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TUSB8041A: Question for TUSB8041 USB2.0 Eyediagram Test on Android OS

Jacky Wang(QD)
Genius 11600 points
Part Number: TUSB8041A
Other Parts Discussed in Thread: TUSB8041

Hi Experts,

Our customer wants to measure the downstream port USB2.0 eye diagram for TUSB8041 on TV Android OS, but after running their test pattern, we can not see any high speed USB test data on the tested downstream port. We confirmed the tested downstream port works normally if you connected a USB device. Can you guide us how to do this eye diagram test based on Android OS for TUSB8041 hub?

Thanks a lot!

  • 0
    TI__Guru 60870 points

    Hi Jacky,

    That is expected, the hub won't pass through a USB test packet since it has no routing information and none of the downstream ports are enabled.

    Two methods to force test packets on the downstream ports of the hub:

    • Have the USB host send a USB test packet command to the downstream port of the hub under test.
    • Have the USB host send a test force enable command to the hub and then send a test packet from the host.  Please note that the hub will impact the number of sync bits and EOP width on a repeated test packet.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Genius 11600 points

    Hi JMMNy,

    Thanks for the reply, but sorry for that we are not familiar with these tests, can you help to give us more details about the USB test packet command or force enable command looks like on Android OS?

    Thanks.

  • 0 in reply to Jacky Wang(QD)
    TI__Genius 11600 points

    Hi JMMN,

    Add another question, customer feedback that during this eye diagram test, they will not run in Android OS level, but just in low level kernel, so they can not send these USB commands. Can you help to check if our hub can work in some hardware pass through modes without additional OS commands needed?

    Thanks a lot! 

  • 0 in reply to Jacky Wang(QD)
    TI__Guru 60870 points

    Hi Jacky,

    The hub can only support USB test modes when sent the expected USB commands, there is no way to force the hub into test mode using external hardware. To test USB signal quality test they will need to generate these commands to the USB hub.

    Regards,

    JMMN