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TUSB2077 - Port disconnect problem

Joost Waegebaert
Prodigy 10 points

Hi,

We've been successfully using a TUSB2077 hub in an industrial system for a long time now. Over the years one problem remained and keeps surfacing now and then : when unplugging the USB device on hub port 3 (connected to pins DP3-DM3), the USB software driver panics and exits with an 'unable to write to USB hub port'.

We have seen this behaviour on both Windows and Linux systems. We never have this issue on the other ports of the hub (which have identical hardware layouts). The PCB uses carefully designed controlled impedance pairs on all ports. We do not have problems with port 3 (or any other port) in normal operation.

Q : is port DP3-DM3 different ? Other suggestions as where to start looking ?

Thank you.

Joost Waegebaert

  • 0
    TI__Guru 60870 points

    Hi Joost,

    Port 3 should not behave differently than the other ports.  It sounds like the USB host is not being notified that the port has been disconnected correctly.  Is there any difference in the power circuitry of Port 3? Or is there a specific downstream device that causes the issue more than others?  This may be some sort of debounce issue.

    Regards,

    Julie Nirchi