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Original question:

TMS320F280049: I2C Repeated Start Behavior / RM bit / Accurate RX Count

TMS320F28386D: I2C Repeat mode in master-receive

Clément Letonnelier
Expert 2586 points
Part Number: TMS320F28386D

Hello,

I saw from another post that the I2C peripheral in the C2000 processors works in repeat mode even in master-receive mode, despite the indication of the RM bit from the I2CMDR register in the TRM.

In order to ensure that it works, we prototyped it on one of our board.

We did the following:

  • Set slave address
  • Write to the I2CMDR register to launch an I2C master-receive operation with RM bit set without stop condition request set

The slave device then continuously transmit bytes which are then stored into the FIFO and we unpack them fast enough to avoid the FIFO from getting full.

As this behavior is not documented, can you please confirm that this behavior is as expected and will always work, as well as maybe request a documentation update ?

Best regards,

Clément

  • 0
    TI__Mastermind 30185 points

    Hello Clément,

    I've contacted the designers to confirm this behavior and see if there is a reason we don't mention the master-receive configuration for repeat mode. I will reply some time mid-next week if I have a response.

    Best regards,

    Omer Amir

  • 0 in reply to Omer Amir
    TI__Mastermind 30185 points

    Apologies for the extended delay, I'm still in discussion to confirm with the design team, it seems like the I2C is expectedly capable of this, but for some reason we haven't documented this. I'm still confirming the reason for this.

  • +1 in reply to Omer Amir
    TI__Mastermind 30185 points

    I have confirmed with the design experts that the I2C is capable of this, and in fact this seems to be documented in most places in the TRM except the RM register bit description. I will file a change for this, and the device TRM should reflect this in its next update.

  • 0 in reply to Omer Amir
    Expert 2586 points

    Great, thanks for confirming with the design team.