AM79C976 datasheet(205/309 Pages) AMD

205 / 309 page

8/01/00

Am79C976

205

P R E L I M INARY

physical, logical filtering, broad-

cast, and promiscuous.

Read/Write accessible. RCVME

is cleared by H_RESET and is

not affected by S_RESET or set-

ting the STOP bit.

XMTE

Transmit Status Enable. When

this bit is set, a value of 1 is

passed to the LEDOUT bit in this

activity on the network.

Read/Write accessible. XMTE is

cleared by H_RESET and is not

affected by S_RESET or setting

the STOP bit.

RES

Reserved location. Written and

read as zeros.

RCVE

Receive Status Enable. When

this bit is set, a value of 1 is

passed to the LEDOUT bit in this

tivity on the network.

Read/Write accessible. RCVE is

cleared by H_RESET and is not

affected by S_RESET or setting

the STOP bit.

SFBDE

Start Frame/Byte Delimiter En-

able. When this bit is set, a value

of 1 is passed to the LEDOUT bit

in this register when the RXD[3:0]

pins are presenting the least sig-

nificant nibble of valid frame data.

Read/Write accessible. RCVE is

cleared by H_RESET and is not

affected by S_RESET or setting

the STOP bit.

COLE

Collision Status Enable. When

this bit is set, a value of 1 is

passed to the LEDOUT bit in this

activity on the network.

Read/Write accessible. COLE is

cleared by H_RESET and is not

affected by S_RESET or setting

the STOP bit.

%&5 /(' 6WDWXV

BCR7 controls the function(s) that the LED3 pin dis-

plays. Multiple functions can be simultaneously enabled

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

OR of the enabled functions. BCR7 defaults to collision

indication (COLE = 1) with pulse stretcher enabled

(PSE = 1) and is fully programmable.

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

gramming of the LED3 Status register is enabled.

When LEDPE is cleared to 0, programming of the

LED3 register is disabled. Writes to this register 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).

This bit is read only; writes have

no effect. LEDOUT is unaffected

H_RESET,

S_RESET,

STOP.

LEDPOL

LED Polarity. When this bit has

the value 0, the LED pin will be

driven to a LOW level whenever

the OR of the enabled signals is

true. The LED pin will be disabled

and allowed to float high whenev-

er the OR of the enabled signals

is false (i.e., the LED output 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, the

LED pin will be driven to a HIGH

level whenever the OR of the en-

abled signals is true. The LED pin

will be driven to a LOW level

whenever the OR of the enabled

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

put will be a Totem Pole output

and the output value will be the

AM79C976 Datasheet(PDF) 205 Page - Advanced Micro Devices

AM79C976 Datasheet(HTML) 205 Page - Advanced Micro Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL