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TUSB8040A Downstream Port Rx Jitter Tolerance Pattern Lock Problem

1859464
Intellectual 575 points
Other Parts Discussed in Thread: TUSB8040A

Is there any known issues or limitations with running USB 3.0 Rx Compliance tests on the TUSB8040A hub downstream ports? We have tried running Long Channel Jitter Tolerance and Short Channel Jitter tolerance on the TUSB8040A Evaluation Board from TI and get the following similar errors from two completely different test equipment setups:

1. LeCroy SDA 830Zi-A with PeRT3 using QualiPHY compliance automation software:

"Failed to obtain pattern lock"

2. Keysight MSOV334A Scope and Keysight M8020A J-BERT using N5990A Test Automation Software Platform:

"Error detector cannot synchronize to the test pattern CP0"

Thanks for your help.

Regards,

KT

  • 0
    TI__Guru 60870 points

    Hi KT,

    Make sure that SSC is enabled (it can be disabled via the EEPROM or SS_SUSPEND input).  The RX compliance test won't pass if SSC is disabled.

    What is being connected to the upstream port of the hub?  Some hosts will try to reset the downstream ports once they enter compliance mode.  I would recommend using the XHSETT tool from the usb-if on usb.org.  It will load special drivers on the USB host that won't generate unexpected resets.  You do not need to run any special tests, just have it enumerate the hub.

    Are you using the standard 3M cable and test fixtures?

    Thanks,

    JMMN

  • 0 in reply to JMMN
    Intellectual 575 points
    Hi JMMN,

    Using the XHSETT tool on the host fixed the problem, and we are now able to run the Rx jitter tolerance test successfully on the downstream ports of the TUSB8040A EVB. Thanks for your help!

    Regards,
    KT
  • 0 in reply to JMMN
    Intellectual 575 points
    Hi JMMN,

    Re: "RX compliance test won't pass if SSC is disabled." Just for clarification, you are saying that TUSB8040A rx jitter tolerance performance gets better if SSC is enabled, and MUST be enabled to pass USB 3.0 rx jitter tolerance testing? I am asking because SSC is disabled on the TUSB8040A EVB, and it seems more likely that rx jitter tolerance should get worse with SSC enabled.

    Thanks for you help,

    KT
  • 0 in reply to 1859464
    TI__Guru 60870 points
    Hi KT,

    I apologize, it looks like I missed your response. In my experience with the USB 3.0 electrical compliance test tools, the RX jitter tolerance test will fail entirely if SSC is not enabled during the test.

    Thanks,
    JMMN