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CS8920A

Crystal LAN ISA Plug-and-Play Ethernet Controller

Cirrus Logic 

CS8920A

EEPROM is not present and the CS8920A

comes out of reset with the default configuration

shown in Table 3.3.

A low-cost serial EEPROM can be used to store

configuration information that is automatically

loaded into the CS8920A after each reset (except

EEPROM reset). The use of an EEPROM is op-

PacketPage Register

Address Contents

Register

Description

0360h

0000h

I/O Base Address*

0370h

XXXX XXXX Interrupt Number

0000 0000

0374h

XXXX XXXX DMA Channel

XXXX XX11

0026h

0000h

DMA Start-of-Frame Offset

0028h

002Ah

X000h

0000h

DMA Frame Count

DMA Byte Count

0348h

0340h

XXX0 0000h

XXX0 0000h

Memory Base Address

Boot PROM Base

Address

0343h

0102h

XXX0 0000h

0003h

Boot PROM Address Mask

Register 3 - RxCFG

0104h

0106h

0005h

0007h

Register 5 - RxCTL

Register 7 - TxCFG

0108h

0009h

Register 9 - TxCMD

010Ah

000Bh

Register B - BufCFG

010Ch

010Eh

000Dh

Undefined

Register D - Advint CTL/ST

Reserved

0110h

0112h

Undefined

0013h

Reserved

Register 13 - LineCTL

0114h

0015h

Register 15 - SelfCTL

0116h

0017h

Register 17 - BusCTL

0118h

0019h

Register 19 - TestCTL

011Ch

001Dh

Register ID - AutoNeg CTL

* I/O base address is unaffected by SW Suspend mode.

Table 3.3. 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 3.4. Supported EEPROM Types

tional and is not required for all applications

(e.g. motherboard designs). However, while op-

eration of the CS8920A is possible without the

use of an attached EEPROM, special design con-

siderations are required. Furthermore, some of

the CS8920A functions, such as Plug and Play

capabilities and wakeup frame recognition are

not possible without an attached EEPROM. Con-

tact Crystal’s CS8920A technical support for

more information on the use of the CS8920A

without an attached EEPROM.

The CS8920A operates with any of six standard

EEPROM’s shown in Table 3.4. To work in a

PNP system, the CS8920A requires at least a

128 word EPROM.

3.4 Plug & Play

Plug and Play is a standard mechanism, devel-

oped by Intel and Microsoft, that provides an

automatic configuration capability for ISA cards.

System resources such as interrupts, memory ad-

dresses, and IO ports are assigned to Plug and

Play compatible devices by the Plug and Play

configuration mechanism.

The CS8920A fully supports Plug and Play and

allows the complete configuration of the ISA in-

terface by the Plug and Play compatible

operating system software or BIOS. Refer to the

Plug and Play ISA Specification for detailed in-

formation about the innerworkings of Plug and

Play.

Plug and Play Configuration Process

The Plug and Play configuration process deter-

mines the resource requirements of the Plug and

Play devices in a system and assigns non-con-

flicting resources to these cards. The

configuration process goes through several

phases:

18

DS238PP2

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