RE: I have a question with flash writing of nRF 52.

Einar Thorsrud — Wed, 23 May 2018 06:53:40 GMT

Hi,

You can write to the same address more than once, but there are some limitations. When you erase a page, all memory cells (holding one bit) are set to '1', and writing can flip any bit from '1' to '0'. However Neighboring memory cells are also affected by the write, so there is a limit of how many writes you can do before you risk corrupting these neighboring bits.

The product specification lists the limitations. For the nRF52832, the NVMC chapter in the PS states that the same block in the Flash can only be written n_WRITE number of times before an erase must be performed, where n_WRITE is 181. For the nRF52832, the NVMC chapter in the PS states that a 32 bit word can only be written n_WRITE number of times before an erase must be performed. In this case, n_WRITE is 2.

This limitation is not enforced by fstorage or SoftDevice, so you must handle it yourself if you do low-level flash access. However, this is taken care of if you use the FDS file system.