5 SD[0:15] 32 31 30 35 15 16 13 14 11 12 INTRQ0 INTRQ1 INTRQ2 INTRQ3 DMARQ0 LANLED LINKLED 100 99 17 680 Ω 680 Ω CSOUT DACK5 DRQ6 DACK6 DRQ7 DACK7 SA[0:14] DMACK0 DMARQ1 DMACK1 DMARQ2 DMACK2 Boot-PROM 27C256 CE 22 OE 20 74LS245 19 1 OE DIR PD[0:7] 15 8 SD[0:7] Figure 3. Typical Connection Diagram CIRRUS LOGIC PRODUCT DATASHEET 10 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 2.0 PIN DESCRIPTION AVSS0 ELCS EECS EESK EEDataOut EEDataIn CHIPSEL DVSS1 DVDD1 DVSS1A DMARQ2 DMACK2 DMARQ1 DMACK1 DMARQ0 DMACK0 CSOUT SD15 SD14 SD13 SD12 DVDD2 DVSS2 SD11 SD10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 LANLED LINKLED or HC0 XTAL2 XTAL1 AVSS4 AVDD3 AVSS3 RES RXD RXD + AVDD1 AVSS1 TXD TXD + AVSS2 AVDD2 DODO+ CICI+ DIDI+ BSTATUS or HC1 SLEEP TEST CS8900A 100-pin TQFP (Q) Top View 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 RESET SD7 SD6 SD5 SD4 DVSS4 DVDD4 SD3 SD2 SD1 SD0 IOCHRDY AEN IOW IOR SA19 SA18 SA17 DVSS3A DVDD3 DVSS3 SA16 SA15 SA14 SA13 DS271PP4 SD09 SD08 MEMW MEMR INTRQ2 INTRQ1 INTRQ0 IOCS16 MEMCS16 INTRQ3 SBHE SA0 SA1 SA2 SA3 SA4 SA5 SA6 SA7 SA8 SA9 SA10 SA11 REFRESH SA12 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 CIRRUS LOGIC PRODUCT DATASHEET 11 CS8900A Crystal LAN™ ISA Ethernet Controller ISA Bus Interface SA[0:19] - System Address Bus, Input PINS 37-48, 50-54, 58-60. Lower 20 bits of the 24-bit System Address Bus used to decode accesses to CS8900A I/O and Memory space, and attached Boot PROM. SA0-SA15 are used for I/O Read and Write operations. SA0-SA19 are used in conjunction with external decode logic for Memory Read and Write operations. SD[0:15] - System Data Bus, Bi-Directional with 3-State Output PINS 65-68, 71-74, 27-24, 21-18. Bi-directional 16-bit System Data Bus used to transfer data between the CS8900A and the host. RESET - Reset, Input PIN 75. Active-high asynchronous input used to reset the CS8900A. Must be stable for at least 400 ns before the CS8900A recognizes the signal as a valid reset. AEN - Address Enable, Input PIN 63. When TEST is high, this active-high input indicates to the CS8900A that the system DMA controller has control of the ISA bus. When AEN is high, the CS8900A will not perform slave I/O space operations. When TEST is low, this pin becomes the shift clock input for the Boundary Scan Test. AEN should be inactive when performing an IO or memory access and it should be active during a DMA cycle. MEMR - Memory Read, Input PIN 29. Active-low input indicates that the host is executing a Memory Read operation. MEMW - Memory Write, Input PIN 28. Active-low input indicates that the host is executing a Memory Write operation. MEMCS16 - Memory Chip Select 16-bit, Open Drain Output PIN 34. Open-drain, active-low output generated by the CS8900A when it recognizes an address on the ISA bus that corresponds to its assigned Memory space (CS8900A must be in Memory Mode with the MemoryE bit (Register 17, BusCTL, Bit A) set for MEMCS16 to go active). 3-Stated when not active. REFRESH - Refresh, Input PIN 49. Active-low input indicates to the CS8900A that a DRAM refresh cycle is in progress. When REFRESH is low, MEMR, MEMW, IOR, IOW, DMACK0, DMACK1, and DMACK2 are ignored. IOR - I/O Read, Input PIN 61. When IOR is low and a valid address is detected, the CS8900A outputs the contents of the selected 16-bit I/O register onto the System Data Bus. IOR is ignored if REFRESH is low. IOW - I/O Write, Input PIN 62. When IOW is low and a valid address is detected, the CS8900A writes the data on the System Data Bus into the selected 16-bit I/O register. IOW is ignored if REFRESH is low. CIRRUS LOGIC PRODUCT DATASHEET 12 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller IOCS16 - I/O Chip Select 16-bit, Open Drain Output PIN 33. Open-drain, active-low output generated by the CS8900A when it recognizes an address on the ISA bus that corresponds to its assigned I/O space. 3-Stated when not active. IOCHRDY - I/O Channel Ready, Open Drain Output PIN 64. When driven low, this open-drain, active-high output extends I/O Read and Memory Read cycles to the CS8900A. This output is functional when the IOCHRDYE bit in the Bus Control register (Register 17) is clear. This pin is always 3-Stated when the IOCHRDYE bit is set. SBHE - System Bus High Enable, Input PIN 36. Active-low input indicates a data transfer on the high byte of the System Data Bus (SD8SD15). After a hardware or a software reset, provide a HIGH to LOW and then LOW to HIGH transition on SBHE signal before any IO or memory access is done to the CS8900A. INTRQ[0:3] - Interrupt Request, 3-State PINS 30-32, 35. Active-high output indicates the presence of an interrupt event. Interrupt Request goes low once the Interrupt Status Queue (ISQ) is read as all 0’s. Only one Interrupt Request output is used (one is selected during configuration). All non-selected Interrupt Request outputs are placed in a high-impedance state. (Section 3.2 on page 17 and Section 5.1 on page 78.) DMARQ[0:2] - DMA Request, 3-State PINS 11, 13, and 15. Active-high, 3-Stateable output used by the CS8900A to request a DMA transfer. Only one DMA Request output is used (one is selected during configuration). All non-selected DMA Request outputs are placed in a high-impedance state. DMACK[0:2] - DMA Acknowledge, Input PINS 12, 14, and 16. Active-low input indicates acknowledgment by the host of the corresponding DMA Request output. CHIPSEL - Chip Select, Input PIN 7. Active-low input generated by external Latchable Address bus decode logic when a valid memory address is present on the ISA bus. If Memory Mode operation is not needed, CHIPSEL should be tied low. The CHIPSEL is ignored for IO and DMA mode of the CS8900A. EEPROM and Boot PROM Interface EESK - EEPROM Serial Clock, PIN 4. Serial clock used to clock data into or out of the EEPROM. EECS - EEPROM Chip Select, PIN 3. Active-high output used to select the EEPROM. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 13 CS8900A Crystal LAN™ ISA Ethernet Controller EEDataIn - EEPROM Data In, Input Internal Weak Pullup PIN 6. Serial input used to receive data from the EEPROM. Connects to the DO pin on the EEPROM. EEDataIn is also used to sense the presence of the EEPROM. ELCS - External Logic Chip Select, Internal Weak Pullup PIN 2. Bi-directional signal used to configure external Latchable Address (LA) decode logic. If external LA decode logic is not needed, ELCS should be tied low. EEDataOut - EEPROM Data Out,PIN 5. Serial output used to send data to the EEPROM. Connects to the DI pin on the EEPROM. When TEST is low, this pin becomes the output for the Boundary Scan Test. CSOUT - Chip Select for External Boot PROM, PIN 17. Active-low output used to select an external Boot PROM when the CS8900A decodes a valid Boot PROM memory address. 10BASE-T Interface TXD+/TXD- - 10BASE-T Transmit, Differential Output Pair PINS 87 and 88. Differential output pair drives 10 Mb/s Manchester-encoded data to the 10BASE-T transmit pair. RXD+/RXD- - 10BASE-T Receive, Differential Input Pair PINS 91 and 92. Differential input pair receives 10 Mb/s Manchester-encoded data from the 10BASE-T receive pair. Attachment Unit Interface (AUI) DO+/DO- - AUI Data Out, Differential Output Pair PINS 83 and 84. Differential output pair drives 10 Mb/s Manchester-encoded data to the AUI transmit pair. DI+/DI- - AUI Data In, Differential Input Pair PINS 79 and 80. Differential input pair receives 10 Mb/s Manchester-encoded data from the AUI receive pair. CI+/CI- - AUI Collision In, Differential Input Pair PINS 81 and 82. Differential input pair connects to the AUI collision pair. A collision is indicated by the presence of a 10 MHz ± 15% signal with duty cycle no worse than 60/40. General Pins XTAL[1:2] - Crystal, Input/Output PINS 97 and 98. A 20 MHz crystal should be connected across these pins. If a crystal is not used, a 20 MHz signal should be connected to XTAL1 and XTAL2 should be left open. (See Section 7.3 on page 110 and Section 7.7 on page 120.) CIRRUS LOGIC PRODUCT DATASHEET 14 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SLEEP - Hardware Sleep, Input Internal Weak Pullup PIN 77. Active-low input used to enable the two hardware sleep modes: Hardware Suspend and Hardware Standby. (See Section 3.7 on page 25.) LINKLED or HC0 - Link Good LED or Host Controlled Output 0, Open Drain Output PIN 99. When the HCE0 bit of the Self Control register (Register 15) is clear, this active-low output is low when the CS8900A detects the presence of valid link pulses. When the HC0E bit is set, the host may drive this pin low by setting the HCBO in the Self Control register. BSTATUS or HC1 - Bus Status or Host Controlled Output 1, Open Drain Output PIN 78. When the HC1E bit of the Self Control register (Register 15) is clear, this active-low output is low when receive activity causes an ISA bus access. When the HC1E bit is set, the host may drive this pin low by setting the HCB1 in the Self Control register. LANLED - LAN Activity LED, Open Drain Output PIN 100. During normal operation, this active-low output goes low for 6 ms whenever there is a receive packet, a transmit packet, or a collision. During Hardware Standby mode, this output is driven low when the receiver detects network activity. TEST - Test Enable, Input Internal Weak Pullup PIN 76. Active-low input used to put the CS8900A in Boundary Scan Test mode. For normal operation, this pin should be high. RES - Reference Resistor, Input PIN 93. This input should be connected to a 4.99KΩ ± 1% resistor needed for biasing of internal analog circuits. DVDD[1:4] - Digital Power, Power PINS 9, 22, 56, and 69. Provides 5 V ± 5% power to the digital circuits of the CS8900A. DVSS[1:4} and DVSS1A, DVSS3A - Digital Ground, Ground PINS 8, 10, 23, 55, 57, and 70. Provides ground reference (0 V) to the digital circuits of the CS8900A. AVDD[1:3] - Analog Power, Power PINS 90, 85, and 95. Provides 5 V ± 5% power to the analog circuits of the CS8900A. AVSS[0:4] - Analog Ground, Ground PINS 1, 89, 86, 94, 96. Provide ground reference (0 V) to the analog circuits of the CS8900A. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 15 CS8900A Crystal LAN™ ISA Ethernet Controller 3.0 FUNCTIONAL DESCRIPTION 3.1 Overview During normal operation, the CS8900A performs two basic functions: Ethernet packet transmission and reception. Before transmission or reception is possible, the CS8900A must be configured. 3.1.1 Configuration The CS8900A must be configured for packet transmission and reception at power-up or reset. Various parameters must be written into its internal Configuration and Control registers such as Memory Base Address; Ethernet Physical Address; what frame types to receive; and which media interface to use. Configuration data can either be written to the CS8900A by the host (across the ISA bus), or loaded automatically from an external EEPROM. Operation can begin after configuration is complete. Section 3.3 on page 18 and Section 3.4 on page 20 describe the configuration process in detail. Section 4.4 on page 46 provides a detailed description of the bits in the Configuration and Control Registers. 3.1.2 Packet Transmission Packet transmission occurs in two phases. In the first phase, the host moves the Ethernet frame into the CS8900A’s buffer memory. The first phase begins with the host issuing a Transmit Command. This informs the CS8900A that a frame is to be transmitted and tells the chip when to start transmission (i.e. after 5, 381, 1021 or all bytes have been transferred) and how the frame should be sent (i.e. with or without CRC, with or without pad bits, etc.). The Host follows the Transmit Command with the Transmit Length, indicating how much buffer space is required. When buffer space is available, the host writes the Ethernet frame into the CS8900A’s internal memory, either as a Memory or I/O space operation. In the second phase of transmission, the CS8900A converts the frame into an Ethernet packet then transmits it onto the network. The second phase begins with the CS8900A transmitting the preamble and Start-of-Frame delimiter as soon as the proper number of bytes has been transferred into its transmit buffer (5, 381, 1021 bytes or full frame, depending on configuration). The preamble and Startof-Frame delimiter are followed by the Destination Address, Source Address, Length field and LLC data (all supplied by the host). If the frame is less than 64 bytes, including CRC, the CS8900A adds pad bits if configured to do so. Finally, the CS8900A appends the proper 32-bit CRC value. The Section 5.7 on page 98 provides a detailed description of packet transmission. 3.1.3 Packet Reception Like packet transmission, packet reception occurs in two phases. In the first phase, the CS8900A receives an Ethernet packet and stores it in on-chip memory. The first phase of packet reception begins with the receive frame passing through the analog front end and Manchester decoder where Manchester data is converted to NRZ data. Next, the preamble and Start-of-Frame delimiter are stripped off and the receive frame is sent through the address filter. If the frame’s Destination Address matches the criteria programmed into the address filter, the packet is stored in the CS8900A’s internal memory. The CS8900A then checks the CRC, and depending on the configuration, informs the processor that a frame has been received. In the second phase, the host transfers the receive frame across the ISA bus and into host memory. Receive frames can be transferred as Memory space operations, I/O space operations, or as DMA operations using host DMA. Also, the CS8900A provides the capability to switch between Memory or I/O operation and DMA operation by using Auto-Switch DMA and StreamTransfer. The Section 5.2 on page 78 through Section 5.6 on page 95 provide a detailed description of packet reception. DS271PP4 CIRRUS LOGIC PRODUCT DATASHEET 16 CS8900A Crystal LAN™ ISA Ethernet Controller 3.2 ISA Bus Interface The CS8900A provides a direct interface to ISA buses running at clock rates from 8 to 11 MHz. Its on-chip bus drivers are capable of delivering 24 mA of drive current, allowing the CS8900A to drive the ISA bus directly, without added external "glue logic". The CS8900A is optimized for 16-bit data transfers, operating in either Memory space, I/O space, or as a DMA slave. Note that ISA-bus operation below 8 MHz should use the CS8900A’s Receive DMA mode to minimize missed frames. See Section 5.4 on page 89 for a description of Receive DMA operation. 3.2.1 Memory Mode Operation When configured for Memory Mode operation, the CS8900A’s internal registers and frame buffers are mapped into a contiguous 4-Kbyte block of host memory, providing the host with direct access to the CS8900A’s internal registers and frame buffers. The host initiates Read operations by driving the MEMR pin low and Write operations by driving the MEMW pin low. For additional information about Memory Mode, see Section 4.9 on page 73. 3.2.2 I/O Mode Operation When configured for I/O Mode operation, the CS8900A is accessed through eight, 16-bit I/O ports that are mapped into sixteen contiguous I/O locations in the host system’s I/O space. I/O Mode is the default configuration for the CS8900A and is always enabled. For an I/O Read or Write operation, the AEN pin must be low, and the 16-bit I/O address on the ISA System Address bus (SA0 - SA15) must match the address space of the CS8900A. For a Read, IOR must be low, and for a Write, IOW must be low. For additional information about I/O Mode, see Section 4.10 on page 75. 3.2.3 Interrupt Request Signals The CS8900A has four interrupt request output pins that can be connected directly to any four of the ISA bus Interrupt Request signals. Only one interrupt output is used at a time. It is selected during initialization by writing the interrupt number (0 to 3) into PacketPage Memory base + 0022h. Unused interrupt request pins are placed in a high-impedance state. The selected interrupt request pin goes high when an enabled interrupt is triggered. The pin goes low after the Interrupt Status Queue (ISQ) is read as all 0’s (see Section 5.1 on page 78 for a description of the ISQ). Table 1 presents one possible way of connecting the interrupt request pins to the ISA bus that utilizes commonly available interrupts and facilitates board layout. CS8900A Interrupt Request Pin INTRQ3 (Pin 35) INTRQ0 (Pin 32) INTRQ1 (Pin 31) INTRQ2 (Pin 30) ISA Bus Interrupt IRQ5 IRQ10 IRQ11 IRQ12 PacketPage base + 0022h 0003h 0000h 0001h 0002h Table 1. Interrupt Assignments 3.2.4 DMA Signals The CS8900A interfaces directly to the host DMA controller to provide DMA transfers of receive frames from CS8900A memory to host memory. The CS8900A has three pairs of DMA pins that can be connected directly to the three 16-bit DMA channels of the ISA bus. Only one DMA channel is used at a time. It is selected during initialization by writing the number of the desired channel (0, 1 or 2) into PacketPage Memory base + 0024h. Unused DMA pins are placed in a high-impedance state. The selected DMA request pin goes high when the CS8900A has received frames to transfer to the host memory via DMA. If the DMABurst bit (register 17, BusCTL, Bit B) is clear, the pin goes low after the DMA operation is complete. If the CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 17 CS8900A Crystal LAN™ ISA Ethernet Controller DMABurst bit is set, the pin goes low 32 µs after the start of a DMA transfer. The DMA pin pairs are arranged on the CS8900A to facilitate board layout. Crystal recommends the configuration in Table 2 when connecting these pins to the ISA bus. CS8900A DMA Signal (Pin #) DMARQ0 (Pin 15) DMACK0 (Pin 16) DMARQ1 (Pin 13) DMACK1 (Pin 14) DMARQ2 (Pin 11) DMACK2 (Pin 12) ISA DMA Signal DRQ5 DACK5 DRQ6 DACK6 DRQ7 DACK7 0002h 0001h PacketPage base + 0024h 0000h 3.3.1.4 EEPROM Reset There is a chip-wide reset if an EEPROM checksum error is detected (see Section 3.4 on page 20). 3.3.1.5 Software Initiated Reset There is a chip-wide reset whenever the RESET bit (Register 15, SelfCTL, Bit 6) is set. 3.3.1.6 Hardware (HW) Standby or Suspend The CS8900A goes though a chip-wide reset whenever it enters or exits either HW Standby mode or HW Suspend mode (see Section 3.7 on page 25 for more information about HW Standby and Suspend). 3.3.1.7 Software (SW) Suspend Whenever the CS8900A enters SW Suspend mode, all registers and circuits are reset except for the ISA I/O Base Address register (located at PacketPage base + 0020h) and the SelfCTL register (Register 15). Upon exit, there is a chip-wide reset (see Section 3.7 on page 25 for more information about SW Suspend). 3.3.2 Allowing Time for Reset Operation After a reset, the CS8900A goes through a self configuration. This includes calibrating on-chip analog circuitry, and reading EEPROM for validity and configuration. Time required for the reset calibration is typically 10 ms. Software drivers should not access registers internal to the CS8900A during this time. When calibration is done, bit INITD in the Self Status Register (register 16) is set indicating that initialization is complete, and the SIBUSY bit in the same register is cleared indicating the EEPROM is no longer being read or programmed. 3.3.3 Bus Reset Considerations The CS8900A reads 3000h from IObase+0Ah after the reset, until the software writes a non-zero value at IObase+0Ah. The 3000h value can be used as part of the CS8900A signature when the system scans for the CS8900A. See Section 4.10 on page 75. Table 2. DMA Assignments For a description of DMA mode, see Section 5.4 on page 89. 3.3 Reset and Initialization 3.3.1 Reset Seven different conditions cause the CS8900A to reset its internal registers and circuits. 3.3.1.1 External Reset, or ISA Reset There is a chip-wide reset whenever the RESET pin is high for at least 400 ns. During a chip-wide reset, all circuitry and registers in the CS8900A are reset. 3.3.1.2 Power-Up Reset When power is applied, the CS8900A maintains reset until the voltage at the supply pins reaches approximately 2.5 V. The CS8900A comes out of reset once Vcc is greater than approximately 2.5 V and the crystal oscillator has stabilized. 3.3.1.3 Power-Down Reset If the supply voltage drops below approximately 2.5 V, there is a chip-wide reset. The CS8900A comes out of reset once the power supply returns to a level greater than approximately 2.5 V and the crystal oscillator has stabilized. CIRRUS LOGIC PRODUCT DATASHEET 18 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller After a reset, the ISA bus outputs INTRx and DMARQx are 3-Stated, thus avoiding any interrupt or DMA channel conflicts on the ISA bus at powerup time. 3.3.4 Initialization After each reset (except EEPROM Reset), the CS8900A checks the sense of the EEDataIn pin to see if an external EEPROM is present. If EEDI is high, an EEPROM is present and the CS8900A automatically loads the configuration data stored in the EEPROM into its internal registers (see next section). If EEDI is low, an EEPROM is not present and the CS8900A comes out of reset with the default configuration shown in Table 3. A low-cost serial EEPROM can be used to store configuration information that is automatically loaded into the CS8900A after each reset (except EEPROM reset). The use of an EEPROM is optional. The CS8900A operates with any of six standard EEPROM’s shown in Table 4. PacketPage Address 0020h 0022h 0024h 0026h 0028h 002Ah 002Ch 0030h 0034h 0102h 0104h 0106h 0108h 010Ah 010Ch 010Eh 0110h 0112h 0114h 0116h 0118h Register Contents 0300h Register Descriptions I/O Base Address* XXXX XXXX Interrupt Number XXXX X100 XXXX XXXX DMA Channel XXXX XX11 0000h X000h 0000h DMA Start of Frame Offset DMA Frame Count DMA Byte Count XXX0 0000h Memory Base Address XXX0 0000h Boot PROM Base Address XXX0 0000h Boot PROM Address Mask 0003h 0005h 0007h 0009h 000Bh Undefined Undefined Undefined 00013h 0015h 0017h 0019h Register 3 - RxCFG Register 5 - RxCTL Register 7 - TxCFG Register 9 - TxCMD Register B - BufCFG Reserved Reserved Reserved Register 13 - LineCTL Register 15 - SelfCTL Register 17 - BusCTL Register 19 - TestCTL * I/O base address is unaffected by Software Suspend mode. Table 3. Default Configuration EEPROM Type ‘C46 (non-sequential) ‘CS46 (sequential) ‘C56 (non-sequential) ‘CS56 (sequential) ‘C66 (non-sequential) ‘CS66 (sequential) Size (16-bit words) 64 64 128 128 256 256 Table 4. Supported EEPROM Types CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 19 CS8900A Crystal LAN™ ISA Ethernet Controller 3.4 Configurations with EEPROM 3.4.1 EEPROM Interface The interface to the EEPROM consists of the four signals shown in Table 5. CS8900A Pin (Pin #) EECS (Pin 3) EESK (PIN 4) EEDO (Pin 5) EEDI (Pin 6) CS8900A Function EEPROM Chip Select 1 MHz EEPROM Serial Clock output EEPROM Data Out (data to EEPROM) EEPROM Data in (data from EEPROM) EEPROM Pin Chip Select Clock Data In Data Out 3.4.3.1 Reset Configuration Block Structure The Reset Configuration Block is a block of contiguous 16-bit words starting at EEPROM address 00h. It can be divided into three logical sections: a header, one or more groups of configuration data words, and a checksum value. All of the words in the Reset Configuration Block are read sequentially by the CS8900A after each reset, starting with the header and ending with the checksum. Each group of configuration data is used to program a PacketPage register (or set of PacketPage registers in some cases) with an initial non-default value. 3.4.3.2 Reset Configuration Block Header The header (first word of the block located at EEPROM address 00h) specifies the type of EEPROM used, whether or not a Reset Configuration block is present, and if so, how many bytes of configuration data are stored in the Reset Configuration Block. 3.4.3.3 Determining the EEPROM Type The LSB of the high byte of the header indicates the type of EEPROM attached: sequential or nonsequential. An LSB of 0 (XXXX-XXX0) indicates a sequential EEPROM. An LSB of 1 (XXXXXXX1) indicates a non-sequential EEPROM. The CS8900A works equally well with either type of EEPROM. The CS8900A will automatically generate sequential addresses while reading the Reset Configuration Block if a non-sequential EEPROM is used. 3.4.3.4 Checking EEPROM for presence of Reset Configuration Block The read-out of either a binary 101X-XXX0 or 101X-XXX1 (X = do not care) from the high byte of the header indicates the presence of configuration data. Any other readout value terminates initialization from the EEPROM. If an EEPROM is attached but not used for configuration, Crystal recommends that the high byte of the first word be programmed with 00h in order to ensure that the Table 5. EEPROM Interface 3.4.2 EEPROM Memory Organization If an EEPROM is used to store initial configuration information for the CS8900A, the EEPROM is organized in one or more blocks of 16-bit words. The first block in EEPROM, referred to as the Configuration Block, is used to configure the CS8900A after reset. An example of a typical Configuration Block is shown in Table 6. Additional blocks containing user data may be stored in the EEPROM. However, the Configuration Block must always start at address 00h and be stored in contiguous memory locations. 3.4.3 Reset Configuration Block The first block in EEPROM, referred to as the Reset Configuration Block, is used to automatically program the CS8900A with an initial configuration after a reset. Additional user data may also be stored in the EEPROM if space is available. The additional data are stored as 16-bit words and can occupy any EEPROM address space beginning immediately after the end of the Reset Configuration Block up to address 7Fh, depending on EEPROM size. This additional data can only be accessed through software control (refer to Section 3.5 on page 23 for more information on accessing the EEPROM). Address space 80h to AFh is reserved. CIRRUS LOGIC PRODUCT DATASHEET 20 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Word Address Value FIRST WORD in DATA BLOCK 00h A120h Description Configuration Block Header. The high byte, A1h, indicates a ‘C46 EEPROM is attached. The Link Byte, 20h, indicates the number of bytes to be used in this block of configuration data. Group Header for first group of words. Three words to be loaded, beginning at 0020h in PacketPage memory. I/O Base Address Interrupt Number DMA Channel Number Group Header for second group of words. Six words to be loaded, beginning at 002Ch in PacketPage memory. Memory Base Address - low word Memory Base Address - high word Boot PROM Base Address - low word Boot PROM Base Address - high word Boot PROM Address Mask - low word Boot PROM Address Mask - high word Group Header for third group of words. Three words to be loaded, beginning at 0158 in PacketPage memory. Individual Address - Octet 0 and 1 Individual Address - Octet 2 and 3 Individual Address - Octet 4 and 5 The high byte, 28h, is the Checksum Value. In this example, the checksum includes word addresses 00h through 0Fh. The hexadecimal sum of the bytes is D8h, resulting in a 2’s complement of 28h. The low byte, 00h, provides a pad to the word boundary. Table 6. EEPROM Configuration Block Example FIRST GROUP of WORDS 01h 2020h 02h 0300h 03h 0003h 04h 0001h SECOND GROUP of WORDS 05h 502Ch 06h E000h 07 000Fh 08h 0000h 09h 000Dh 0Ah C000h 0Bh 000Fh THIRD GROUP of WORDS 0Ch 2158h 0Dh 0Eh 0Fh CHECKSUM Value 10h 0010h 0000h 0000h 2800h * FFFFh is a special code indicating that there are no more words in the EEPROM. CS8900A will not attempt to read configuration data from the EEPROM. 3.4.3.5 Determining Number of Bytes in the Reset Configuration Block The low byte of the Reset Configuration Block header is known as the link byte. The value of the Link Byte represents the number of bytes of configuration data in the Reset Configuration Block. The two bytes used for the header are excluded when calculating the Link Byte value. For example, a Reset Configuration Block header of A104h indicates a non-sequential EEPROM programmed with a Reset Configuration Block containing 4 bytes of configuration data. This Reset Configuration Block occupies 6 bytes (3 words) of EEPROM space (2 bytes for the header and 4 bytes of configuration data). 3.4.4 Groups of Configuration Data Configuration data are arranged as groups of words. Each group contains one or more words of data that are to be loaded into PacketPage registers. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 21 CS8900A Crystal LAN™ ISA Ethernet Controller The first word of each group is referred to as the Group Header. The Group Header indicates the number of words in the group and the address of the PacketPage register into which the first data word in the group is to be loaded. Any remaining words in the group are stored in successive PacketPage registers. 