preserve data in the flash over DFU using FDS [sdk 14.2]

RE: preserve data in the flash over DFU using FDS [sdk 14.2]

bjorn-spockeli — Wed, 03 Oct 2018 08:22:29 GMT

Hi Fabiano,

Yes, you are correct. The fds_record_update documentation states that updating a record first writes a new record to flash and then deletes the old record.

Note that deleting a record does not free the space it occupies in flash memory. To reclaim flash space used by deleted records, call fds_gc to run garbage collection.

RE: preserve data in the flash over DFU using FDS [sdk 14.2]

Fabiano — Tue, 02 Oct 2018 15:53:27 GMT

Thank you very much Bjørn, I have just another question:

I noticed that every time I modify the value of any data (uploading it in the flash with the function fds_record_update(); like in the example flash_fds_example) the address where are saved my data keep increase, I guess till will reach the last address available in the space reserved to store data. At that point will I receive an FDS_ERR_NO_SPACE_IN_FLASH error when I try to update the data? if yes do I have just to use the garbace collector and then proceed to keep storing data?

thank you very much for your help

Fabiano

RE: preserve data in the flash over DFU using FDS [sdk 14.2]

bjorn-spockeli — Tue, 02 Oct 2018 14:30:12 GMT

Hi Fabiano,

the DFU_APP_DATA_RESERVED define is by default set to CODE_PAGE_SIZE * 3 in nrf_dfu_types.h in the bootloader code. This will ensure that both the bonding data and the application data is retained during a DFU.

So unless you expect your application data to exceed one flash page, i.e. 4kB, then you do not need to do anything with either the application or bootloader code.

Best regards

Bjørn