User`s manual

Am486
®
Microprocessor PCI Customer Development Platform
2-13
Onboard Ethernet Controller (F7)
The PCI CDP includes an onboard, full-duplex 10/100BaseT Ethernet port based
on the AMD Am79C972 PCnet
-FA S T + Ethernet Controller (part U51). A
separate voltage regulator provides 3.3-V power for the Ethernet controller. The
Ethernet port is part J10 at location E1 on the board. Three LEDs near the port
indicate transmit and receive activity and link speed. The link LED lights if 100
Mbit/s operation is established.
The Ethernet controller’s interrupt output (INTA) is routed to the chipset’s PCI
INT2 signal. The initialization code dynamically assigns INT2 to an interrupt
request (IRQ) in the chipset’s PCI INTx routing table mapping registers. See the
chipset documentation for details on the mapping registers.
The Am79C972 PCnet-FA S T + device is a highly integrated 10/100 Mbps PCI
Ethernet controller. It includes an IEEE 802.3-compliant Ethernet Media Access
Controller (MAC) with Auto-Negotiation of 10 or 100 Mbps and half- or full-
duplex operation, and a Media Independent Interface (MII) for connection to any
standard IEEE 802.3 compliant 10/100 Mbps physical layer (PHY) device.
The Am79C972 contains a high performance 32-bit PCI bus master interface, as
well as large, flexible internal memory buffers, to provide high-speed data
throughput and low CPU and system bus utilization. For PCI configuration, the
Ethernet controller is accessed as device number 5.
The Am79C972 can be configured by the PCI configuration space mechanism or
it can download its configuration from a 1-Kbyte serial EEPROM (part U54 at
location D6). The PCI CDP uses the serial EEPROM interface to configure the
Am79C972 device. The EEPROM is preprogrammed with an Ethernet
configuration suitable for the PCI CDP.
In addition to the Ethernet configuration EEPROM, a 4-Kbyte serial EEPROM is
provided for user nonvolatile data. See “4-Kbyte Serial EEPROM (C4)” on page
2-14.
For customer designs, the PCnet-FA S T + controller is offered with AMD’s
extensive suite of industry-proven PCnet software drivers, remote boot ROM
firmware (not supported by the PCI CDP), and a complete set of supporting utilities
and design tools. Follow the Networking link at www.amd.com for information
about networking software, support, and tools.