fstorage page info

[rdecker]

I am attempting to integrate examples/peripheral/flash_fstorage into my project (SDK 14.1.0).

When calling nrf_fstorage_write I get NRF_ERROR_INVALID_LENGTH in response. I assume because I am only trying to write 20 bytes not ~2K. However, for some reason the example can write m_hello_world which is only a handful of bytes. Additionally, a minimum erase size of 536MiB seems too large to be correct. Diffing the example sdk_config.h with the default didn't reveal anything interesting I could change.

nrf5_flash_end_addr_get returns 1048576 (dec?) AKA 0x10000.

print_flash_info displays the following:

erase unit: 536871936 bytes

program unit: 2277 bytes

Any help on why the minimums are so large would be appreciated. Thanks.

[Petter Myhre]

The program unit should be the word size, which is 4 bytes. The length has to be a multiple of 4 bytes, like the length of m_hello_world.

Edit 29.11.2017:

This is a bug. The fix is (as you figured out) to put p_fs->p_flash_info = &m_flash_info; before the if in the init function of nrf_fstorage_sd.c

This will be fixed in the next SDK release.

[rdecker]

I did some more digging and it turns out that p_flash_info is 0x00000000 and so program_unit is some "random" value. I see that it should be set to 4 in nrf_fstorage_sd.c which I am including in my build system.

Edit: with some logging it seems that the init function is being called twice (once for peer_manager, and once for my code?). However in the second call the if !m_flags.initialized branch is not taken and thus p_flash_info is not set (nrf_fstorage_sd.c:380). This seems incorrect to me. I was under the impression multiple fstorage instances could be constructed and used in different application modules.