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Original question:

MCU-PLUS-SDK-AM263X: i2c transaction failure after a read to a non-existent device address

MCU-PLUS-SDK-AM263X: MCU-PLUS-SDK-AM263X

Kedar Chitnis
Prodigy 45 points
Part Number: MCU-PLUS-SDK-AM263X

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1310642/mcu-plus-sdk-am263x-i2c-transaction-failure-after-a-read-to-a-non-existent-device-address

Can we get a solution to this issue ? This is easy to recreate using standard MCU+ SDK and AM263x control card ?

Just access do a rd or wr on a non-existing I2C device say 7b addres 0x61 and then do a vali I2C transaction on the LED IO expander on AM263x control card at address 0x60 and you will need that the valid access fails.

  • 0
    TI__Prodigy 580 points

    Hi kedar,

    we have already replicated the issue and confirmed this as a valid bug on SDK I2C Driver. We'll fix this in our upcoming 09.02v release. 

    Team is working on the fix. We'll share the fix in 3-4 days.

     

    Regards,

    Abishek S S

  • +1
    TI__Prodigy 580 points

    Hi Kedar, 

    As per the current driver in case of a NACK condition when in BLOCKING mode, the Semaphore gets posted before the STOP is initiated.
    After initiating the STOP condition the interrupts are disabled; therefore, no further interrupts occur.
    Checking whether the bus is busy is one way of solving the problem although is a quite primitive way.

    A better way would be to handle the nack in a different way, Below is one such way.

    - NACK Happens
    - Object State becomes I2C_ERROR
    - Store the interrupt in intStatusErr
    - Clear and disable all interrupts except STOP
    - Initiate STOP
    - Controller interrupt fires again due to stop completion
    - In I2C_ERROR/I2C_IDLE_STATE check whether NACK happened from intStatusErr
    - Clear and Disable Stop interrupt
    - Post Semaphore

    In this way, by the time the semaphore is posted, the bus will be free.

    I have attached the patch file. Could you please try applying it to your code and let me know if it works?

    Regards,

    Abishek S S

    8345.i2c_nak_interrupt_fix.patch

  • 0 in reply to Abishek S S
    Prodigy 45 points

    Thanks this fixes the issue. 

    ps, the patch you gave is "inverted"