3.4.4.1 Group Header Bits F through C of the Group Header specify the number of words in each group that are to be transferred to PacketPage registers (see Figure 4). This value is two less than the total number of words in the group, including the Group Header. For example, if bits F through C contain 0001, there are three words in the group (a Group Header and two words of configuration data). First Word of a Group of Words 3.4.5 Reset Configuration Block Checksum A checksum is stored in the high byte position of the word immediately following the last group of data in the Reset Configuration Block. (The EEPROM address of the checksum value can be determined by dividing the value stored in the Link Byte by two). The checksum value is the 2’s complement of the 8-bit sum (any carry out of eighth bit is ignored) of all the bytes in the Reset Configuration Block, excluding the checksum byte. This sum includes the Reset Configuration Block header at address 00h. Since the checksum is calculated as the 2’s complement of the sum of all preceding bytes in the Reset Configuration Block, a total of 0 should result when the checksum value is added to the sum of the previous bytes. 3.4.6 EEPROM Example Table 6 shows an example of a Reset Configuration Block stored in a C46 EEPROM. Note that littleendian word ordering is used, i.e., the least significant word of a multiword datum is located at the lowest address. 3.4.7 EEPROM Read-out If the EEDI pin is asserted high at the end of reset, the CS8900A reads the first word of EEPROM data by: FEDCBA9876543210 0 0 0 Number of Words in Group 9-bit PacketPage Address 1) Asserting EECS 2) Clocking out a Read-Register-00h command on EEDO (EESK provides a 1MHz serial clock signal) 3) Clocking the data in on EEDI. If the EEDI pin is low at the end of the reset signal, the CS8900A does not perform an EEPROM readout (uses its default configuration). 3.4.7.1 Determining EEPROM Size The CS8900A determines the size of the EEPROM by checking the sense of EEDI on the tenth rising edge of EESK. If EEDI is low, the EEPROM is a Figure 4. Group Header Bits 8 through 0 of the Group Header specify a 9bit PacketPage Address. This address defines the PacketPage register that will be loaded with the first word of configuration data from the group. Bits B though 9 of the Group Header are forced to 0, restricting the destination address range to the first 512 bytes of PacketPage memory. Figure 4 shows the format of the Group header. CIRRUS LOGIC PRODUCT DATASHEET 22 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller ’C46 or ’CS46. If EEDI is high, the EEPROM is a ’C56, ’CS56, ’C66, or ’CS66. 3.4.7.2 Loading Configuration Data The CS8900A reads in the first word from the EEPROM to determine if configuration data is contained in the EEPROM. If configuration data is not stored in the EEPROM, the CS8900A terminates initialization from EEPROM and operates using its default configuration (See Table 3). If configuration data is stored in EEPROM, the CS8900A automatically loads all configuration data stored in the Reset Configuration Block into its internal PacketPage registers. 3.4.8 EEPROM Read-out Completion Once all the configuration data are transferred to the appropriate PacketPage registers, the CS8900A performs a checksum calculation to verify the Reset Configuration Blocks data are valid. If the resulting total is 0, the read-out is considered valid. Otherwise, the CS8900A initiates a partial reset to restore the default configuration. If the read-out is valid, the EEPROMOK bit (Register 16, SelfST, bit A) is set. EEPROMOK is cleared if a checksum error is detected. In this case, the CS8900A performs a partial reset and is restored to its default. Once initialization is complete (configuration loaded from EEPROM or reset to default configuration) the INITD bit is set (Register 16, SelfST, bit 7). 3.5 Programming the EEPROM After initialization, the host can access the EEPROM through the CS8900A by writing one of seven commands to the EEPROM Command register (PacketPage base + 0040h). Figure 5 shows the format of the EEPROM Command register. 3.5.1 EEPROM Commands The seven commands used to access the EEPROM are: Read, Write, Erase, Erase/Write Enable, Erase/Write Disable, Erase-All, and Write-All. They are described in Table 7. 3.5.2 EEPROM Command Execution During the execution of a command, the two Opcode bits, followed by the six bits of address (for a ’C46 or ’CS46) or eight bits of address (for a ’C56, ’CS56, ’C66 or ’CS66), are shifted out of the CS8900A, into the EEPROM. If the command is a Write, the data in the EEPROM Data register (PacketPage base + 0042h) follows. If the command is a Read, the data in the specified EEPROM AD7 - AD0 used with ’C56, ’CS56, ’C66 and ’CS66 F X E X D X C X B X A 9 8 7 6 5 4 3 2 1 0 ELSEL OP1 OP0 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0 AD5 - AD0 used with ’C46 and ’CS46 Bit [F:B] [A] [9:8] [7:0] Name ELSEL OP1, OP0 AD7 to AD0 Description Reserved External Logic Select: When clear, the EECS pin is used to select the EEPROM. When set, the ELCS pin is used to select the external LA decode circuit. Opcode: Indicates what command is being executed (see next section). EEPROM Address: Address of EEPROM word being accessed. Figure 5. EEPROM Command Register Format CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 23 CS8900A Crystal LAN™ ISA Ethernet Controller Command Read Register Write Register Erase Register Erase/Write Enable Erase/Write Disable Erase-All Registers Write-All Register Opcode (bits 9,8) 1,0 0,1 1.1 0,0 0,0 0,0 0,0 0,0 0,0 0,0 EEPROM Address (bits 7 to 0) word address word address word address XX11-XXXX 11XX-XXXX XX00-XXXX 00XX-XXXX XX10-XXXX 10XX-XXXX XX01-XXXX 01XX-XXXX Data yes yes no no no no no no no yes yes EEPROM Type all all all ‘CS46, ‘C46 ‘CS56, ‘C56, ‘CS66, ‘C66 ‘CS46, ‘C46 ‘CS56, ‘C56, ‘CS66, ‘C66 ‘CS46, ‘C46 ‘CS56, ‘C56, ‘CS66, ‘C66 ‘CS46, ‘C46 ‘CS56, ‘C56, ‘CS66, ‘C66 Execution Time 25 µs 10 ms 10 ms 9 µs 9 µs 9 µs 9 µs 10 ms 9 µs 10 ms 10 ms Table 7. EEPROM Commands location is written into the EEPROM Data register. If the command is an Erase or Erase-All, no data is transferred to or from the EEPROM Data register. Before issuing any command, the host must wait for the SIBUSY bit (Register 16, SelfST, bit 8) to clear. After each command has been issued, the host must wait again for SIBUSY to clear. 3.5.3 Enabling Access to the EEPROM The Erase/Write Enable command provides protection from accidental writes to the EEPROM. The host must write an Erase/Write Enable command before it attempts to write to or erase any EEPROM memory location. Once the host has finished altering the contents of the EEPROM, it must write an Erase/Write Disable command to prevent unwanted modification of the EEPROM. 3.5.4 Writing and Erasing the EEPROM To write data to the EEPROM, the host must execute the following series of commands: 1) Issue an Erase/Write Enable command. 2) Load the data into the EEPROM Data register. 3) Issue a Write command. 4) Issue an Erase/Write Disable command. During the Erase command, the CS8900A writes FFh to the specified EEPROM location. During the Erase-All command, the CS8900A writes FFh to all locations. 3.6 Boot PROM Operation The CS8900A supports an optional Boot PROM used to store code for remote booting from a network server. 3.6.1 Accessing the Boot PROM To retrieve the data stored in the Boot PROM, the host issues a Read command to the Boot PROM as a Memory space access. The CS8900A decodes the command and drives the CSOUT pin low, causing the data stored in the Boot PROM to be shifted into the bus transceiver. The bus transceiver then drives the data out onto the ISA bus. 3.6.2 Configuring the CS8900A for Boot PROM Operation Figure 6 shows how the CS8900A should be connected to the Boot PROM and ’245 driver. To configure the CS8900A’s internal registers for Boot PROM operation, the Boot PROM Base Address must be loaded into the Boot PROM Base Address register (PacketPage base + 0030h) and the Boot PROM Address Mask must be loaded into the CIRRUS LOGIC PRODUCT DATASHEET 24 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller BootPROM Address Mask register (PacketPage base + 0034h). The Boot PROM Base Address provides the starting location in host memory where the Boot PROM is mapped. The Boot PROM Address Mask indicates the size of the attached Boot PROM and is limited to 4-Kbyte increments. The lower 12 bits of the Address Mask are ignored and should be 000h. CS8900A CSOUT (Pin 17) 27C256 20 22 dicating that the EEPROM is no longer being read or programmed. Time required for the reset calibration is typically 10 ms. Software drivers should not access registers internal to CS8900A during this time. 3.7.1 Hardware Standby Hardware (HW) Standby is designed for use in systems, such as portable PC’s, that may be temporarily disconnected from the 10BASE-T cable. It allows the system to conserve power while the LAN is not in use, and then automatically restore Ethernet operation once the cable is reconnected. In HW Standby mode, all analog and digital circuitry in the CS8900A is turned off, except for the 10BASE-T receiver which remains active to listen for link activity. If link activity is detected, the LANLED pin is driven low, providing an indication to the host that the network connection is active. The host can then activate the CS8900A by deasserting the SLEEP pin. During this mode, all ISA bus accesses are ignored. To enter HW Standby mode, the SLEEP pin must be low and the HWSleepE bit (Register 15, SelfCTL, Bit 9) and the HWStandbyE bit (Register 15, SelfCTL, Bit A) must be set. When the CS8900A enters HW Standby, all registers and circuits are reset except for the SelfCTL register. Upon exit from HW Standby, the CS8900A performs a complete reset, and then goes through normal initialization. 3.7.2 Hardware Suspend During Hardware Suspend mode, the CS8900A uses the least amount of current of the three lowpower modes. All internal circuits are turned off and the CS8900A’s core is electronically isolated from the rest of the system. Accesses from the ISA bus and Ethernet activity are both ignored. HW Suspend mode is entered by driving the SLEEP pin low and setting the HWSleepE bit (Register 15, SelfCTL, bit 9) while the HWStandbyE bit (Register 15, SelfCTL, bit A) is clear. To CE OE 19 74LS245 OE DIR B1 . . . B8 A1 . . SD(0:7) . A8 SA(0:14) ISA BUS Figure 6. Boot PROM Connection Diagram In the EEPROM example shown in Table 6, the Boot PROM starting address is D0000h and the Address Mask is FC000h. This configuration describes a 16-Kbyte (128 Kbit) PROM mapped into host memory from D0000h to D3FFFh. 3.7 Low-Power Modes For power-sensitive applications, the CS8900A supports three low-power modes: Hardware Standby, Hardware Suspend, and Software Suspend. All three low-power modes are controlled through the SelfCTL register (Register 15). See also Section 4.4.4 on page 48. An internal reset occurs when the CS8900A comes out of any suspend or standby mode. After a reset (internal or external), the CS8900A goes through a self configuration. This includes calibrating onchip analog circuitry, and reading EEPROM for validity and configuration. When the calibration is done, bit InitD in Register 16 (Self Status register) is set indicating that initialization is complete, and the SIBUSY bit in the same register is cleared (inDS271PP4 CIRRUS LOGIC PRODUCT DATASHEET 25 CS8900A Crystal LAN™ ISA Ethernet Controller exit from this mode, the SLEEP pin must be driven high. Upon exit, the CS8900A performs a complete reset, and then goes through a normal initialization procedure. 3.7.3 Software Suspend Software (SW) Suspend mode can be used to conserve power in applications, like adapter cards, that do not have power management circuitry available. During this mode, all internal circuits are shut off except the I/O Base Address register (PacketPage base + 0020h) and the SelfCTL register (Register 15). CS8900A Configuration To enter SW Suspend mode, the host must set the SWSuspend bit (Register 15, SelfCTL, bit 8). To exit SW Suspend, the host must write to the CS8900A’s assigned I/O space (the Write is only used to wake the CS8900A, the Write itself is ignored). Upon exit, the CS8900A performs a complete reset, and then goes through a normal initialization procedure. Any hardware reset takes the chip out of any sleep mode. Table 8 summarizes the operation of the three lowpower modes. CS8900A Operation SLEEP HWStandbyE HWSleepE SWSuspend (Pin 77) (SelfCTL, Bit A) (SelfCTL, Bit 9) (SelfCTL, Bit 8) Link Activity Low 1 1 N/A Not Present HW Standby mode: 10BASE-T receiver listens for link activity Low 1 1 N/A Present HW Standby mode: LANLED low Low 0 1 N/A N/A HW Suspend mode Low to N/A 1 0 N/A CS8900A resets and goes through High initialization High N/A N/A 0 N/A Not in low-power mode High N/A N/A N/A SW Suspend mode Low N/A 0 1 N/A SW Suspend mode Low N/A 0 0 N/A Not in low-power mode Notes: 1. Both HW and HW Suspend take precedence over SW Suspend. Table 8. Low-Power Mode Operation CIRRUS LOGIC PRODUCT DATASHEET 26 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 3.8 LED Outputs The CS8900A provides three output pins that can be used to control LEDs or external logic. 3.8.0.1 LANLED LANLED goes low whenever the CS8900A transmits or receives a frame, or when it detects a collision. LANLED remains low until there has been no activity for 6 ms (i.e. each transmission, reception, or collision produces a pulse lasting a minimum of 6 ms). 3.8.0.2 LINKLED or HC0 LINKLED or HC0 can be controlled by either the CS8900A or the host. When controlled by the CS8900A, LINKLED is low whenever the CS8900A receives valid 10BASE-T link pulses. To configure this pin for CS8900A control, the HC0E bit (Register 15, SelfCTL, Bit C) must be clear. When controlled by the host, LINKLED is low whenever the HCB0 bit (Register 15, SelfCTL, Bit E) is set. To configure it for host control, the HC0E bit must be set. Table 9 summarizes this operation. HC0E HCB0 Pin Function (Bit C) (Bit E) 0 N/A Pin configured as LINKLED: Output is low when valid 10BASE-T link pulses are detected. Output is high if valid link pulses are not detected 1 0 Pin configured as HC0: Output is high 1 1 Pin configured as HC0: Output is low Table 9. LINKLED/HC0 Pin Operation host, BSTATUS is low whenever the HCB1 bit (Register 15, SelfCTL, Bit F) is set. To configure it for host control, HC1E must be set. Table 10 summarizes this operation. HC1E HCB1 Pin Function (Bit D) (Bit F) 0 N/A Pin configured as BSTATUS: Output is low when a receive frame begins transfer across the ISA bus. Output is high otherwise 1 0 Pin configured as HC1: Output is high 1 1 Pin configured as HC1: Output is low Table 10. BSTATUS/HCI Pin Operation 3.8.1 LED Connection Each LED output is capable of sinking 10 mA to drive an LED directly through a series resistor. The output voltage of each pin is less than 0.4 V when the pin is low. Figure 7 shows a typical LED circuit. +5V LANLED LINKLED Figure 7. LED Connection Diagram 3.8.0.3 BSTATUS or HC1 BSTATUS or HC1 can be controlled by either the CS8900A or the host. When controlled by the CS8900A, BSTATUS is low whenever the host reads the RxEvent register (PacketPage base + 0124h), signaling the transfer of a receive frame across the ISA bus. To configure this pin for CS8900A control, the HC1E bit (Register 15, SelfCTL, Bit D) must be clear. When controlled by the 3.9 Media Access Control 3.9.1 Overview The CS8900A’s Ethernet Media Access Control (MAC) engine is fully compliant with the IEEE 802.3 Ethernet standard (ISO/IEC 8802-3, 1993). It handles all aspects of Ethernet frame transmission and reception, including: collision detection, preamble generation and detection, and CRC genera- CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 27 CS8900A Crystal LAN™ ISA Ethernet Controller tion and test. Programmable MAC features include automatic retransmission on collision, and padding of transmitted frames. Figure 8 shows how the MAC engine interfaces to other CS8900A functions. On the host side, it interfaces to the CS8900A’s internal data/address/control bus. On the network side, it interfaces to the internal Manchester encoder/decoder (ENDEC). The primary functions of the MAC are: frame encapsulation and decapsulation; error detection and handling; and, media access management. LED Logic 1021 bytes, or full frame), and providing that access to the network is permitted, the MAC automatically transmits the 7-byte preamble (1010101b...), followed by the Start-of-Frame Delimiter (SFD, 10101011b), and then the serialized frame data. It then transmits the Frame Check Sequence (FCS). The data after the SFD and before the FCS (Destination Address, Source Address, Length, and data field) is supplied by the host. FCS generation by the CS8900A may be disabled by setting the InhibitCRC bit (Register 9, TxCMD, bit C). Figure 9 shows the Ethernet frame format. 3.9.2.2 Reception The MAC receives the incoming packet as a serial stream of NRZ data from the Manchester encoder/decoder. It begins by checking for the SFD. Once the SFD is detected, the MAC assumes all subsequent bits are frame data. It reads the DA and compares it to the criteria programmed into the address filter (see Section 5.3 on page 86 for a description of Address Filtering). If the DA passes the address filter, the frame is loaded into the CS8900A’s memory. If the BufferCRC bit (Register 3, RxCFG, bit B) is set, the received FCS is also loaded into memory. Once the entire packet has been received, the MAC validates the FCS. If an error is detected, the CRCerror bit (Register 4, RxEvent, Bit C) is set. 3.9.2.3 Enforcing Minimum Frame Size The MAC provides minimum frame size enforce- CS8900A Internal Bus 802.3 MAC Engine Encoder/ Decoder & PLL 10BASE-T & AUI Figure 8. MAC Interface 3.9.2 Frame Encapsulation and Decapsulation The CS8900A’s MAC engine automatically assembles transmit packets and disassembles receive packets. It also determines if transmit and receive frames are of legal minimum size. 3.9.2.1 Transmission Once the proper number of bytes have been transferred to the CS8900A’s memory (either 5, 381, Packet Frame up to 7 bytes 1 byte 6 bytes 6 bytes 2 bytes 4 bytes alternating 1s / 0s SFD DA SA Length Field LLC data Pad FCS preamble Direction of Transmission frame length min 64 bytes max 1518 bytes SFD = Start of Frame Delimiter DA = Destination Address SA = Source Address LLC = Logical Link Control FCS = Frame Check Sequence (also called Cyclic Redundancy Check, or CRC) Figure 9. Ethernet Frame Format CIRRUS LOGIC PRODUCT DATASHEET 28 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller ment of both transmit and receive packets. When the TxPadDis bit (Register 9, TxCMD, Bit D) is clear, transmit frames will be padded with additional bits to ensure that the receiving station receives a legal frame (64 bytes, including CRC). When TxPadDis is set, the CS8900A will not add pad bits and will transmit frames less that 64 bytes. If a frame is received that is less than 64 bytes (including CRC), the Runt bit (Register 4, RxEvent, Bit D) will be set indicating the arrival of an illegal frame. 3.9.3 Transmit Error Detection and Handling The MAC engine monitors Ethernet activity and reports and recovers from a number of error conditions. For transmission, the MAC reports the following errors in the TxEvent register (Register 8) and BufEvent register (Register C): 3.9.3.1 Loss of Carrier Whenever the CS8900A is transmitting on the AUI port, it expects to see its own transmission "looped back" to its receiver. If it is unable to monitor its transmission after the end of the preamble, the MAC reports a loss-of-carrier error by setting the Loss-of-CRS bit (Register 8, TxEvent, Bit 6). If the Loss-of-CRSiE bit (Register 7, TxCFG, Bit 6) is set, the host will be interrupted. 3.9.3.2 SQE Error After the end of transmission on the AUI port, the MAC expects to see a collision within 64 bit times. If no collision is detected, the SQEerror bit (Register 8, TxEvent, Bit 7) is set. If the SQEerroriE bit is set (Register 7, TxCFG, Bit 7), the host is interrupted. An SQE error may indicate a fault on the AUI cable or a faulty transceiver (it is assumed that the attached transceiver supports this function). 3.9.3.3 Out-of-Window (Late) Collision If a collision is detected after the first 512 bits have been transmitted, the MAC reports a late collision by setting the Out-of-window bit (Register 8, TxEvent, Bit 9). The MAC then forces a bad CRC and terminates the transmission. If the Out-of-windowDS271PP4 iE bit (Register 7, TxCFG, Bit 9) is set, the host is interrupted. A late collision may indicate an illegal network configuration. 3.9.3.4 Jabber Error If a transmission continues longer than about 26 ms, the MAC disables the transmitter and sets the Jabber bit (Register 8, TxEvent, Bit A). The output of the transmitter returns to idle and remains there until the host issues a new Transmit Command. If the JabberiE bit (Register 7, TxCFG, Bit A) is set, the host is interrupted. A Jabber condition indicates that there may be something wrong with the CS8900A transmit function. To prevent possible network faults, the host should clear the transmit buffer. Possible options include: Reset the chip with either software or hardware reset (see Section 3.3 on page 18). Issue a Force Transmit Command by setting the Force bit (Register 9, TxCMD, bit 8). Issue a Transmit Command with the TxLength field set to zero. 3.9.3.5 Transmit Collision The MAC counts the number of times an individual packet must be retransmitted due to network collisions. The collision count is stored in bits B through E of the TxEvent register (Register 8). If the packet collides 16 times, transmission of that packet is terminated and the 16coll bit (Register 8, TxEvent, Bit F) is set. If the 16colliE bit (Register 7, TxCFG, Bit F) is set, the host will be interrupted on the 16th collision. A running count of transmit collisions is recorded in the TxCOL register. 3.9.3.6 Transmit Underrun If the CS8900A starts transmission of a packet but runs out of data before reaching the end of frame, the TxUnderrun bit (Register C, BufEvent, Bit 9) is set. The MAC then forces a bad CRC and terminates the transmission. If the TxUnderruniE bit CIRRUS LOGIC PRODUCT DATASHEET 29 CS8900A Crystal LAN™ ISA Ethernet Controller (Register B, BufCFG, Bit 9) is set, the host is interrupted. 3.9.4 Receive Error Detection and Handling The following receive errors are reported in the RxEvent register (Register 4): 3.9.4.1 CRC Error If a frame is received with a bad CRC, the CRCerror bit (Register 4, RxEvent, Bit C) is set. If the CRCerrorA bit (Register 5, RxCTL, Bit C) is set, the frame will be buffered by CS8900A. If the CRCerroriE bit (Register 3, RxCFG. Bit C) is set, the host is interrupted. 3.9.4.2 Runt Frame If a frame is received that is shorter than 64 bytes, the Runt bit (Register 4, RxEvent, Bit D) is set. If the RuntA bit (Register 5, RxCTL, Bit D) is set, the frame will still be buffered by CS8900A. If the RuntiE bit (Register 3, RxCFG. Bit D) is set, the host is interrupted. 3.9.4.3 Extra Data If a frame is received that is longer than 1518 bytes, the Extradata bit (Register 4, RxEvent, Bit E) is set. If the ExtradataA bit (Register 5, RxCTL, Bit E) is set, the first 1518 bytes of the frame will still be buffered by CS8900A. If the ExtradataiE bit (Register 3, RxCFG. Bit E) is set, the host is interrupted. 3.9.4.4 Dribble Bits and Alignment Error Under normal operating conditions, the MAC may detect up to 7 additional bits after the last full byte of a receive packet. These bits, known as dribble bits, are ignored. If dribble bits are detected, the Dribblebit bit (Register 4, RxEvent, Bit 7) is set. If both the Dribblebits bit and CRCerror bit (Register 4, RxEvent, Bit C) are set at the same time, an alignment error has occurred. 3.9.5 Media Access Management The Ethernet network topology is a single shared medium with several attached stations. The Ethernet protocol is designed to allow each station equal access to the network at any given time. Any node can attempt to gain access to the network by first completing a deferral process (described below) after the last network activity, and then transmitting a packet that will be received by all other stations. If two nodes transmit simultaneously, a collision occurs and the colliding packets are corrupted. Two primary tasks of the MAC are to avoid network collisions, and then recover from them when they occur. In addition, when the CS8900A is using the AUI, the MAC must support the SQE Test function described in section 7.2.4.6 of the Ethernet standard. 3.9.5.1 Collision Avoidance The MAC continually monitors network traffic by checking for the presence of carrier activity (carrier activity is indicated by the assertion of the internal Carrier Sense signal generated by the ENDEC). If carrier activity is detected, the network is assumed busy and the MAC must wait until the current packet is finished before attempting transmission. The CS8900A supports two schemes for determining when to initiate transmission: Two-Part Deferral, and Simple Deferral. Selection of the deferral scheme is determined by the 2-partDefDis bit (Register 13, LineCTL, Bit D). If the 2-partDefDis bit is clear, the MAC uses a two-part deferral process defined in section 4.2.3.2.1 of the Ethernet standard (ISO/IEC 8802-3, 1993). If the 2-partDefDis bit is set, the MAC uses a simplified deferral scheme. Both schemes are described below: 3.9.5.2 Two-Part Deferral In the two-part deferral process, the 9.6 µs Inter Packet Gap (IPG) timer is started whenever the internal Carrier Sense signal is deasserted. If activity is detected during the first 6.4 µs of the IPG timer, the timer is reset and then restarted once the activity has stopped. If there is no activity during the first 6.4 µs of the IPG timer, the IPG timer is allowed to time out (even if network activity is detected during CIRRUS LOGIC PRODUCT DATASHEET 30 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller the final 3.2 µs). The MAC then begins transmission if a transmit packet is ready and if it is not in Backoff (Backoff is described later in this section). If no transmit packet is pending, the MAC continues to monitor the network. If activity is detected before a transmit frame is ready, the MAC defers to the transmitting station and resumes monitoring the network. The two-part deferral scheme was developed to prevent the possibility of the IPG being shortened due to a temporary loss of carrier. Figure 10 diagrams the two-part deferral process. 3.9.5.3 Simple Deferral In the simple deferral scheme, the IPG timer is started whenever Carrier Sense is deasserted. Once the IPG timer is finished (after 9.6 µs), if a transmit frame is pending and if the MAC is not in Backoff, transmission begins the 9.6 µs IPG). If no transmit packet is pending, the MAC continues to monitor the network. If activity is detected before a transmit frame is ready, the MAC defers to the transmitting station and resumes monitoring the network. Figure 11 diagrams the simple deferral process. 3.9.5.4 Collision Resolution If a collision is detected while the CS8900A is transmitting, the MAC responds in one of three ways depending on whether it is a normal collision (within the first 512 bits of transmission) or a late collision (after the first 512 bits of transmission): 3.9.5.5 Normal Collisions If a collision is detected before the end of the preamble and SFD, the MAC finishes the preamble and SFD, transmits the jam sequence (32-bit pattern of all 0’s), and then initiates Backoff. If a collision is detected after the transmission of the preamble and SFD but before 512 bit times, the MAC immediately terminates transmission, transmits the jam sequence, and then initiates Backoff. In either case, if the Onecoll bit (Register 9, TxCMD, Bit 9) is clear, the MAC will attempt to transWait 3.2 µ s mit a packet a total of 16 times (the initial attempt plus 15 retransmissions) due to normal collisions. On the 16th collision, it sets the 16coll bit (Register 8, TxEvent, Bit F) and discards the packet. If the Onecoll bit is set, the MAC discards the packet without attempting any retransmission. Start Monitoring Network Activity Yes Network Active? No Start IPG Timer Yes IPG Timer = 6.4 µ s? No Network Active? Yes No No Tx Frame No Ready and Not in Backoff? Yes Transmit Frame Network Active? Yes Figure 10. Two-Part Deferral CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 31 CS8900A Crystal LAN™ ISA Ethernet Controller 3.9.5.6 Late Collisions If a collision is detected after the first 512 bits have been transmitted, the MAC immediately terminates transmission, transmits the jam sequence, discards the packet, and sets the Out-of-window bit (Register 8, TxEvent, Bit 9). The CS8900A does not initiate backoff or attempt to retransmit the frame. For additional information about Late Collisions, see Out-of-Window Error in this section. 