How to check pstorage operation is complete ?

[Thomas]

Hi, When I write data synchronously to memory (nRF51822), I do :

APP_ERROR_CHECK(pstorage_block_identifier_get(flash_handler, 2, &block_handler));
APP_ERROR_CHECK(pstorage_clear(&block_handler, 16));
// check here ?
APP_ERROR_CHECK(pstorage_store(&block_handler, data_to_store, 16, 0)); 
// check here ?

Where I say 'check here' : I wonder if I should wait to move to next line by checking pstorage_access_status_get returns 0 or by having a variable that waits for the flash callback to be called.

Is it equivalent (apart from the details you get in the callback) ? Thanks

EDIT :

I call this synchronous function after every flash operation (clear or write), and this seems like the proper way to go. In the flash callback handler, I reset if there is anything else than a success

void wait_pstorage_access() {
    uint32_t count;
    do {
        app_sched_execute();
        pstorage_access_status_get(&count);
    } while (count > 0);
}

[Nick Pelis]

You need to exit out to the main scheduler and give the SoftDevice control of the system until the flash callback is executed, at which point you can continue to the next step of your original code. A blocking wait in the "check here" lines won't work as the SoftDevice is what invokes the flash callback in the first place.

[Thomas]

Thanks but what about the first kind of blocking code in the "check here" ? uint16_t count; do pstorage_access_status_get(&count); while(count > 0)

[Susheel Nuguru]

Hi Nick,

What do you mean by "blocking wait in the check here wont work"? This is communicated to SD through an SVC call, app can still block and wait for a flag that is set in the sys_event handler. May be i misunderstood your text?

[Thomas]

Hi @Nick, could you update on this ? I realized that when I compile my code with keil/windows doing while (count > 0) pstorage_access_status_get(&count); works, but when I compile with gcc, I need to add app_sched_execute() in the loop. Is that correct ?

[Nick Pelis]

app_sched_execute() is the proper way to go, as this gives the SoftDevice opportunities to complete its asynchronous flash operation, which is asynchronous due to the length of time it takes to program and erase flash. I can't possibly think of any reason why your Keil code would work, and I suspect it's not. Is count <= 0 just before executing the while(), or did you invoke pstorage_load() immediately beforehand, or you did you do anything else that gave the SoftDevice a chance to run?

[Thomas]

hi @Nick, thank you for your quick answer. I don't know what could go on, maybe some code is slower or something. In keil, I didn't call app_sched_execute in the loop but everything was working. On gcc, I saw that the firmware was hanging somewhere and I tracked this to my wait function and discovered that app_sched_execute did the trick. I have edited the question, it is clearer. If my edit is good, I would think that nordic should give this snippet to other people