AM79C940中文資料超威半導(dǎo)體數(shù)據(jù)手冊PDF規(guī)格書

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