3.9.5.7 Backoff After the MAC has completed transmitting the jam sequence, it must wait, or "Back off", before attempting to transmit again. The amount of time it must wait is determined by one of two Backoff alStart Monitoring Network Activity gorithms: the Standard Backoff algorithm (ISO/IEC 4.2.3.2.5) or the Modified Backoff algorithm. The host selects which algorithm through the ModBackoffE bit (Register 13, LineCTL, Bit B). 3.9.5.8 Standard Backoff The Standard Backoff algorithm, also called the "Truncated Binary Exponential Backoff", is described by the equation: 0 ≤ r ≤ 2k where r (a random integer) is the number of slot times the MAC must wait (1 slot time = 512 bit times), and k is the smaller of n or 10, where n is the number of retransmission attempts. 3.9.5.9 Modified Backoff The Modified Backoff is described by the equation: 0 ≤ r ≤ 2k where r (a random integer) is the number of slot times the MAC must wait, and k is 3 for n < 3 and k is the smaller of n or 10 for n ≥ 3, where n is the number of retransmission attempts. The advantage of the Modified Backoff algorithm over the Standard Backoff algorithm is that it reduces the possibility of multiple collisions on the first three retries. The disadvantage is that it extends the maximum time needed to gain access to the network for the first three retries. Yes Network Active? No Wait 9.6 µ s No Tx Frame No Ready and Not i n Backoff? Yes Transmit Frame Figure 11. Simple Deferral Network Active? Yes The host may choose to disable the Backoff algorithm altogether by setting the DisableBackoff bit (Register 19, TestCTL, Bit B). When disabled, the CS8900A only waits the 9.6 µs IPG time before starting transmission. 3.9.5.10 SQE Test If the CS8900A is transmitting on the AUI, the external transceiver should generate an SQE Test signal on the CI+/CI- pair following each transmission. The SQE Test is a 10 MHz signal lasting 5 to 15 bit times and starting within 0.6 to CIRRUS LOGIC PRODUCT DATASHEET 32 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 1.6 µs after the end of transmission. During this period, the CS8900A ignores receive carrier activity (see SQE Error in this section for more information). 3.10 Encoder/Decoder (ENDEC) The CS8900A’s integrated encoder/decoder (ENDEC) circuit is compliant with the relevant portions of section 7 of the Ethernet standard (ISO/IEC 8802-3, 1993). Its primary functions include: Manchester encoding of transmit data; informing the MAC when valid receive data is present (Carrier Detection); and, recovering the clock and NRZ data from incoming Manchester-encoded data. Figure 12 provides a block diagram of the ENDEC and how it interfaces to the MAC, AUI and 10BASE-T transceiver. 3.10.1 Encoder The encoder converts NRZ data from the MAC and a 20 MHz Transmit Clock signal into a serial stream of Manchester data. The Transmit Clock is produced by an on-chip oscillator circuit that is driven by either an external 20 MHz quartz crystal or a TTL-level CMOS clock input. If a CMOS input is used, the clock should be 20 MHz ±0.01% with a duty cycle between 40% and 60%. The specifications for the crystal are described in Section 7.7 on page 120. The encoded signal is routed to either the 10BASE-T transceiver or AUI, depending on configuration. 3.10.2 Carrier Detection The internal Carrier Detection circuit informs the MAC that valid receive data is present by asserting the internal Carrier Sense signal as soon it detects a valid bit pattern (1010b or 0101b for 10BASE-T, and 1b or 0b for AUI). During normal packet reception, Carrier Sense remains asserted while the frame is being received, and is deasserted 1.3 to 2.3 bit times after the last low-to-high transition of the End-of-Frame (EOF) sequence. Whenever the receiver is idle (no receive activity), Carrier Sense is deasserted. The CRS bit (Register 14, LineST, Bit E) reports the state of the Carrier Sense signal. 3.10.3 Clock and Data Recovery When the receiver is idle, the phase-lock loop (PLL) is locked to the internal clock signal. The assertion of the Carrier Sense signal interrupts the PLL. When it restarts, it locks on the incoming data. The receive clock is then compared to the incoming data at the bit cell center and any phase difference is corrected. The PLL remains locked as long as the receiver input signal is valid. Once the PLL has locked on the incoming data, the ENDEC converts the Manchester data to NRZ and passes the decoded data and the recovered clock to the MAC for further processing. ENDEC Carrier Sense RX CLK RX NRZ Carrier Detector Decoder & PLL RX MUX RXSQL RX TX 10BASE-T Transceiver MAC TXCLK TX NRZ TEN Port Select Collision Encoder TX MUX AUISQL AUIRX AUITX AUI AUICol Clock Figure 12. ENDEC CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 33 CS8900A Crystal LAN™ ISA Ethernet Controller LinkOK (to MAC) Link Pulse Detector RXSQL RX 10BASE-T Transceiver RX Squelch ENDEC TX TX PreDistortion RX Comparator RX Filters RXDRXD+ TXDTXD+ TX Filters Filter Tuning TX Drivers Figure 13. 10BASE-T Transceiver 3.10.4 Interface Selection Physical interface selection is determined by AUIonly bit (Bit 8) and the AutoAUI/10BT (Bit 9) in the LineCTL register (Register 13). Table 11 describes the possible configurations. AUIonly (Bit 8) 0 1 0 AutoAUI/10BT (Bit 9) 0 N/A 1 Physical Interface 10BASE-T Only AUI Only Auto-Select the AUI. Whenever the AUI is selected, the 10BASE-T receiver remains active to listen for link pulses or packets. If 10BASE-T activity is detected, the CS8900A switches back to 10BASE-T. 3.11 10BASE-T Transceiver The CS8900A includes an integrated 10BASE-T transceiver that is compliant with the relevant portions of section 14 of the Ethernet standard (ISO/IEC 8802-3, 1993). It includes all analog and digital circuitry needed to interface the CS8900A directly to a simple isolation transformer (see Section 7.5 on page 119 for a connection diagram). Figure 13 provides a block diagram of the 10BASE-T transceiver. 3.11.1 10BASE-T Filters The CS8900A’s 10BASE-T transceiver includes integrated low-pass transmit and receive filters, eliminating the need for external filters or a filter/transformer hybrid. On-chip filters are gm/c implementations of fifth-order Butterworth low-pass filters. Internal tuning circuits keep the gm/c ratio tightly controlled, even when large temperature, supply, and IC process variations occur. The nominal 3 dB cutoff frequency of the filters is 16 MHz, and the nominal attenuation at 30 MHz (3rd harmonic) is -27 dB. DS271PP4 Table 11. Interface Selection 3.10.4.1 10BASE-T Only When configured for 10BASE-T only operation, the 10BASE-T transceiver and its interface to the ENDEC are active, and the AUI is powered down. 3.10.4.2 AUI Only When configured for AUI-only operation, the AUI and its interface to the ENDEC are active, and the 10BASE-T transceiver is powered down. 3.10.4.3 Auto-Select In Auto-Select mode, the CS8900A automatically selects the 10BASE-T interface and powers down the AUI if valid packets or link pulses are detected by the 10BASE-T receiver. If valid packets and link pulses are not detected, the CS8900A selects 34 CIRRUS LOGIC PRODUCT DATASHEET CS8900A Crystal LAN™ ISA Ethernet Controller 3.11.2 Transmitter When configured for 10BASE-T operation, Manchester encoded data from the ENDEC is fed into the transmitter’s predistortion circuit where initial wave shaping and preequalization is performed. The output of the predistortion circuit is fed into the transmit filter where final wave shaping occurs and unwanted noise is removed. The signal then passes to the differential driver where it is amplified and driven out of the TXD+/TXD- pins. In the absence of transmit packets, the transmitter generates link pulses in accordance with section 14.2.1.1. of the Ethernet standard. Transmitted link pulses are positive pulses, one bit time wide, typically generated at a rate of one every 16 ms. The 16 ms timer starts whenever the transmitter completes an End-of-Frame (EOF) sequence. Thus, there is a link pulse 16 ms after an EOF unless there is another transmitted packet. Figure 14 diagrams the operation of the Link Pulse Generator. If no link pulses are being received on the receiver, the 10BASE-T transmitter is internally forced to an inactive state unless bit DisableLT in register 19 (Test Control register) is set to one. 3.11.3 Receiver The 10BASE-T receive section consists of the receive filter, squelch circuit, polarity detection and correction circuit, and link pulse detector. 3.11.3.1 Squelch Circuit The 10BASE-T squelch circuit determines when valid data is present on the RXD+/RXD- pair. Incoming signals passing through the receive filter Time are tested by the squelch circuit. Any signal with amplitude less than the squelch threshold (either positive or negative, depending on polarity) is rejected. 3.11.3.2 Extended Range The CS8900A supports an Extended Range feature that reduces the 10BASE-T receive squelch threshold by approximately 6 dB. This allows the CS8900A to operate with 10BASE-T cables that are longer than 100 meters (100 meters is the maximum length specified by the Ethernet standard). The exact additional distance depends on the quality of the cable and the amount of electromagnetic noise in the surrounding environment. To activate this feature, the host must set the LoRxSquelch bit (Register 13, LineCTL, Bit E). 3.11.4 Link Pulse Detection To prevent disruption of network operation due to a faulty link segment, the CS8900A continually monitors the 10BASE-T receive pair (RXD+/ RXD-) for packets and link pulses. After each packet or link pulse is received, an internal LinkLoss timer is started. As long as a packet or link pulse is received before the Link-Loss timer finishes (between 25 and 150 ms), the CS8900A maintains normal operation. If no receive activity is detected, the CS8900A disables packet transmission to prevent "blind" transmissions onto the network (link pulses are still sent while packet transmission is disabled). To reactivate transmission, the receiver must detect a single packet (the packet itself is ignored), or two link pulses separatLink Pulse Link Pulse Packet Less Than 16ms Packet 16ms 16ms Figure 14. Link Pulse Transmission CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 35 CS8900A Crystal LAN™ ISA Ethernet Controller ed by more than 2 to 7 ms and no more than 25 to 150 ms (see Section 7.4 on page 112 for 10BASET timing). The state of the link segment is reported in the LinkOK bit (Register 14, LineST, Bit 7). If the HC0E bit (Register 15, SelfCTL, Bit D) is clear, it is also indicated by the output of the LINKLED pin. If the link is "good", the LinkOK bit is set and the LINKLED pin is driven low. If the link is "bad" the LinkOK bit is clear and the LINKLED pin is high. To disable this feature, the host must set the DisableLT bit (Register 19, TestCTL, Bit 7). If DisableLT is set, the CS8900A will transmit and receive packets independent of the link segment. 3.11.5 Receive Polarity Detection and Correction The CS8900A automatically checks the polarity of the receive half of the twisted pair cable. If the polarity is correct, the PolarityOK bit (Register 14, LineST, bit C) is set. If the polarity is reversed, the PolarityOK bit is clear. If the PolarityDis bit (Register 13, LineCTL, Bit C) is clear, the CS8900A automatically corrects a reversal. If the PolarityDis bit is set, the CS8900A does not correct a reversal. The PolarityOK bit and the PolarityDis bit are independent. To detect a reversed pair, the receiver examines received link pulses and the End-of-Frame (EOF) sequence of incoming packets. If it detects at least one reversed link pulse and at least four frames in a row with negative polarity after the EOF, the receive pair is considered reversed. Any data received before the correction of the reversal is ignored. 3.11.6 Collision Detection If half-duplex operation is selected (Register 19, Bit E, FDX), the CS8900A detects a 10BASE-T collision whenever the receiver and transmitter are active simultaneously. When a collision is present, the Collision Detection circuit informs the MAC by asserting the internal Collision signal (see Section 3.9 on page 27 for collision handling). 3.12 Attachment Unit Interface (AUI) The CS8900A Attachment Unit Interface (AUI) provides a direct interface to external 10BASE2, 10BASE5, and 10BASE-FL Ethernet transceivers. It is fully compliant with Section 7 of the Ethernet standard (ISO/IEC 8802-3), and as such, is capable of driving a full 50-meter AUI cable. The AUI consists of three pairs of signals: Data Out (DO+/DO-), Data In (DI+/DI-), and Collision In (CI+/CI-). To select the AUI, the host should set the AUI bit (Register 13, LineCTL, Bit 8). The AUI can also be selected automatically as described in the previous section (Section 3.10.4 on page 34). Figure 15 provides a block diagram of the AUI. (For a connection diagram, see Section 7.6 on page 120). AUI CL+ CL-+ Collision Detect AUICol (to MAC) AUIRX DI+ DIDO+ DO- -+ AUISQL ENDEC AUITX Figure 15. AUI 3.12.1 AUI Transmitter The AUI transmitter is a differential driver designed to drive a 78 Ω cable. It accepts data from the ENDEC and transmits it directly on the DO+/DO- pins. After transmission has started, the CS8900A expects to see the packet "looped-back" (or echoed) to the receiver, causing the Carrier Sense signal to be asserted. This Carrier Sense presence indicates that the transmit signal is getting through to the transceiver. If the Carrier Sense signal remains deasserted throughout the transmis- CIRRUS LOGIC PRODUCT DATASHEET 36 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller sion, or if the Carrier Sense signal is deasserted before the end of the transmission, there is a Lossof-Carrier error and the Loss-of-CRS bit (Register 8, TxEvent, Bit 6) is set. 3.12.2 AUI Receiver The AUI receiver is a differential pair circuit that connects directly to the DI+/DI- pins. It is designed to distinguish between transient noise pulses and incoming Ethernet packets. Incoming packets with proper amplitude and pulse width are passed on to the ENDEC section, while unwanted noise is rejected. 3.12.3 Collision Detection The AUI collision circuit is a differential pair receiver that detects the presence of collision signals on the CI+/CI- pins. The collision signal is generated by an external Ethernet transceiver whenever a collision is detected on the Ethernet segment. (Section 7.3.1.2 of ISO/IEC 8802-3, 1993, defines the collision signal as a 10 MHz ± 15% signal with a duty cycle no worse than 60/40). When a collision is present, the AUI Collision circuit informs the MAC by asserting the internal Collision signal. 3.13 External Clock Oscillator A 20-MHz quartz crystal or CMOS clock input is required by the CS8900A. If a CMOS clock input is used, it should be connected the to XTAL1 pin, with the XTAL2 pin left open. The clock signal should be 20 MHz ±0.01% with a duty cycle between 40% and 60%. The specifications for the crystal are described in Section 7.7 on page 120. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 37 CS8900A Crystal LAN™ ISA Ethernet Controller 4.0 PACKETPAGE ARCHITECTURE 4.1 PacketPage Overview The CS8900A architecture is based on a unique, highly-efficient method of accessing internal registers and buffer memory known as PacketPage. PacketPage provides a unified way of controlling the CS8900A in Memory or I/O space that minimizes CPU overhead and simplifies software. It provides a flexible set of performance features and configuration options, allowing designers to develop Ethernet circuits that meet their particular system requirements. 4.1.1 Integrated Memory Central to the CS8900A architecture is a 4-Kbyte page of integrated RAM known as PacketPage memory. PacketPage memory is used for temporary storage of transmit and receive frames, and for internal registers. Access to this memory is done directly, through Memory space operations (Section 4.9 on page 73), or indirectly, through I/O space operations (Section 4.10 on page 75). In most cases, Memory Mode will provide the best overall performance, because ISA Memory operations require fewer cycles than I/O operations. I/O Mode is the CS8900A’s default configuration and is used when memory space is not available or when special operations are required (e.g. waking the CS8900A from the Software Suspend State requires the host to write to the CS8900A’s assigned I/O space). The user-accessible portion of PacketPage memory is organized into the following six sections: PacketPage Address 0000h - 0045h 0100h - 013Fh 0140h - 014Fh 0150h - 015Dh 0400h 0A00h Contents Bus Interface Registers Status and Control Registers Initiate Transmit Registers Address Filter Registers Receive Frame Location Transmit Frame Location 4.1.2 Bus Interface Registers The Bus Interface registers are used to configure the CS8900A’s ISA-bus interface and to map the CS8900A into the host system’s I/O and Memory space. Most of these registers are written only during initialization, remaining unchanged while the CS8900A is in normal operating mode. The exceptions to this are the DMA registers which are modified continually whenever the CS8900A is using DMA. These registers are described in more detail in Section 4.3 on page 41. 4.1.3 Status and Control Registers The Status and Control registers are the primary means of controlling and getting status of the CS8900A. They are described in more detail in Section 4.4 on page 46. 4.1.4 Initiate Transmit Registers The TxCMD/TxLength registers are used to initiate Ethernet frame transmission. These registers are described in more detail in Section 4.5 on page 70. (See Section 5.7 on page 98 for a description of frame transmission.) 4.1.5 Address Filter Registers The Filter registers store the Individual Address filter and Logical Address filter used by the Destination Address (DA) filter. These registers are described in more detail in Section 4.6 on page 71. For a description of the DA filter, see Section 5.3 on page 86. 4.1.6 Receive and Transmit Frame Locations The Receive and Transmit Frame PacketPage locations are used to transfer Ethernet frames to and from the host. The host simply writes to and reads from these locations and internal buffer memory is dynamically allocated between transmit and receive as needed. This provides more efficient use of buffer memory and better overall network performance. As a result of this dynamic allocation, only one receive frame (starting at PacketPage base + 0400h) and one transmit frame (starting at PackDS271PP4 CIRRUS LOGIC PRODUCT DATASHEET 38 CS8900A Crystal LAN™ ISA Ethernet Controller etPage base + 0A00h) are directly accessible. See Section 4.7 on page 72. 4.2 PacketPage Memory Map Table 12 shows the CS8900A PacketPage memory address map: s Cross Reference PacketPage # of Type Description Address Bytes Bus Interface Registers 0000h 4 Read-only Product Identification Code 0004h 28 Reserved 0020h 2 Read/Write I/O Base Address 0022h 0024h 0026h 0028h 002Ah 002Ch 0030h 0034h 0038h 0040h 0042h 0044h 0050h 2 2 2 2 2 4 4 4 8 2 2 12 2 Read/Write Interrupt Number (0,1,2,or 3) Read/Write DMA Channel Number (0, 1, or 2) Read-only DMA Start of Frame Read-only DMA Frame Count (12 Bits) Read-only RxDMA Byte Count Read/Write Memory Base Address Register (20 Bit) Read/Write Boot PROM Base Address Read/Write Boot PROM Address Mask Reserved Read/Write EEPROM Command Read/Write EEPROM Data Reserved Read only Received Frame Byte Counter 0052h 174 Reserved Status and Control Registers 0100h 32 Read/Write Configuration & Control Registers (2 bytes per regiseter) 0120h 32 Read-only Status & Event Registers (2 bytes per register) 0140h 4 Reserved Initiate Transmit Registers Notes: 1. All registers are accessed as words only. Section 4.3 on page 41 Note 2 Section 4.3 on page 41, Section 4.7 on page 72 Section 3.2 on page 17, Section 4.3 on page 41 Section 3.2 on page 17, Section 4.3 on page 41 Section 4.3 on page 41, Section 5.4 on page 89 Sections Section 4.3 on page 41, ”Receive DMA” Section 4.3 on page 41, Section 5.4 on page 89 Section 4.3 on page 41, Section 4.9 on page 73 Section 3.6 on page 24, Section 4.3 on page 41 Section 3.6 on page 24, Section 4.3 on page 41 Note 2 Section 3.5 on page 23, Section 4.3 on page 41 Section 3.5 on page 23, Section 4.3 on page 41 Note 2 Section 4.3 on page 41, Section 5.2.9 on page 86 Note 2 Section 4.4 on page 46 Section 4.4 on page 46 Note 2 2. Read operation from the reserved location provides undefined data. Writing to a reserved location or undefined bits may result in unpredictable operation of the CS8900A. Table 12. PacketPage Memory Address Map CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 39 CS8900A Crystal LAN™ ISA Ethernet Controller PacketPage # of Type Description Address Bytes 0144h 2 Write-only TxCMD (transmit command) 0146h 2 Write-only TxLength (transmit length) Cross Reference Section 4.5 on page 70, Section 5.7 on page 98 Section 4.5 on page 70, Section 5.7 on page 98 Note 2 Section 4.6 on page 71, Section 5.3 on page 86 Section 4.6 on page 71, Section 5.3 on page 86 Note 2 Section 4.7 on page 72, Section 5.2 on page 78 Section 4.7 on page 72, Section 5.2 on page 78 Section 4.7 on page 72, Section 5.2 on page 78 Section 4.7 on page 72, Section 5.7 on page 98 0148h 8 Reserved Address Filter Registers 0150h 8 Read/Write Logical Address Filter (hash table) 0158h 6 Read/Write Individual Address Reserved 015Eh 674 Frame Location 0400h 2 0402h 0404h 0A00 2 - Read-only RXStatus (receive status) Read-only RxLength (receive length, in bytes) Read-only Receive Frame Location Write-only Transmit Frame Location Notes: 1. All registers are accessed as words only. 2. Read operation from the reserved location provides undefined data. Writing to a reserved location or undefined bits may result in unpredictable operation of the CS8900A. Table 12. PacketPage Memory Address Map (continued) CIRRUS LOGIC PRODUCT DATASHEET 40 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.3 Bus Interface Registers 4.3.1 Product Identification Code (Read only, Address: PacketPage base + 0000h) Address 0000h First byte of EISA registration number for Crystal Semiconductor Address 0001h Second byte of EISA registration number for Crystal Semiconductor Address 0002h First 8 bits of Product ID number Address 00003h Last 3 bits of the Product ID number (5 “X” bits are the revision number) The Product Identification Code Register is located in the first four bytes of the PacketPage (0000h to 0003h). The register contains a unique 32-bit product ID code that identifies the chip as a CS8900A. The host can use this number to determine which software driver to load and to check which features are available. Reset value is: 0000 1110 0110 0011 0000 0000 000X XXXX The X XXXX codes for the CS8900A are: Rev B: 0 0111 Rev C: 0 1000 Rev D: 0 1001 4.3.2 I/O Base Address (Read/Write, Address: PacketPage base + 0020h) Address 0021h Most significant byte of I/O Base Address Address 0020h Least significant byte of I/O Base Address The I/O Base Address Register describes the base address for the sixteen contiguous locations in the host system’s I/O space, which are used to access the PacketPage registers. See Section 4.10 on page 75. The default location is 0300h. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: 0000 0011 0000 0000 CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 41 CS8900A Crystal LAN™ ISA Ethernet Controller 4.3.3 Interrupt Number (Read/Write, Address: PacketPage base + 0022h) Address 0023h Address 0022h Interrupt number assignment: 0000 0000b= pin INTRQ0 0000 0001b= pin INTRQ1 0000 0010b= pin INTRQ2 0000 0011b= pin INTRQ3 0000 01XXb= All INTRQ pins high-impedance 00h The Interrupt Number Register defines the interrupt pin selected by the CS8900A. In a typical application the following bus signals are tied to the following pins: Bus signal IRQ5 IRQ10 IRQ11 IRQ12 Typical pin connection INTRQ3 INTRQ0 INTRQ1 INTRQ2 See Section 3.2 on page 17. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state, which corresponds to placing all the INTRQ pins in a high-impedance state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: XXXX XXXX XXXX X100 4.3.4 DMA Channel Number (Read/Write, Address: PacketPage base + 0024h) Address 0025h Address 0024h DMA channel assignment: 0000 0000b= pin DMRQ0 and DMACK0 0000 0001b= pin DMRQ1 and DMACK1 0000 0010b= pin DMRQ2 and DMACK2 0000 0011b= All DMRQ pins high-impedance 00h The DMA Channel register defines the DMA pins selected by the CS8900A. In the typical application, the following bus signals are tied to the following pins: Bus signal DRQ5 DACK5 DRQ6 DACK6 DRQ7 DACK7 Typical pin connection DMRQ0 DMACK0 DMRQ1 DMACK1 DMRQ2 DMACK2 See Section 3.2 on page 17 and Section 5.4 on page 89. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state which corresponds to setting all DMRQ pins to high-impedance. If a EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: XXXX XXXX XXXX XX11 CIRRUS LOGIC PRODUCT DATASHEET 42 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.3.5 DMA Start of Frame (Read only, Address: PacketPage base + 0026h) Address 0027h Most significant byte of offset value Address 0026h Least significant byte of offset value The DMA Start of Frame Register contains a 16-bit value which defines the offset from the DMA base address to the start of the most recently transferred received frame. See Section 5.4 on page 89. Reset value is: 0000 0000 0000 0000 4.3.6 DMA Frame Count (Read only, Address: PacketPage base + 0028h) Address 0029h Most significant byte of frame count (most-significant nibble always 0h) Address 0028h Least significant byte of frame count The lower 12 bits of the DMA Frame Count register define the number of valid frames transferred via DMA since the last readout of this register. The upper 4 bits are reserved. See Section 5.4 on page 89. Reset value is: XXXX 0000 0000 0000 4.3.7 RxDMA Byte Count (Read only, Address: PacketPage base + 002Ah) Address 002Bh Most significant byte of byte count Address 002Ah Least significant byte of byte count The RxDMA Byte Count register describes the valid number of bytes DMAed since the last readout. See Section 5.4 on page 89. Reset value is: 0000 0000 0000 0000 4.3.8 Memory Base Address (Read/Write, Address: PacketPage base + 002Ch) Address 002Fh Reserved Address 002Eh The most significant nibble of memory base address. The high-order nibble is reserved. Address 002Dh Contains portion of memory base address. Address 002Ch The least significant byte of the memory base address. Memory Base Address: The lower three bytes (002Ch, 002Dh, and 002Eh) are used for the 20-bit memory base address. The upper three nibbles are reserved. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: XXXX XXXX XXXX 0000 0000 0000 0000 0000 CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 43 CS8900A Crystal LAN™ ISA Ethernet Controller 4.3.9 Boot PROM Base Address (Read/Write, Address: PacketPage base + 0030h) Address 0033h Reserved Address 0032h Address 0031h The most significant nibble of Boot PROM base address. Contains portion of Boot PROM The high-order nibble is base address. reserved. Address 0030h The least significant byte of the Boot PROM base address. The lower three bytes (0030h, 0031h, and 0032h) of the Boot PROM Base Address register are used for the 20-bit Boot PROM base address. The upper three nibbles are reserved. See Section 3.6 on page 24. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: XXXX XXXX XXXX 0000 0000 0000 0000 0000 4.3.10 Boot PROM Address Mask (Read/Write, Address: PacketPage base + 0034h) Address 0037h Reserved Address 0036h Address 0035h Address 0034h The most significant nibble of The least significant byte of Contains portion of Boot PROM Boot PROM mask address. the Boot PROM mask mask address. The lower-order The high-order nibble is address. Must be written as nibble must be written as 0h. reserved. 