AM79C984 datasheet(26/44 Pages) AMD

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P R E L I M I N A R Y

Am79C984A

Enable Software Override of Bank B LEDs (Per Port -

AUI and TP, Global)

SI Data

1100 ####

SO Data

None

This command forces the LEDs in Bank B to blink. In-

dividual LEDs and combinations of LEDs can be select-

ed via the lower four bits of the command byte as follows:

####

Port(s) affected

0000-0011 TP0 - TP3

0100-0111 Reserved

1000

AUI port

1001

Reserved

1010

Reserved

1011

All TP ports

1100

All ports

1101

Global

1110

Reserved

1111

Reserved

The designated LED driver(s) will switch between LOW

and ‘off’ at the rate set by the Software Override of LED

Blink Rate command. Enable Software Override of

Bank B LEDs references the blink rate last issued and

overrides any other attribute speciﬁed by LDC0-2. Soft-

ware Override of LEDs is disabled after reset.

Software Override of LED Blink Rate

SI Data

1110 1###

SO Data

None

This command sets the blink period of the LEDs with

Software Override enabled. The duty cycle is 50%. This

command defaults to ‘off’ at reset.

Setting

Blink Period

1110 1000

Off

1110 1001

512 ms

1110 1010

1560 ms

1110 1011

Solid On

These settings apply to the blink rate for both Bank A

and Bank B. This command must precede the Enable

Software Override of Bank A/B LEDs command. All LED

combinations selected for Software Override will refer-

ence the blink rate last issued.

GET (Read Commands)

AUI Port(s) Status

SI Data

1000 1111

SO Data

PBSL 0000

The combined AUI status of the eIMR device allows a

single instruction to be used to monitor the AUI port.

The four local status bits are:

Partitioning Status

This bit is ‘0’ if the AUI port is partitioned and ‘1’ if the

AUI port is connected.

Bit Rate Error

This bit is set to ‘1’ if there is an instance of FIFO overﬂow

or underﬂow. The bit is cleared when the eIMR device

is read.

SQE Test Status

This bit is set to ‘1’ if the SQE test error is detected by

the eIMR chip.The bit is cleared when the status is read.

Loopback Error

The MAU attached to the AUI port is required to loop-

back data transmitted to DO onto the DI circuit. If the

loopback carrier is not detected by the eIMR device, this

bit is set to ‘1’.This bit is cleared when the status is read.

Alternate AUI Port(s) Status

There are three further variations of the AUI Port Status

Command allowing selective clearing of a combination

of B,S, and L bits. These are the following:

Alternate 1: B is not cleared, S and L are Cleared

SI Data

1000 1011

SO Data

PBSL 0000

Alternate 2: S and L are not cleared, B is Cleared

SI Data

1000 1101

SO Data

PBSL 0000

Alternate 3: None of S, B, and L are Cleared

SI Data

1000 1001

SO Data

PBSL 0000

TP Port Partitioning Status

SI Data

1000 0000

SO Data

0000 P3..P0

n = 0

TP Port Partitioned

n = 1

TP port Connected

where

n is a port number in the range 0–3.

The response to this command gives the partitioning

status of all four TP ports. If a port is disabled, reading

its partitioning status will indicate that it is connected.

Bit Rate Error Status of TP Ports

SI Data

1010 0000

SO Data

0000 E3..E0

n = 0

No Error

n = 1

FIFO Overﬂow

where

n is a port number in the range 0–3.

The response to this command gives the bit-rate-over-

ﬂow or underﬂow (data rate mismatch) condition of all

the TP ports. A 1 indicates that the FIFO has overﬂowed

or underﬂowed due to the amount of data received by

the corresponding port.

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