Durability of 80-byte User Memory in Backup Domain of STM32F405

majorbulk · ‎2012-07-21

Posted on July 22, 2012 at 03:26

Greetings,

I have a small number of bytes (less than 80 bytes) that I need to store in persistent storage, but the values may change in excess of 10,000 times. I believe the SRAM would work fine for this, but I would rather not use the extra battery power to maintain the SRAM if the 80-byte memory in the backup domain can handle the write frequency I anticipate. What kind of memory is this 80-byte user memory? What are the specs for number of writes?

Thanks,

Valkyrie-MT

#sram-backup-rtc

jpeacock2399 · ‎2012-07-23

Posted on July 23, 2012 at 16:02

The backup registers are SRAM powered from the backup (Vbat) power domain. For the STM32F1xx series these are 16-bit half words; don't try to use 32-bit access. You will need a battery or some other backup supply (i.e. supecap) in order to save data in the backup registers. Be aware that a tamper event (if you have it enabled) will erase the 80 byte backup register area.

Jack Peacock

majorbulk · ‎2012-07-23

Posted on July 24, 2012 at 06:28

Excellent! Exactly the answer I was hoping for! And thanks for the tip on the tampering. I'll have to figure out how to disable that.

-Valkyrie-MT