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DS90UB927Q-Q1: How to confirm that DS90UB927Q-Q1 has video signal input

Don Cheng
Prodigy 80 points
Part Number: DS90UB927Q-Q1

Hi Team,

    I  found that DOUT+/DOUT- would have signal output when UB927 powered on and without video data input; Is that correct?

   If I want to confirm that UB927 has video signal input, which register could I read to confirm its status?

  Thanks.

best regards

DonCheng

  • 0
    TI__Guru** 103215 points

    Hello Don,

    Yes, if there is no video input to 927, the device will generate an FPD-Link forward channel signal using always on internal clock to establish a link which is why you see DOUT togging. 

    To check if there is video input to the device, you can use register 0x0C[2] to see if there is a valid PCLK input 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 80 points

    Hi Casey,

    Understood.thanks for your support.

    One more question, If UB927's PDB pin is always set to a low level state, will register 0x0C[2] of 927 will detect a valid PCLK input?

    Or is there a way to reset UB927 when a valid PCLK input is detected?

    Thanks.

    best regards

    DonCheng

  • 0 in reply to Don Cheng
    TI__Guru** 103215 points

    Hello Don,

    When PDB = L, the 927 device is not functional. The I2C interface will not even be active until PDB is set to logic high. 

    To reset the device, you must either toggle PDB low -> high externally or issue a digital reset from an external I2C controller using register 0x01

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 80 points

    Hi Casey,

    When PDB = L, the 927 device is not functional.

    If I toggle PDB low to high through an external MCU when there is a valid PCLK input, will register 0x0C[2] will be reset to default value when PDB=L?

    Thanks.

    best regards

    DonCheng

  • 0 in reply to Don Cheng
    TI__Guru** 103215 points

    Hello Don,

    Yes, toggling PDB L-> resets all the registers in the device 

    Best Regards,

    Casey