00h. The Boot PROM address mask register indicates the size of the attached Boot PROM and is limited to 4K bit increments. The lower 12 bits of the Address Mask are ignored, and should be 000h. The next lowest-order bits describe the size of the PROM. The upper three nibbles are reserved. For example: Size of Boot PROM 4k bits 8k bits 16k bits Register value XXXX XXXX XXXX 1111 1111 0000 0000 0000 XXXX XXXX XXXX 1111 1110 0000 0000 0000 XXXX XXXX XXXX 1111 1100 0000 0000 0000 See Section 3.6 on page 24. After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: XXXX XXXX XXXX 0000 0000 0000 0000 0000 CIRRUS LOGIC PRODUCT DATASHEET 44 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.3.11 EEPROM Command (Read/Write, Address: PacketPage base + 0040h) 7 F 6 E 5 D Reserved 4 3 ADD7 to ADD0 C B 2 A ELSEL 1 9 OB1 0 8 OB0 This register is used to control the reading, writing and erasing of the EEPROM. See Section 3.5. ADD7-ADD0 OB1,OB0 ELSEL Reserved Address of the EEPROM word being accessed. Indicates the Opcode of the command being executed. See Table 7. External logic select: When clear, the EECS pin is used to select the EEPROM. When set, the ELCS pin is used to select the external LA decode circuit. Reserved and must be written as 0. Reset value is: XXXX XXXX XXXX XXXX 4.3.12 EEPROM Data (Read/Write, Address: PacketPage base + 0042h) Address 0043h Most significant byte of the EEPROM data. Address 0042h Least significant byte of the EEPROM data. This register contains the word being written to, or read from, the EEPROM. See Section 3.5 on page 23. Reset value is: XXXX XXXX XXXX XXXX 4.3.13 Receive Frame Byte Counter (Read only, Address: PacketPage base + 0050h) Address 0051h Most significant byte of the byte count. Address 0050h Least significant byte of the byte count. This register contains the count of the total number bytes received in the current received frame. This count continuously increments as more bytes in this frame are received. See Section 5.2.9 on page 86. Reset value is: XXXX XXXX XXXX XXXX CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 45 CS8900A Crystal LAN™ ISA Ethernet Controller 4.4 Status and Control Registers The Status and Control registers are the primary registers used to control and check the status of the CS8900A. They are organized into two groups: Configuration/Control Registers and Status/Event Registers. All Status and Control Registers are 16bit words as shown in Figure 16. Bit 0 indicates whether it is a Configuration/Control Register (Bit 0 = 1) or a Status/Event Register (Bit 0 = 0). Bits 0 through 5 provide an internal address code that describes the exact function of the register. Bits 6 through F are the actual Configuration/Control and Status/Event bits. 4.4.1 Configuration and Control Registers Configuration and Control registers are used to setup the following: • • • • how frames will be transmitted and received; which frames will be transmitted and received; which events will cause interrupts to the host processor; and, how the Ethernet physical interface will be configured. read-only. The second location, PacketPage base + 0144h, is where the actual transmit commands are issued and is write-only. See Section 4.4.4 on page 48 (Register 9) and Section 5.7 on page 98 for a more detailed description of the TxCMD register. 4.4.2 Status and Event Registers Status and Event registers report the status of transmitted and received frames, as well as information about the configuration of the CS8900A. They are read-only and are designated by even numbers (e.g. Register 2, Register 4, etc.). The Interrupt Status Queue (ISQ) is a special type of Status/Event register. It is located at PacketPage base + 0120h and is the first register the host reads when responding to an Interrupt. A more detailed description of the ISQ can be found in Section 5.1 on page 78. Three 10-bit counters are included with the Status and Event registers. RxMISS counts missed receive frames, TxCOL counts transmit collisions, and TDR is a time domain reflectometer useful in locating cable faults. The following sections contain more information about these counters. Table 13 provides a summary of PacketPage Register types. 4.4.3 Status and Control Bit Definitions This section provides a description of the special bit types used in the Status and Control registers. These registers are read/write and are designated by odd numbers (e.g. Register 1, Register 3, etc.). The Transmit Command Register (TxCMD) is a special type of register. It appears in two separate locations in the PacketPage memory map. The first location, PacketPage base + 0108h, is within the block of Configuration/Control Registers and is 16-bit Register Word Bit Number FEDCBA9876543210 Internal Address (bits 0 - 5) 1 = Control/Configuration 0 = Status/Event 10 Register Bits Figure 16. Status and Control Register Format CIRRUS LOGIC PRODUCT DATASHEET 46 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Suffix CMD CFG Type Read/Write Read/Write CTL Read/Write Event ST Read-only Read-only Read-only Description Command: Written once per frame to initiate transmit. Configuration: Written at setup and used to determine what frames will be transmitted and received and what events will cause interrupts. Control: Written at setup and used to determine what frames will be transmitted and received and how the physical interface will be configured. Event: Reports the status of transmitted and received frames. Status: Reports information about the configuration of the CS8900A. Counters: Counts missed receive frames and collisions. Provides time domain for locating coax cable faults. Table 13. PacketPage Register Types Comments cleared when read cleared when read Section 4.4.4 on page 48 provides a detailed description of the bits in each register. 4.4.3.1 Act-Once Bits There are four bits that cause the CS8900A to take a certain action only once when set. These "ActOnce" bits are: Skip_1 (Register 3, RxCFG, Bit 6), RESET (Register 15, SelfCTL, Bit 6), ResetRxDMA (Register 17, BusCTL, Bit 6), and SWint-X (Register B, BufCFG, Bit 6). To cause the action again, the host must set the bit again. Act-Once bits are always read as clear. 4.4.3.2 Temporal Bits Temporal bits are bits that are set and cleared by the CS8900A without intervention of the host processor. This includes all status bits in the three status registers (Register 14, LineST; Register 16, SelfST; and, Register 18, BusST), the RxDest bit (Register C, BufEvent, Bit F), and the Rx128 bit (Register C, BufEvent, Bit B). Like all Event bits, RxDest and Rx128 are cleared when read by the host. 4.4.3.3 Interrupt Enable Bits and Events Interrupt Enable bits end with the suffix iE and are located in three Configuration registers: RxCFG (Register 3), TxCFG (Register 7), and BufCFG (Register B). Each Interrupt Enable bit corresponds to a specific event. If an Interrupt Enable bit is set and its corresponding event occurs, the CS8900A generates an interrupt to the host processor. The bits that report when various events occur are located in three Event registers and two counters. The Event registers are RxEvent (Register 4), TxEvent (Register 8), and BufEvent (Register C). The counters are RxMISS (Register 10) and TxCOL (Register 12). Each Interrupt Enable bit and its associated Event are identified in Table 14. An Event bit will be set whenever the specified event happens, whether or not the associated Interrupt Enable bit is set. All Event registers are cleared upon read-out by the host. 4.4.3.4 Accept Bits There are nine Accept bits located in the RxCTL register (Register 5), each of which is followed by the suffix A. Accept bits indicate which types of frames will be accepted by the CS8900A. (A frame is said to be "accepted" by the CS8900A when the frame data are placed in either on-chip memory, or in host memory by DMA.) Four of these bits have corresponding Interrupt Enable (iE) bits. An Accept bit and an Interrupt Enable bit are independent CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 47 CS8900A Crystal LAN™ ISA Ethernet Controller event occurs, but then does not accept the receive frame (the length of the receive frame is set to zero). The other five Accept bits in RxCTL are used for destination address filtering (see Section 5.3 on page 86). The Accept mechanism is explained in more detail in Section 5.2 on page 78. 4.4.4 Status and Control Register Summary The table on the following page (Table 15) provides a summary of the Status and Control registers. Section 4.4.4 on page 48 gives a detailed description of each Status and Control register. Interrupt Enable Bit (register name) ExtradataiE (RxCFG) RuntiE (RxCFG) CRCerroriE (RxCFG) RxOKiE (RxCFG) 16colliE (TxCFG) AnycolliE (TxCFG) Event Bit or Counter (register name) Extradata (RxEvent) Runt (RxEvent) CRCerror (RxEvent) RxOK (RxEvent) 16coll (TxEvent) “Number-of Tx-collisions” counter is incremented (TxEvent) JabberiE (TxCFG) Jabber (TxEvent) Out-of-windowiE (TxCFG) Out-of-window (TxEvent) TxOKiE (TxCFG) TxOK (TXEvent) SQEerroriE (TxCFG) SQEerror (TxEvent) Loss-of-CRSiE (TxCFG) Loss-of-CRS (TxEvent) MissOvfloiE (BufCFG) TxColOvfloiE (BufCFG) RxDestiE (BufCFG) Rx128iE (BufCFG) RxMissiE (BufCFG) TxUnderruniE (BufCFG) Rdy4TxiE (BufCFG) RxDMAiE (BufCFG) RxMISS counter overflows past 1FFh TxCOL counter overflows past 1FFh RxDest (BufEvent) Rx128 (BufEvent) RxMISS (BufEvent) TxUnderrun (BufEvent) Rdy4Tx (BufEvent) RxDMAFrame (BufEvent) Table 14. Interrupt Enable Bits and Events operations. It is possible to set either, neither, or both bits. The four corresponding pairs of bits are: IE Bit in RxCFG ExtradataiE RuntiE CRCerroriE RxOKiE A Bit in RxCTL ExtradataA RuntA CRCerrorA RxOKA If one of the above Interrupt Enable bits is set and the corresponding Accept bit is clear, the CS8900A generates an interrupt when the associated receive CIRRUS LOGIC PRODUCT DATASHEET 48 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Control and Configuration Bits F E D C B A 9 8 7 6 Register Number (Offset) 1 3 (0102h) 5 (0104h) 7 (0106h) 9 (0108h) B (010Ah) D-11 13 (0112h) 15 (0114h) 17 (0116) 19 (0118) 1B -1F Name Extra dataiE Extra dataA 16colli E RuntiE RuntA RxDestiE TxPadDis Miss OvfloiE LoRx 2-part Squelch DefDis HCB1 HCB0 HC1E Enabl e IRQ FDX RxDMA size Reserved (register contents undefined) CRC Buffer AutoRx RxDMA RxOKiE erroriE CRC DMAE only CRC Broad Individ Multi RxOKA errorA castA ualA castA AnycolliE Jab Out-of- TxOKiE beriE windowiE InhibitOnecoll Force CRC TxCol Rx128iE Rxmis- TxUnder- Rdy4Txi OvfloiE siE runiE E Reserved (register contents undefined) Polarity Mod AutoAUI/ AUIonly Dis BackoffE 10BT HC0E HWStan HW SW SusdbyE SleepE pend IOCH DMA Memo- UseSA DMAexRDYE Burst ryE tend Disable AUIloop ENDEC Backoff loop Reserved (register contents undefined) StreamE Skip_1 Promis IAHash cuousA A SQErro- Loss-ofriE CRSiE TxStart RxDMAiE Ser TxON SWint-X RxCFG RxCTL TxCFG TxCMD BufCFG Ser RxON RESET Reset RxDMA Line CTL SelfCTL BusCTL TestCTL Disable LT Table 15. Status and Control Register Descriptions CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 49 CS8900A Crystal LAN™ ISA Ethernet Controller Status and Event Bits F E D C B A 9 8 7 6 Register Name ISQ Number (Offset) Interrupt Status Queue 0 (0120h) Reserved (register contents undefined) 2 Extra Runt CRC Broad- Individ- Hashed RxOK Dribble IAHash 4 data error cast ual Adr bits (0124h) Hash Table Index (alternate RxEvent meaning if Hashed RxOK Dribble IAHash 4 Hashed = 1 and RxOK = 1) bits (0124h) Reserved (register contents undefined) 6 16coll Number-of-Tx-collisions Jabber Out-ofTxOK SQE Loss-of8 Window error CRS (0128h) Reserved (register contents undefined) A Rx Rx128 RxMiss TxUnder- Rdy4Tx RxDMA SWint C Dest run Frame (012Ch) Reserved (register contents undefined) E 10-bit Receive Miss (RxMISS) counter, cleared when read 10 (0130h) 10-bit Transmit Collision (TxCOL) counter, cleared when read 12 (0132h) CRS Polarity 10BT AUI LinkOK 14 OK (0134h) EESize EL EEPRO EEPRO SIBUSY INITD 3.3 V 16 present M OK Mpresent Active (0136h) Rdy4Tx TxBid 18 NOW Err (0138h) Reserved (register contents undefined) 1A 10-bit AUI Time Domain Reflectometer (TDR) counter, cleared when read 1C (013Ch) Reserved (register contents undefined) 1E Table 15. Status and Control Register Descriptions (continued) Rx Event Rx Eventalt TxEvent Buf Event RxMISS TxCOL LineST SelfST BusST TDR CIRRUS LOGIC PRODUCT DATASHEET 50 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.4.5 Register 0: Interrupt Status Queue (ISQ, Read-only, Address: PacketPage base + 0120h) 7 RegContent F E D C RegContent B 6 5 4 3 RegNum A 9 8 2 1 0 The Interrupt Status Queue Register is used in both Memory Mode and I/O Mode to provide the host with interrupt information. Whenever an event occurs that triggers an enabled interrupt, the CS8900A sets the appropriate bit(s) in one of five registers, maps the contents of that register to the ISQ register, and drives an IRQ pin high. Three of the registers mapped to ISQ are event registers: RxEvent (Register 4), TxEvent (Register 8), and BufEvent (Register C). The other two registers are counter-overflow reports: RxMISS (Register 10) and TxCOL (Register 12). In Memory Mode, ISQ is located at PacketPage base + 120h. In I/O Mode, ISQ is located at I/O Base + 0008h. See Section 5.1 on page 78. RegNum RegContent The lower six bits describe which register (4, 8, C, 10 or 12) is contained in the ISQ. The upper ten bits contain the register data contents. Reset value is: 0000 0000 0000 0000 CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 51 CS8900A Crystal LAN™ ISA Ethernet Controller 4.4.6 Register 3: Receiver Configuration (RxCFG, Read/Write, Address: PacketPage base + 0102h) 7 StreamE F 6 Skip_1 E ExtradataiE 5 D RuntiE 4 C CRCerroriE 3 000011 B BufferCRC A AutoRx DMAE 9 RxDMA only 8 RxOKiE 2 1 0 RxCFG determines how frames will be transferred to the host and what frame types will cause interrupts. 000011 Skip_1 These bits provide an internal address used by the CS8900A to identify this as the Receiver Configuration Register. When set, this bit causes the last committed received frame to be deleted from the receive buffer. To skip another frame, the host must rewrite a “1” to this bit. This bit is not to be used if RxDMAonly (Bit 9) is set. Skip_1 is an Act-Once bit. See Section 5.2.5 on page 83. When set, StreamTransfer mode is used to transfer receive frames that are back-to-back and that pass the Destination Address filter (see Section 5.3 on page 86). When StreamE is clear, StreamTransfer mode is not used. This bit must not be set unless either bit AutoRxDMA or bit RXDMAonly is set. When set, there is an RxOK Interrupt if a frame is received without errors. RxOK interrupt is not generated when DMA mode is used for frame reception. The Receive-DMA mode is used for all receive frames when this bit is set. When set, the CS8900A will automatically switch to Receive-DMA mode if the conditions specified in Section 5.5 on page 92 are met. RxDMAonly (Bit 9) has precedence over AutoRxDMAE. When set, the received CRC is included with the data stored in the receive-frame buffer, and the four CRC bytes are included in the receive-frame length (PacketPage base + 0402h). When clear, neither the receive buffer nor the receive length include the CRC. When set, there is a CRCerror Interrupt if a frame is received with a bad CRC. When set, there is a Runt Interrupt if a frame is received that is shorter than 64 bytes. The CS8900A always discards any frame that is shorter than 8 bytes. When set, there is an Extradata Interrupt if a frame is received that is longer than 1518 bytes. The operation of this bit is independent of the received packet integrity (good or bad CRC). StreamE RxOKiE RxDMAonly AutoRxDMAE BufferCRC CRCerroriE RuntiE ExtradataiE After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 18. Reset value is: 0000 0000 0000 0011 CIRRUS LOGIC PRODUCT DATASHEET 52 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.4.7 Register 4: Receiver Event (RxEvent, Read-only, Address: PacketPage base + 0124h) 7 Dribblebits F 6 IAHash E Extradata 5 D Runt 4 C CRCerror 3 000100 B Broadcast A Individual Adr 9 Hashed 8 RxOK 2 1 0 Alternate meaning if bits 8 and 9 are both set (see Section 5.3 on page 86 for exception regarding Broadcast frames). 7 Dribblebits F 6 IAHash 5 4 3 000100 A 9 Hashed = 1 8 RxOK = 1 2 1 0 E D C B Hash Table Index (see Section 5.3 on page 86) RxEvent reports the status of the current received frame. 000100 IAHash These bits identify this as the Receiver Event Register. When reading this register, these bits will be 000100, where the LSB corresponds to Bit 0. If the received frame’s Destination Address is accepted by the hash filter, then this bit is set if, and only if IAHashA (Register 5, RxCTL, Bit 6) is set, and Hashed (Bit 9) is set. See Section 5.3 on page 86. If set, the received frame had from one to seven bits after the last received full byte. An "Alignment Error" occurs when Dribblebits and CRCerror (Bit C) are both set. If set, the received frame had a good CRC and valid length (i.e., there is not a CRC error, Runt error, or Extradata error). When RxOK is set, then the length of the received frame is contained at PacketPage base + 0402h. If RxOKiE (Register 3, RxCFG, Bit 8) is set, there is an interrupt. If set, the received frame had a Destination Address that was accepted by the hash filter. If Hashed and RxOK (Bit 8) are set, Bits F through A of RxEvent become the Hash Table Index for this frame [See Section 5.3 on page 86 for an exception regarding broadcast frames!].If Hashed and RxOK are not both set, then Bits F through A are individual event bits as defined below. If the received frame had a Destination Address which matched the Individual Address found at PacketPage base + 0158h, then this bit is set if, and only if, RxOK (Bit 8) is set and IndividualA (Register 5, RxCTL, Bit A) is set. If the received frame had a Broadcast Address (FFFF FFFF FFFFh) as the Destination Address, then this bit is set if, and only if, RxOK is set and BroadcastA (Register 5, RxCTL, Bit B) is set. If set, the received frame had a bad CRC. If CRCerroriE (Register 3, RxCFG, Bit C) is set, there is an interrupt If set, the received frame was shorter than 64 bytes. If RuntiE (Register 3, RxCFG, Bit D) is set, there is an interrupt. If set, the received frame was longer than 1518 bytes. All bytes beyond 1518 are discarded. If ExtradataiE (Register 3, RxCFG, Bit E) is set, there is an interrupt. Dribblebits RxOK Hashed IndividualAdr Broadcast CRCerror Runt Extradata Reset value is: 0000 0000 0000 0100 Notes: 3. All RxEvent bits are cleared upon readout. The host is responsible for processing all event bits. 4. RxStatus register (PacketPage base + 0400h) is the same as the RxEvent register except RxStatus is not cleared when RxEvent is read. See Section 5.2 on page 78. The value in the RxEvent register is undefined when RxDMAOnly bit (Bit 9, Register 3, RxCFG) is set. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 53 CS8900A Crystal LAN™ ISA Ethernet Controller 4.4.8 Register 5: Receiver Control (RxCTL, Read/Write, Address: PacketPage base +0104h) 7 PromiscuousA F 6 IAHashA E ExtradataA 5 D RuntA 4 C CRCerrorA 3 000101 B BroadcastA A IndividualA 9 MulticastA 8 RxOKA 2 1 0 RxCTL has two functions: Bits 8, C, D, and E define what types of frames to accept. Bits 6, 7, 9, A, and B configure the Destination Address filter. See Section 5.3 on page 86. 000101 These bits provide an internal address used by the CS8900A to identify this as the Receiver Control Register. For a received frame to be accepted, the Destination Address of that frame must pass the filter criteria found in Bits 6, 7, 9, A, and B (see Section 5.3 on page 86). When set, receive frames are accepted when the Destination Address is an Individual Address that passes the hash filter. Frames with any address are accepted when this bit is set. When set, the CS8900A accepts frames with correct CRC and valid length (valid length is: 64 bytes 3 and < 1519. Since this register is write-only, it’s initial state after reset is undefined. CIRRUS LOGIC PRODUCT DATASHEET 70 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 4.6 Address Filter Registers 4.6.1 Logical Address Filter (hash table) (Read/Write, Address: PacketPage base + 0150h) Address 0157h Address 0156h Address 0155h Address 0154h Address 0153h Address 0152h Address 0151h Address 0150h Most-signifiLeast-significant byte of cant byte of hash filter. hash filter. The CS8900A hashing decoder circuitry compares its output with one bit of the Logical Address Filter Register. If the decoder output and the Logical Address Filter bit match, the frame passes the hash filter and the Hashed bit (Register 4, RxEvent, Bit 9) is set. See Section 5.3 on page 86. Reset value is: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 4.6.2 Individual Address (IEEE address) (Read/Write, Address: PacketPage base + 0158h) Address 0015Dh Octet 5 of IA Address 0015Ch Address 0015Bh Address 0015Ah Address 0159h Address 00158h Octet 0 of IA The unique, IEEE 48-bit Individual Address (IA) begins at 0158h. The first bit of the IA (Bit IA[00]) must be "0". See Section 5.3 on page 86. The value of this register must be loaded from external storage, for example, from the EEPROM. See Section 3.3 on page 18. If the CS8900A is not able to load the IA from the EEPROM, then after a reset this register is undefined, and the driver must write an address to this register. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 71 CS8900A Crystal LAN™ ISA Ethernet Controller 4.7 Receive and Transmit Frame Locations The Receive and Transmit Frame PacketPage locations are used to transfer Ethernet frames to and from the host. The host sequentially writes to and reads from these locations, and internal buffer memory is dynamically allocated between transmit and receive as needed. One receive frame and one transmit frame are accessible at a time. 4.7.1 Receive PacketPage Locations In IO mode, the receive status/length/frame locations are read through repetitive reads from one IO port at the IO base address. See Section 4.10 on page 75. In memory mode, the receive status/length/frame locations are read using memory reads of a block of memory starting at memory base address + 0400h. Typically the memory locations are read sequentially using repetitive Move instructions (REP MOVS). See Section 4.9 on page 73. Random access is not needed. However, the first 118 bytes of the receive frame can be accessed randomly if word reads, on even word boundaries, are used. Beyond 118 bytes, the memory reads must be sequential. Byte reads, or reads on odd-word boundaries, can be performed only in sequential read mode. See Section 4.8 on page 72. The RxStatus word reports the status of the current received frame. RxEvent register 4 (PacketPage base + 0124h) has the same contents as the RxStatus register, except RxEvent is cleared when RxEvent is read. The RxLength (receive length) word is the length, in bytes, of the data to be transferred to the host across the ISA bus. The register describes the length from the start of Destination Address to the end of CRC, assuming that CRC has been selected (via Register 3 RxCFG, bit BufferCRC). If CRC has not been selected, then the length does not include the CRC, and the CRC is not present in the receive buffer. After the RxLength has been read, the receive frame can be read. When some portion of the frame is read, the entire frame should be read before reading the RxEvent register either directly or through the ISQ register. Reading the RxEvent register signals to the CS8900A that the host is finished with the current frame, and wants to start processing the next frame. In this case, the current frame will no longer be accessible to the host. The current frame will also become inaccessible if a Skip command is issued, or if the entire frame has been read. See Section 5.2 on page 78. 4.7.2 Transmit Locations The host can write frames into the CS8900A buffer using Memory writes using REP MOVS to the TxFrame location. See Section 5.7 on page 98. 4.8 Eight and Sixteen Bit Transfers A data transfer to or from the CS8900A can be done in either I/O or Memory space, and can be either 16 bits wide (word transfers) or 8 bits wide (byte transfers). Because the CS8900A’s internal architecture is based on a 16-bit data bus, word transfers are the most efficient. To transfer transmit frames to the CS8900A and receive frames from the CS8900A, the host may mix word and byte transfers, provided it follows three rules: 1) The primary method used to access CS8900A memory is word access. 2) Word accesses to the CS8900A’s internal memory are kept on even-byte boundaries. 3) When switching from byte accesses to word accesses, a byte access to an even byte address must be followed by a byte access to an oddbyte address before the host may execute a word access (this will realign the word transfers to even-byte boundaries). On the other hand, a byte access to an odd-byte address may be followed by a word access. CIRRUS LOGIC PRODUCT DATASHEET 72 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Failure to observe these three rules may cause data corruption. 4.8.1 Transferring Odd-Byte-Aligned Data Some applications gather transmit data from more than one section of host memory. The boundary between the various memory locations may be either even- or odd-byte aligned. When such a boundary is odd-byte aligned, the host should transfer the last byte of the first block to an even address, followed by the first byte of the second block to the following odd address. It can then resume word transfers. An example of this is shown in Figure 17. Word Transfer First Block of Data Word Transfer Word Transfer Byte Transfer Byte Transfer Word Transfer Word Transfer all of the CS8900A’s registers can be accessed directly. In Memory Mode, the CS8900A supports Standard or Ready Bus cycles without introducing additional wait states. Memory moves can use MOVD (double-word transfers) as long as the CS8900A’s memory base address is on a double word boundary. Since 286 processors don’t support the MOVD instruction, word and byte transfers must be used with a 286. Description Mnemonic Read/Write Location: PocketPage base + 0400h-0401h 0402h-0403h Second Block of Data Receive Status Receive Length Receive Frame Transmit Frame RxStatus RxLength RxFrame TxFrame Read-only Read-only Read-only starts at 0404h Write-only starts at 0A00h Table 16. Receive/Transmit Memory Locations Word Transfer Figure 17. Odd-Byte Aligned Data 4.8.2 Random Access to CS8900A Memory The first 118 bytes of a receive frame held in the CS8900A’s on-chip memory may be randomly accessed in Memory mode. After the first 118 bytes, only sequential access of received data is allowed. Either byte or word access is permitted, as long as all word accesses are executed to even-byte boundaries. 4.9 Memory Mode Operation To configure the CS8900A for Memory Mode, the PacketPage memory must be mapped into a contiguous 4-kbyte block of host memory. The block must start at an X000h boundary, with the PacketPage base address mapped to X000h. When the CS8900A comes out of reset, its default configuration is I/O Mode. Once Memory Mode is selected, 4.9.1 Accesses in Memory Mode The CS8900A allows Read/Write access to the internal PacketPage memory, and Read access of the optional Boot PROM. (See Section 3.7 on page 25 for a description of the optional Boot PROM.) A memory access occurs when all of the following are true: • The address on the ISA System Address bus (SA0 - SA19) is within the Memory space range of the CS8900A or Boot PROM. The CHIPSEL input pin is low. Either the MEMR pin or the MEMW pin is low. • • 4.9.2 Configuring the CS8900A for Memory Mode There are two different methods of configuring the CS8900A for Memory Mode operation. One method allows the CS8900A's internal memory to be mapped anywhere within the host system's 24-bit CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 73 CS8900A Crystal LAN™ ISA Ethernet Controller memory space. The other method limits memory mapping to the first 1 Mbyte of host memory space. General Memory Mode Operation: Configuring the CS8900A so that its internal memory can be mapped anywhere within host Memory space requires the following: • a simple circuit must be added to decode the Latchable Address bus (LA20 - LA23) and the BALE signal. the host must configure the external logic with the correct address range as follows: 1) Check to see if the INITD bit (Register 16, SelfST, bit 7) is set, indicating that initialization is complete. 2) Check to see if the ELpresent bit (Register 16, SelfST, bit B) is set. This bit indicates that external logic for the LA bus decode is present. 3) Set the ELSEL bit of the EEPROM Command Register to activate the ELCS pin for use with the external decode circuit. 