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C6474 antenna interface disparity error

RY9983
Guru 10570 points


Hello,
We are using C6474 antenna interface to communicate with FPGA.
We are facing disparity error during operate as 3Gbps with the high temperature.
(not facing during operate as 1.5Gbps with the high temperature.)

Could you let me know the idea to find the root cause?
  a) Do you have any setting to try?
  b) Do you have any idea other than configuration?
  c) Are there any errata? (I can not find it on sprz283C)
  d) We appreciate any trivial informations.

We have checked the following:
 - We changed the C6474 side configuration(TX_DE, TX_SWING, SD_TX_CM of LINK_CFG), but it was no effect.
 - We changed the FPGA side configuration(Equalizing, Termination Resister, AC Coupling), but it was no effect.
 - We checked Eye pattern, but it is cleared completely.
 - We can not connect CCS during disparity error.  (It seems that DSP core is hanging up.)
 - Some devices occur disparity error in about 90 degree. but in many cases that occurs in 100 degree.

Best regards,
RY 

  • 0
    TI__Prodigy 360 points

    RY,

    Can you please give us more details on "disparity error". What specifically do you mean by "disparity error" and the eye is "completely cleared". Is the eye closed? Is the eye being measured at the RX pins?

    Thanks,

    Jayanth

  • 0 in reply to Jayanth Rangaraju
    Guru 10570 points

    Jayanth-san,

    Thank you so much for your reply.
    First, I would like to report.
    I found that the DSP CVDD is dropped down on our system.
    So, I am testing the problem of power side.
    Can I close this question once?
    If the problem does not clear, I would like to ask again.

    I would like to answer your questions:
     - disparity error means the error of FPGA OBSAI side.
      DSP encode the 8b data to the 10b and transmit 10bit data to the FPGA.
      FPGA receives the 10bit data and decode the 10b data to the 8b and recognize 8bit data.
      Disparity error happens  when the 10b data which is received by FPGA does not exist in the decode table.

     - Eye opens clearly.
       But, I am sorry, I can not attach the actual wave form now.

     - Yes, I measured the eys at the RX pins.

    Best regards, RY