CC2642R: Issue with I2C repeated start

Nicholas Carley

Part Number: CC2642R

We have a TI CC2642R1F (die rev E) using TI RTOS SDK 3.20.00.68. It is currently acting as a I2C bus master. We have a slave device that requires I2C repeated start for communication.

Chapter 23 of the TRM and this E2E post says that CC2642 does provide an I2C repeated start, after several permutations calling TI-RTOS call such as I2C_transfer() using the I2C_Transaction data structure, we have yet to see an I2C repeated start generated from the CC2642 running as an I2C master. Does this version of the TI-RTOS have parameters to call an I2C Repeated Start?

over 5 years ago

0 IUsedToBeARealPerson (M-W) over 5 years ago

TI__Guru 58425 points

Hi Nicholas,

The I2C driver does generate repeated stars, what in particular are you looking for? The driver only generates a repeated start when moving from performing write to read. This means you would need to perform an transaction with at least 1 write and 1 read.

0 Nicholas Carley over 5 years ago in reply to IUsedToBeARealPerson (M-W)

TI__Genius 9885 points

Please refer to the following PDF for the repeated start condition.

https://www.mouser.com/datasheet/2/256/MAX86150-1282822.pdf

Pages 36 to 39 describes the Repeated Start I2C protocol for communication. So far, the customer have not been able to have the CC2642 communicating with this IC. Is the I2c read sequence possible with the TI-RTOS on the CC2642?

0 IUsedToBeARealPerson (M-W) over 5 years ago in reply to Nicholas Carley

TI__Guru 58425 points

Hi Nicholas,

Yes, both the device and driver should be able to handle this. The question is how the customer is using the driver. For example, there will only be repeated start generated for a transaction that is setup to contain both write and read operations.

Could the customer share the test code they use?

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CC2642R: Issue with I2C repeated start