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DS90UB934-Q1: Hot plug application--camera connect detection

Dongbao Zhou
Expert 4170 points
Part Number: DS90UB934-Q1

Hello team,

My customer is working on an E-mirror project, with below configuration: camera sensor+933---934+ISP, they would like to have hot-plug function. That's to say, if camera module disconnect with 934, it will connect automatically after re-connect.

The problem is how to detect whether camera module is connected with 934?

Need this information to reconfigure the 933 register after power-on to enable I2C/GPIO passthrough. Customer configures 934 as 12-bit HF mode, from the datasheet, LOCK pin only indicate the PCLK status, not the link status. Can we use the LOCK_STS to indicate the link status? (High= link ok, Low= disconnect)

Thanks.

Best regards,

Dongbao

  • 0
    TI__Mastermind 30515 points

    Dongbao,

    PCLK status is transmitted by link, so the LOCK indication in 12HF bits mode does not impact the camera detection. also, adaptive equalization value and cable Link detect diagnostics in UB934 also can help the camera insertion detection.

     

    best regards,

    Steven

  • 0
    TI__Genius 12705 points
    Hello,
    You are correct that LOCK_STS 0x4D[0] or LOCK pin should be monitored. As stated in the pasted text, LOCK status indicates a link has been established, which is more than just PCLK detected. Lock status is a current status and so you would need to ensure enough time also for startup transients (~30ms) when lock may be going high and low.
    LOCK_STS_CHG 0x4D[4] is also helpful as this can monitor if lock has toggled since last read.
    For detecting a valid FPD Link III input, it is best to use RX_PORT_STS2 0x4E[2:1].
    If there is cable disconnected these bits would read out 01b = 0x4E[2]=0: Frequency measurement unstable
    0x4E[1]=1: No FPD-Link III clock detected.
    The 933 934 should have LOCK = HIGH before attempting any remote configuration or I2C transactions as stated above.
  • 0 in reply to Liam Keese
    TI__Expert 4170 points

    Liam, steven,

    Thanks for your feedback, just make a short summary based on your comments. Please let me know if I misunderstand your advice.

    Two ways to achieve hot-plug detection:

    1. LOCK status: logic level from high--low (duration>30ms)--high
    2. Read 934 register continuously: 0x4E[2:1]=？01b， this method need more software resource

    After detecting a valid FPD-LINK III input, what would be the next steps? 

    Hardware/digital reset 934, then enable I2C/GPIO pass through, let ISP initialize camera sensor through I2C. Is that correct?

    Thanks.

    Dongbao

  • 0 in reply to Dongbao Zhou
    TI__Mastermind 30515 points
    Dongbao,
    dependent on system design (hardware + software), you can detect the LOCK pin, and then visit UB913a internal registers, if the returned values are correct, it means the link is created correctly.

    best regards,
    Steven
  • 0 in reply to Liam Keese
    TI__Expert 4170 points
    Hello,
    I wanna point out that "lock_sts=H doesn't mean Lock=H in 12-bit HF mode", it should be LOCK_STS=H before remote I2C configure is availabe to serializer, just as descripted in d/s. Also confirmed this jugement through 933 and 934 evm.
    Dongbao