SNLA371B December   2020  – February 2024 DP83TG720R-Q1 , DP83TG720S-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Hardware Configuration
    1. 2.1 Schematic
  6. 3 Software Configuration
  7. 4 Testing PMA
    1. 4.1 PMA Testing Procedure
  8. 5 Testing IOP: Link-up and Link-down
    1. 5.1 IOP Testing Procedure
  9. 6 Testing SQI
    1. 6.1 SQI Testing Procedure
    2. 6.2 Mapping SQI with Link Quality
  10. 7 Testing TDR
    1. 7.1 TDR Testing Procedure
  11. 8 Testing EMC/EMI
  12. 10Revision History

7.1 TDR Testing Procedure

Table 7-1 TDR Run Procedure
SequenceDescriptionRegister Read/Write
Step 1: For DP83TG720 as master

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

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

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

Write register[0x0576] = 0x0400
Step 1: For DP83TG720 as slave

Link-partner should be made silent.

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

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

Step 2 TDR configuration: Pre-runreg[0x0301] = 0xA008

reg[0x0303] = 0x0928

reg[0x0304] = 0x0004

reg[0x0405] = 0x6400

reg[0x083F] = 0x3003

Step 3Start TDR0x001E[15] = 1
Step 4Wait for 100ms (should be sufficient for TDR to converge for maximum cable length)
Step 5

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

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

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

Step 6Fault type and location is read.

Read register 0x030F for fault status and fault type. Refer to Table 7-2

Table 7-2 TDR Result Registers : 0x030F
Register Bits Description
[1:0]
  • 01 = TDR ready for activation
  • 10 = TDR On
  • 00,11 = TDR Not Available
[3:2] Reserved
[7:4]
  • 0011 = Short
  • 0110 = Open
  • 0101 = Noise
  • 0111 = Cable OK
  • 1000 = Test in progress; initial value with TDR ON
  • 1101 = Test not possible (for example, noise, active link)
  • Other values are not valid
[13:8]
  • Fault distance = Value in decimal of [13:8]
  • 'b111111 = Resolution not possible/out of distance
[15:14] Reserved