NV address to save custom data

[Jake]

I want to save custom data in NV address. Which address is safe to save custom data in NV?

I'm working on nRF51822-xxAC with very simple and small code. And, using s110 Softdevice.

In my understanding, 0x40000 is tail address of NV. So, I'm trying to save 4bytes of data at address of 0x40000-0x400. I saved data using nrfjprog as below in linux(ubuntu) prompt.

$ nrfjprog --memwr 0x3fc00 --val 0x00112233

And, read it from nRF source code as below.

memcpy(dest, 0x3fc00, 4);

It worked fine at first boot. But, in some time the value in the address, 0x3fc00 is modified to some other value.

[John]

When the value becomes "corrupt" is it always set to the same value? If so, what is it? Are you resetting or reprogramming after the first boot before it becomes corrupt?

[Stefan Birnir Sverrisson]

Hi Jake

This thread contains some information on where data is stored in flash, and also where pstorage library stores information in flash. There is also new libraries available in most recent nRF5 SDK, called fstorage and flash data storage, to manage flash operations.

[Jake]

Thank you. The thread you linked is very helpful and informative.