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SI test fail for the SFP+ Ports through the Retimer DS100DF410

Dear Sir,

I have a project which uses the SFI Retimer DS100DF410 to output 16x SFP+ Port.  But, with the initial retimer configuration, the SI test result of the 16x SFP+ Ports are all failed.  The fail phenomenon are descripled as blow:

A. The 8180 Pattern is wrong.

B. The PRBS9 Pattern is fail.

C. Just PRBS31 Pattern is pass. 

So, Is this SI fail caused by the initial retimer configuration ?  If yes, why the 8180 pattern is wrong ? Thank you very much !

  • Hi,

    The 8180 pattern is a simple 8-UI square wave.  Have you looked at the result on an oscilloscope?

    Without any single bit transitions this test pattern will be interpreted as a 1.289 (10.3125/8) Gbps pattern.  To lock to this pattern you will have to change the DS100DF410 Channel Register 0x0C value.  Default = 08'h, Change to = 00'h.

    If the attenuation in your system is not high I would also change the value in Channel Register 0x3A. Default = A5'h, Change to = 00'h.

    Regards,

    Lee

  • In reply to Lee Sledjeski:

    Hi Lee,

    I'm sorry for reply late.  For me, this is the first time to use E2E and it takes me some time to familiar with how to use it.

    Thanks for your answer.  I still have some questions.

    1. For 8180. I have checked the register 0x0C, the initial value is already 00'h. But the waveform captured by oscilloscope is as below. It’s really strange. So, waht else shoud i do to improve this? By the way, the SFP+ port function test is ok. no problem.

     

    2. For PRBS9, should i set the Channel Register 0x0C value as "Default = 08'h" or "Change to = 00'h" ?  Now, with the initial setting (0x0C = 00'h) on my board, the PRBS9 fail report as blow. It's the DDPWS item fail.

  • In reply to bingbing Niu:

    Hi,

    I have never seen a waveform of that rate on an SFP+ interface.  Can you take a picture or draw a block diagram of your setup.  According to the horizontal timebase the high portion is over 4 microseconds in duration.

    Lee

  • In reply to Lee Sledjeski:

    Hi Lee,

    Do you mean the 8180 Pattern test setup about the Oscilloscope ? This SI test  in the charge of my SI team colleague in TaiPei. So i can't get related picture. But, i'm sure the Oscilloscope setup is right. Because, there are also another 20 SFP+ ports from the same Switch Chip, the only difference is they are connected to Switch chip dirrectly, don't through the Retimer DS100DF410. And, the 20 SFP+ Ports SI test result are all pass.  

    About the 8180, do you think whether there are some other settings are wrong ?  Because, for the initial configuration i got for my board. the channel register 0x0C default value is 00'h, it's not 08'h as you told before.

    How about the PRBS9? Should I  set the channel register 0x0C as 08'h when test PRBS9 & PRBS31 ?

    Thank you !

     

  • In reply to bingbing Niu:

    I would like to understand how the DS100DF410 is connected in the system.  If you can send a schematic it would be helpful.

    Does the setup look like this?

    System -> DS100DF410 -> SPF+  -> oscilloscope ?

    I would also like to see a register dump for all the DS100DF410 registers, this is useful for trying to debug the setup.

    Thanks and Regards,

    Lee

  • In reply to Lee Sledjeski:

    Hi Lee,

    Please refer to the following block diagram about how the DS100DF410 is coonected in our board. And i hope it would be helpful. (I don't know how to send a attchment via the E2E, ).  

        

    About the setup, yes, it is :  System -> DS100DF410 -> SPF+  -> oscilloscope

    Thank you that you will check all the retimer registers to help on our case, and i'm looking forward to your new comments.

    At the same time, we are also working on this bug, if there is any findings, i will update to you ASAP.

    Thank you!

  • In reply to bingbing Niu:

    Hi,

    If you could copy the register download to E2E that would be good enough to read through them.

    Just checking.  Are the connections between the RRC and retimer AC coupled?  Is your oscilloscope AC coupled to the retimer outputs?

    Regards,

    Lee 

  • In reply to Lee Sledjeski:

    Hi Lee,

    Thanks for your great support..

    For the 8180 abnormal waveform, maybe we have found the reason: As i told you before, the initial channel register 0x0C value = 00'h. So, when the 8180 pattern is abnormal with the initial configuration, I just re-write the register ="00'h", and as the feedback to you, the waveform is still abnormal.  But, when I try to write the register ="08'h" first, and then write it ="00'h" again, then, the 8180 pattern can be generated normally. and the test result is pass on one port. (Another ports will be arranged to test tomorrow ).

    So, for this phenomenon, can you explain it ? It seams the direct setting 00'h is not valid, but the value is indeed read as 00'h.

  • In reply to bingbing Niu:

    Since the 8180 signal has no single bit transitions, the DS100DF410 will not lock to this pattern by default.  Removing the signal bit transition check and restarting the DS100DF410's attempt to lock should result in a lock condition and an 8T clock pattern at the output.

    Regards,

    Lee

  • In reply to Lee Sledjeski:

    Thanks for your detailed explaination !