Retrieve saved info on restard with pstorage module

[ppatierno]

Hello,

I need to store some app configuration on the FLASH and I'd like to use the features of pstorage module. I don't understand the following thing ...

When the application starts, it uses the pstorage_register (after the pstorage_init of course) to register itself to the pstorage module and then uses it with load and store feature. On restart I can't read what I stored on the previous execution. How for each reboot of application the pstorage knows what's my app FLASH area with my saved info ? I can't find this information ...

Thanks. Paolo.

rgr_cfg.c rgr_cfg.h

[Susheel Nuguru]

Hi ppatierno,

I am sure this question has been asked many times here, but I will try to answer you. pstorage_register will reserve flash page(s) and the flash page number it reserves depend on the the settings in pstorage_platform.h and the sequence of pstorage_register.

For exampleyou code has something like this:

pstorage_init
.....
.....
pstorage_register two pages --> returns block_id1
......
......
pstorage_register three pages -->return block_id2

If the sequence of these two register function never changes over system reboots then they will always register the same physical flash page numbers, the block_id1 and block_id2 have same physical address mapping in this case and you can safely write and read your information over reboots.

but if pstorage_register is done depending on some state machine after reboot, and if the order changes like this after reset

pstorage_init
.....
.....
pstorage_register three pages -->return block_id2
......
......
pstorage_register two pages  --> returns block_id1

Then the block_id to physical address mapping has changed and you wont find the information you stored at the block_id you registered before this reboot.

[Petter Myhre]

How do you check that your data is actually is stored?

[ppatierno]

The pstorage is initialize by the device manager module (I started from ANCS BLE example).

My current code does following ...

Registers to pstorage :

pstorage_register(&param, &m_storage_handle);

get the block identifier :

pstorage_block_identifier_get(&m_storage_handle, 0, &block_handle);

After, I read from this block to check if there is a pattern of data (it's my way to check if I already wrote first configuration on the first device startup). I need to read first 2 bytes at start of the block (offset 0).

pstorage_load(data, &block_handle, 2, 0);

Then I compare "data" with a pattern I know and if they are different I store the pattern in the first two bytes :

pstorage_store(&block_handle, pattern, sizeof(pattern), 0);

On reboot I'd like to have that the code read the first 2 bytes of the block and verifiy that the pattern is there ... but it doesn't happen !

[ppatierno]

Just to add that all pstorage calls return 0 (so NRF_SUCCESS) and the same is in the callback called after the pstorage_store.

[Susheel Nuguru]

debug it and see if block_handle->block_id which should be the physical address of the block is the same for both load and store.