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"Don't care" bit in SCCB protocol vs. I2C

Nicolas Göddel
Intellectual 795 points
Other Parts Discussed in Thread: EK-TM4C1294XL

Hi there,

I am using the Tiva C Series Connected Launchpad EK-TM4C1294XL and CCS 6.0.1 to connect to the OV5642DS camera module. This module uses the SCCB protocol to send and receive control data. Because SCCB don't uses the ACK/NACK bit, I run into problems if I want to use the I2C bus from my µC. Is it possible to disable the ACK/NACK handling and simply let the µC think all data has sent/received correctly?

Thank you!

  • 0
    TI__Guru**** 244400 points
    Hello Nicolas,

    The I2C module does not ignore a NAK during the address phase. As per the SCCB specification, the slave device may respond to the 9th bit and I think you should check with Omnivision if indeed the 9th bit is left floating or not.

    Alternatively, there is another method that may be used during Write phase. That would be to enable the I2C Slave module and have the same address as the SCCB slave. The I2C Slave will acknowledge the data and echo the same data into it's Data Register which can be flushed out by the CPU. However read may still be an issue, but if my understanding of the SCCB specification is correct then by writting 1's during the read phase to the I2C Slave the control data from the Camera may still be received by the TM4C I2C Master.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Intellectual 795 points

    Okay. I suppose it would be a better idea to use BitBanging for SCCB.

  • 0 in reply to Nicolas Göddel
    TI__Guru**** 244400 points
    Hello Nicolas,

    Do check on SCCB protocol as I am not sure if the 9th bit is going to be NAK.

    Regards
    Amit