4) Configure the external logic serially. • the host must write the memory base address into the Memory Base Address register (PacketPage base + 002Ch); the host must set the MemoryE bit (Register 17, BusCTL, Bit A); and the host must set the UseSA bit (Register 17, BusCTL, Bit 9). • • the ISA-bus SMEMW signal must be connected to the MEMW pin; the host must write the memory base address into the Memory Base Address register (PacketPage base + 002Ch); the host must set the MemoryE bit (Register 17, BusCTL, Bit A); and the host must clear the UseSA bit (Register 17, BusCTL, Bit 9). • • • 4.9.3 Basic Memory Mode Transmit Memory Mode transmit operations occur in the following order (using interrupts): 1) The host bids for storage of the frame by writing the Transmit Command to the TxCMD register (memory base + 0144h) and the transmit frame length to the TxLength register (memory base + 0146h). If the transmit length is erroneous, the command is discarded and the TxBidErr bit (Register 18, BusST, Bit 7) is set. 2) The host reads the BusST register (Register 18, memory base + 0138h). If the Rdy4TxNOW bit (Bit 8) is set, the frame can be written. If clear, the host must wait for CS8900A buffer memory to become available. If Rdy4TxiE (Register B, BufCFG, Bit 8) is set, the host will be interrupted when Rdy4Tx (Register C, BufEvent, Bit 8) becomes set. 3) Once the CS8900A is ready to accept the frame, the host executes repetitive memory-tomemory move instructions (REP MOVS) to memory base + 0A00h to transfer the entire frame from host memory to CS8900A memory. For a more detailed description of transmit, see Section 5.7 on page 98. 4.9.4 Basic Memory Mode Receive Memory Mode receive operations occur in the following order (interrupts used to signal the presence of a valid receive frame): • • Limiting Memory Mode to the First 1 Mbyte of Host Memory Space: Configuring the CS8900A so that its internal memory can be mapped only within the first 1 Mbyte of host memory space requires the following: • • the CHIPSEL pin must be tied low; the ISA-bus SMEMR signal must be connected to the MEMR pin; CIRRUS LOGIC PRODUCT DATASHEET 74 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 1) A frame is received by the CS8900A, triggering an enabled interrupt. 2) The host reads the Interrupt Status Queue (memory base + 0120h) and is informed of the receive frame. 3) The host reads RxStatus (memory base + 0400h) to learn the status of the receive frame. 4) The host reads RxLength (memory base + 0402h) to learn the frame’s length. 5) The host reads the frame data by executing repetitive memory-to-memory move instructions (REP MOVS) from memory base + 0404h to transfer the entire frame from CS8900A memory to host memory. For a more detailed description of receive, see Section 5.2 on page 78. 4.9.5 Polling the CS8900A in Memory Mode If interrupts are not used, the host can poll the CS8900A to check if receive frames are present and if memory space is available for transmit. However, this is beyond the scope of this data sheet. 4.10 I/O Space Operation In I/O Mode, PacketPage memory is accessed through eight 16-bit I/O ports that are mapped into 16 contiguous I/O locations in the host system’s I/O space. I/O Mode is the default configuration for the CS8900A and is always enabled. On power up, the default value of the I/O base address is set at 300h. (Note that 300h is typically assigned to LAN peripherals). The I/O base address may be changed to any available XXX0h location, either by loading configuration data from the EEPROM, or during system setup. Table 17 shows the CS8900A I/O Mode mapping. Offset Type Description 0000h Read/Write Receive/Transmit Data (Port 0) 0002h Read/Write Receive/Transmit Data (Port 1) Table 17. I/O Mode Mapping Offset Type 0004h Write-only 0006h Write-only 0008h Read-only 000Ah Read/Write 000Ch Read/Write 000Eh Read/Write Description TxCMD (Transmit Command) TxLength (Transmit Length) Interrupt Status Queue PacketPage Pointer PacketPage Data (Port 0) PacketPage Data (Port 1) Table 17. I/O Mode Mapping 4.10.1 Receive/Transmit Data Ports 0 and 1 These two ports are used when transferring transmit data to the CS8900A and receive data from the CS8900A. Port 0 is used for 16-bit operations and Ports 0 and 1 are used for 32-bit operations (lowerorder word in Port 0). 4.10.2 TxCMD Port The host writes the Transmit Command (TxCMD) to this port at the start of each transmit operation. The Transmit Command tells the CS8900A that the host has a frame to be transmitted, as well as how that frame should be transmitted. This port is mapped into PacketPage base + 0144h. See Register 9 in Section 4.4 on page 46 for more information. 4.10.3 TxLength Port The length of the frame to be transmitted is written here immediately after the Transmit Command is written. This port is mapped into PacketPage base + 0146h. 4.10.4 Interrupt Status Queue Port This port contains the current value of the Interrupt Status Queue (ISQ). The ISQ is located at PacketPage base + 0120h. For a more detailed description of the ISQ, see Section 5.1 on page 78. 4.10.5 PacketPage Pointer Port The PacketPage Pointer Port is written whenever the host wishes to access any of the CS8900A’s internal registers. The first 12 bits (bits 0 through B) provide the internal address of the target register to be accessed during the current operation. The next CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 75 CS8900A Crystal LAN™ ISA Ethernet Controller three bits (C, D, and E) are read-only and will always read as 011b. Any convenient value may be written to these bits when writing to the PacketPage Pointer Port. The last bit (Bit F) indicates whether or not the PacketPage Pointer should be auto-incremented to the next word location. Figure 18 shows the structure of the PacketPage Pointer. I/O base + 000Bh I/O base + 000Ah 1) The host bids for storage of the frame by writing the Transmit Command to the TxCMD Port (I/O base + 0004h) and the transmit frame length to the TxLength Port (I/O base + 0006h). 2) The host reads the BusST register (Register 18) to see if the Rdy4TxNOW bit (Bit 8) is set. To read the BusST register, the host must first set the PacketPage Pointer at the correct location by writing 0138h to the PacketPage Pointer Port (I/O base + 000Ah). It can then read the BusST register from the PacketPage Data Port (I/O base + 000Ch). If Rdy4TxNOW is set, the frame can be written. If clear, the host must wait for CS8900A buffer memory to become available. If Rdy4TxiE (Register B, BufCFG, Bit 8) is set, the host will be interrupted when Rdy4Tx (Register C, BufEvent, Bit 8) becomes set. If the TxBidErr bit (Register 18, BusST, Bit 7) is set, the transmit length is not valid. 3) Once the CS8900A is ready to accept the frame, the host executes repetitive write instructions (REP OUT) to the Receive/Transmit Data Port (I/O base + 0000h) to transfer the entire frame from host memory to CS8900A memory. For a more detailed description of transmit, see Section 5.7 on page 98. 4.10.9 Basic I/O Mode Receive I/O Mode receive operations occur in the following order (In this example, interrupts are enabled to signal the presence of a valid receive frame): 1) A frame is received by the CS8900A, triggering an enabled interrupt. 2) The host reads the Interrupt Status Queue Port (I/O base + 0008h) and is informed of the receive frame. 3) The host reads the frame data by executing repetitive read instructions (REP IN) from the Receive/Transmit Data Port (I/O base + 0000h) to transfer the frame from CS8900A memory to DS271PP4 FEDCBA9876543210 PacketPage Register Address Bit F: 0 = Pointer remains fixed 1 = Auto-Increments to next word location Figure 18. PacketPage Pointer 4.10.6 PacketPage Data Ports 0 and 1 The PacketPage Data Ports are used to transfer data to and from any of the CS8900A’s internal registers. Port 0 is used for 16-bit operations and Port 0 and 1 are used for 32-bit operations (lower-order word in Port 0). 4.10.7 I/O Mode Operation For an I/O Read or Write operation, the AEN pin must be low, and the 16-bit I/O address on the ISA System Address bus (SA0 - SA15) must match the address space of the CS8900A. For a Read, the IOR pin must be low, and for a Write, the IOW pin must be low. Note: The ISA Latchable Address Bus (LA17 LA23) is not needed for applications that use only I/O Mode and Receive DMA operation. 4.10.8 Basic I/O Mode Transmit I/O Mode transmit operations occur in the following order (using interrupts): CIRRUS LOGIC PRODUCT DATASHEET 76 CS8900A Crystal LAN™ ISA Ethernet Controller host memory. Preceding the frame data are the contents of the RxStatus register (PacketPage base + 0400h) and the RxLength register (PacketPage base + 0402h). For a more detailed description of receive, see Section 5.2 on page 78. 4.10.10 Accessing Internal Registers To access any of the CS8900A’s internal registers in I/O Mode, the host must first setup the PacketPage Pointer. It does this by writing the PacketPage address of the target register to the PacketPage Pointer Port (I/O base + 000Ah). The contents of the target register is then mapped into the PacketPage Data Port (I/O base + 000Ch). If the host needs to access a sequential block of registers, the MSB of the PacketPage address of the first word to be accessed should be set to "1". The PacketPage Pointer will then move to the next word location automatically, eliminating the need to setup the PacketPage Pointer between successive accesses (see Figure 18). 4.10.11 Polling the CS8900A in I/O Mode If interrupts are not used, the host can poll the CS8900A to check if receive frames are present and if memory space is available for transmit. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 77 CS8900A Crystal LAN™ ISA Ethernet Controller 5.0 OPERATION 5.1 Managing Interrupts and Servicing the Interrupt Status Queue The Interrupt Status Queue (ISQ) is used by the CS8900A to communicate Event reports to the host processor. Whenever an event occurs that triggers an enabled interrupt, the CS8900A sets the appropriate bit(s) in one of five registers, maps the contents of that register to the ISQ, and drives the selected interrupt request pin high (if an earlier interrupt is waiting in the queue, the interrupt request pin will already be high). When the host services the interrupt, it must first read the ISQ to learn the nature of the interrupt. It can then process the interrupt (the first read to the ISQ causes the interrupt request pin to go low.) Three of the registers mapped to the ISQ are event registers: RxEvent (Register 4), TxEvent (Register 8), and BufEvent (Register C). The other two registers are counter-overflow reports: RxMISS (Register 10) and TxCOL (Register 12). There may be more than one RxEvent report and/or more than one TxEvent report in the ISQ at a time. However, there may be only one BufEvent report, one RxMISS report and one TxCOL report in the ISQ at a time. Event reports stored in the ISQ are read out in the order of priority, with RxEvent first, followed by TxEvent, BufEvent, RxMiss, and then TxCOL. The host only needs to read from one location to get the interrupt currently at the front of the queue. In Memory Mode, the ISQ is located at PacketPage base + 0120h. In I/O Mode, it is located at I/O base + 0008h. Each time the host reads the ISQ, the bits in the corresponding register are cleared and the next report in the queue moves to the front. When the host starts reading the ISQ, it must read and process all Event reports in the queue. A readout of a null word (0000h) indicates that all interrupts have been read. The ISQ is read as a 16-bit word. The lower six bits (0 through 5) contain the register number (4, 8, C, 10, or 12). The upper ten bits (6 through F) contain the register contents. The host must always read the entire 16-bit word. The active interrupt pin (INTRQx) is selected via the Interrupt Number register (PacketPage base + 22h). As an additional option, all of the interrupt pins can be 3-Stated using the same register. see Section 4.3 on page 41. An event triggers an interrupt only when the EnableIRQ bit of the Bus Control register (bit F of register 17) is set. After the CS8900A has generated an interrupt, the first read of the ISQ makes the INTRQ output pin go low (inactive). INTRQ remains low until the null word (0000h) is read from the ISQ, or for 1.6us, whichever is longer. 5.2 Basic Receive Operation 5.2.0.1 Overview Once an incoming packet has passed through the analog front end and Manchester decoder, it goes through the following three-step receive process: 1) Pre-Processing 2) Temporary Buffering 3) Transfer to Host Figure 20 shows the steps in frame reception. As shown in the figure, all receive frames go through the same pre-processing and temporary buffering phases, regardless of transfer method Once a frame has been pre-processed and buffered, it can be accessed by the host in either Memory or I/O space. In addition, the CS8900A can transfer receive frames to host memory via host DMA. This section describes receive frame pre-processing and Memory and I/O space receive operation. Section 5.4 on page 89 through Section 5.5 on page 92 describe DMA operation. CIRRUS LOGIC PRODUCT DATASHEET 78 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller An enabled interrupt occurs. The selected interrupt request pin is driven high (active) if not already high. The host reads the ISQ. The selected interrupt request pin is driven low. EXIT. Interrupts re-enabled. (Interrupts will be disabled for at least 1.6 us.) Yes ISQ = 0000h? No RxEvent Process applicable RxEvent bits: Extradata, Runt, CRCerror, RxOK. Process applicable TxEvent bits: 16coll, Jabber, Out-of-window, TxOK. Process applicable BufEvent bits: RxDest, Rx128, RxMiss, TxUnderrun, Rdy4Tx, RxDMAFrame, SWint. TxEvent Which Event report type? BufEvent RxMISS Process RxMISS counter. TxCOL Process TxCOL counter. None of the above Figure 19. Interrupt Status Queue Service Default CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 79 CS8900A Crystal LAN™ ISA Ethernet Controller tion Address (DA), Source Address (SA), Length field, Data field, pad bits (if necessary), and Frame Check Sequence (FCS, also called CRC). Figure 9 shows the format of a frame. The term "frame data" refers to all the data from the DA to the FCS that is to be transmitted, or that has been received. 5.2.1.3 Transfer The term "transfer" refers to moving data across the ISA bus, to and from the CS8900A. During receive operations, only frame data are transferred from the CS8900A to the host (the preamble and SFD are stripped off by the CS8900A’s MAC engine). The FCS may or may not be transferred, depending on the configuration. All transfers to and from the CS8900A are counted in bytes, but may be padded for double word alignment. 5.2.2 Receive Configuration After each reset, the CS8900A must be configured for receive operation. This can be done automatically using an attached EEPROM or by writing configuration commands to the CS8900A’s internal registers (see Section 3.4 on page 20). The items that must be configured include: • • • • which physical interface to use; which types of frames to accept; which receive events cause interrupts; and, how received frames are transferred. Packet Received Preamble and Start-of-Frame Delimiter Removed Frame PreProcessed Frame Temporarily Buffered No Use DMA? Yes Frame Held On Chip Frame DMAed to Host Memory Host Reads Frame from CS8900A Memory Host Reads Frame from Host Memory Figure 20. Frame Reception 5.2.1 Terminology: Packet, Frame, and Transfer The terms Packet, Frame, and Transfer are used extensively in the following sections. They are defined below for clarity: 5.2.1.1 Packet The term "packet" refers to the entire serial string of bits transmitted over an Ethernet network. This includes the preamble, Start-of-Frame Delimiter (SFD), Destination Address (DA), Source Address (SA), Length field, Data field, pad bits (if necessary), and Frame Check Sequence (FCS, also called CRC). Figure 9 shows the format of a packet. 5.2.1.2 Frame The term "frame" refers to the portion of a packet from the DA to the FCS. This includes the Destina- 5.2.2.1 Configuring the Physical Interface Configuring the physical interface consists of determining which Ethernet interface should be active, and enabling the receive logic for serial reception. This is done via the LineCTL register (Register 13) and is described in Table18. 5.2.2.2 Choosing which Frame Types to Accept The RxCTL register (Register 5) is used to determine which frame types will be accepted by the CS8900A (a receive frame is said to be "accepted" when the frame is buffered, either on chip or in host CIRRUS LOGIC PRODUCT DATASHEET 80 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 5.2.2.3 Selecting which Events Cause Interrupts The RxCFG register (Register 3) and the BufCFG register (Register B) are used to determine which receive events will cause interrupts to the host processor. Table 21 describes the interrupt enable (iE) bits in these registers. Register 3, RxCFG Bit 8 Bit Name Operation RxOKiE When set, there is an interrupt if a frame is received with valid length and CRC*. C CRCerroriE When set, there is an interrupt if a frame is received with bad CRC*. D RuntiE When set, there is an interrupt if a frame is received that is shorter than 64 bytes*. E ExtradataiE When set, there is an interrupt if a frame is received that is longer than 1518 bytes*. Table 20. Register 13, LineCTL Bit 6 8 Operation When set, reception enabled. When set, AUI selected (takes precedence over AutoAUI/10BT). 9 AutoAUI/10BT When set, automatic interface selection enabled. When both bits 8 and 9 are clear, 10BASE-T selected. E LoRx Squelch When set, receiver squelch level reduced by approximately 6 dB. Table 18. Physical Interface Configuration Bit Name SerRxON AUIonly memory via DMA). Table 19 describes the configuration bits in this register. Refer to Section 5.3 on page 86 for a detailed description of Destination Address filtering. Register 5, RxCTL Bit Bit Name Operation 6 IAHashA When set, Individual Address frames that pass the hash filter are accepted*. 7 Promis When set, all frames are accepted*. cuousA 8 RxOKA When set, frames with valid length and CRC and that pass the DA filter are accepted. 9 MulticastA When set, Multicast frames that pass the hash filter are accepted*. A IndividualA When set, frames with DA that matches the IA at PacketPage base + 0158h are accepted*. B Broad- When set, all broadcast frames are castA accepted*. C CRCerrorA When set, frames with bad CRC that pass the DA filter are accepted. D RuntA When set, frames shorter than 64 bytes that pass the DA filter are accepted. E ExtradataA When set, frames longer than 1518 bytes that pass the DA filter are accepted (only the first 1518 bytes are buffered). * Must also meet the criteria programmed into bits 8, C, D, and E. * Must also pass the DA filter before there is an interrupt. Register B, BufCFG Bit 7 Bit Name Operation RxDMAiE When set, there is an interrupt if one or more frames are transferred via DMA. RxMissiE When set, there is an interrupt if a frame is missed due to insufficient receive buffer space. Rx128iE When set, there is an interrupt after the first 128 bytes of receive data have been buffered. MissOvfloiE When set, there is an interrupt if the RxMISS counter overflows. RxDestiE When set, there is an interrupt after the DA of an incoming frame has been buffered. A B D F Table 21. Registers 3 and B Interrupt Configuration Table 19. Frame Acceptance Criteria 5.2.2.4 Choosing How to Transfer Frames The RxCFG register (Register 3) and the BusCTL register (Register 17) are used to determine how frames will be transferred to host memory, as described in Table 22. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 81 CS8900A Crystal LAN™ ISA Ethernet Controller Register 3, RxCFG Bit 7 9 Operation When set, Stream Transfer enabled. RxDMAonly When set, DMA slave operation used for all receive frames. AutoRX DMAE When set, Auto-Switch DMA enabled. BufferCRC When set, the received CRC is buffered. Register 17, BusCTL Bit B Bit Name DMABurst Operation When set, DMA operations hold the bus for up to approximately 28 µs. When clear, DMA operations are continuous. When set, DMA buffer size is 64 Kbytes. When clear, DMA buffer size is 16 Kbytes. Bit Name StreamE Receive Frame Destination Address Filter Check: - PromiscuousA? - IAHashA? - MulticastA? - IndividualA? - BroadcastA? A B Pass DA Filter? No Discard Frame Yes Generate Early Interrupts if Enabled (see next figure) D RxDMAsize Acceptance Filter Check: - RxOKA? - ExtradataA? - RuntA? - CRCerrorA? Table 22. Receive Frame Pre-Processing 5.2.3 Receive Frame Pre-Processing The CS8900A pre-processes all receive frames using a four step process: 1) Destination Address filtering; Yes 2) Early Interrupt Generation; 3) Acceptance filtering; and, 4) Normal Interrupt Generation. Figure 21 provides a diagram of frame pre-processing. 5.2.3.1 Destination Address Filtering All incoming frames are passed through the Destination Address filter (DA filter). If the frame’s DA passes the DA filter, the frame is passed on for further pre-processing. If it fails the DA filter, the frame is discarded. See Section 5.3 on page 86 for a more detailed description of DA filtering. Status of receive frame reported in RxEvent register, frame accepted into on-chip RAM Pass Accept. Filter? No Status of receive frame reported in RxEvent register, frame discarded. Generate Interrupts Check: - RxOKiE? - ExtradataiE? - CRCerroriE? - RuntiE? - RxDMAiE? Pre-Processing Complete Figure 21. Receive Frame Pre-Processing CIRRUS LOGIC PRODUCT DATASHEET 82 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 5.2.3.2 Early Interrupt Generation The CS8900A support the following two early interrupts that can be used to inform the host that a frame is being received: • RxDest: The RxDest bit (Register C, BufEvent, Bit F) is set as soon as the Destination Address (DA) of the incoming frame passes the DA filter. If the RxDestiE bit (Register B, BufCFG, bit F) is set, the CS8900A generates a corresponding interrupt. Once RxDest is set, the host is allowed to read the incoming frame's DA (the first 6 bytes of the frame). Rx128: The Rx128 bit (Register C, BufEvent, Bit B) is set as soon as the first 128 bytes of the incoming frame have been received. If the Rx128iE bit (Register B, BufCFG, bit B) is set, the CS8900A generates a corresponding interrupt. Once the Rx128 bit is set, the RxDest bit is cleared and the host is allowed to read the first 128 bytes of the incoming frame. The Rx128 bit is cleared by the host reading the BufEvent register (either directly or through the Interrupt Status Queue) or by the CS8900A detecting the incoming frame's End-of-Frame (EOF) sequence. CTL register (Register 5). If the receive frame passes the Acceptance filter, the frame is buffered, either on chip or in host memory via DMA. If the frame fails the Acceptance filter, it is discarded. The results of the Acceptance filter are reported in the RxEvent register (Register 4). 5.2.3.4 Normal Interrupt Generation The final step of pre-processing is to generate any enabled interrupts that are triggered by the incoming frame. Interrupt generation occurs when the entire frame has been buffered (up to the first 1518 bytes). For more information about interrupt generation, see Section 5.1 on page 78. 5.2.4 Held vs. DMAed Receive Frames All accepted frames are either held in on-chip RAM until processed by the host, or stored in host memory via DMA. A receive frame that is held in on-chip RAM is referred to as a held receive frame. A frame that is stored in host memory via DMA is a DMAed receive frame. This section describes buffering and transferring held receive frames. Section 5.4 on page 89 through Section 5.6 on page 95 describe DMAed receive frames. 5.2.5 Buffering Held Receive Frames If space is available, an incoming frame will be temporarily stored in on-chip RAM, where it awaits processing by the host. Although this receive frame now occupies on-chip memory, the CS8900A does not commit the memory space to it until one of the following two conditions is true: 1) The entire frame has been received and the host has learned about the frame by reading the RxEvent register (Register 4), either directly or through the ISQ. Or: 2) The frame has been partially received, causing either the RxDest bit (Register C, BufEvent, Bit F) or the Rx128 bit (Register C, BufEvent, Bit B) to become set, and the host has learned about • Like all Event bits, RxDest and Rx128 are set by the CS8900A whenever the appropriate event occurs. Unlike other Event bits, RxDest and Rx128 may be cleared by the CS8900A without host intervention. All other event bits are cleared only by the host reading the appropriate event register, either directly or through the Interrupt Status Queue (ISQ). (RxDest and Rx128 can also be cleared by the host reading the BufEvent register, either directly or through the Interrupt Status Queue). Figure 22 provides a diagram of the Early Interrupt process. 5.2.3.3 Acceptance Filtering The third step of pre-processing is to determine whether or not to accept the frame by comparing the frame with the criteria programmed into the RxDS271PP4 CIRRUS LOGIC PRODUCT DATASHEET 83 CS8900A Crystal LAN™ ISA Ethernet Controller Receive Frame Yes DA Filter Passed? No Discard Frame RxDest set. Host may read the DA (first 6 received bytes). Yes 64 bytes Received? No EOF Received? No Yes RxDest cleared and Runt set. If RuntA is set, frame accepted and Host may read frame. Yes 128 bytes Received? No Rx128 set and RxDest cleared. Host may read first 128 received bytes. EOF Received? No RxDest cleared and RxOK or CRCerror set, as appropriate. If RxOKA or CRCerrorA is set, frame accepted and Host may read frame. Yes EOF Received? No Rx128 cleared and RxOK, CRCerror or Extradata set, as appropriate. If ExtradataA, RxOKA or CRCerrorA is set, frame is accepted and Host may read frame. Yes Figure 22. Early Interrupt Generation CIRRUS LOGIC PRODUCT DATASHEET 84 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller the receive frame by reading the BufEvent register (Register C), either directly or through the ISQ. When the CS8900A commits buffer space to a particular held receive frame (termed a committed received frame), no data from subsequent frames can be written to that buffer space until the frame is freed from commitment. (The committed received frame may or may not have been received error free.) A received frame is freed from commitment by any one of the following conditions: 1) The host reads the entire frame sequentially in the order that it was received (first byte in, first byte out). Or: 2) The host reads part or none of the frame, and then issues a Skip command by setting the Skip_1 bit (Register 3, RxCFG, bit 6). Or: 3) The host reads part of the frame and then reads the RxEvent register (Register 5), either directly or through the ISQ, and learns of another receive frame. This condition is called an "implied Skip". Ensure that the host does not do “implied skips.” Both early interrupts are disabled whenever there is a committed receive frame waiting to be processed by the host. 5.2.6 Transferring Held Receive Frames The host can read-out held receive frames in Memory or I/O space. To transfer frames in Memory space, the host executes repetitive Move instructions (REP MOVS) from PacketPage base + 0404h. To transfer frames in I/O space, the host executes repetitive In instructions (REP IN) from I/O base + 0000h, with status and length preceding the frame. There are three possible ways that the host can learn the status of a particular frame. It can: 1) Read the Interrupt Status Queue; 2) Read the RxEvent register directly (Register4); or 3) Read the RxStatus register (PacketPage base + 0400h). 5.2.7 Receive Frame Visibility Only one receive frame is visible to the host at a time. The receive frame's status can be read from the RxStatus register (PacketPage base + 0400h), and its length can be read from the RxLength register (PacketPage base + 0402h). For more information about Memory space operation, see Section 4.9 on page 73. For more information about I/O space operation, see Section 4.10 on page 75. 