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Original question:

MSP430FR2433: Backup memory documentation needs improvement

MSP430FG6426: Do backup memory retention need active RTC running mandatorily

Surya Prakash95
Intellectual 260 points
Part Number: MSP430FG6426

Hi Team,

We have a usecase where we need to retain few bytes of data in the backup ram memory even during power down.

I have used a 3V battery in VBAT terminal (VBAK not used-Open) and XT1 32Khz crystal not mounted which mean i do not need the RTC feature at all.

In this case i do not see the backup memory retained during power down, and it always reads 0 after complete power down.

So my question is,

- is VBAK pin really required to have a supercap here although VBAT is supplied with a 3V constant battery backup ?

- Is XT1 required with 32khz and running the RTC module to have the backup memory active even during power down ?

this is how my register settings look like during runtime (if it helps)

Thanks

Surya

  • 0
    Intellectual 260 points

    Hi Team,

    Meanwhile i was able to do some experiments and get it working.

    I had to switch this bit LOCKBAK to 0 and then write on some data to the backup memory which is now restored even during power down.

    Description in the documentation talks about using this bit for RTC handling but i find it hard to interpret that this bit has effect to the backup memory. Not sure if i read the documentation well, but for me this info was not straight forward to understand the relation between LOCKBAK and the memory backup system.

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