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TMS320F28P550SJ: The behaviors of I2C module

Luke Chen
Prodigy 40 points

Part Number: TMS320F28P550SJ

Hi champs,

Our engineers are evaluating the I2C functionality and have the following questions:

  1. When the I2C module is operating in master mode and I2COAR is set to equal I2CTAR, I2CDRR receives data transmitted by the I2C master. Is this normal? Is this due to the I2C arbitration function?
  2. With digital loopback mode enabled, we can still see the I2C signal on the I2C bus when the I2C master sends data. Is this correct?

Please advise, thanks.

Regards,

Luke

  • 0
    TI__Mastermind 20435 points

    Hi Luke,

    1. If you have DLB enabled, this would explain what you're seeing as otherwise, the data is being transmitted out of the device.

    2. Yes, this is correct.

    Best Regards,

    Aishwarya

  • 0 in reply to Aishwarya Rajesh
    Prodigy 40 points

    Hi Aishwarya,

    Regarding question 1, we are sure that the DLB is disabled. However, when I2COAR is set to equal I2CTAR, the I2CDRR receives data transmitted by the I2C master.

    We would like to know is this normal? In what situations would this feature be used?

    Thanks and regards,

    Luke

  • 0
    TI__Mastermind 20435 points

    Luke,

    The DXR is technically connected the DRR, so it does makes sense you are seeing this on your setup. However, this is there for DLB mode specifically. Even though the I2C HW itself won't stop you from setting these two values equal, we don't recommend it (as we support DLB mode for this use case) and can't guarantee timing or other related requirements.

    Best Regards,

    Aishwarya