Storing characteristic data after on_disconnect

[kerem]

I am trying to persist characteristic data written by the central side after on_disconnect. I can see the data written inside the evt_write->data ptr and I copy it to store once the central disconnects.

This is on nrf51-dk sd 7.0.0 and sdk 6.1.0.

Pstorage works when I try to do debug it, without disconnecting from device. What would be the preferred way for persisting characteristic values written by the central side?

EDIT: My first problem was not being able to receive on_disconnect callbacks. The reason on_disconnect not being called was the missing 4 byte alignment. I was getting NRF_ERROR_INVALID_ADDR from store operation. Now on_disconnect gets called and no errors returned from pstorage operations, but when the app is trying to restart advertising, the command queue still shows unfinished pstorage memory access. The count is 2 in the below code, I'm issuing 2 store operations at on_disconnect. I tried stopping the advertisement and reducing the interval but none of it seems to change anything.

// Verify if there is any flash access pending, if yes delay starting advertising until 
// it's complete.
err_code = pstorage_access_status_get(&count);
APP_ERROR_CHECK(err_code);

if (count != 0)
{
    m_memory_access_in_progress = true;
    return;
}

I see this post devzone.nordicsemi.com/.../ with similar problem but still not sure how to fix this for my case.

The example hrs code checks for the command queue for pstorage access before restarting advertising, since the queue is not empty after writing a value to a characteristic and disconnecting from peripheral, the app stops at that point. Should i just force it to wait?

EDIT 2: Now i do receive pstorage callbacks once i call them from main, outside ble event callbacks. What i do is to setup a boolean flag(could not find ble idle macro in sdk 6.1.0) when on_disconnect event is received, then check this flag inside main loop and start by cleaning first. Once i receive the clean op_code i setup another flag for storing and store the data. Then on next init, i try to load data, again waiting for the callback. I believe the last wait could be unnecessary if pstorage works async but nothing is loaded either way, apart from lots of 0s. What could i be doing wrong? Are you sure pstorage works on nrf51-dk with my sd and sdk? Should i share any code if that would help?

EDIT 3: Attaching example project:ble_app_hrs_pstorage_test.rar where I added one example characteristic in hrs example and trying to run the example code Stefan has linked. Increased PSTORAGE_MAX_APPLICATIONS as 2 since the device manager also using it and commented out pstorage_init() not to do it for a second time.

I get assert inside the pstorage clean method when its checking for alignment.

[michaeld]

As you see in my post the problem for me was that you can never execute a pstorage action on a BLE event. So try adding a if statement in your main loop and checking the disconnect from there to execute your pstorage.

[kerem]

I was just about to try that, thank you.

[kerem]

Is it possible that pstorage is unstable on nrfdk-51 with sdk 6.1.0 and sd 7/7.1? I tried exactly as you did, made sure all store operation waits for clear callback and even load waits for callback. All called from main, outside BLE callbacks and i made sure the data im copying around is correct. What else i can try? I received all callbacks btw for clear, store and load. It's just like nothing is being stored or loaded.