5.2.8 Example of Memory Mode Receive Operation A common length for short frames is 64 bytes, including the 4-byte CRC. Suppose that such a frame has been received with the CS8900A configured as follows: • The BufferCRC bit (Register 3, RxCFG, Bit B) is set causing the 4-byte CRC to be buffered with the rest of the receive data. The RxOKA bit (Register 5, RxCTL, Bit 8) is set, causing the CS8900A to accept good frames (a good frame is one with legal length and valid CRC). The RxOKiE bit (Register 3, RxCFG, Bit 8) is set, causing an interrupt to be generated whenever a good frame is received. • • Then the transfer to the host would proceed as follows: 1) The CS8900A generates an RxOK interrupt to the host to signal the arrival of a good frame. 2) The host reads the ISQ (PacketPage base + CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 85 CS8900A Crystal LAN™ ISA Ethernet Controller 0120h) to assess the status of the receive frame and sees the contents of the RxEvent register (Register 4) with the RxOK bit (Bit 8) set. 3) The host reads the receive frame’s length from the RxLength register (PacketPage base + 0402h). 4) The host reads the frame data by executing 32 consecutive MOV instructions starting with PacketPage base + 0404h. The memory map of the 64-byte frame is given in Table 23. Memory Space Description of Data Stored in OnWord Offset chip RAM 0400h RxStatus Register (the host may skip reading 0400h since RxEvent was read from the ISQ.) 0402h RxLength Register (In this example, the length is 40h bytes. The frame starts at 0404h, and runs through 0443h.) 0404h to 0409h 6-byte Source Address. 040Ah to 040Fh 6-byte Destination Address. 0410h to 0411h 2-byte Length or Type Field. 0412h to 043Fh 46 bytes of data. 0440h CRC, bytes 1 and 2 0442h CRC, bytes 3 and 4 Table 23. Example Memory Map The byte count register resides at PacketPage base + 50h. Following an RxDest or Rx128 interrupt the register contains the number of bytes which are available to be read by the CPU. When the end of frame is reached, the count contains the final count value for the frame, including the allowance for the BufferCRC option. When this final count is read by the CPU the count register is set to zero. Therefore to read a complete frame using the byte count register, the register can be read and the data moved until a count of zero is detected. Then the RxEvent register can be read to determine the final frame status. The sequence is as follows: 1) At the start of a frame, the byte counter matches the incoming character counter. The byte counter will have an even value prior to the end of the frame. 2) At the end of the frame, the final count, including the allowance for the CRC (if the BufferCRC option is enabled), is held until the byte counter is read. 3) When a read of the byte counter returns a count of zero, the previous count was the final count. The count may now have an odd value. 4) RxEvent should be read to obtain a final status of the frame, followed by a Skip command to complete the operation. Note that all RxEvent’s should be processed before using the byte counter. The byte counter should be used following a BufEvent when RxDest or Rx128 interrupts are enabled. 5.3 Receive Frame Address Filtering The CS8900A is equipped with a Destination Address (DA) filter used to determine which receive frames will be accepted. (A receive frame is said to be "accepted" by the CS8900A when the frame data are placed in either on-chip memory, or in host 5.2.9 Receive Frame Byte Counter The receive frame byte counter describes the number of bytes received for the current frame. The counter is incremented in real time as bytes are received from the Ethernet. The byte counter can be used by the driver to determine how many bytes are available for reading out of the CS8900A. Maximum Ethernet throughput can be achieved by using I/O or memory modes, and by dedicating the CPU to reading this counter, and using the count to read the frame out of the CS8900A at the same time it is being received by the CS8900A from the Ethernet (parallel frame-reception and frame-read-out tasks). CIRRUS LOGIC PRODUCT DATASHEET 86 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller memory by DMA). The DA filter can be configured to accept the following frame types: 5.3.0.1 Individual Address Frames For all Individual Address frames, the first bit of the DA is a "0" (DA[0] = 0), indicating that the address is a Physical Address. The address filter accepts Individual Address frames whose DA matches the Individual Address (IA) stored at PacketPage base + 0158h, or whose hash-filtered DA matches one of the bits programmed into the Logical Address Filter (the hash filter is described later in this section). 5.3.0.2 Multicast Frames For Multicast Frames, the first bit of the DA is a "1" (DA[0] = 1), indicating that the frame is a Logical Address. The address filter accepts Multicast frames whose hash-filtered DA matches one of the bits programmed into the Logical Address Filter (the hash filter is described later is this section). As shown in Table 25, Broadcast Frames can be accepted as Multicast frames under a very specific set of conditions. 5.3.0.3 Broadcast Frames Frames with DA equal to FFFF FFFF FFFFh are broadcast frames. In addition, the CS8900A can be configured for Promiscuous Mode, in which case it will accept all receive frames, irrespective of DA. 5.3.1 Configuring the Destination Address Filter The DA filter is configured by programming five DA filter bits in the RxCTL register (Register 5): IAHashA, PromiscuousA, MulticastA, IndividualA, and BroadcastA. Four of these bits are associated with four status bits in the RxEvent register (Register 4): IAHash, Hashed, IndividualAdr, and Broadcast. The RxEvent register reports the results of the DA filter for a given receive frame. The bits associated with DA filtering are summarized below: Bit # 6 7 9 A B RxCTL Register 5 IAHashA PromiscuousA MulticastA IndividualA BroadcastA RxEvent Register 4 IAHash (used only if IAHashA = 1) Hashed IndividualAdr (used only if IndividualA = 1) Broadcast (used only if BroadcastA = 1) The IAHashA, MulticastA, IndividualA, and BroadcastA bits are used independently. As a result, many DA filter combinations are possible. For example, if MulticastA and IndividualA are set, then all frames that are either Multicast or Individual Address frames are accepted. The PromiscuousA bit, when set, overrides the other four DA bits, and allows all valid frames to be accepted. Table 24 summarizes the configuration options available for DA filtering. BroadcastA 0 Frames Accepted Individual Address frames with DA matching the IA at PacketPage base + 0158h Individual Address frames with DA that pass the hash filter (DA[0] must be “0”) Multicast frames with DA that pass the hash filter (DA[0] must be “1”) Broadcast frames All frames IAHashA 0 PromiscuousA MulticastA 0 0 IndividualA 1 1 0 0 0 0 0 0 1 0 0 0 X 0 1 0 X 0 X 1 X Table 24. DA Filtering Options CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 87 CS8900A Crystal LAN™ ISA Ethernet Controller It may become necessary for the host to change the Destination Address (DA) filter criteria without resetting the CS8900A. This can be done as follows: 1) Clear SerRxON (Register 13, LineCTL, Bit 6) to prevent any additional receive frames while the filter is being changed. 2) Modify the DA filter bits (B, A, 9, 7, and 6) in the RxCTL register. Modify the Logical Address Filter at PacketPage base + 0150h, if necessary. Modify the Individual Address at PacketPage base + 0158h, if necessary. 3) Set SerRxON to re-enable the receiver. Because the receiver has been disabled, the CS8900A will ignore frames while the host is changing the DA filter. 5.3.2 Hash Filter The hash filter is used to help determine which Multicast frames and which Individual Address frames should be accepted by the CS8900A. 5.3.2.1 Hash Filter Operation See Figure 23. The DA of the incoming frame is passed through the CRC logic, generating a 32-bit CRC value. The six most-significant bits of the CRC are latched into the 6-bit hash register (HR). The contents of the HR are passed through a 6-to64-bit decoder, asserting one of the decoder’s outputs. The asserted output is compared with a corresponding bit in the 64-bit Logical Address Filter, located at PacketPage base + 0150h. If the decoder output and the Logical Address Filter bit match, the frame passes the hash filter and the Hashed bit (Register 4, RxEvent, Bit 9) is set. If the two do not match, the frame fails the filter and the Hashed bit is clear. Whenever the hash filter is passed by a "good" frame, the RxOK bit (Register 4, RxEvent, Bit 8) is set and the bits in the HR are mapped to the Hash Table Index bits (Register 4, RxEvent, Bits A through F). 5.3.3 Broadcast Frame Hashing Exception Table 25 describes in detail the content of the RxEvent register for each output of the hash and address filters, and describes an exception to normal processing. That exception can occur when the hash-filter Broadcast address matches a bit in the Logical Address Filter. To properly account for this exception, the software driver should use the following test to determine if the RxEvent register contains a normal RxEvent (meaning bits E-A are used for Extra data, Runt, CRC Error, Broadcast and IndividualAdr) or a hash-table RxEvent (meaning bits F-A contain the Hash Table Index). If bit Hashed =0, or bit RxOK=0, or (bits F-A = 02h and the destination address is all ones) then RxEvent contains a normal RxEvent, else RxEvent contained a hash RxEvent. (MSB) Destination Address (DA) from incoming frame CS8900A CRC Logic 32-bit CRC value (LSB) 6-bit Hash Register (HR) [Hash Table Index] 6-to-64 decoder to Hashed bit 64-input OR gate 64-bit Logical Address Filter (LAF) Written into PacketPage base + 150h 1 64 Figure 23. Hash Filter Operation CIRRUS LOGIC PRODUCT DATASHEET 88 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Passes Address Erred Hash Type of Frame? Filter? Received Frame Individual no yes Address no no yes don’t care Multicast no yes Address no no yes don’t care Broadno yes cast (Note 6) Address no yes (Note 7) no no yes don’t care Contents of RxEvent Bits F-A Bit 9 Bit 8 Bit 6 Hashed RxOK IAHash 1 0 0 1 0 0 1 0 0 0 1 1 0 1 1 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 ExtraData ExtraData ExtraData ExtraData ExtraData ExtraData Hash Table Index Runt CRC Error Broadcast Runt CRC Error Broadcast Hash table index Runt CRC Error Broadcast Runt CRC Error Broadcast Runt CRC Error Broadcast (actual value X00010) Runt CRC Error Broadcast Individual Adr Individual Adr Individual Adr Individual Adr Individual Adr Individual Adr ExtraData Runt CRC Error Broadcast Individual Adr ExtraData Runt CRC Error Broadcast Individual Adr Notes: 6. Broadcast frames are accepted as Multicast frames if and only if all the following conditions are met simultaneously: a) the Logical Address Filter is programmed as: (MSB) 0000 8000 0000 0000h (LSB). Note that this LAF value corresponds to a Multicast Addresses of both all 1s and 03-00-00-00-00-01. b) the Rx Control Register (register 5) is programmed to accept IndividualA, MulticastA, RxOK-only, and the following address filters were enabled: IAHashA and BroadcastA. 7. NOT (Note 1). Table 25. Contents of RxEvent Upon Various Conditions 5.4 Receive DMA 5.4.1 Overview The CS8900A supports a direct interface to the host DMA controller allowing it to transfer receive frames to host memory via slave DMA. The DMA option applies only to receive frames, and not transmit operation. The CS8900A offers three possible Receive DMA modes: 1) Receive-DMA-only mode: All receive frames are transferred via DMA. 2) Auto-Switch DMA: DMA is used only when needed to help prevent missed frames. 3) StreamTransfer: DMA is used to minimize the number of interrupts to the host. This section provides a description of ReceiveDMA-only mode. Section 5.5 on page 92 describes Auto-Switch DMA and Section 5.6 on page 95 describes StreamTransfer. 5.4.2 Configuring the CS8900A for DMA Operation The CS8900A interfaces to the host DMA controller through one pair of the DMA request/acknowledge pins (see Section 3.2 on page 17 for a description of the CS8900A’s DMA interface). Four 16-bit registers are used for DMA operation. These are described in Table 26. Receive-DMA-only mode is enabled by setting the RxDMAonly bit (Register 3, RxCFG, Bit 9). Note: If the RxDMAonly bit and the AutoRxDMAE bit (Register 3, RxCFG, Bit A) are both set, then RxDMAonly takes precedence, and the CS8900A is in DMA mode for all receive frames. 5.4.3 DMA Receive Buffer Size In receive DMA mode, the CS8900A stores received frames (along with their status and length) in a circular buffer located in host memory space. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 89 CS8900A Crystal LAN™ ISA Ethernet Controller driving the selected DMA Request pin high. The DMA controller acknowledges the request by driving the DMA Acknowledge pin low. The CS8900A then transfers the contents of the RxStatus register (PacketPage base + 0400h) and the RxLength register (PacketPage base + 0402h) to host memory, followed by the frame data. If the DMABurst bit (Register 17, BusCTL, Bit B) is clear, the DMA Request pin remains high until the entire frame is transferred. If the DMABurst bit is set, the DMA Request pin (DMARQ) remains high for approximately 28 ms then goes low for approximately 1.3 ms to give the CPU and other peripherals access to the bus. When the transfer is complete, the CS8900A does the following: • • • • • updates the DMA Start-of-Frame register (PacketPage base + 0026h); updates the DMA Frame Count register (PacketPage base + 0028h); updates DMA Byte Count register (PacketPage base + 002Ah); sets the RxDMAFrame bit (Register C, BufEvent, Bit 7); and, deallocates the buffer space used by the transferred frame. PacketPage Register Description Address 0024h DMA Channel Number: DMA channel number (0, 1, or 2) that defines the DMARQ/DMACK pin pair used. 0026h DMA Start of Frame: 16-bit value that defines the offset from the DMA base address to the start of the most recently transferred received frame. 0028h DMA Frame Count: The lower 12 bits define the number of valid frames transferred via DMA since the last read-out of this register. The upper 4 bits are reserved and not applicable. 002Ah DMA Byte Count: Defines the number of bytes that have been transferred via DMA since the last read-out of this register. Table 26. Receive DMA Registers The size of the circular buffer is determined by the RxDMAsize bit (Register 17, BusCTL, Bit D). When RxDMAsize is clear, the buffer size is 16 Kbytes. When RxDMAsize is set, the buffer is 64 Kbytes. It is the host’s task to locate and keep track of the DMA receive buffer’s base address. The DMA Start-of-Frame register is the only circuit affected by this bit. APPLICATION NOTE: As a result of the PC architecture, DMA cannot occur across a 128K boundary in memory. Thus, the DMA buffer reserved for the CS8900A must not cross a 128K boundary in host memory if DMA operation is desired. Requesting a 64K, rather than a 16K buffer, increases the probability of crossing a 128K boundary. After the driver requests a DMA buffer, the driver must check for a boundary crossing. If the boundary is crossed, then the driver must disable DMA functionality. 5.4.4 Receive-DMA-Only Operation If space is available, an incoming frame is temporarily stored in on-chip RAM. When the entire frame has been received, pre-processed, and accepted, the CS8900A signals the DMA controller that a frame is to be transferred to host memory by In addition, if the RxDMAiE bit (Register B, BufCFG, Bit 7) is set, a corresponding interrupt occurs. When the host processes DMAed frames, it must read the DMA Frame Count register. Whenever a receive frame is missed (lost) due to insufficient receive buffer space, the RxMISS counter (Register 10) is incremented. A missed receive frame causes the counter to increment in either DMA or non-DMA modes. Note that when in DMA mode, reading the contents of the RxEvent register will return 0000h. Status CIRRUS LOGIC PRODUCT DATASHEET 90 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller information should be obtained from the DMA buffer. 5.4.5 Committing Buffer Space to a DMAed Frame Although a receive frame may occupy space in the host memory’s circular DMA buffer, the CS8900A’s Memory Manager does not commit the buffer space to the receive frame until the entire frame has been transferred and the host learns of the frame’s existence by reading the Frame Count register (PacketPage base + 0028h). When the CS8900A commits DMA buffer space to a particular DMAed receive frame (termed a committed received frame), no data from subsequent frames can be written to that buffer space until the committed received frame is freed from commitment. (The committed received frame may or may not have been received error free.) A committed DMAed receive frame is freed from commitment by any one of the following conditions: 1) The host rereads the DMA Frame Count register (PacketPage base + 0028h). 2) New frames have been transferred via DMA, and the host reads the BufEvent register (either directly or from the ISQ) and sees that the RxDMAFrame bit is set (this condition is termed an "implied Skip"). 3) The host issues a Reset-DMA command by setting the ResetRxDMA bit (Register 17, BusCTL, Bit 6). 5.4.6 DMA Buffer Organization When DMA is used to transfer receive frames, the DMA Start-of-Frame register (PacketPage Base + 0026h) defines the offset from the DMA base to the start of the most recently transferred received frame. Frames stored in the DMA buffer are transferred as words and maintain double-word (32-bit) alignment. Unfilled memory space between successive frames stored in the DMA buffer may result from double-word alignment. These "holes" may be 1, 2, or 3 bytes, depending on the length of the frame preceding the hole. 5.4.7 RxDMAFrame Bit The RxDMAFrame bit (Register C, BufEvent, bit 7) is controlled by the CS8900A and is set whenever the value in the DMA Frame Count register is non-zero. The host cannot clear RxDMAFrame by reading the BufEvent register (Register C). Table 27 summarizes the criteria used to set and clear RxDMAFrame. Non-Stream Transfer Mode Stream Transfer Mode (see Section 5.6) The RxDMAFrame bit is set at the end of a Stream Transfer cycle. To set RxD- The RxDMAFrame MAFrame bit is set whenever the DMA Frame Count register (PacketPage base + 0028h) transitions to non-zero. To Clear The DMA Frame The DMA Frame RxDMACount is zero. Count is zero. Frame Table 27. RxDMAFrame Bit 5.4.8 Receive DMA Example Without WrapAround Figure 24 shows three frames stored in host memory by DMA without wrap-around. 5.4.9 Receive DMA Operation for RxDMA-Only Mode In an RxDMAOnly mode, a system DMA moves all the received frames from the on-chip memory to an external 16- or 64-Kbyte buffer memory. The received frame must have passed the destination address filter, and must be completely received. Usually, the DMA receive frame interrupt (RxDMAiE, bit 7, Register B, BufCFG) is set so that the CS8900A generates an interrupt when a frame is transferred by DMA. Figure 25 shows how a DMA Receive Frame interrupt is processed. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 91 CS8900A Crystal LAN™ ISA Ethernet Controller In the interrupt service routine, the BufEvent register (register C), bit RxDMA Frame (bit 7) indicates that one or more receive frames were transferred using DMA. The software driver should maintain a pointer (e.g. PDMA_START) that will point to the beginning of a new frame. After the CS8900A is initialized and before any frame is received, pointer PDMA_START points to the beginning of the DMA buffer memory area. The first read of the DMA Frame Count, CDMA, commits the memory covered by the CDMA count, and the DMA cannot overwrite this committed space until the space is freed. The driver then processes the frames described by the CDMA count and makes a second read of the DMA frame count. This second read frees the buffer memory space described by the CDMA counter. During the frame processing, the software should advance the PDMA_START pointer. At the end of processing a frame, pointer PDMA_START should be made to align with a double-word boundary. The software remains in the loop until the DMA frame count read is zero. 5.5 Auto-Switch DMA 5.5.1 Overview The CS8900A supports a unique feature, AutoSwitch DMA, that allows it to switch between Memory or I/O mode and Receive DMA automatically. Auto-Switch DMA allows the CS8900A to realize the performance advantages of Memory or I/O mode while minimizing the number of missed frames that could result due to slow processing by the host. DMA Buffer Base Address RxStatus - Frame 1 RxLength - Frame 1 Frame 1 DMA Byte Count (PacketPage base + 012Ah) RxStatus - Frame 2 RxLength - Frame 2 Frame 2 "Holes" due to double-word alignment RxStatus - Frame 3 RxLength - Frame 3 DMA Start of Frame register (PacketPage base + 0126H) points here. Frame 3 Figure 24. Example of Frames Stored in DMA Buffer CIRRUS LOGIC PRODUCT DATASHEET 92 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Host Enters Interrupt Routine RxDMA Frame bit set? Yes No Process other events that caused interrupt Read the DMA frame Count (C DMA) (PacketPage base + 0028h) Yes CDMA =0? No Process the CDMA Frames Process other events that caused interrupt Figure 25. RxDMA Only Operation 5.5.2 Configuring the CS8900A for Auto-Switch DMA Auto-Switch DMA mode requires the same configuration as Receive-DMA-only mode, with one exception: the AutoRxDMAE bit (Register 3, RxCFG, Bit A) must be set, and the RxDMAonly bit (Register 3, RxCFG, Bit 9) must be clear (see Section 5.4 on page 89, Configuring the CS8900A for DMA Operation). In Auto-Switch DMA mode, the CS8900A operates in non-DMA mode if possible, only switching to slave DMA if necessary. Note that if the AutoRxDMAE bit and the RxDMAonly bit (Register 3, RxCFG, bit 9) are both set, the CS8900A uses DMA for all receive frames. 5.5.3 Auto-Switch DMA Operation Whenever a frame begins to be received in AutoSwitch DMA mode, the CS8900A checks to see if there is enough on-chip buffer space to store a maximum length frame. If there is, the incoming frame is pre-processed and buffered as normal. If there isn’t, the CS8900A’s MAC engine compares the frame’s Destination Address (DA) to the criteria programmed into the DA filter. If the incoming DA fails the DA filter, the frame is discarded. If the DA passes the DA filter, the CS8900A automatically switches to DMA mode and starts transferring the frame(s) currently being held in the on-chip buffer into host memory. This frees up buffer space for the incoming frame. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 93 CS8900A Crystal LAN™ ISA Ethernet Controller Figure 26 shows the steps the CS8900A goes through in determining when to automatically switch to DMA. frame to be transferred. Instead, the oldest noncommitted frame in the on-chip buffer is the first frame to use DMA. When DMA begins, any pending RxEvent reports in the Interrupt Status Queue are discarded because the host cannot process those events until the corresponding frames have been completely DMAed. Auto-Switch DMA works only on entire received frames. The CS8900A does not use Auto-Switch DMA to transfer partial frames. Also, when a frame has been committed (see Section 5.2.5 on page 83), the CS8900A will not switch to DMA mode until the committed frame has been transferred completely or skipped. After a complete frame has been moved to host memory, the CS8900A updates the DMA Start-ofFrame register (PacketPage base + 0126h), the DMA Frame Count register (PacketPage base + 0128h), and the DMA Byte Count register, then sets the RxDMAFrame bit (Register C, BufEvent, bit 7). If RxDMAiE (Register B, BufCFG, bit 7) is set, a corresponding interrupt occurs. 5.5.4 DMA Channel Speed vs. Missed Frames When the CS8900A starts DMA, the entire oldest, noncommitted frame must be placed in host memory before on-chip buffer space will be freed for the next incoming frame. If the oldest frame is relatively large, and the next incoming frame also large, the incoming frame may be missed, depending on the speed of the DMA channel. If this happens, the CS8900A will increment the RxMiss counter (Register 10) and clear any event reports (RxEvent and BufEvent) associated with the missed frame. 5.5.5 Exit From DMA When the CS8900A has activated receive DMA, it remains in DMA mode until all of the following are true: • The host processes all RxEvent and BufEvent reports pending in the ISQ. Packet Received Frame Passed the No DA filter? Yes Frame Discarded RxDMA only Bit=1 No Yes All Frames use DMA More Yes Buffer Space Available? No Frame Buffered in On-chip RAM AutoRxDMA Bit=1? Yes No Auto-Switch DMA Disabled Auto-Switch to DMA Figure 26. Conditions for Switching to DMA Whenever the CS8900A automatically enters DMA, at least one complete frame is already stored in the on-chip buffer. Because frames are transferred to the host in the same order as received (first in, first out), the beginning of the received frame that triggered the switch to DMA is not the first CIRRUS LOGIC PRODUCT DATASHEET 94 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller • The host reads a zero value from the DMA Frame Count register (PacketPage base + 0028h). The CS8900A is not in the process of transferring a frame via DMA. Register 5, RxCTL Register B, BufCFG Register Name Register 3, RxCFG • 5.5.6 Auto-Switch DMA Example Figure 27 shows how the CS8900A enters and exits Auto-Switch DMA mode. 5.6 StreamTransfer 5.6.1 Overview The CS8900A supports an optional feature, StreamTransfer, that can reduce the amount of CPU overhead associated with frame reception. StreamTransfer works during periods of high receive activity by grouping multiple receive events into a single interrupt, thereby reducing the number of receive interrupts to the host processor. During periods of peak loading, StreamTransfer will eliminate 7 out of every 8 interrupts, cutting interrupt overhead by up to 87%. 5.6.2 Configuring the CS8900A for StreamTransfer StreamTransfer is enabled by setting the StreamE bit along with either the AutoRxDMAE bit or the RxDMAonly bit in register Receiver Configuration (register 3). (StreamTransfer must not be selected unless either one of AutoRxDMAE or RxDMAonly is selected.)StreamTransfer only applies to "good" frames (frames of legal length with valid CRC). Therefore, the RxOKA bit and the RxOKiE bit must both be set. Finally, StreamTransfer works on whole packets and is not compatible with early interrupts. This requires that the RxDestiE bit and the Rx128iE bit both be clear. Table 28 summarizes how to configure the CS8900A for StreamTransfer. 5.6.3 StreamTransfer Operation When StreamTransfer is enabled, the CS8900A will initiate a StreamTransfer cycle whenever two Bit 7 8 9 or A 8 7 F B Bit Name StreamE RxOKiE RxDMAonly or AutoRxDMA RxOKA RxDMAiE RxDestiE Rx128iE Value 1 1 1 or 1 1 1 0 0 Table 28. Stream Transfer Configuration or more frames with the following characteristics are received: 1) pass the Destination Address filter; 2) are of legal length with valid CRC; and, 3) are spaced "back-to-back" (between 9.6 and 52 µs apart). During a StreamTransfer cycle the CS8900A does the following: • • • • • • • • delays the normal RxOK interrupt associated with the first receive frame; switches to receive DMA mode; transfers up to eight receive frames into host memory via DMA; updates the DMA Start-of-Frame register (PacketPage base + 0026h); updates the DMA Frame Count register (PacketPage base + 0028h); updates DMA Byte Count register (PacketPage base + 002Ah); sets the RxDMAFrame bit (Register C, BufEvent, Bit 7); and, generates an RxDMAFrame interrupt. 5.6.4 Keeping StreamTransfer Mode Active When the CS8900A initiates a StreamTransfer cycle, it will continue to execute cycles as long as the following conditions hold true: CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 95 CS8900A Crystal LAN™ ISA Ethernet Controller Enter Example Here Fra me 1 Fra me 2 Entering this example, the receive buffer is empty and the DMA Frame Count (PacketPage base + 0028h) is zero. Frame 1 received and completely stored in on-chip RAM. Frame 2 received and completely stored in on-chip RAM. At this point, the CS8900A does not have sufficient buffer space for another complete large frame (1518 bytes). Time Fra me 3 Frame 3 starts to be received and passes the DA filter. This activates Auto-Switch DMA. Frame 1 is placed in host memory via DMA freeing space for the incoming Frame 3. The CS8900A updates the DMA Frame Count, DMA Start of Frame and DMA Byte Count registers. It then sets the RxDMA DMAFrame bit and generates an interrupt. Receive DMA used during this time. Frame 2 is placed in host memory via DMA and the CS8900A updates the DMA registers. The host responds to the RxDMAFrame interrupt, and reads the Frame Count register, which is cleared when read. Since there are no receive interrupts pending, the CS8900A exits DMA (assumes Frame 3 is still coming in). Frame 3 is completely buffered in on-chip RAM, and awaits processing by the host. Exit Example Figure 27. Example of Auto-Switch DMA CIRRUS LOGIC PRODUCT DATASHEET 96 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller • • • all packets received are of legal length with valid CRC; each packet follows its predecessor by less than 52 ms; and, the DA of each packet passes the DA filter. 