• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 887 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.

DP83TG720S-Q1: As a result of performing TDR (Time Domain Reflectometry), different states are displayed.

user6377398
Prodigy 190 points
Part Number: DP83TG720S-Q1
Other Parts Discussed in Thread: DP83TC811,

As a result of performing TDR (Time Domain Reflectometry), different states are displayed.

I am executing TDR under the following conditions, but the result is displayed as cable OK.
(1) Use DP83TG720 Media Converter Evaluation Module
(2) Use USB2MDIO. (Power supply)
(3) 1000Base-T is connected to a PC
(4) 1000Base-T1 is released

The script does the following
// Time Domain Reflectometry
// MMD1F
000D 001F
000E 001E
000D 401F
000E 8000
// Read
// MMD1F
000D 001F
000E 001E
000D 401F
000E
// Read
// MMD1F
000D 001F
000E 030F
000D 401F
000E

READ result
001E: 0002
030F: 0071 ← Cable OK

Normally, I think that 0m should be displayed in the open state.

thanks!

  • 0
    TI__Genius 9920 points

    Can you please explan what you mean by 1000BASE-T1 is released? We have a similar set up steps that mayve you can verify but may involve different registers on the DP83TC811 

    Let me know if the steps there give you more clarity on what to expect

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 190 points

    The following data sheet (SNLS604 – SEPTEMBER 2020)excerpt.
    -------------------------------------------------- ------------------------------------------------
    7.3.1.2 Time Domain Reflectometry
    Time domain reflectometry helps detecting and estimating the location of OPEN and SHORT faults along acable.
    TDR is activated by setting bit [15] ='b1 in the register [0x001E].
    When TDR diagnostic process gets completed successfully, Bit [1: 0] of register [0x001E] will become'b10.
    After this status change, TDR results can be read in the register of following table.
    -------------------------------------------------- ---------------------------------------------
    To check TDR, which is one of the functions of DP83TG720S-Q1
    TDR was performed with the cable released (cable not connected: open state).
    Result is
    Register 001e is: 8000 (write)
    Register 001e is: 0002 (Read)
    Register 030f is: 0071 (Read)
    It will be.
    Actually, I think it will be as follows.
    001E: 8000 (write)
    001E: 0002 (Read)
    030F: 0061 (Read)
    Why is it 0071 instead of 0061?

  • 0 in reply to user6377398
    TI__Genius 9920 points

    I will have to review internally and see if this is the expected case. Let me get back to you in 1-2 days

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 190 points

    Hello
    Cecilia
    When can I get the answer?

  • 0 in reply to user6377398
    TI__Genius 9920 points

    Hi there, apologies on the delay as this was around holidays. I am confirming with our design team again and seeing if i can get the follow up answer for you.

  • 0 in reply to Cecilia Reyes
    TI__Genius 9920 points

    Apologies on the delay. It looks like there was a bug in the past where the read was not working properly. Here is the feedback from our team:

    The following additional register settings (to be done before TDR start) –

    WriteRegister(0x1F, 0x0301, 0xD708);

    WriteRegister(0x1F, 0x0303, 0x092D);

  • 0 in reply to Cecilia Reyes
    Prodigy 190 points

    When I executed the command you presented, I was able to confirm the open status.

    I would like to confirm one point with the following results.
    (1) Use DP83TG720 Media Converter Evaluation Module
    (2) 1000Base-T1 is open (cable not connected)

    001E: 8000 (write)
    001E: 0002 (Read)
    030F: 0161 (Read)

    Checklist
    The open distance is displayed at 1m.
    As shown in (2), since the cable is not connected, it will be displayed as "0061" at 0m.
    Is the distance of 1m within the margin of error for 0m? Or is it a bug?