• State Answer Suggested
  • Locked Locked
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 228 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.

DS160PR410: PCIe Gen4 Issue

GARETH OU
Guru 11865 points
Part Number: DS160PR410


Hi

The customer is using the TI DS160PR410 to perform a PCIe Gen4 compliance test. The test produces waveforms, but the report cannot interpret the values. Attached are waveforms from other manufacturers that passed the test, and the waveform from the DS160PR410. Are there any parameters on the circuit that need to be adjusted?

NG and GEN4 cannot capture values ​​(the oscilloscope will capture 3 times, and no value is detected in 3 of them, but the waveform is present).

NG.jpg872bb47f-f680-4db8-994b-b07715dd6abb.jpg

ds160pr4.pdf ds160pr410_NG.pdf 

  • 0
    TI__Mastermind 21786 points

    Hi Gareth, 

    Could the customer verify that they were outputting P07 Gen4 signal? These tests will not run unless the customer outputs Gen4 P07 compliance waveform from the PCIe source. 
    Could the customer also check if the source can output Gen 4 compliance waveforms?

    Best,
    J

  • 0 in reply to J
    Guru 11865 points

    Hi

    1. It is indeed outputting the P07 Gen4 waveform. The attached image shows a comparison between the PASS board and the DS160PR410. The customer has tested it more than 10 times, but still cannot capture the value.

    2. Test environment.jpg

    3. PASS board and DS160PR410.jpg

    Adding some information: When testing the DS160PR410, this message will appear before the report is generated.

     pass will not receive this information.

  • 0 in reply to GARETH OU
    TI__Mastermind 21786 points

    Hi Gareth, 

    Thank you for the pictures. That clears a lot of information I needed. It looks like the equalization that DS160PR410 is giving in this system is not enough. Could the customer increase the EQ on the redriver and re-run the compliance test for P07 compliance pattern. I suggest to increase one by one as the customer will have to re-run the entire compliance with the new configuration. 

    I accidentally clicked on the TI Resolved Button, so I will keep the thread open internally so we can keep discuss this. 

    Please let me know. 

    Best,
    J

  • 0 in reply to GARETH OU
    Guru 11865 points

    Hi J

    I'd like to try adjusting the EQ, since the PASS board has already been adjusted. However, the DS160PR410 has three adjustable parameters:

    1. GAIN

    2. VOD

    3. EQ

    Any suggestions for these values?

  • 0 in reply to GARETH OU
    TI__Mastermind 21786 points

    Hi Gareth, 

    I apologize for missing this post. 

    It looks like this post has fallen through the cracks. 

    The settings will depend on the loss from the trace length. What is the trace length from the SoC to the the RX of DS160PR410?

    Best,
    J

  • 0 in reply to J
    Guru 11865 points

    The following are the lengths from CPU Board_TX to DS160PR410_RX.

    The following is the length from DS160PR410_TX to CPU Board_RX.

  • 0 in reply to GARETH OU
    TI__Mastermind 21786 points

    Hi Gareth, 

    In this case, I suggest EQ=9, GAIN=0dB, VOD=0dB as a starting point. 
    As a general rule, we assume around 2dB loss per inch in FR4 trace. 

    Best,
    J