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MSP430FR6989: Backup memory in LPM3.5 low power mode

Mehmet Vural
Prodigy 20 points
Part Number: MSP430FR6989
Other Parts Discussed in Thread: MSP-EXP430FR6989, MSP430WARE

I am curious that when we enter the LPM3.5 mode, is there anyway to keep some of contents that are used in the FRAM? Otherwise, do I need to add a battery backed-up memory to my hardware? My solution that comes into mind is that; before going to LPM mode, I should save the content (that I want to keep) to that external memory and after exiting LPM mode, load the FRAM from that memory again?

I have seen that some RTC registers are retained in LPM3.5 mode. However I also have some critical memory that I need to retain in my FRAM? Could some one please advise? 

Thanks..

  • 0
    TI__Expert 6635 points

    Hi Mehmet,

    You might be interested in our Compute Through Power Loss library. I am providing a link below that will explain it in more detail, but it enables an application to easily save the CPU and peripheral states into non-volatile FRAM, before powering down or entering a deep-sleep mode like LPMx.5.

    You will want to look at section 2:

    http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/FRAM_Utilities/latest/exports/FRAM-Utilities-UsersGuide.pdf

    CTPL code examples can also be found by going to CCS and navigating to View > Resource Explorer. Then in Resource Explorer, navigate to Software > MSP430Ware > Libraries > FRAM Utilities > Example Projects > CTPL > MSP-EXP430FR6989. 

    Please let me know if you have additional questions or if this does not fulfill what you need.

    Thanks,

    Mitch

  • 0 in reply to Mitch Ridgeway
    Prodigy 20 points

    Hello,

    thanks for your attention.

    Actually the papers that you have proposed are focused on how to keep the stack, etc. when a power loss occurs on the controller.

    My main concern was to keep the variables(e.g. a counter in my software) that are used in the FRAM. I have found slaa628 document whose name is 'MSP430 FRAM Technology- How to and Best Practices'  where it is told that by defining the variables with the #PERSISTENT pragma, the value of the variables are retained even in power loss-sleep.

    I think this pragma will solve my problem.

    Thanks again.

  • 0 in reply to Mehmet Vural
    TI__Expert 6635 points

    Hi Mehmet,

    Thanks for the clarification! Yes, it sounds like the #PERSISTENT pragma is what you are looking for.

    Thanks,

    Mitch

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