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MSP430FR5959: FRAM Information Memory: what are the A, B, C, D parts for? May I use Info Memory as one section?

Iurii Vlasenko
Expert 1050 points
Part Number: MSP430FR5959

Hi, everybody!

I intend to use the msp430fr5959 chip in my project. I see 4 parts of Information Memory: A, B, C and D. Every part has 128 bytes. What if I use these 4 parts as a single memory section with a size of 512 bytes?
I don't see any objections to such use, but if it is permitted - why do 4 parts exist? What is a possible use case to use INFOB (0x1980), for example?

I cannot check my idea since the PCB is not ready, but I need to develop the firmware already.

Thanks in advance,

Yury

  • 0
    Guru 34453 points
    Some factory calibrated data for 2xx devices are store inside INFO A segment, that can be protected for erase/write. 5xx / 6xx factory calibrated data are inside TLV ROM section, and segment A is not used.
  • 0 in reply to zrno soli
    Expert 1050 points

    Thanks for the answer!
    Yes, I know that Info A and Info B are free - from my experience with FR57xx family. And I've used them. But there were reasons to use different sections - and I used them separately. Now I'd like to use 256-byte sections, melting A+B and C+D.
    So is this partitioning a mere historical thing?

  • 0 in reply to Iurii Vlasenko
    Guru 298560 points
    The partitions are useful if you do not want to erase all four flash segments at the same time.

    But FRAM does not have flash segments. This is indeed a purely historical artifact.
  • 0 in reply to Clemens Ladisch
    Expert 1050 points

    Thanks! This is the way I hoped to be!

    I'll check the issue when I can, anyway :)

  • 0 in reply to Iurii Vlasenko
    Expert 1050 points

    Well, I have an answer I'd like to get at the beginning of the thread.

    Now I use Info Memory to hold a list of variables and the space needed is beyond the partition size (128 bytes). There is not a single problem to use the memory across the border, for example in a loop with a pointer, that points to InfoD, then to Info C partition.

    But we have to keep in mind one thing: the partitions play role in declaration and instantiation. For example my code:

    int32_t __attribute__((section(".infoD"))) pDir,    pXOR,   pTunld, pTopen, pTsmin,
    // some vars ...
    pDozZ;                                                       
int32_t __attribute__((section(".infoC"))) cs_conf;

    I had to change section name at the cs_conf variable because of the limited size of D section.

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