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MSP430FR2111: FRAM uncorrectable bit PUC behaviour

Brian Stewart
Prodigy 120 points
Part Number: MSP430FR2111


Hi folks,

I have a question regarding how to handle a PUC due to an uncorrectable bit error on the MSP FRAM devices.  

Let's say at the start of my program, I enable the PUC by setting the UBDRSTEN flag in the GCCTL0 register. At some time later, an external event causes a problem with one of the FRAM cells (flips a single bit say) and the ECC cannot correct the issue. If the bit stays stuck after PUC, will the device just continually reset as the ECC will be unable to correct the bit?

Maybe this can't happen due to the FRAM being near immune to SEU type effects, but I don't know enough about it to say that for sure.

In general I guess the question is, can I just assume that after a PUC due to an uncorrectable bit, I can enable the UBDRSTEN again and not have an immediate reset?

Cheers

  • 0
    TI__Guru 71216 points
    Hi Brian,

    The users guide is not clear in this case so I'm reaching out to our experts on FRAM module.
  • 0 in reply to Dennis Lehman
    Prodigy 120 points
    Hi Dennis,

    Thanks for the response, I'm wondering if you managed to receive an answer on this yet?

    Regards,
    Brian
  • 0 in reply to Brian Stewart
    TI__Guru 71216 points
    Hi Brian,

    Sorry for the delay.
    I was able to get some help, although I don't think it answers your question.
    I'm reaching out to our team in Germany to get a definitive answer.

    Response:
    For normal condition, after PUC set, UBDIFG will be set, and user can clear the IFG by reading SYSRSTIV or handling it in ISR with UBDIE enabled.
    PUC will not be generated for this ECC error again before the IFG is cleared.
  • 0 in reply to Dennis Lehman
    Prodigy 120 points

    Ok thanks for that. Yeah I don't think that response fully answers the question, since if the bit is still 'broken', I would imagine the device would reset again immediately after re-enabling the PUC, but I'm not sure how I could possibly test this. I guess you could maybe use the UBDIFG flag to perform some sort of checks on startup, or maybe keep a counter to see if it's occurring repeatedly, but ultimately I'm not sure I'd enable the PUC if I can't be sure I know how to handle it.

    I actually have another question on putting the stack in FRAM which I can't quite solve, but I guess that'll need another thread. Thanks for your help so far.

  • 0 in reply to Brian Stewart
    TI__Guru 71216 points
    Hi Brian,

    Sorry this is taking so long to resolve your question. I am still working with our FRAM team to determine the behavior of this bit.
  • 0 in reply to Dennis Lehman
    TI__Guru 71216 points
    Hi Brian,

    Ok, again, many apologies for the response regarding your question. It took me some time to locate the appropriate person to answer your question.

    Basically as you already know, in the unlikely event of an uncorrectable bit error that cannot be corrected by the ECC, setting the UBDRSTEN bit will allow a PUC reset to be generated. Should the bit remain flagged as uncorrectable after the PUC, the code/data will not be recoverable without some type of additional software ECC. Re-programming the device may also correct this error.
  • 0 in reply to Dennis Lehman
    Prodigy 120 points

    Hi Dennis,

    Thanks for the answer, I just needed to clarify the behaviour after a reset.

    Brian.

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