If the NVM data is read prior to erase or write, what will the flash storage return

[NanElv]

I would like to know and understand the implication of what will happen, if i use the 

nrf_fstorage_read before calling either nrf_fstorage_write or  nrf_fstorage_erase. 

Which will be a good place to erase the flash storage just once? prior to writing any data.

[Kenneth]

Hello,

Data in UICR can not be changed during the product lifetime, so if you need to change the data then you can't use the UICR for the purpose.

The Flash endurance is minimum 10 000 Write/erase cycles.

If you want to store data in flash you can use FDS (or Fstorage) directly, there should be example for both in nRF5 SDK. Also check out the FDS_VIRTUAL_PAGES_RESERVED define:

// <o> FDS_VIRTUAL_PAGES_RESERVED - The number of virtual flash pages that are used by other modules.
// <i> FDS module stores its data in the last pages of the flash memory.
// <i> By setting this value, you can move flash end address used by the FDS.
// <i> As a result the reserved space can be used by other modules.

Kenneth