5.6.5 Example of StreamTransfer Figure 28 shows how four back-to-back frames, followed by five back-to-back frames, would be received without StreamTransfer. Figure 29 shows how the same sequence of frames would be received with StreamTransfer. 5.6.6 Receive DMA Summary Table 29 summarize the Receive DMA configuration options supported by the CS8900A. If any of these conditions are not met, the CS8900A exits StreamTransfer by generating RxOK and RxDMA interrupts. The CS8900A then returns to either Memory, I/O, or DMA mode, depending on configuration. RxDMAonly AutoRxDMAiE RxDMAiE RxOKiE CS8900A Configuration (Register 3, (Register 3, (Register B, (Register 3, RxCFG,Bit 9) RxCFG, Bit A) BufCFG, Bit 7) RxCFG, Bit 8) 1 NA 0 NA Receive DMA used for all receive frames, without interrupts. 1 NA 1 NA Receive DMA used for all receive frames, with BufEvent interrupts. 0 1 0 0 Auto-Switch DMA used if necessary, without interrupts. 0 1 1 1 Auto-Switch DMA used if necessary, with RxEvent and BufEvent interrupts possible. 0 0 NA NA Memory or I/O Mode only. Table 29. Receive DMA Configuration Options 4 Back-to-Back Frames T > 52 us 5 Back-to-Back Frames Interrupt Request 9 Interrupts for 9 "Good" Packets Time Figure 28. Receive Example Without Stream Transfer 4 Back-to-Back Frames T > 52 us 5 Back-to-Back Frames Interrupt Request 2 Interrupts for 9 "Good" Packets Time Figure 29. Receive DMA Configuration Options CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 97 CS8900A Crystal LAN™ ISA Ethernet Controller 5.7 Transmit Operation 5.7.1 Overview Packet transmission occurs in two phases. In the first phase, the host moves the Ethernet frame into the CS8900A’s buffer memory. The first phase begins with the host issuing a Transmit Command. This informs the CS8900A that a frame is to be transmitted and tells the chip when (i.e. after 5, 381, or 1021 bytes have been transferred or after the full frame has been transferred to the CS8900A) and how the frame should be sent (i.e. with or without CRC, with or without pad bits, etc.). The host follows the Transmit Command with the Transmit Length, indicating how much buffer space is required. When buffer space is available, the host writes the Ethernet frame into the CS8900A’s internal memory, using either Memory or I/O space. In the second phase of transmission, the CS8900A converts the frame into an Ethernet packet then transmits it onto the network. The second phase begins with the CS8900A transmitting the preamble and Start-of-Frame delimiter as soon as the proper number of bytes has been transferred into its transmit buffer (5, 381, 1021 bytes or full frame, depending on configuration). The preamble and Startof-Frame delimiter are followed by the data transferred into the on-chip buffer by the host (Destination Address, Source Address, Length field and LLC data). If the frame is less than 64 bytes, including CRC, the CS8900A adds pad bits if configured to do so. Finally, the CS8900A appends the proper 32-bit CRC value. 5.7.2 Transmit Configuration After each reset, the CS8900A must be configured for transmit operation. This can be done automatically using an attached EEPROM, or by writing configuration commands to the CS8900A’s internal registers (see Section 3.4 on page 20). The items that must be configured include which physical interface to use and which transmit events cause interrupts. 98 5.7.2.1 Configuring the Physical Interface Configuring the physical interface consists of determining which Ethernet interface should be active (10BASE-T or AUI), and enabling the transmit logic for serial transmission. Configuring the Physical Interface is accomplished via the LineCTL register (Register 13) and is described in Table 30. Register 13, LineCTL Bit 7 8 Operation When set, transmission enabled. When set, AUI selected (takes precedence over AutoAUI/10BT). When clear, 10BASE-T selected. AutoAUI/10BT When set, automatic interface selection enabled. Mod When set, the modified backoff BackoffE algorithm is used. When clear, the standard backoff algorithm is used. 2-part When set, two-part deferral is DefDis disabled. Table 30. Physical Interface Configuration Bit Name SerTxON AUIonly 9 B D Note that the CS8900A transmits in 10BASE-T mode when no link pulses are being received only if bit DisableLT is set in register Test Control (Register 19). 5.7.2.2 Selecting which Events Cause Interrupts The TxCFG register (Register 7) and the BufCFG register (Register B) are used to determine which transmit events will cause interrupts to the host processor. Tables 31 and 32 describe the interrupt enable (iE) bits in these registers. 5.7.3 Changing the Configuration When the host configures these registers it does not need to change them for subsequent packet transmissions. If the host does choose to change the TxCFG or BufCFG registers, it may do so at any time. The effects of the change are noticed immediately. That is, any changes in the Interrupt Enable (iE) bits may affect the packet currently being transmitted. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Bit 7), and then set it when the changes are complete. 5.7.4 Enabling CRC Generation and Padding Whenever the host issues a Transmit Request command, it must indicate whether or not the Cyclic Redundancy Check (CRC) value should be appended to the transmit frame, and whether or not pad bits should be added (if needed). Table 33 describes how to configure the CS8900A for CRC generating and padding. Register 9, TxCMD Inhibit CRC (Bit C) 0 1 0 1 TxPad Operation Dis (Bit D) 0 Pad to 64 bytes if necessary (including CRC). 0 Send a runt frame if specified length less than 60 bytes. 1 Pad to 60 bytes if necessary (without CRC). 1 Send runt if specified length less than 64. The CS8900A will not transmit a frame that is less than 3 bytes. Register 7, TxCFG Bit 6 Bit Name Loss-ofCRSiE Operation When set, there is an interrupt whenever the CS8900A fails to detect Carrier Sense after transmitting the preamble (applies to the AUI only). When set, there is an interrupt whenever there is an SQE error. When set, there is an interrupt whenever a frame is transmitted successfully.. When set, there is an interrupt whenever a late collision is detected. When set, there is an interrupt whenever there is a jabber condition. When set, there is an interrupt whenever there is a collision. When set, there is an interrupt whenever the CS8900A attempts to transmit a single frame 16 times. 7 8 SQErroriE TxOKiE 9 Out-ofwindowiE JabberiE A B F AnycolliE 16colliE Table 31. Transmitting Interrupt Configuration Register B, BufCFG Bit 8 Bit Name Rdy4TxiE Operation When set, there is an interrupt whenever buffer space becomes available for a transmit frame (used with a Transmit Request). When set, there is an interrupt whenever the CS8900A runs out of data after transmit has started. When set, there is an interrupt whenever the TxCol counter overflows. Table 33. CRC and Paddling Configuration 9 TxUnder runiE TxCol OvfloiE 5.7.5 Individual Packet Transmission Whenever the host has a packet to transmit, it must issue a Transmit Request to the CS8900A consisting of the following three operations in the exact order shown: 1) The host must write a Transmit Command to the TxCMD register (PacketPage base + 0144h). The contents of the TxCMD register may be read back from the TxCMD register (Register 9). 2) The host must write the frame’s length to the TxLength register (PacketPage base + 0146h). 3) The host must read the BusST register (Register 18) The information written to the TxCMD register tells the CS8900A how to transmit the next frame. C Table 32. Transmit Interrupt Configuration If the host chooses to change bits in the LineCTL register after initialization, the ModBackoffE bit and any receive related bit (LoRxSquelch, SerRxON) may be changed at any time. However, the Auto AUI/10BT and AUIonly bits should not be changed while the SerTxON bit is set. If any of these three bits are to be changed, the host should first clear the SerTxON bit (Register 13, LineCTL, CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 99 CS8900A Crystal LAN™ ISA Ethernet Controller The bits that must be programmed in the TxCMD register are described in Table 34. Register 9, TxCMD Bit 6 7 clear clear Bit Name Tx Start Operation (memory base+ 0144h in memory mode and I/O base + 0004h in I/O mode). 2) The host writes the transmit frame length to the TxLength register (memory base + 0146h in memory mode and I/O base + 0006h in I/O mode). If the transmit length is erroneous, the command is discarded and the TxBidErr bit (Register 18, BusST, Bit 7) is set. 3) The host reads the BusST register. This read is performed in memory mode by reading Register 18, at memory base + 0138h. In I/O mode, the host must first set the PacketPage Pointer at the correct location by writing 0138h to the PacketPage Pointer Port (I/O base + 000Ah). The host can then read the BusST register from the PacketPage Data Port (I/O base + 000Ch). 4) After reading the register, the Rdy4TxNOW bit (Bit 8) is checked. If the bit is set, the frame can be written. If the bit is clear, the host must continue reading the BusST register (Register 18) and checking the Rdy4TxNOW bit (Bit 8) until the bit is set. When the CS8900A is ready to accept the frame, the host transfers the entire frame from host memory to CS8900A memory using “REP” instruction (REP MOVS starting at memory base + 0A00h in memory mode, and REP OUT to Receive/Transmit Data Port (I/O base + 0000h) in I/O mode). 5.7.7 Transmit in Interrupt Mode In interrupt mode, Rdy4TxiE bit (Register B, BufCFG, Bit 8) must be set for transmit operation. Transmit operation occurs in the following order and is shown in Figure 31. 1) The host bids for frame storage by writing the Transmit Command to the TxCMD register (memory base + 0144h in memory mode and I/O base + 0004h in I/O mode). 2) The host writes the transmit frame length to the TxLength register (memory base + 0146h in memory mode and I/O base + 0006h in I/O DS271PP4 clear set set clear set set 8 9 C D Start preamble after 5 bytes have been transferred to the CS8900A. Start preamble after 381 bytes have been transferred to the CS8900A. Start preamble after 1021 bytes have been transferred to the CS8900A. Start preamble after entire frame has been transferred to the CS8900A. Force When set, the CS8900A discards any frame data currently in the transmit buffer. Onecoll When set, the CS8900A will not attempt to retransmit any packet after a collision. InhibitCRC When set, the CS8900A does not append the 32-bit CRC value to the end of any transmit packet. TxPadDis When set, the CS8900A will not add pad bits to short frames. Table 34. Tx Command Configuration For each individual packet transmission, the host must issue a complete Transmit Request. Furthermore, the host must write to the TxCMD register before each packet transmission, even if the contents of the TxCMD register does not change. The Transmit Request described above may be in either Memory Space or I/O Space. 5.7.6 Transmit in Poll Mode In poll mode, Rdy4TxiE bit (Register B, BufCFG, Bit 8) must be clear (Interrupt Disabled). The transmit operation occurs in the following order and is shown in Figure 30. 1) The host bids for frame storage by writing the Transmit Command to the TxCMD register 100 CIRRUS LOGIC PRODUCT DATASHEET CS8900A Crystal LAN™ ISA Ethernet Controller Enter Packet Transmit Process Exit: can’t Issue command Yes Note: Issuing a command at this point will cause previous transmit frame to be lost. Is TxCMD pending? No Host Writes Transmit Command to the TxCMD Register Host Writes Transmit Frame Length to the TxLength Register Transmit Request Host Reads the BusST Register (Register 18) Rdy4 TxNOW bit = 1? Yes No Polling Loop CS8900A Commits Buffer Space to Transmit Frame Host Writes Transmit Frame to CS8900A CS8900A Transmits Frame Exit Transmit Process Figure 30. Transmit Operation in Polling Mode mode). If the transmit length is erroneous, the command is discarded and the TxBidErr, bit 7, in BusST register is set. 3) The host reads the BusST register. This read is performed in memory mode by reading Register 18, at memory base + 0138h. In I/O mode, the host must first set the PacketPage Pointer at CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 101 CS8900A Crystal LAN™ ISA Ethernet Controller the correct location by writing 0138h to the PacketPage Pointer Port (I/O base + 000Ah), it than can read the BusST register from the PacketPage Data Port (I/O base + 000Ch).After reading the register, the Rdy4TxNOW bit is checked. If the bit is set, the frame can be written to CS8900A memory. If Rdy4TxNOW is clear, the host will have to wait for the CS8900A buffer memory to become available at which time the host will be interrupted. On interrupt, the host enters the interrupt service routine and reads ISQ register (Memory base + 0120h in memory mode and I/O base + 0008h in I/O) and checks the Rdy4Tx bit (bit 8). If Rdy4Tx is clear then the CS8900A waits for the next interrupt. If Rdy4Tx is set, then the CS8900A is ready to accept the frame. 4) When the CS8900A is ready to accept the frame, the host transfers the entire frame from host memory to CS8900A memory using REP instruction (REP MOVS to memory base + 0A00h in memory mode, and REP OUT to Receive/Transmit Data Port (I/O base + 0000h) in I/O mode). 5.7.8 Completing Transmission When the CS8900A successfully completes transmitting a frame, it sets the TxOK bit (Register 8, TxEvent, Bit 8). If the TxOKiE bit (Register 7, TxCFG, bit 8) is set, the CS8900A generates a corresponding interrupt. 5.7.9 Rdy4TxNOW vs. Rdy4Tx The Rdy4TxNOW bit (Register 18, BusST, bit 8) is used to tell the host that the CS8900A is ready to accept a frame for transmission. This bit is used during the Transmit Request process or after the Transmit Request process to signal the host that space has become available when interrupts are not being used (i.e. the Rdy4TxiE bit (Register B, BufCFG, Bit 8) is not set). Also, the Rdy4Tx bit is used with interrupts and requires the Rdy4TxiE bit be set. 102 Figure 30 provides a diagram of error free transmission without collision. 5.7.10 Committing Buffer Space to a Transmit Frame When the host issues a transmit request, the CS8900A checks the length of the transmit frame to see if there is sufficient on-chip buffer space. If there is, the CS8900A sets the Rdy4TxNOW bit. If not, and the Rdy4TxiE bit is set, the CS8900A waits for buffer space to free up and then sets the Rdy4Tx bit. If Rdy4TxiE is not set, the CS8900A sets the Rdy4TxNOW bit when space becomes available. Even though transmit buffer space may be available, the CS8900A does not commit buffer space to a transmit frame until all of the following are true: 1) The host must issues a Transmit Request; 2) The Transmit Request must be successful; and, 3) Either the host reads that the Rdy4TxNOW bit (Register 18, BusST, Bit 8) is set, or the host reads that the Rdy4Tx bit (Register C, BufEvent, bit 8) is set. If the CS8900A commits buffer space to a particular transmit frame, it will not allow subsequent frames to be written to that buffer space as long as the transmit frame is committed. After buffer space is committed, the frame is subsequently transmitted unless any of the following occur: 1) The host completely writes the frame data, but transmission failed on the Ethernet line. There are three such failures, and these are indicated by three transmit error bits in the TxEvent register (Register 8): 16coll, Jabber, or Out-ofWindow. Or: 2) The host aborts the transmission by setting the Force (Register 9, TxCMD, bit 8) bit. In this case, the committed transmit frame, as well as CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller Enter Packet Transmit Process Exit: can’t Issue command Yes Note: Issuing a command at this point will cause previous transmit frame to be lost. Is TxCMD pending? No Host Writes Transmit Command to the TxCMD Register Host Writes Transmit Frame Length to the TxLength Register Transmit Request Host Reads the BusST Register (Register 18) Rdy4 TxNOW bit = 1? No Yes Exit WAIT-for-interrupt Host Enters Interrupt Routine Host Reads ISQ No Rdy4Tx bit = 1? Yes CS8900A Commits Buffer Space to Transmit Frame Process other events that caused interrupt Host Writes Transmit Frame to CS8900A CS8900A Transmits Frame Exit Transmit Process Figure 31. Transmit Operation in Interrupt Mode any yet-to-be-transmitted frames queued in the on-chip memory, are cleared and not transmitted. The host should make TxLength = 0 when using the Force bit. Or: 3) There is a transmit under-run, and the TxUnderrun bit (Register C, BufEvent, Bit 9) is set. Successful transmission is indicated when the TxOK bit (Register 8, TxEvent, Bit 8) is set. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 103 CS8900A Crystal LAN™ ISA Ethernet Controller 5.7.11 Transmit Frame Length The length of the frame transmitted is determined by the value written into the TxLength register (PacketPage base + 0146h) during the Transmit Request. The length of the transmit frame may be modified by the configuration of the TxPadDis bit (Register 9, TxCMD, Bit D) and the InhibitCRC bit (Register 9, TxCMD, Bit C). Table 35 defines how these bits affect the length of the transmit frame. In addition, it shows which frames the CS8900A will send. 5.8 Full duplex Considerations The driver should not bid to transmit a long frame (i.e., a frame greater than 118 bytes) if the prior transmit frame is still being transmitted. The end of the transmission of this prior frame is indicated by a TxOK bit being set in the TxEvent register (register 8). 5.9 Auto-Negotiation Considerations When the CS8900A is connected to an auto negotiation hub, and if auto-media detection is selected (bits 8 and 9 of register 13), then the CS8900A may not auto-select the 10BASE-T media. The cause of this situation is described in the following paragraphs. The original IEEE 802.3 specification requires the MAC to wait until 4 valid link-pulses are received before asserting Link-OK. Any time an invalid link-pulse is received, the count is restarted. When auto-negotiation occurs, a transmitter sends FLPs (auto-negotiation Fast Link Pulses) bursts instead of the original IEEE 802.3 NLP (Normal Link Pulses). If the hub is attempting to auto-negotiate with the CS8900A, the CS8900A will never get more than 1 "valid" link pulse (valid NLP). This is not a problem if the CS8900A is already sending link-pulses, because when the hub receives NLPs from the CS8900A, the hub is required to stop sending FLPs and start sending NLPs. The NLP transmitted by the hub will put the CS8900A into Link-OK. However, if the CS8900A is in Auto-Switch mode, the CS8900A will never send any link-pulses, and the hub will never change from sending FLPs to sending NLPs. Register 9, TxCMD Host specified transmit length at 0146h (in bytes) TxPad- InhibitCRC 3 < TxLength < 60 60 < TxLength < 1514 < TxLength < 1518 TxLength > 1518 Dis (Bit D) (Bit C) 1514 0 0 Pad to 60 and add Send frame and add Will not send Will not send CRC CRC [Normal Mode] 0 1 Pad to 60 and Send frame without Send frame without Will not send send without CRC CRC CRC 1 0 Send without Send frame and add Will not send Will not send pads, and add CRC CRC 1 1 Send without Send frame without Send frame without Will not send pads and without CRC CRC CRC Notes: 8. If the TxPadDis bit is clear and InhibitCRC is set and the CS8900A is commanded to send a frame of length less than 60 bytes, the CS8900A pads. 9. The CS8900A will not send a frame with TxLength less than 3 bytes. Table 35. Transmit Frame Length CIRRUS LOGIC PRODUCT DATASHEET 104 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 6.0 TEST MODES 6.0.1 Loopback & Collision Diagnostic Tests Internal and external Loopback and Collision tests can be used to verify the CS8900A’s functionality when configured for either 10BASE-T or AUI operation. 6.0.2 Internal Tests Internal tests allow the major digital functions to be tested, independent of the analog functions. During these tests, the Manchester encoder is connected to the decoder. All digital circuits are operational, and the transmitter and receiver are disabled. 6.0.3 External Tests External test modes allow the complete chip to be tested without connecting it directly to an Ethernet network. 6.0.4 Loopback Tests During Loopback tests, the internal Carrier Sense (CRS) signal, used to detect collisions, is ignored, allowing packet reception during packet transmission. 6.0.5 10BASE-T Loopback and Collision Tests 10BASE-T Loopback and Collision Tests are controlled by two bits in the Test Control register: FDX (Register 19, TestCTL, Bit E) and ENDECloop (Register 19, TestCTL, Bit 9). Table 36 describes these tests. 6.0.6 AUI Loopback and Collision Tests AUI Loopback and Collision tests are controlled by two bits in the Test Control register: AUIloop (Register 19, TestCTL, Bit A) and ENDECloop (Register 19, TestCTL, Bit 9). Table 37 describes these tests. Test Mode 10BASE-T Internal Loopback 10BASE-T Internal Collision 10BASE-T External Loopback 10BASE-T External Collision FDX 1 0 ENDECloop 1 1 1 0 Description of Test Transmit a frame and verify that the frame is received without error. Transmit frames and verify that collisions are detected and that the internal counters function properly. After 16 collisions, verify that 16coll (Register 8, TxEvent, Bit F) is set. Connect TXD+ to RXD+ and TXD- to RXD-. Transmit a frame and verify that the frame is received without error. Connect TXD+ to RXD+ and TXD- to RXD-. Transmit frames and verify that collisions are detected and that internal counters function properly. After 16 collisions, verify that 16coll (Register 8, TxEvent, Bit F) is set. 0 0 Table 36. 10BASE-T Loopback and Collision Tests Test Mode AUI Internal Loopback AUI External Loopback AUI Collision AUIloop ENDECloop Description of Test 1 1 Transmit a frame and verify that the frame is received without error. 1 0 Connect DO+ to DI+ and DO- to DI-. Transmit a frame and verify that the frame is received without error (since there is no collision signal, an SQE error will occur). Start transmission and observe DO+/DO- activity. Input a 10 MHz sine wave to Cl+/Cl- pins and observe collisions. 0 0 Table 37. AUI Loopback and Collision Tests CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 105 CS8900A Crystal LAN™ ISA Ethernet Controller 6.1 Boundary Scan Boundary Scan test mode provides an easy and efficient board-level test for verifying that the CS8900A has been installed properly. Boundary Scan will check to see if the orientation of the chip is correct, and if there are any open or short circuits. Boundary Scan is controlled by the TEST pin. When TEST is high, the CS8900A is configured for normal operation. When TEST is low, the following occurs: • • the CS8900A enters Boundary Scan test mode and stays in this mode as long as TEST is low; the CS8900A goes through an internal reset and remains in internal reset as long as TEST is low; the AEN pin, normally the ISA bus Address Enable, is redefined to become the Boundary Scan shift clock input; and all digital outputs and bi-directional pins are placed in a high-impedance state (this electrically isolates the CS8900A digital outputs from the rest of the circuit board). The following is a list of output pins and bi-directional pins that are tested during the Output Cycle: Pin Name Pin # Pin Name Pin # ELCS 2 INTRQ1 31 EECS 3 INTRQ0 32 EESK 4 IOCS16 33 EEDataOut 5 MEMCS16 34 DMARQ2 11 INTRQ3 35 DMARQ1 13 IOCHRDY 64 DMARQ0 15 SD0 - SD7 65-68, 71-74 CSOUT 17 BSTATUS 78 SD08-SD15 27-24, 21-18 LINKLED 99 INTRQ2 30 LANLED 100 Table 38. The output pins not included in this test are: Pin Name DO+ DOTXD+ Pin # 83 84 87 Pin Name TXDRES XTAL2 Pin # 88 93 98 • • Table 39. For Boundary Scan to be enabled, AEN must be low before TEST is driven low. A complete Boundary Scan test is made up of two separate cycles. The first cycle, known as the Output Cycle, tests all digital output pins and all bi-directional pins. The second cycle, known as the Input Cycle, tests all digital input pins and all bi-directional pins. 6.1.1 Output Cycle During the Output Cycle, the falling edge of AEN causes each of the 17 digital output pins and each of the 17 bi-directional pins to be driven low, one at a time. The cycle begins with LINKLED and advances in order counterclockwise around the chip through all 34 pins. This test is referred to as a "walking 0" test. 6.1.2 Input Cycle During the Input Cycle, the falling edge of AEN causes the state of each selected pin to be transferred to EEDataOut (that is, EEDataOut will be high or low depending on the input level of the selected pin). This cycle begins with SLEEP and advances clockwise through each of 33 input pins (all digital input pins except for AEN) and each of the 17 bi-directional pins, one pin at a time. The following is a list of input pins and bi-directional pins that are tested during the Input Cycle: Pin Name Pin # ELCS 2 EEDataIn 6 CHIPSEL 7 DMACK2 12 DMACK1 14 DMACK0 16 SD08-SD15 27-24, 21-18 MEMW 28 MEMR 29 Pin Name Pin # SBHE 36 SA0 - SA11 37-48 REFRESH 49 SA12 - SA19 50-54, 58-60 IOR 61 IOW 62 SD0 - SD7 65-68, 71-74 RESET 75 SLEEP 77 Table 40. CIRRUS LOGIC PRODUCT DATASHEET 106 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller The input pins not included in this test are: Pin Name AEN TEST Dl+ DlCl+ Pin # 63 76 79 80 81 Pin Name ClRXD+ RXDXTAL1 Pin # 82 91 92 97 Table 41. After the Input Cycle is complete, one more cycle of AEN returns all digital output pins and bi-directional pins to a high-impedance state. 6.1.3 Continuity Cycle The combination of a complete Output Cycle, a complete Input Cycle, and an additional AEN cycle is called a Continuity Cycle. Each Continuity Cycle lasts for 85 AEN clock cycles. The first Continuity Cycle can be followed by additional Continuity Cycles by keeping TEST low and continuing to cycle AEN. When TEST is driven high, the CS8900A exits Boundary Scan mode and AEN is again used as the ISA-bus Address Enable. Figure 32 shows a complete Boundary Scan Continuity Cycle. Figure 33 shows Boundary Scan timing. