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TUSB2077 (2046)

Chris Rainey
Prodigy 10 points

It appears there is a bug in the above chips admitted in http://focus.ti.com/lit/er/sllz052/sllz052.pdf (errata)

It states the problem can be resolved by asserting DP before DM. Unfortunately this in not under the control of the chip(unless I am not understanding the errata)  it is surely the external device over which we have no control. I also note the errata is 2006 is possible that this problem is now resolved?

 

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    TI__Genius 16440 points

    Chris,

    These devices are over 10 years old and as USB high-speed becomes the standard use case, USB full-speed hub applications are becoming fewer and more select in where they are implemented.  Due to the age and the declining market for full-speed hubs, as the errata document states:
    TI has no planned fix in the pipeline, but wants users to be aware of this issue...

    A further potential fix proposed in the errata is to modify the USB hub class driver in the system - note that these are native to all operating systems and TI does not have any code for such:
    In the event that a false low speed detection is observed, the situation can be resolved by performing a CLEAR_PORT_FEATURE(PORT_ENABLE) followed by a RESET_PORT in the software driver, assuming both DP and DM are now stable.