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TUSB4020BI: USB 2.0 mask test

Obinna Ezeilo
Intellectual 2385 points
Part Number: TUSB4020BI

Hi Team, 

My customer is trying to carry out the downstream mask tests (of the USB 2.0 compliance tests) on the TUSB4020BI. However they are running into the issue that whenever they set  the upstream device in the "Test packet mode" the test packets are not sent downstream by the USB hub.

With the oscilloscope they've verified the presence of the test packet on the internal bus from the upstream device into the TUSB4020BI, but no signal comes out on either of the outputs. This happens both when a downstream device (USB-stick) is connected and when no downstream device is connected.

Other data than the test packet does appear on the downstream path when a downstream device is connected.

Hence their questions: 

Does the USB hub need to be put in a special mode to be able to forward the test packets from the upstream device?

And if so, how would this have to be done?

Thanks and looking forward to your response. 

KR, Obinna. 

  • 0
    TI__Guru 60870 points

    Hi Obina,

    Yes, the hub will need to be set in a special test mode for USB HS test packets.  You will want to configure the hub to generate its own USB test packets rather than pass through test packets from the host since the repeated test packets will have dropped sync bits and EOP dribble.

    Please download the XHCI HSETT tool from the USB-IF at usb.org and it will allow you to send the test packet commands to the hub.

    Can you connect your hub to a Windows based system to run this tool?

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 10 points

    Hi JMMN,

    Obinna was kind enough to forward this question to this forum for me.

    We have the USB hub connected to a processor running a linux distro, is there a similar tool for linux? Or a list of commands we could use to set up the USB hub?

    Kind regards,

    Ernst

  • 0 in reply to Elv
    TI__Guru 60870 points

    HI Elv,

    There is not a similar tool for Linux.  The commands are explained in the USB 2.0 specification, section 7.1.20.  The host would need to send the USB Test Packet command to the port under test, the command structure is explained in USB 2.0 specification, section 9.4.9.  There is some support of USB test commands in Linux, but not a tool similar to the Windows one.

    Regards,

    JMMN