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MSP430FR6047: disabling BOR

Akira555
Intellectual 335 points
Part Number: MSP430FR6047

Hello experts,

I would like to know about BOR (Brown Out Reset) of MSP430FR6047.
My understanding is that BOR is basically enable, but can it be disable?

if it can be disable ,please let me know how to disable it .

If it cannot be Disable, I believe that BOR will occur when the condition is met.

Is there any way for the user to check whether BOR or WDT occurred after the reset?

Best Regards

  • 0
    TI__Genius 11960 points

    Hi Akira,

    Reviewing the device family users guide, it looks like the BOR cannot be disabled.

    You are correct that the BOR will always occur when the voltage drops to the BOR level, amongst other conditions like a software BOR.

    You can check if a reset was due to a BOR by checking the PMMIFG register, and checking the PMMBORIFG bit. 

    Please review the BOR system and the mentioned registers in the device family users guide for more information.

  • 0
    Guru 39490 points

    BTW, Akira, the BOR is a Good Thing (TM). Otherwise the chip will enter undefined behavior land and you won't be able to count on *anything*. You need to change your design so that the MCU does *not* get into BOR territory.

  • 0 in reply to Keith Barkley
    Intellectual 335 points

    Keith san,

    Thank you for your answer and advise.

    I opened this thread for our customer.

    They don’t know if BOR really occurred ,because the function to check the PMMBORIFG bit has not yet been implemented.

    Because of this situation, please let us know one more point.
    If VCC_BOR+ (MIN:0.79V, MAX:1.68V) is exceeded after BOR occurs, does MCU start up as usual? Or, does it fall into some abnormal state?

    Their system performs USS initialization processing before it starts up and transitions to the main routine.
    This initialization process does not end normally and WDT resets repeatedly.

    The same event occurs when an illegal value is intentionally written to the USS configuration used in the USS initialization process.
    I would like to know what to do after the BOR occurs.

    Best Regards,

  • 0 in reply to Akira555
    TI__Genius 11960 points

    Hi Akira,

    Please see section 1.2.1 of the device family users guide to review the device conditions after a BOR. 

    To summarize, a BOR resets the device, so after a BOR the program counter is loaded with the boot code address, and the device reboots. After booting the device will go on to execute application code as normal. This section of the users guide also states that the watchdog timer powers up active in watchdog mode, so you will need to either service the watchdog, or disable it early in your application code.

    As for the behavior when an illegal value is written to the USS configuration and used for initialization, I would say this is expected behavior depending on what exactly you are misconfiguring.

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