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.

[Susheel Nuguru]

Also i am assuming that you have done this

    // Register with the SoftDevice handler module for BLE events.
    err_code = softdevice_sys_evt_handler_set(sys_evt_dispatch);
    APP_ERROR_CHECK(err_code);


static void sys_evt_dispatch(uint32_t sys_evt)
{
    pstorage_sys_event_handler(sys_evt);
     .......
}

else you will not get pstorage callbacks and you cannot know if you have finished flash write succesfully or not. This info is given here