AM79C975VCW datasheet(259/304 Pages) AMD

259 / 304 page

Am79C973/Am79C975

259

P R E L I M INARY

Default: 00

Read only, write has no effect.

This two bit field indicates the current power

state of the Am79C975 controller. The defini-

tion of the field values is given below:

00b - D0

01b - D1

10b - D2

11b - D3

RESERVED Default: 0Read as ZERO only

Reserved bits. For future use only

PVALID

Default: 0Read only, write has no

effect.

When PVALID is set to a 1, it indicates that

there is an EEPROM connected to the

Am79C975 controller and that the read opera-

tion of the EEPROM has passed the checksum

verification. All registers that are loaded from

the EEPROM contain data read from the EE-

PROM. PVALID is cleared by H_RESET.

3RXON

Default: 0

Read only, write has no effect.

When RXON is set to a 1, it indicates that the

receive function for normal operation is en-

abled. Note that the reception of management

frames via the SMIU is only controlled by the

MRX_ENABLE bit in the Receive Status regis-

ter, but not of the state of RXON. RXON is

cleared by H_RESET.

2TXON

Default: 0

Read only, write has no effect.

When TXON is set to a 1, it indicates that the

transmit function for normal operation is en-

abled. Note that the transmission of manage-

ment frames via the SMIU is always active,

independent of the state of TXON. TXON is

cleared by H_RESET.

1STOP

Default: 1

Read only, write has no effect.

When STOP is set to a 1, it indicates that all

bus master activity of the Am79C975 controller

is disabled. STOP is set to 1 by H_RESET.

0STRT

Default: 0

Read only, write has no effect.

When STRT is set to a 1, it indicates that the

Am79C975 controller is initialized for normal

mode of operation and that the device is setup

to perform bus master activity. STRT is cleared

by H_RESET.

MIU Transceiver Status (MReg Address 30)

This register is a shadow register of some bits in the

transceiver status register.

Bit No.

Name and Description

7:4

RESERVED

Default: 0000Read as ZERO only

Reserved bits. For future use only

3LINK

Default: 0

Read only, write has no effect.

When LINK is set to 1, it indicates that the

physical layer interface of the Am79C975 con-

troller is in Link Pass state. A value of 0 indi-

cates a Link Fail state.

DUPLEX

Default: 0

Read only, write has no effect.

When DULPEX is set to 1, it indicates that the

physical layer interface is operating in full-du-

plex mode. A value of 0 indicates half-duplex

mode.

SPEED

Default: 0

Read only, write has no effect.

When SPEED is set to 1, it indicates that the

physical layer interface is operating at 100

Mbps. A value of 0 indicates a speed of 10

Mbps.

AUTONEG_DONEDefault: 0Read only, write

has no effect.

When AUTONEG_DONE is set to 1, it indi-

cates that the autonegotiation process of the

physical layer interface with the other end of

the network cable has completed.

Control and Status Registers

The following registers control the transmission and re-

ception of management frames and provide status of

the operation.

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