Flash Data Storage place in memory

[jroorda]

Hi,

I'm using the FDS library to store some data (configuration data). For production, I'd like to flash an initial configuration to the nRF52832. I know the storage format because it is well documented in the FDS library documentation, but I don't know where I should write the initial data in flash. In what way does the FDS library figure out where to store the data?

Does anyone have experience with this case?

[FormerMember]

FDS/fstorage will place the data in the last available physical pages. Where the FDS/fstorage data ends depends on if there is a bootloader present or not. The end address is calculated by fs_flash_page_end_addr() in fstorage_internal_defs.h.

If there is no bootloader present, the end address for nRF52832 is 0x80000.

The amount of flashed used by (reserved for) FDS/fstorage depends on:

• FDS_VIRTUAL_PAGES (sdk_config.h) (3)
• FDS_VIRTUAL_PAGE_SIZE (sdk_config.h) (1024, number of 4-byte words)
• FDS_PHY_PAGE_SIZE (fds_internal_defs.h) (1024, number of 4-byte words)

The default values for nRF52832 are in parenthesis.

Based on the above numbers, the start address for the three virtual pages will be the following:

• 0x80000 - (1 * 0x1000) = 0x7F000)
• 0x80000 - (2 * 0x1000) = 0x7E000)
• 0x80000 - (3 * 0x1000) = 0x7D000)

The stored data will be written up-wards.

It means that the start address for the FDS/fstorage data in this case is 0x7D000.

The start address can be doubled check by reading the address, and checking that the address contains the tag 0xDEAD0DE.