AM79C975VCW datasheet(164/304 Pages) AMD

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164

Am79C973/Am79C975

P R E L I M INARY

See the section on External Ad-

dress Detection for more details.

Read/Write accessible always.

EADISEL

cleared

H_RESET and is unaffected by

S_RESET or by setting the STOP

bit.

SLEEP_SFEX

Setting this bit will reduce the

power consumption of the inter-

nal PHY substantially.

Read/Write accessible always.

SLEEP_SFEX is cleared to 0 by

H_RESET and is unaffected by

S_RESET or by setting the STOP

bit.

I2C_N1

(Am79C975 only). This bit is used

to set the operating frequency of

the SMIU core. It represents the

value in the D1 bit position (see

Appendix B on SMIU Bus Fre-

quency.

Read/Write accessible always.

I2C_N1 is cleared by H_RESET

and is unaffected by S_RESET or

by setting the STOP bit.

I2C_N0

(Am79C975 only). This bit is used

to set the operating frequency of

the SMIU core. It represents the

value in the D0 bit position (see

Appendix B on SMIU Bus Fre-

quency.

Read/Write accessible always.

I2C_N0 is cleared by H_RESET

and is unaffected by S_RESET or

by setting the STOP bit.

BCR4: LED 0 Status

BCR4 controls the function(s) that the LED0 pin dis-

plays. Multiple functions can be simultaneously en-

abled on this LED pin. The LED display will indicate the

logical OR of the enabled functions. BCR4 defaults to

Link Status (LNKST) with pulse stretcher enabled

(PSE = 1) and is fully programmable.

Note: When LEDPE (BCR2, bit 12) is set to 1, pro-

gramming of the LED0 Status register is enabled.

When LEDPE is cleared to 0, programming of the

LED0 register is disabled. Writes to those registers will

be ignored.

Note: Bits 15-0 in this register are programmable

through the EEPROM.

Bit

Name

Description

31-16 RES

Reserved locations. Written as

zeros and read as undefined.

LEDOUT

This bit indicates the current

(non-stretched) value of the LED

output pin. A value of 1 in this bit

indicates that the OR of the en-

abled signals is true.

The logical value of the LEDOUT

status signal is determined by the

settings of the individual Status

Enable bits of the LED register

(bits 8 and 6-0).

Read accessible always. This bit

is read only; writes have no ef-

fect. LEDOUT is unaffected by

H_RESET, S_RESET, or STOP.

LEDPOL

LED Polarity. When this bit has

the value 0, then the LED pin will

be driven to a LOW level whenev-

er the OR of the enabled signals

is true, and the LED pin will be

disabled and allowed to float high

whenever the OR of the enabled

signals is false (i.e., the LED out-

put will be an Open Drain output

and the output value will be the

inverse of the LEDOUT status

bit).

When this bit has the value 1,

then the LED pin will be driven to

a HIGH level whenever the OR of

the enabled signals is true, and

the LED pin will be driven to a

LOW level whenever the OR of

the enabled signals is false (i.e.,

the LED output will be a Totem

Pole output and the output value

will be the same polarity as the

LEDOUT status bit.).

The setting of this bit will not ef-

fect the polarity of the LEDOUT

bit for this register.

Read/Write accessible always.

LEDPOL is cleared by H_RESET

and is not affected by S_RESET

or setting the STOP bit.

AM79C975VCW Datasheet(PDF) 164 Page - Advanced Micro Devices

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