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USB2.0 eye diagram test on DM8148

SherryC
Intellectual 935 points

Hi all,

I did the USB2.0 eye diagram test on DM8148, but eye diagram failed as below.

Is there any registers can fine tune DM8148 USB2.0 signal drive strength?

Is there any suggestions to improve eye diagram test result(hardware or software)?

Could anyone please give me some hints?

Thanks.

  • 0
    TI__Guru**** 170625 points
    Hi Sherry,

    See if the below e2e threads will be in help:
    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/261933
    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/154545
    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/165644

    We have guidelines for the USB hardware design:

    http://processors.wiki.ti.com/index.php/DM814x_Hardware_Design_Guide

    For detailed information on USB board design, see the USB 2.0 Board Design and Layout Guidelines application report.

    To improve USB eye diagram, try with modifying register 0x47401300.

    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Intellectual 935 points

    Hi Pavel,

    Thanks for your advice.

    About "To improve USB eye diagram, try with modifying register 0x47401300.", I have a question.

    I found DM8148 register descriptions in DM8148 datasheet "Table 8-113. USB0 Controller Registers", the register 0x47401300 is reserved.

    I also checked the DM8148_TRM, there was no description about 0x47401300.

    Could you please help where I can find information?

    Thanks.

    B.R.

    Sherry

  • 0 in reply to SherryC
    TI__Guru**** 170625 points

    Sherry,

    Sherry Chung said:

    I also checked the DM8148_TRM, there was no description about 0x47401300.

    Could you please help where I can find information?

    There is internal document which is available only with NDA and through local TI FAE. Could you please contact your local TI FAE/representative and provide him my name for contact.

    Best regards,
    Pavel