Retaining a few bytes in the nRF51 after a restart from system_off

[Russ Mirov]

I'd like to retain a few bytes after a restart from system_off. I know the GPIO state is retained, are there any other registers other than that? It looks like RTC1->CC[0] is, but oddly enough CC[1] isn't (or is getting clobbered). I'm using the softdev. Am I just getting lucky with CC[0] ? My application doesn't use RTC1, nor does it use the bsp manager if that is an issue.

[RK]

You're just getting lucky. On the nRF51 the only registers retained after a start from system off are listed in the manual, and the only one you can really use is GPREGRET, which gives you 32 bits. If you need more than that then you really have to store your data in flash.