Wasting nRF51 Flash memory erase cycles

[Mihail]

Hi, In pstorage.c, function uint32_t pstorage_init(void), there a call to sd_flash_page_erase (line 846):

 // Erase swap region in case it is dirty.
  retval = sd_flash_page_erase(PSTORAGE_SWAP_ADDR / PSTORAGE_FLASH_PAGE_SIZE);

Call to pstorage_init is made every time, processor is restarted (in case we use pstorage). Having in mind that according to Table 16 in the Product Specification which gives an endurance of 20,000 minimum write/erase cycles, is such a call wasting of resources or not?

[Charles Manning]

Whether or not this is a problem will depend very much on what you're doing.

If you're using flash to store settings (eg. whitelist) that change seldom, then you need to figure out if typical lifetime/usage will be enough.

If not, you can add a small EEPROM for a few cents.

[Mihail]

Question is more about: the way flash is erased. May be there is a way to check first, if it is dirty and then to erase it. Like this it seems more like wasting of a resource.

[Stefan Birnir Sverrisson]

Hi

Thank you for your feedback. Your observation is valid. The flash swap page seems to be erased on every start-up of the chip, which in my opinion could be done better. I have suggested your fix to the SDK team.