nrf_fstorage_write len 6 bytes only write 4

[ThierryC]

I'm using nrf_fstorage_wrile() which work fine on most of the cases, except for len == 6 bytes. When I read back on the Flash, after successful write, I found that only 6 bytes are written.

As a workaround, I had to split in two writes:

nrf_fstorage_write(addr, p_buffer, 4, NULL);
nrf_fstorage_write(addr+4, p_buffer+4, 2, NULL);

Note a write of 4 bytes or 8 bytes is working fine in my case. 

Is there some constraints about the len ?

I'm using SDK15.2, nRF52840 and CrossWorks IDE.

[Einar Thorsrud]

Hi,

It is expected that writing 6 bytes does not work, but I do not see how it could fail silently. You should get an error from this parameter check in the nrf_fstorage_write(), since you are trying to write a length which is not a multiple of 4 bytes:

    /* Length must be a multiple of the program unit. */
    NRF_FSTORAGE_PARAM_CHECK(!(len % p_fs->p_flash_info->program_unit), NRF_ERROR_INVALID_LENGTH);

[ThierryC]

I see, param check was disabled on my case. But I'm surprise that the return code was successful.
Anyway, this behavior is expected. Thanks for the answer !

[awneil]

Doesn't fstorage work in units of 4 bytes ... ?