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21143 PCI/CardBus 10/100Mb/s Ethernet LAN Controller
Design Guide 5
This design guide provides a description of how to implement 100BASE-TX and 10BASE-T
network connections using the 21143 PCI/CardBus 10/100 Mb/s Ethernet LAN Controller
(referred to as the 21143).
While this document will not provide specific recommendations for physical layer devices, it will
provide design recommendations and layout recommendations.
This application note provides a description of how to implement 100BASE-TX and 10BASE-T
network connections using the 21143 PCI/CardBus 10/100 Mbs/s Ethernet LAN Controller
(referred to as the 21143).
1.0 Functional Overview
This section provides an overview of the 21143 and the implementation of 100 Mb/s and 10 Mb/s
network connections using MII-based or SYM-based PHY devices.
1.1 21143 Overview
The 21143 is a single-chip bus master Ethernet/Fast Ethernet device that supports direct memory
access (DMA) and has direct interfaces to both the CardBus and the PCI local bus. The 21143
implements a direct interface to the CardBus or PCI bus through a single 50-pin connection, which
consists of the control and address/data signals.
The 21143 provides a complete implementation of the IEEE 802.3 Ethernet specification. This
includes the attachment unit interface (AUI), twisted-pair (10BASE-T) interface, MII SYM port
interface, and the interface through the media access control (MAC) layer that creates a direct
interface to the PCI bus.
The PCI interface utilizes only about 10% of the bus bandwidth during fully networked operation
for 100 Mb/s Fast Ethernet reception or transmission. This bus master design results in high
throughput between the system and the network.
1.2 Network Interface
The 21143 physical layer design supports AUI drop cable Ethernet and 10BASE-T twisted-pair
(TP) Ethernet connections. The 21143 gep<0>/aui_bnc (pin 100), which is software controlled,
provides for a connection of either the AUI (10BASE5) or BNC (10BASE2) network connector.
Table 1 describes the function of this pin.
AUI signals interface with the Manchester encoder/decoder portion of the 21143. The 21143
supports 10BASE5 thickwire and 10BASE2 ThinWire connections. The 10BASE2 connection
requires an external transceiver.
Table 1. Signal gep<0>/
aui_bnc Description
Program State Function
0 AUI port enabled; BNC port disabled.
1 BNC transceiver (or DC-to-DC converter) enabled; AUI port disabled