AM79C875KC datasheet(32/48 Pages) AMD

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Am79C875

Diagnostic Register (Register 18)

Table 18.

Reg

Bit

Name

Description

Read/

Write

Default

15:12

Reserved

Ignore when read.

DPLX

This bit indicates the result of the Auto-Negotiation for duplex

arbitration.

1 = Full Duplex.

0 = Half Duplex.

Speed

This bit indicates the result of the Auto-Negotiation for data speed

arbitration.

1 = 100 Mbps.

0 = 10 Mbps.

RX_PASS

In 10BASE-T mode, a 1 indicates that Manchester data has been

detected.

In 100BASE-TX mode, a 1 indicates a valid signal has been

received but not necessarily locked onto.

RX_LOCK

1 = Received RLL has locked onto the received signal for selected

data-rate (10BASE-T or 100BASE-TX)

0 = Receive PLL has not locked onto received signal.

This bit remains set until read.

RO/RC

7:0

Reserved

Ignore when read.

0x22

Diagnostic Register (Register 18)

Test Register (Register 19)

Table 19.

Reg

Bit

Name

Description

Read/

Write

Default

15:12

Reserved

Ignore when read, write as Default (0x1000).

0x1000

11:8

Reserved

Ignore when read, write as Default (0x0010).

0x0010

Reserved

Ignore when read, write as 0.

1.25:1

Selects transformer ratio.

1 = 1.25:1

0 = 1:1

The default value is controlled by the TP1_1 pin.

10/100 Mbps

Transmit

Compliance Test

This bit controls internal logic, including power-saving circuitry. For 10

and 100 Mbps transmit compliance testing ONLY, this bit must be

turned off, but should be turned on for normal operation. The default

is 1 (on).

1 = Normal operation.

0 = Compliance test mode.

4:0

Reserved

Ignore when read, write as 0.

Test Register (Register 19)

Miscellaneous Features 2 Register (Register 20)

Table 20.

Reg

Bit

Name

Description

Read/

Write

Default

15:12

Reserved

Ignore when read, write as Default (0x0110).

0x0110

11:8

Reserved

Ignore when read, write as Default (0x1001).

0x1001

7:4

Cable length

indicator

These bits are the cable length indicators. Increment from 0000 to

1111, or approximately every 10 meters. The equivalent is 0 to 32dB

with an increment of 2dB @ 100Mhz. The value is read back from the

equalizer, and the measured value is not absolute.

3:0

Reserved

Ignore when read.

0x0010

Miscellaneous Features 2 Register (Register 20)

AM79C875KC Datasheet(PDF) 32 Page - Advanced Micro Devices

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