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DS90UB935-Q1: I2C error

Colt Zhang
Expert 4985 points
Part Number: DS90UB935-Q1

hi expert,

my customer use 935 pair with 960, When using i2c to write to the 935 register, there is a high probability that i2c will fail to write, and after testing, it was found that when writing 0x7d to the 0x7 register of 935, from the scope analysis , found that the slave address 0x34 has a ack, the register 0x7 has a ack, and the register value 0x7d does not have a ack. could you help review this problem.

  • 0
    TI__Guru** 107670 points

    Hello Colt,

    let me double check if I understood what is going on.

    You are trying to write the SER register 0x07 with the value 0x7d? is that right?

    Are you able to write/read any other registers on the SER with Ack?

    Are you able to write/read any registers on the imager with Ack?

    How is the DES reg 0x58 configured? i.e. with which value?

  • 0 in reply to Hamzeh Jaradat
    Prodigy 30 points

    Hello  

    You are trying to write the SER register 0x07 with the value 0x7d? is that right?
            yes, All registers have a probability of random write failure (when writing i2c, the first two acks are answered, but the third ACK is not answered)
    Are you able to write/read any other registers on the SER with Ack?
            yes, All registers have a probability of random write failure (when writing i2c, the first two acks are answered, but the third ACK is not answered)
    Are you able to write/read any registers on the imager with Ack?
            yes
    How is the DES reg 0x58 configured? i.e. with which value?
            The 0x58 register is configured as 0x5E
  • 0 in reply to z l
    TI__Guru** 107670 points

    Hello Lin Zhang,

    Does that mean, you can communicate with the image sensor without any problem, but when communicating with the SER sometimes it works and other times not. Is that correct? If that is the case, please check the IDx pin configurations on the SER (voltage and resistors). Also, make sure the I2C voltage on the board matches with settings in the SER reg 0x02[0].

  • 0 in reply to Hamzeh Jaradat
    Prodigy 30 points

    Ok, let's try it

    In addition, I would like to ask a question, want to use the BIST function, we configure the 0xB3 register to 0x01, and read the value of the 0x57 register, the actual use found that the 0xB3 register configured to 0x01 will cause i2c abnormal congestion, why?

  • 0 in reply to z l
    TI__Guru** 107670 points

    Hello,

    once BIST is enabled, you will not have a functioning I2C remote communication between SER and DES. This is expected.

  • 0 in reply to Hamzeh Jaradat
    Prodigy 30 points

    After the bist function is enabled, is it necessary to turn off the i2c communication of the remote serializer in advance when reading the 0x57 register

  • 0 in reply to z l
    TI__Guru** 107670 points

    BIST registers can only be read after you stop BIST. Any reading while BIST is still running will not give a correct answer.