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Original question:

Linux/DS90UB940-Q1: DS90ub940 unable to see the camera

Linux/DS90UB940-Q1: DS90ub940 unable to see the camera

user5607428
Prodigy 30 points
Part Number: DS90UB940-Q1

Tool/software: Linux

The Serializer is DS90UB925, the voltage on LOCK pin is 1.79V, the voltage on PASS pin is 0.89V. 

I think the PASS is not at the right voltage, it means the error is detected, is it right? 

If so, what is the reason?

  • 0
    TI__Genius 10475 points
    Hello,
    Are you using BIST mode? If PASS is not high in BIST mode then there are some errors in the link. You can enable BIST from the deserializer side, refer to the datasheet for additional information on BIST.

    Also measure the power supplies to ensure they are at the right levels within the datasheet specifications.
  • 0 in reply to Palaniappan Manickam
    Prodigy 30 points
    Hello Manickam,

    Thank you for so quick reply.
    Yes, the reason is the Pattern Generator is enabled.
    Remove these code to disable the Pattern Generator.

    Now work in the normal mode.
    The LOCK is still not valid, the voltage on on LOCK pin is not HIGH, even program the General Configuration 0 register (addr: 0x02) to 0xd0.

    Best Regards,
    Wenyou Yang
  • 0 in reply to user5607428
    Prodigy 30 points
    Hello Manickam,

    According to the Table 2 on page 25 of ds90ub940-q1 datasheet, (www.ti.com/.../ds90ub940-q1.pdf),
    The PDB, OUTPUT ENABLE (Reg 0x02 [7]) and OUTPUT SLEEP STATE SELECT (Reg 0x02 [4]) have been satisfied (H, H and H), but the LOCK is not HIGH.
    Could you give me some advice?

    Thanks a lot.


    Best Regards,
    Wenyou Yang
  • 0 in reply to user5607428
    TI__Mastermind 30515 points

    If the link is unlocked, the LOCK pin voltage will be NOT high if you use multi-meter test.

    please use oscilloscope to capture the LOCK pin signal to observe, it seems the link in your test is not marginal, and unlock is reported frequently.

    if yes, please analyze your link robust.

    best regards,

    Steven