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AM335X USB host data lost

Peng Liu50174
Expert 1500 points

Hi,

I'm experiencing one strange issue with AM335X USB host port.

I use AM335X to drive one USB printer. The AM335X USB port 1 is configured as USB host, when connected directly with the USB printer though typical 1.5m USB2.0 cable sometimes the printout have obvious data lost. Tried two printers, the issue is the same.

But when inserted one HUB betweent the AM335X and the USB printer, no data lost happen, everything is OK.

I suspect signal integerity issue first. But when added very long cable betweenthe AM335x USB host port and HUB, still no data loss, so SI seems not the cause.

Any other possible cause to this data loss problem?

Thanks,

Peng

 

 

 

 

 

 

  • 0
    TI__Mastermind 25235 points

    Hi Peng,

    I'll try to ask the factory team USB expert to assist with your issue.

    In the meantime please let us know which Linux version you are using and provide any relevant logs if available.

    Best regards,
    Miroslav

  • 0
    TI__Mastermind 27890 points

    Could you tell us more about the printer in question?

    HighSpeed or FullSpeed USB?

  • 0 in reply to -DK-
    Expert 1500 points

    Hi,

    When the AM335X host controller is set to work at full-speed. The printer works fine, just the speed is slower.

    Whent he AM335X host controleris is set to high-speed, the printer can't work well when printer connected to AM335X USB host port directly. We suspected the signal integrity might be issue, but when we removed all the common mode chokes and ferrite beads to the USB signals and ground, the issue still there.

    But when inserted one high-speed hub between the AM335X and the printer w/o any rework on the USB circuit, the printer woks fine, even we added a long cable between the AM335X host port and the HUB upstream port.

    Our S/W people hasn't provided me the detail log information yet.

    Thanks,

    Peng,

     

  • 0 in reply to Peng Liu50174
    TI__Mastermind 27890 points

    1) Are you sure the hub is actually enumerating at HighSpeed?

    2) How do other HighSpeed devices behave when connected directly to AM335x?

    3) Do you have access to a USB protocol analyzer?

  • 0 in reply to -DK-
    Expert 1500 points

    Hi,

    When the hub is connected, it is enuerated as high-speed. I measured signal wavefrom when hub or USB stick were connected, the signals were indicating 480MHz high-speed.

    We tested USB stick, it works well.

    We don't have USB high-speed protocol analyzer, so can't get the signalling information.

    Regards,

    Peng,