AM79C940数据手册AMD中文资料规格书

描述 Description

GENERAL DESCRIPTION
The Media Access Controller for Ethernet (MACE) chip is a CMOS VLSI device designed to provide flexibility in customized LAN design. The MACE device is specifically designed to address applications where multiple I/O peripherals are present, and a centralized or system specific DMA is required. The high speed, 16-bit synchronous system interface is optimized for an external DMA or I/O processor system, and is similar to many existing peripheral devices, such as SCSI and serial link controllers.
The MACE device is a slave register based peripheral. All transfers to and from the system are performed using simple memory or I/O read and write commands. In conjunction with a user defined DMA engine, the MACE chip provides an IEEE 802.3 interface tailored to a specific application. Its superior modular architecture and versatile system interface allow the MACE device to be configured as a stand-alone device or as a connectivity cell incorporated into a larger, integrated system.DISTINCTIVE CHARACTERISTICS
■ Integrated Controller with Manchester encoder/decoder and 10BASE-T transceiver and AUI port
■ Supports IEEE 802.3/ANSI 8802-3 and Ethernet standards
■ 84-pin PLCC and 100-pin PQFP Packages
■ 80-pin Thin Quad Flat Pack (TQFP) package available for space critical applications such as PCMCIA
■ Modular architecture allows easy tuning to specific applications
■ High speed, 16-bit synchronous host system interface with 2 or 3 cycles/transfer
■ Individual transmit (136 byte) and receive (128 byte) FlFOs provide increase of system latency and support the following features:
   — Automatic retransmission with no FIFO reload
   — Automatic receive stripping and transmit padding (individually programmable)
   — Automatic runt packet rejection
   — Automatic deletion of collision frames
   — Automatic retransmission with no FIFO reload
■ Direct slave access to all on board configuration/status registers and transmit/ receive FlFOs
■ Direct FIFO read/write access for simple interface to DMA controllers or l/O processors
■ Arbitrary byte alignment and little/big endian memory interface supported
■ Internal/external loopback capabilities
■ External Address Detection Interface (EADI™) for external hardware address filtering in bridge/router applications
■ JTAG Boundary Scan (IEEE 1149.1) test access port interface for board level production test
■ Integrated Manchester Encoder/Decoder
■ Digital Attachment Interface (DAI™) allows by-passing of differential Attachment Unit Interface (AUI)
■ Supports the following types of network interface:
   — AUI to external 10BASE2, 10BASE5 or 10BASE-F MAU
   — DAI port to external 10BASE2, 10BASE5, 10BASE-T, 10BASE-F MAU
   — General Purpose Serial Interface (GPSI) to external encoding/decoding scheme
   — Internal 10BASE-T transceiver with automatic selection of 10BASE-T or AUI port
■ Sleep mode allows reduced power consumption for critical battery powered applications
■ 5 MHz-25 MHz system clock speed
■ Support for operation in industrial temperature range (–40°C to +85°C) available in all three packages