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TUSB2077A: low-speed hub with USB 3.x devices

Simon Steinegger
Prodigy 170 points
Part Number: TUSB2077A

Hello everybody,

We are currently facing problems with the TUSB2077A hub not recognizing our USB3.x sticks. I would like to find out whether it makes sense to further investigate on this, therefore the following questions:

Can anybody share his (positive) experience regarding this?

Or is it simply not possible for some reasons (probably within TUSB2077A - as USB3.x specification requires USB2.0 compatibility at low-, full- and hi-speed)?

Thanks and best regards

Simon

  • 0
    TI__Guru 60870 points
    Hi Simon,

    This should work, any USB 3.x device should be backward compatible to the lower USB speeds. In the case of TUSB2077, the devices would need to drop to full-speed. Possible issues would be if the USB devices relied on USB 3.x compatible amounts of VBUS power (900 mA) instead of the 500 mA provided by USB 1.1/2.0 or if the drives are large and take a long time to load over full-speed. Do you see anything connected on the downstream ports in Device Manager or usbview?

    Regards,
    JMMN
  • 0 in reply to JMMN
    TI__Guru 60870 points
    Hi Simon,

    Do you have any additional debug information?

    Thanks,
    JMMN
  • 0 in reply to JMMN
    Prodigy 170 points
    Hi JMMN,
    Thanks for asking.
    By now I have to state more precisely. It is NOT a general issue with USB3.x devices (memory sticks). It is only when they are already plugged in on device start-up. If the device is already running - no problem.
    It's an embedded system, so Device Manager or usbview are unfortunately not available on our WinCE version.

    I'll check power on start-up, when first activity on USB lines occurs to get more info.
    However the USB host should poll and find the stick sooner or later... This is what I don't understand at the moment. If power is ok, I think I'll hand over to our SW developers who are in charge of the USB host.

    Best Regards
    Simon
  • 0 in reply to Simon Steinegger
    TI__Guru 60870 points

    Hi Simon,

    Do you see any issues with USB 2.0 devices that are plugged in before start up?   Any debug info your SW developers could provide would be helpful.

    Thanks,

    JMMN