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I2C Deinit on MSP reset

Arun Ravi
Prodigy 30 points
Other Parts Discussed in Thread: MSP430F5438A

Hello,

I'm working on a project in which there is an inter-board I2C link between the master MSP430F5438A and the slave STM32F207IG. Now whenever the master MSP430 resets(due to the external watchdog), the PE bit (Peripheral Enable bit) present in the I2C control register of STM32F2 is set to zero. This reset of the PE bit causes a deinitialisation of the I2C link. Any idea why the PE bit changes? 

  • 0
    TI__Genius 15370 points
    Hi Arun,

    I can provide my expertise on the MSP430F5438A and try to help as much as possible with your question. However, it looks like it is more directed toward the STM32 device. Nonetheless, I'm assuming you're resetting the MSP430 via the RST pin. Is this correct?

    When reset via the RST pin, the MSP430 performs a Brownout Reset (BOR), Power On Reset (POR), and a Power Up Clear (PUC) in that order. This can be seen in Figure 1-6 of the User's Guide. When the device undergoes a PUC the USCI I2C registers are set to default values and the connection to the STM32 is most likely lost. This could be the reason the PE bit is reset.

    Best regards,
    Caleb Overbay
  • 0 in reply to Caleb Overbay
    Prodigy 30 points

    I'm also running Micrium 3 OS on MSP430. The PE bit does not reset when Micrium is not running on MSP, the reset occurs only when Micrium runs on MSP.Is it possible that the RTOS is a cause for the reseting of the PE bit? If yes HOW?

  • 0 in reply to Arun Ravi
    TI__Genius 17205 points
    Hello Arun,
    I moved this to the MSP forum for better support.
    -Francis Houde
  • 0 in reply to Arun Ravi
    TI__Genius 15370 points
    Hi Arun,

    Micrium 3 OS is not a TI product so unfortunately we don't have expertise on how it works and interacts on our devices and I can't provide a definitive yes or no as to whether it is the culprit. Regardless, I wouldn't expect an I2C connection to remain established through a device reset for the reasons I've mentioned above. Have you monitored the I2C lines when the issue appears? What do you see?

    Best regards,
    Caleb Overbay

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