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 107 CS8900A Crystal LAN™ ISA Ethernet Controller Not in Boundary Scan Test Mode TEST switches low (AEN must be low) ENTER BOUNDARY SCAN: CS8900A resets, all digital output pins and bi-directional pins enter High-Z state, and AEN becomes shift clock AEN switches high AEN switches low OUTPUT CYCLE 34 cycles AEN switches high Selected output goes low AEN switches low INPUT CYCLE 50 cycles AEN switches high Selected input copied out to the EEDataOut pin AEN switches low AEN switches high All digital output pins and bi-directional pins enters High-Z state TEST switches high EXIT BOUNDARY SCAN: AEN becomes ISA bus Address Enable Figure 32. Boundary Scan Continuity Cycle CIRRUS LOGIC PRODUCT DATASHEET 108 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller TESTSEL AEN Outputs All outputs tri-state LINKLED LANLED low low BSTATUS low EEDataOut SLEEP copied out RESET copied out ELCS copied out OUTPUTS Hi Z OUTPUT TEST 34 Clocks COMPLETE CONTINUITY CYCLE 85 Clocks INPUT TEST 50 Clocks OUTPUTS Hi Z 1 clock Figure 33. Boundary Scan Timing CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 109 CS8900A Crystal LAN™ ISA Ethernet Controller 7.0 CHARACTERISTICS/SPECIFICATIONS - COMMERCIAL 7.1 ABSOLUTE MAXIMUM RATINGS (AVSS, DVSS = 0 V, all voltages with respect to 0 V.) Parameter Power Supply Input Current Analog Input Voltage Digital Input Voltage Ambient Temperature Storage Temperature WARNING: Normal operation is not guaranteed at these extremes. Symbol Digital Analog (Except Supply Pins) DVDD AVDD Min -0.3 -0.3 -0.3 -0.3 Max 6.0 6.0 ±10.0 (AVDD+) + 0.3 (DVDD) + 0.3 +125 +150 Unit V V mA V V °C °C (Power Applied) -55 -65 7.2 RECOMMENDED OPERATING CONDITIONS (AVSS, DVSS = 0 V, all voltages with respect to 0 V.) Parameter 5.0V Power Supply CS8900A-CQ & -IQ 3.3V Power Supply CS8900A-CQ3 & -IQ3 Digital Analog Digital Analog Symbol DVDD AVDD DVDD AVDD Min 4.75 4.75 3.135 3.135 0 -40 Max 5.25 5.25 3.465 3.465 +70 +85 Unit V V V V °C °C Operating Ambient Temperature CS8900A-CQ & -CQ3 Operating Ambient Temperature CS8900A-IQ & -IQ3 TA TA 7.3 DC CHARACTERISTICS (TA = 25 °C; VDD = 5.0 V or VDD = 3.3V) Parameter Crystal (when using external clock - square wave) XTAL1 Input Low Voltage XTAL1 Input High Voltage XTAL1 Input Low Current XTAL1 Input High Current Power Supply Power Supply Current while Active 5.0V Power Supply Current while Active 3.3V Hardware Standby Mode Current Hardware Suspend Mode Current Software Suspend Mode Current IDD IDD (Note 1) IDDSTNDBY (Note 1) IDDHWSUS (Note 1) IDDSWSUS 55 45 1.0 100 1.0 mA mA mA µA mA VIXH VIXH IIXL IIXH -0.5 3.5 -40 0.4 DVDD Symbol Min Max Unit V V µA µA + 0.5 40 Notes: 1. With digital outputs connected to CMOS loads. CIRRUS LOGIC PRODUCT DATASHEET 110 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller DC CHARACTERISTICS (Continued) Parameter Digital Inputs and Outputs Output Low Voltage IOL = 24 mA IOL = 10 mA IOL = 4 mA IOH = -12 mA IOH = -2 mA (Note 2) OD24, B24, O24ts OD10 B4w, O4 B24 B4w, O24ts, O4 VOL 2.4 2.4 -10 -20 VIL VIH IL I Iw 10BASE-T Interface Transmitter Differential Output Voltage (Peak) Receiver Normal Squelch Level (Peak) Receiver Low Squelch Level (LoRxSquelch bit set) AUI Interface Transmitter Differential Output Voltage (DO+/DO- Peak) Transmitter Undershoot Voltage Transmitter Differential Idle Voltage (DO+/DO- Peak) Receiver Squelch Level (DI+/DI- Peak) VAOD VAODU VIDLE VAISQ ±0.45 180 ±1.2 100 40 300 V mV mV mV VOD VISQ VSQL 2.2 300 125 2.8 525 290 V mV mV -10 -20 10 10 2.4 0.4 0.4 0.4 0.425 10 10 0.8 V V µA V V V V V V µA Symbol Min Typ Max Unit Output Low Voltage (all outputs) VDD = 3.3V and TA = >70°C Output High Voltage Output Leakage Current VOL VOH ILL 0 ≤ VOUT ≤ VCC OD24, OD10, B24, O24ts B4w I, Iw I, Iw 0 ≤ VIN ≤ VCC Input Low Voltage Input High Voltage Input Leakage Current Notes: 2. OD24: Open Drain Output with 24 mA Drive OD10: Open Drain Output with 10 mA Drive B24: Bi-Directional with 3-State Output and 24 mA Drive B4w: Bi-Directional with 3-State Output, Internal Weak Pullup, and 4 mA Drive O24ts: 3-State Output with 24 mA Drive O4: Output with 4 mA Drive I: Input Iw: Input with Internal Weak Pullup CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 111 CS8900A Crystal LAN™ ISA Ethernet Controller 7.4 SWITCHING CHARACTERISTICS (TA = 25 °C; VDD = 5.0 V or VDD = 3.3V) Parameter 16-Bit I/O Read, IOCHRDY Not Used Address, AEN, SBHE active to IOCS16 low Address, AEN, SBHE active to IOR active IOR low to SD valid Address, AEN, SBHE hold after IOR inactive IOR inactive to active IOR inactive to SD 3-state 16-Bit I/O Read, With IOCHRDY IOR active to IORCHRDY inactive IOCHRDY low pulse width IOCHRDY active to SD valid tIOR7 tIOR8 tIOR9 125 30 175 0 ns ns ns tIOR1 tIOR2 tIOR3 tIOR4 tIOR5 tIOR6 10 0 35 30 35 135 ns ns ns ns ns ns Symbol Min Typ Max Unit DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE Valid Address t IOR1 t IOR4 IN IOCS16 t IOR2 IOR t IOR3 SD [15:0] t IOR6 Valid Data OUT t IOR5 IN OUT Figure 34. 16-Bit I/O Read, IOCHRDY not used DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE IOCS16 Valid Address IN OUT IOR t IOR7 IOCHRDY t IOR8 SD [15:0] t IOR9 Valid Data IN OUT OUT Figure 35. 16-Bit I/O Read, with IOCHRDY CIRRUS LOGIC PRODUCT DATASHEET 112 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 16-Bit Memory Read, IOCHRDY Not Used SA [19:0], SBHE, CHIPSEL, active to MEMCS16 low Address, SBHE, CHIPSEL active to MEMR active MEMR low to SD valid Address, SBHE, CHIPSEL hold after MEMR inactive MEMR inactive to SD 3-state MEMR inactive to active 16-Bit Memory Read, With IOCHRDY MEMR low to IOCHRDY inactive IOCHRDY low pulse width IOCHRDY active to SD valid tMEMR7 tMEMR8 tMEMR9 125 35 DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL Valid Address IN Symbol tMEMR1 tMEMR2 tMEMR3 tMEMR4 tMEMR5 tMEMR6 Min 10 0 35 Typ 30 - Max 30 135 175 0 Unit ns ns ns ns ns ns ns ns ns t MEMR1 MEMCS16 t MEMR2 MEMR t MEMR3 SD [15:0] Valid Data t MEMR5 OUT t MEMR4 t MEMR6 OUT IN Figure 36. 16-Bit Memory Read, IOCHRDY not used DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL MEMCS16 Valid Address IN OUT MEMR t MEMR7 IOCHRDY t MEMR8 SD [15:0] Valid Data IN OUT OUT t MEMR9 Figure 37. 16-Bit Memory Read, with IOCHRDY CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 113 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter DMA Read DMACKx active to IOR active AEN active to IOR active IOR active to Data Valid IOR inactive to SD 3-state IOR n-1 high to DMARQx inactive DMACKx, AEN hold after IOR high 16-Bit I/O Write Address, AEN, SBHE valid to IOCS16 low Address, AEN, SBHE valid to IOW low IOW pulse width SD hold after IOW high IOW low to SD valid IOW inactive to active Address hold after IOW high tIOW1 tIOW2 tIOW3 tIOW4 tIOW5 tIOW6 tIOW7 tDMA5 DMARQx tDMA1 DMACKx tDMA6 IN IN tDMA2 IOR tDMA3 SD[15:0] Valid Data Symbol tDMAR1 tDMAR2 tDMAR3 tDMAR4 tDMAR5 tDMAR6 Min 60 10 20 20 110 0 35 0 Typ 30 - Max 135 20 Unit ns ns ns ns ns ns DIRECTION: IN or OUT of chip OUT 35 10 - ns ns ns ns ns ns ns AEN IORn-1 tDMA4 Valid Data Valid Data IORn IN OUT Figure 38. 16-Bit DMA Read DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE IOCS16 t IOW2 IOW Valid Address t IOW1 t IOW7 IN OUT t IOW3 t IOW6 IN t IOW5 SD [15:0] Valid Data In t IOW4 IN Figure 39. 16-Bit I/O Write CIRRUS LOGIC PRODUCT DATASHEET 114 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 16-Bit Memory Write Address, SBHE, CHIPSEL valid to MEMCS16 low Address, SBHE, CHIPSEL valid to MEMW low MEMW pulse width MEMW low to SD valid SD hold after MEMW high Address hold after MEMW inactive MEMW inactive to active 10BASE-T Transmit TXD Pair Jitter into 100 Ω Load TXD Pair Return to ≤ 50 mV after Last Positive Transition TXD Pair Positive Hold Time at End of Packet tTTX1 tTTX2 tTTX3 250 8 4.5 ns µs ns tMEMW1 tMEMW2 tMEMW3 tMEMW4 tMEMW5 tMEMW6 tMEMW7 20 110 0 0 35 30 40 ns ns ns ns ns ns ns Symbol Min Typ Max Unit DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL MEMCS16 t MEMW2 MEMW Valid Address IN t MEMW1 t MEMW6 OUT t MEMW3 t MEMW7 IN SD [15:0] t MEMW4 t MEMW5 Valid Data In IN Figure 40. 16-Bit Memory Write tTTX2 TXD± tTTX1 tTTX3 Figure 41. 10BASE-T Transmit CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 115 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 10BASE-T Receive Allowable Received Jitter at Bit Cell Center Allowable Received Jitter at Bit Cell Boundary Carrier Sense Assertion Delay Invalid Preamble Bits after Assertion of Carrier Sense Carrier Sense Deassertion Delay 10BASE-T Link Integrity First Transmitted Link Pulse after Last Transmitted Packet Time Between Transmitted Link Pulses Width of Transmitted Link Pulses Minimum Received Link Pulse Separation Maximum Received Link Pulse Separation Last Receive Activity to Link Fail (Link Loss Timer) tLN1 tLN2 tLN3 tLN4 tLN5 tLN6 8 8 60 2 25 50 16 16 100 24 24 200 7 150 150 ms ms ns ms ms ms tTRX1 tTRX2 tTRX3 tTRX4 tTRX5 1 540 270 ±13.5 ±13.5 2 ns ns ns bits ns Symbol Min Typ Max Unit RXD± tTRX1 tTRX3 Carrier Sense (internal) tTRX4 tTRX2 tTRX5 Figure 42. 10BASE-T Receive t LN1 t LN2 t LN3 TXD± t LN4 t LN5 RXD± t LN6 LINKLED Figure 43. 10BASE-T Link Integrity CIRRUS LOGIC PRODUCT DATASHEET 116 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter AUI Transmit DO Pair Rise and Fall Times DO Pair Jitter at Bit Cell Center DO Pair Positive Hold Time at Start of Idle DO Pair Return to ≤ 40 mVp after Last Positive Transition AUI Receive DI Pair Rise and Fall Time Allowable Bit Cell Center and Boundary Jitter in Data Carrier Sense Assertion Delay Invalid Preamble Bits after Carrier Sense Asserts Carrier Sense Deassertion Delay AUI Collision CI Pair Cycle Time CI Pair Rise and Fall Times CI Pair Return to Zero from Last Positive Transition Collision Assertion Delay Collision Deassertion Delay 0 DO± t ATX1 t ATX1 t ATX2 Symbol tATX1 tATX2 tATX3 tATX4 tARX1 tARX2 tARX3 tARX4 tARX5 tACL1 tACL2 tACL3 tACL4 tACL5 0 0 Min 200 1 150 85 160 50 150 1 Typ 240 100 t ATX4 t ATX3 Max 5 0.5 8.0 10 ±18 2 250 115 10 200 300 Unit ns ns ns µs ns ns ns bits ns ns ns ns ns ns Figure 44. AUI Transmit 0 DI± t ARX1 t ARX3 t ARX1 t ARX4 1 t ARX2 0 1 t ARX5 Carrier Sense (Internal) Figure 45. AUI Receive CI± t ACL1 t ACL4 Collision (Internal) t ACL3 t ACL2 t ACL2 t ACL5 Figure 46. AUI Collision CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 117 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter External Boot PROM Access Address active to MEMR MEMR active to CSOUT low MEMR inactive to CSOUT high EEPROM EESK Setup time relative to EECS EECS/ELCS_b Setup time wrt ↑ EESK EEDataOut Setup time wrt ↑ EESK EEDataOut Hold time wrt ↑ EESK EEDataIn Hold time wrt ↑ EESK EECS Hold time wrt ↓ EESK Min EECS Low time during programming tSKS tCCS tDIS tDIH tDH tCSH tCS 100 250 250 500 10 100 1000 ns ns ns ns ns ns ns tBPROM1 tBPROM2 tBPROM3 20 35 40 ns ns ns Symbol Min Typ Max Unit CS SA [19:0] t BPROM1 MEMR t BPROM2 t BPROM3 CSOUT Figure 47. External Boot PROM Access EESK t SKS t CSH t CS EECS t CSS t DIS t DIH EEData Out t DH EEData In (Read) Figure 48. EEPROM CIRRUS LOGIC PRODUCT DATASHEET 118 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 7.5 10BASE-T WIRING CS8900A TXD + TXD Rt 68 pF 1: 2 TD + 1 Rt 0.01 µ F TD - 2 RJ45 RXD+ 1:1 0.01 µ F Rr Rr RD + + RXD- 3 RD - 6 • • • If a center tap transformer is used on the RXD+ and RXD- inputs, replace the pair of Rr resistors with a single 2xRr resistor. The Rt and Rr resistors are ±1% tolerance. The CS8900A supports 100, 120, and 150 Ω unshielded twisted pair cables. The proper values of Rt and Rr, for a given cable impedance, are shown below: Cable Impedance (Ω) 100 120 150 Rt (Ω) 24.3 30.1 37.4 Rr (Ω) 49.9 60.4 75 • Note: for 3.3V operation the turns ratio on TXD+ and TXD- is 1:2.5, rt is 8Ω for 100Ω cable and the 68pF cap changes to 560pF. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 119 CS8900A Crystal LAN™ ISA Ethernet Controller 7.6 AUI WIRING CS8900A 1:1 DB15 3 10 4 DO + Tx DO - 1:1 CI + + Col CI 0.01 uF 39.2 Ω 39.2 Ω 2 9 1:1 DI + + Rx DI 0.01 uF 39.2 Ω 39.2 Ω 5 12 13 6 +12 V 7.7 QUARTZ CRYSTAL REQUIREMENTS (If a 20 MHz quartz crystal is used, it must meet the following specifications) Parameter Parallel Resonant Frequency Resonant Frequency Error (CL = 18 pF) Resonant Frequency Change Over Operating Temperature Crystal Capacitance Motional Crystal Capacitance Series Resistance Shunt Capacitance Min -50 -40 Typ 20 0.022 Max +50 +40 18 50 7 Unit MHz ppm ppm pF pF Ohm pF CIRRUS LOGIC PRODUCT DATASHEET 120 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 8.0 CHARACTERISTICS/SPECIFICATIONS - INDUSTRIAL 8.1 ABSOLUTE MAXIMUM RATINGS (AVSS, DVSS = 0 V, all voltages with respect to 0 V.) Parameter Power Supply Input Current Analog Input Voltage Digital Input Voltage Ambient Temperature Storage Temperature WARNING: Normal operation is not guaranteed at these extremes. Symbol Digital Analog (Except Supply Pins) DVDD AVDD Min -0.3 -0.3 -0.3 -0.3 Max 6.0 6.0 ±10.0 (AVDD+) + 0.3 (DVDD) + 0.3 +125 +150 Unit V V mA V V °C °C (Power Applied) -55 -65 8.2 RECOMMENDED OPERATING CONDITIONS (AVSS, DVSS = 0 V, all voltages with respect to 0 V.) Parameter 5.0V Power Supply CS8900A-CQ & -IQ 3.3V Power Supply CS8900A-CQ3 & -IQ3 Digital Analog Digital Analog Symbol DVDD AVDD DVDD AVDD Min 4.75 4.75 3.135 3.135 0 -40 Max 5.25 5.25 3.465 3.465 +70 +85 Unit V V V V °C °C Operating Ambient Temperature CS8900A-CQ & -CQ3 Operating Ambient Temperature CS8900A-IQ & -IQ3 TA TA 8.3 DC CHARACTERISTICS (TA = 25 °C; VDD = 5.0 V or VDD = 3.3V) Parameter Crystal (when using external clock - square wave) XTAL1 Input Low Voltage XTAL1 Input High Voltage XTAL1 Input Low Current XTAL1 Input High Current Power Supply Power Supply Current while Active 5.0V Power Supply Current while Active 3.3V Hardware Standby Mode Current Hardware Suspend Mode Current Software Suspend Mode Current IDD IDD (Note 1) IDDSTNDBY (Note 1) IDDHWSUS (Note 1) IDDSWSUS 55 45 1.0 100 1.0 mA mA mA µA mA VIXH VIXH IIXL IIXH -0.5 3.5 -40 0.4 DVDD Symbol Min Max Unit V V µA µA + 0.5 40 Notes: 1. With digital outputs connected to CMOS loads. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 121 CS8900A Crystal LAN™ ISA Ethernet Controller DC CHARACTERISTICS (Continued) Parameter Digital Inputs and Outputs Output Low Voltage IOL = 24 mA IOL = 10 mA IOL = 4 mA IOH = -12 mA IOH = -2 mA (Note 2) OD24, B24, O24ts OD10 B4w, O4 B24 B4w, O24ts, O4 VOL 2.4 2.4 -10 -20 VIL VIH IL I Iw 10BASE-T Interface Transmitter Differential Output Voltage (Peak) Receiver Normal Squelch Level (Peak) Receiver Low Squelch Level (LoRxSquelch bit set) AUI Interface Transmitter Differential Output Voltage (DO+/DO- Peak) Transmitter Undershoot Voltage Transmitter Differential Idle Voltage (DO+/DO- Peak) Receiver Squelch Level (DI+/DI- Peak) VAOD VAODU VIDLE VAISQ ±0.45 180 ±1.2 100 40 300 V mV mV mV VOD VISQ VSQL 2.2 300 125 2.8 525 290 V mV mV -10 -20 10 10 2.4 0.4 0.4 0.4 0.425 10 10 0.8 V V µA V V V V V V µA Symbol Min Typ Max Unit Output Low Voltage (all outputs) VDD = 3.3V and TA = >70°C Output High Voltage Output Leakage Current VOL VOH ILL 0 ≤ VOUT ≤ VCC OD24, OD10, B24, O24ts B4w I, Iw I, Iw 0 ≤ VIN ≤ VCC Input Low Voltage Input High Voltage Input Leakage Current Notes: 2. OD24: Open Drain Output with 24 mA Drive OD10: Open Drain Output with 10 mA Drive B24: Bi-Directional with 3-State Output and 24 mA Drive B4w: Bi-Directional with 3-State Output, Internal Weak Pullup, and 4 mA Drive O24ts: 3-State Output with 24 mA Drive O4: Output with 4 mA Drive I: Input Iw: Input with Internal Weak Pullup CIRRUS LOGIC PRODUCT DATASHEET 122 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 8.4 SWITCHING CHARACTERISTICS (TA = 25 °C; VDD = 5.0 V or VDD = 3.3V) Parameter 16-Bit I/O Read, IOCHRDY Not Used Address, AEN, SBHE active to IOCS16 low Address, AEN, SBHE active to IOR active IOR low to SD valid Address, AEN, SBHE hold after IOR inactive IOR inactive to active IOR inactive to SD 3-state 16-Bit I/O Read, With IOCHRDY IOR active to IORCHRDY inactive IOCHRDY low pulse width IOCHRDY active to SD valid tIOR7 tIOR8 tIOR9 125 30 175 0 ns ns ns tIOR1 tIOR2 tIOR3 tIOR4 tIOR5 tIOR6 10 0 35 30 35 135 ns ns ns ns ns ns Symbol Min Typ Max Unit DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE Valid Address t IOR1 t IOR4 IN IOCS16 t IOR2 IOR t IOR3 SD [15:0] t IOR6 Valid Data OUT t IOR5 IN OUT Figure 49. 16-Bit I/O Read, IOCHRDY not used DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE IOCS16 Valid Address IN OUT IOR t IOR7 IOCHRDY t IOR8 SD [15:0] t IOR9 Valid Data IN OUT OUT Figure 50. 16-Bit I/O Read, with IOCHRDY CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 123 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 16-Bit Memory Read, IOCHRDY Not Used SA [19:0], SBHE, CHIPSEL, active to MEMCS16 low Address, SBHE, CHIPSEL active to MEMR active MEMR low to SD valid Address, SBHE, CHIPSEL hold after MEMR inactive MEMR inactive to SD 3-state MEMR inactive to active 16-Bit Memory Read, With IOCHRDY MEMR low to IOCHRDY inactive IOCHRDY low pulse width IOCHRDY active to SD valid tMEMR7 tMEMR8 tMEMR9 125 35 DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL Valid Address IN Symbol tMEMR1 tMEMR2 tMEMR3 tMEMR4 tMEMR5 tMEMR6 Min 10 0 35 Typ 30 - Max 30 135 175 0 Unit ns ns ns ns ns ns ns ns ns t MEMR1 MEMCS16 t MEMR2 MEMR t MEMR3 SD [15:0] Valid Data t MEMR5 OUT t MEMR4 t MEMR6 OUT IN Figure 51. 16-Bit Memory Read, IOCHRDY not used DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL MEMCS16 Valid Address IN OUT MEMR t MEMR7 IOCHRDY t MEMR8 SD [15:0] Valid Data IN OUT OUT t MEMR9 Figure 52. 16-Bit Memory Read, with IOCHRDY CIRRUS LOGIC PRODUCT DATASHEET 124 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter DMA Read DMACKx active to IOR active AEN active to IOR active IOR active to Data Valid IOR inactive to SD 3-state IOR n-1 high to DMARQx inactive DMACKx, AEN hold after IOR high 16-Bit I/O Write Address, AEN, SBHE valid to IOCS16 low Address, AEN, SBHE valid to IOW low IOW pulse width SD hold after IOW high IOW low to SD valid IOW inactive to active Address hold after IOW high tIOW1 tIOW2 tIOW3 tIOW4 tIOW5 tIOW6 tIOW7 tDMA5 DMARQx tDMA1 DMACKx tDMA6 IN IN tDMA2 IOR tDMA3 SD[15:0] Valid Data Symbol tDMAR1 tDMAR2 tDMAR3 tDMAR4 tDMAR5 tDMAR6 Min 60 10 20 20 110 0 35 0 Typ 30 - Max 135 20 Unit ns ns ns ns ns ns DIRECTION: IN or OUT of chip OUT 35 10 - ns ns ns ns ns ns ns AEN IORn-1 tDMA4 Valid Data Valid Data IORn IN OUT Figure 53. 16-Bit DMA Read DIRECTION: IN or OUT of chip SA [15:0], AEN, SBHE IOCS16 t IOW2 IOW Valid Address t IOW1 t IOW7 IN OUT t IOW3 t IOW6 IN t IOW5 SD [15:0] Valid Data In t IOW4 IN Figure 54. 16-Bit I/O Write CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 125 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 16-Bit Memory Write Address, SBHE, CHIPSEL valid to MEMCS16 low Address, SBHE, CHIPSEL valid to MEMW low MEMW pulse width MEMW low to SD valid SD hold after MEMW high Address hold after MEMW inactive MEMW inactive to active 10BASE-T Transmit TXD Pair Jitter into 100 Ω Load TXD Pair Return to ≤ 50 mV after Last Positive Transition TXD Pair Positive Hold Time at End of Packet tTTX1 tTTX2 tTTX3 250 8 4.5 ns µs ns tMEMW1 tMEMW2 tMEMW3 tMEMW4 tMEMW5 tMEMW6 tMEMW7 20 110 0 0 35 30 40 ns ns ns ns ns ns ns Symbol Min Typ Max Unit DIRECTION: IN or OUT of chip SA [19:0], SBHE, CHIPSEL MEMCS16 t MEMW2 MEMW Valid Address IN t MEMW1 t MEMW6 OUT t MEMW3 t MEMW7 IN SD [15:0] t MEMW4 t MEMW5 Valid Data In IN Figure 55. 16-Bit Memory Write tTTX2 TXD± tTTX1 tTTX3 Figure 56. 10BASE-T Transmit CIRRUS LOGIC PRODUCT DATASHEET 126 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter 10BASE-T Receive Allowable Received Jitter at Bit Cell Center Allowable Received Jitter at Bit Cell Boundary Carrier Sense Assertion Delay Invalid Preamble Bits after Assertion of Carrier Sense Carrier Sense Deassertion Delay 10BASE-T Link Integrity First Transmitted Link Pulse after Last Transmitted Packet Time Between Transmitted Link Pulses Width of Transmitted Link Pulses Minimum Received Link Pulse Separation Maximum Received Link Pulse Separation Last Receive Activity to Link Fail (Link Loss Timer) tLN1 tLN2 tLN3 tLN4 tLN5 tLN6 8 8 60 2 25 50 16 16 100 24 24 200 7 150 150 ms ms ns ms ms ms tTRX1 tTRX2 tTRX3 tTRX4 tTRX5 1 540 270 ±13.5 ±13.5 2 ns ns ns bits ns Symbol Min Typ Max Unit RXD± tTRX1 tTRX3 Carrier Sense (internal) tTRX4 tTRX2 tTRX5 Figure 57. 10BASE-T Receive t LN1 t LN2 t LN3 TXD± t LN4 t LN5 RXD± t LN6 LINKLED Figure 58. 10BASE-T Link Integrity CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 127 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter AUI Transmit DO Pair Rise and Fall Times DO Pair Jitter at Bit Cell Center DO Pair Positive Hold Time at Start of Idle DO Pair Return to ≤ 40 mVp after Last Positive Transition AUI Receive DI Pair Rise and Fall Time Allowable Bit Cell Center and Boundary Jitter in Data Carrier Sense Assertion Delay Invalid Preamble Bits after Carrier Sense Asserts Carrier Sense Deassertion Delay AUI Collision CI Pair Cycle Time CI Pair Rise and Fall Times CI Pair Return to Zero from Last Positive Transition Collision Assertion Delay Collision Deassertion Delay 0 DO± t ATX1 t ATX1 t ATX2 Symbol tATX1 tATX2 tATX3 tATX4 tARX1 tARX2 tARX3 tARX4 tARX5 tACL1 tACL2 tACL3 tACL4 tACL5 0 0 Min 200 1 150 85 160 50 150 1 Typ 240 100 t ATX4 t ATX3 Max 5 0.5 8.0 10 ±18 2 250 115 10 200 300 Unit ns ns ns µs ns ns ns bits ns ns ns ns ns ns Figure 59. AUI Transmit 0 DI± t ARX1 t ARX3 t ARX1 t ARX4 1 t ARX2 0 1 t ARX5 Carrier Sense (Internal) Figure 60. AUI Receive CI± t ACL1 t ACL4 Collision (Internal) t ACL3 t ACL2 t ACL2 t ACL5 Figure 61. AUI Collision CIRRUS LOGIC PRODUCT DATASHEET 128 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller SWITCHING CHARACTERISTICS (Continued) Parameter External Boot PROM Access Address active to MEMR MEMR active to CSOUT low MEMR inactive to CSOUT high EEPROM EESK Setup time relative to EECS EECS/ELCS_b Setup time wrt ↑ EESK EEDataOut Setup time wrt ↑ EESK EEDataOut Hold time wrt ↑ EESK EEDataIn Hold time wrt ↑ EESK EECS Hold time wrt ↓ EESK Min EECS Low time during programming tSKS tCCS tDIS tDIH tDH tCSH tCS 100 250 250 500 10 100 1000 ns ns ns ns ns ns ns tBPROM1 tBPROM2 tBPROM3 20 35 40 ns ns ns Symbol Min Typ Max Unit CS SA [19:0] t BPROM1 MEMR t BPROM2 t BPROM3 CSOUT Figure 62. External Boot PROM Access EESK t SKS t CSH t CS EECS t CSS t DIS t DIH EEData Out t DH EEData In (Read) Figure 63. EEPROM CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 129 CS8900A Crystal LAN™ ISA Ethernet Controller 8.5 10BASE-T WIRING CS8900A TXD + TXD Rt 68 pF 1: 2 TD + 1 Rt 0.01 µ F TD - 2 RJ45 RXD+ 1:1 0.01 µ F Rr Rr RD + + RXD- 3 RD - 6 • • • If a center tap transformer is used on the RXD+ and RXD- inputs, replace the pair of Rr resistors with a single 2xRr resistor. The Rt and Rr resistors are ±1% tolerance. The CS8900A supports 100, 120, and 150 Ω unshielded twisted pair cables. The proper values of Rt and Rr, for a given cable impedance, are shown below: Cable Impedance (Ω) 100 120 150 Rt (Ω) 24.3 30.1 37.4 Rr (Ω) 49.9 60.4 75 • Note: for 3.3V operation the turns ratio on TXD+ and TXD- is 1:2.5, rt is 8Ω for 100Ω cable and the 68pF cap changes to 560pF. CIRRUS LOGIC PRODUCT DATASHEET 130 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 8.6 AUI WIRING CS8900A 1:1 DB15 3 10 4 DO + Tx DO - 1:1 CI + + Col CI 0.01 uF 39.2 Ω 39.2 Ω 2 9 1:1 DI + + Rx DI 0.01 uF 39.2 Ω 39.2 Ω 5 12 13 6 +12 V 8.7 QUARTZ CRYSTAL REQUIREMENTS (If a 20 MHz quartz crystal is used, it must meet the following specifications) Parameter Parallel Resonant Frequency Resonant Frequency Error (CL = 18 pF) Resonant Frequency Change Over Operating Temperature Crystal Capacitance Motional Crystal Capacitance Series Resistance Shunt Capacitance Min -50 -40 Typ 20 0.022 Max +50 +40 18 50 7 Unit MHz ppm ppm pF pF Ohm pF CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 131 CS8900A Crystal LAN™ ISA Ethernet Controller 9.0 PHYSICAL DIMENSIONS 100L TQFP PACKAGE DRAWING E E1 D D1 1 e ∝ A1 L INCHES MIN MAX --0.063 0.002 0.006 0.007 0.011 0.618 0.642 0.547 0.555 0.618 0.642 0.547 0.555 0.016 0.024 0.018 0.030 ∝ 0.000° 7.000° * Nominal pin pitch is 0.50 mm DIM A A1 B D D1 E E1 e* L Controlling dimension is mm. JEDEC Designation: MS026 MILLIMETERS MIN MAX --1.60 0.05 0.15 0.17 0.27 15.70 16.30 13.90 14.10 15.70 16.30 13.90 14.10 0.40 0.60 0.45 0.75 0.00° 7.00° B A CIRRUS LOGIC PRODUCT DATASHEET 132 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 10.0 GLOSSARY OF TERMS 10.1 Acronyms AUI CRC CS CSMA/CD DA EEPROM EOF FCS FDX IA IPG ISA LA LLC MAC MAU MIB RX SA SFD SNMP SOF SQE TDR TX UTP Attachment Unit Interface Cyclic Redundancy Check Carrier Sense Carrier Sense Multiple Access with Collision Detection Destination Address Electrically Erasable Programmable Read Only Memory End-of-Frame Frame Check Sequence Full Duplex Individual Address Inter-Packet Gap Industry Standard Architecture ISA Latchable Address Bus (LA17 - LA23) Logical Link Control Media Access Control Medium Attachment Unit Management Information Base Receive Source Address or ISA System Address Bus (SA0 - SA19) Start-of-Frame Delimiter Simple Network Management Protocol Start-of-Frame Signal Quality Error Time Domain Reflectometer Transmit Unshielded Twisted Pair CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 133 CS8900A Crystal LAN™ ISA Ethernet Controller 10.2 Definitions Cyclic Redundancy Check The method used to compute the 32-bit frame check sequence (FCS). Frame Check Sequence The 32-bit field at the end of a frame that contains the result of the cyclic redundancy check (CRC). Frame An Ethernet string of data bits that includes the Destination Address (DA), Source Address (SA), optional length field, Logical Link Control data (LLC data), pad bits (if needed) and Frame Check Sequence (FCS). Individual Address The specific Ethernet address assigned to a device attached to the Ethernet media. Inter-Packet Gap Time interval between packets on the Ethernet. Minimum interval is 9.6 µs. Jabber A condition that results when a Ethernet node transmits longer than between 20 ms and 150 ms. Packet An Ethernet string of data bits that includes the Preamble, Start-of-Frame Delimiter (SFD), Destination Address (DA), Source Address (SA), optional length field, Logical Link Control data (LLC data), pad bits (if needed) and Frame Check Sequence (FCS). A packet is a frame plus the Preamble and SFD. Receive Collision A receive collision occurs when the CI+/CI- inputs are active while a packet is being received. Applies only to the AUI. Signal Quality Error When transmitting on the AUI, the MAC expects to see a collision signal on the CI+/CI- pair within 64 bit times after the end of a transmission. If no collision occurs, there is said to be an "SQE error". Applies only to the AUI. Slot Time Time required for an Ethernet Frame to cross a maximum length Ethernet network. One Slot Time equals 512 bit times. Transmit Collision A transmit collision occurs when the receive inputs, RXD+/RXD- (10BASE-T) or CI+/CI(AUI) are active while a packet is being transmitted. CIRRUS LOGIC PRODUCT DATASHEET 134 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 10.3 Acronyms Specific to the CS8900A BufCFG Buffer Configuration - Register B BufEvent Buffer Event - Register C BusCTL Bus Control - Register 17 BusST Bus State - Register 18 ENDEC Manchester encoder/decoder ISQ Interrupt Status Queue - register 0 LineCTL Ethernet Line Control - Register 13 LineST Ethernet Line Status - Register 14 RxCFG Receive Configuration - Register 3 RxCTL Receive Control - Register 5 RxEvent Receive Event - Register 4 SelfCTL Self Control - Register 15 SelfST Self Status - Register 16 TestCTL Test Control - Register 19 TxCFG Transmit Configuration - Register 7 TxCMD Transmit Command - Register 9 TxEvent Transmit Event - Register 8 10.4 Terms Specific to the CS8900A Act-Once bit A control bit that causes the CS8900A to take a certain action once when a logic "1" is written to that bit. To cause the action again, the host must rewrite a "1". Committed Receive Frame A receive frame is said to be "committed" after the frame has been buffered by the CS8900A, and the host has been notified, but the frame has not yet been transferred by the host. Committed Transmit Frame A transmit frame is said to be "committed" after the host has issued a Transmit Command, and the CS8900A has reserved buffer space and notified the host that it is ready for transmit. Event or Interrupt Event The term "Event" is used in this document to refer to something that can trigger an interrupt. Items that are considered "Events" are reported in the three Event registers (RxEvent, TxEvent, or BufEvent) and in two counter-overflow bits (RxMISS and TxCOL). StreamTransfer A method used to significantly reduce the number of interrupts to the host processor during block data transfers (Patent Pending). PacketPage A unified, highly-efficient method of controlling and getting status of a peripheral controller in I/O or Memory space. CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 135 CS8900A Crystal LAN™ ISA Ethernet Controller Standby A feature of the CS8900A used to conserve power. When in Standby mode, the CS8900A can be awakened either by 10BASE-T activity or host command. Suspend A feature of the CS8900A used to conserve power. When in Suspend mode, the CS8900A can be awakened only by host command. Transfer The term "transfer" refers to moving frame data across the ISA bus to or from the CS8900A. Transmit Request A Transmit Request is issued by the host to initiate the start of a new packet transmission. A Transmit Request consists of the following three steps in exactly the order shown: 1) The host writes a Transmit Command to the TxCMD register (PacketPage base + 0144h). 2) The host writes the transmit frame’s length to the TxLength register (PacketPage base + 0146h). 3) The host reads BusST (Register 18) to see in the Rdy4TxNOW bit (Bit 8) is set. 10.5 Suffixes Specific to the CS8900A. These terms have meaning only at the end of a term: A CMD CFG CTL Dis E h iE ST Accept Command Configure Control Disable Enable Indicates the number is hexadecimal Interrupt Enable Status CIRRUS LOGIC PRODUCT DATASHEET 136 DS271PP4 CS8900A Crystal LAN™ ISA Ethernet Controller 11.0 REVISION HISTORY 12 APR 2001 Page 13 ,1754>@ changed to,1754>@ Page 41 Added bit definitions for Revisions C and D Page 56 3DFNHW3DJH EDVH  K changed to 3DFNHW3DJH EDVH  K Page 81 Table 19: 5HJLVWHU /5[&7/ changed to 5HJLVWHU 5[&7/ Page 86 Table 23: K WR K changed to K WR K CIRRUS LOGIC PRODUCT DATASHEET DS271PP4 137