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TUSB4041I: About Device Descriptor at address -assigning phase.

user1757799
Prodigy 40 points
Part Number: TUSB4041I

TUSB4041I:About Device Descriptor at address -assigning phase.

In enumeration phase of TUSB4041I.

1.When system request 64byte length device descriptor, TUSB4041I returns 0x00 as bDeviceProtocol.

2.When system request 8byte length device descriptor, TUSB4041I returns 0x02 as　bDeviceProtocol.

Our System requests 8byte length devide descriptor in Address-assigning phase, then System returns [Illegal Device Protocol] & enumeration failed.

(Tther system (windows 7,etc),System request 64byte length device descriptor in Address-assigning phase, Enumeration finished successfully.

  • 0
    TI__Expert 7395 points

    Hello,

    If bDeviceProtocol is 0x00, that would indicate the TUSB4041I was somehow enumerated as FS/LS device.

    For 2.0 hubs operating in HS, bDeviceProtocol indicates whether hub has multiple TTs (0x02) or only a single TT (0x01). TUSB4041A has multiple TTs.

    Check the USB 2.0 specification at section 11.23.1

    Regarding to the error you are seeing when requesting 8 bytes from the device descriptor, I would recommend you to check your system's host controller driver for other possible issues, as the TUSB4041I would properly return the requested 8-bytes. The screenshot bellow shows a protocol analyzer capture when using the USB 3 Gen X CV tool to get 8 bytes from the device descriptor; as you can see data is being properly returned.

    Do you have a protocol analyzer capture you can share showing the issue you are experiencing?

    Regards,

    Jorge

  • 0 in reply to Jorge Llamas (SWAT)
    Prodigy 40 points

    Very Thanks

     I will send this information to customer.

    Regards

    K.Fujii