• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 1 answer
  • Subscribers 34 subscribers
  • Views 745 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83TC811S-Q1: How to use DP83TC811S-Q1 loopback

Yangbo
Intellectual 1690 points
Part Number: DP83TC811S-Q1

Hi,

My customer want to use the loopback to test and very the link. When they are doing xMII loopback, there is no data on TX and RX. Below is how they configure the register, could you help to check and give an example.

1. set 0x0000 bit14 to 1 to enable xMII loopback

2. write data 0x6180

Regards, 

Yangbo

  • 0
    TI__Genius 9920 points

    Hi Yangbo,

    Are you reading back the data properly to confirm the loopback mode has been set? Can you share the read registers to confirm?

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 20 points

    HI

    I'm here to test loopback

    Only TX has data for analog loopback and PCs loopback

    Reverse loopback and xmii loopback TX and Rx have no data

    PCs loopback: Operation register 0x0016, write data 0x104

    Runtime partial register status:

    Register value

    0x0000 0x2180 ;

    0x0001 0x65;

    0x0009 0x3000;

    0x0016 0x104

    Analog loopback: Operation register 0x0016, write data 0x108

    Runtime partial register status:

    Register value

    0x0000 0x2180 ;

    0x0001 0x65;

    0x0009 0x3000;

    0x0016 0x108

    ethtool -S eth0 | grep ok

    rx ok: 0

    tx ok: 43

    Reverse loopback: Operation register 0x0016, write data 0x110

    Xmii loopback: Operation register 0x0000, set bit14 to 1, write data 0x6180

    No data for TX RX

    Please help to check,

    1) Is it standard for me to do this..

    2) RX has no data. How to troubleshoot the problem point..

    3) Whether there are other important registers to check the operation status of the chip, or whether you can provide normal register values for comparison..

    thank you

  • 0 in reply to user6365736
    TI__Genius 9920 points

    Hello,

    You should not expect to see data lines on reverse loopback since the loopback occurs on the the cable side. Here is a useful diagram that may help you understand the different loopacks. 

    In terms of operation of the PHY, you can look at register 0x1 to review the status of the PHY and determine if there is a link on the device. 

  • 0 in reply to Cecilia Reyes
    TI__Intellectual 1690 points

    Hi Cecilia,

    Could you give an example to check PCS lookback? How do we configure the registers and check if PCS lookback works? 

  • 0 in reply to Yangbo
    TI__Genius 9920 points

    Hi Yangbo,

    PCS Loopback is enabled by setting bits[6:2] = 0b0001 in the BISTCR Register 0x0016 – BIST Control Register.

    You can check if PCS loopback is working by probing your MAC receive and transmit data lines. But if you are looking at just confirming link up status, you may also read register 0x1.

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 20 points

    Hi:

    So, when we test PCs, the link status should be OK, but the receiving data line has no data. How to deal with it?

  • 0 in reply to Cecilia Reyes
    TI__Intellectual 1690 points

    Cecilia,

    PCS lookback is enabled, transmit data can be captured, but no date on receive line. Could you give us any example code? It has been stuck a while.

    Regards, 

    Yangbo

  • 0 in reply to user6365736
    TI__Intellectual 1690 points

    Hi,

    please let us know how you configure register for PCS loopback? 

  • 0 in reply to Yangbo
    TI__Genius 9920 points

    Hi Yangbo,

    PCS Loopback is enabled by setting bits[6:2] = 0b0001 in the BISTCR Register 0x0016 – BIST Control Register

    Thanks,

    Cecilia