Force the link-down by writing register and enable link-partner to go silent. Wait for about 1 s after register write.

In case of valid open and short cable faults, TDR still works fine without step 1.

For good cable case, TDR register 0x001E may show Fail on bypassing this step.

Write

To make master go silent.

Force the link-down by writing register and enable link-partner to go silent. Wait for about 1 s after register write.

In case of valid open and short cable faults, TDR still works fine without step 1.

For good cable case, TDR register 0x001E may show Fail on bypassing this step.

If DP83TC81x is link partner, write reg[0x1834] = 0x8001 to make it silent. If other PHY is used, a different write may be required

Reg[0x0523] = 0x0001 //Transmit disable

Reg[0x0827] = 0x4800

Reg[0x0301] = 0x1701

Reg[0x0303] = 0x023D

Reg[0x0305] = 0x0015

Reg[0x0306(4)] = 1 //Detect half wire open

Reg[0x0831] = 0x0903

Reg[0x001F] = 0x4000

Reg[0x0523] = 0x0000 //Transmit enable

Reg[0x001F] = 0x0000

Read 0x001E[1:0] = [TDR done : TDR fail].

Value should be [1,0]. Fault type and locations are valid only if this correct value is read.

Value other than [1,0] means that there is some noise on the line which is causing TDR to fail.

Read Reg 0x0310 for fault status and fault type.

For fault types:

TDR_TC-1 Reg 0x0310[8] = half_open_detect

0b

short

1b

open

**peak_sign only valid if Fault detected in cable

If a valid fault detected: register

0x0310[5:0] = is the fault location in meters.