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OPT3001-Q1: Behavior in case of initialization failure

Hironobu Tomita
Prodigy 30 points

Part Number: OPT3001-Q1
Other Parts Discussed in Thread: OPT3001

Hello Support team,

I want to know the irregular behavior.
If a NACK error occurs during initialization for some reason and the configuration fails, and after that, we try to read operation to Register 0h, what happens?
Because I am considering controlling the process sequentially from initial setup to the Read operation, we would like to confirm this.

Regards,

Tomita

  • 0
    TI__Expert 7000 points

    Hello Tomita,

    I'm responding on behalf of our Optical Support team while they are out of office. Typically when an I2C device NACKs during setup, especially if it fails to acquire its address, the measurement result register will read back junk data.


    Regards,

    Harry

  • 0 in reply to HarryG
    Prodigy 30 points

    Hello Harry,

    Thank you for your reply.

    Just to be sure, please allow me to confirm.

    When an I2C device NACKs during setup, after that, if we read the measurement result register, the read operation executes as normally protocol, but the read data is junk data.

    In other words, it is better not to read that register in this situation, or if we do read, it is better to ignore the read data.

    Please let me know if my understanding is correct.

    Regards,

    Tomita

  • 0 in reply to Hironobu Tomita
    TI__Expert 6560 points

    Hi Hironobu, 

    Yes, if setup did not complete correctly I would discard the read data.

    Thank you, 

    Joseph Scherphorn

  • 0 in reply to Hironobu Tomita
    TI__Expert 7000 points

    Hello Tomita,

    That is correct. At least in the case of another I2C device I've tested before (a temperature sensor) the device's temperature register contained junk data (0xFF etc.) since it couldn't acquire its address during setup. This would most likely be the case with the OPT3001 if it couldn't acquire its address during setup.

    Regards,

    Harry

  • 0 in reply to Joseph Scherphorn
    Prodigy 30 points

    Hi Joseph,

    Thank you for informing me about how to use the read data.

    Best regards,

    Tomita

  • 0 in reply to HarryG
    Prodigy 30 points

    Hello Harry,

    Thank you for testing I2C device and sharing the results.
    0xFF is not good. I was able to understand that we should not use the read data in that case.

    Best regards,
    Tomita