Flash Storage not working in ble_evt_handler

RE: Flash Storage not working in ble_evt_handler

Vidar Berg — Mon, 14 Oct 2019 13:54:42 GMT

Assume this is related to the issue you reported here: https://devzone.nordicsemi.com/f/nordic-q-a/53201/fds-storing-random-value-when-called-in-ble_evt_handler?

RE: Flash Storage not working in ble_evt_handler

Ameer Usman — Mon, 14 Oct 2019 07:52:01 GMT

Any possible suggestions?

RE: Flash Storage not working in ble_evt_handler

Ameer Usman — Sun, 13 Oct 2019 06:48:38 GMT

Just by removing the wait_for_flash_ready() function the program worked in the ble_evt_handler.

This seems to have solved one issue but here comes another one! 😃

The read function is not working properly and is not giving the right value. Ideally it should give the same value which I saved but it is not. Is there a specific prerequisite before performing the read function?

NRF_LOG_INFO("Writing \"%x\" to flash.", p_data);
err_code = nrf_fstorage_write(&fstorage, 0x3e100, &p_data, length, NULL);
APP_ERROR_CHECK(err_code);

uint8_t m_hello_world[] = "33333333";
err_code = nrf_fstorage_read(&fstorage, 0x3e100, &m_hello_world, length);

err_code = nrf_fstorage_read(&fstorage, 0x3e100, &p_data, length);
                
NRF_LOG_INFO("Reading p_data \"%02x%02x%02x%02x\" to flash.", p_data[0], p_data[1], p_data[2], p_data[3]);
                
NRF_LOG_INFO("Reading \"%02x%02x%02x%02x\" to flash.", m_hello_world[0], m_hello_world[1], m_hello_world[2], m_hello_world[3]);
APP_ERROR_CHECK(err_code);

The output I get it:

<info> app: Initializing nrf_fstorage_sd implementation...
<info> app: Writing "2003FEC6" to flash.
<info> app: Reading p_data "00040020" to flash.
<info> app: Reading "00000000" to flash.
<info> app: UUID Identified
<info> app: Storage event handler
<info> app: --> Event received: wrote 4 bytes at address 0x3E100.

I can't even get the correct data in p_data.

Thank you for sticking with me :)

RE: Flash Storage not working in ble_evt_handler

Hung Bui — Thu, 10 Oct 2019 14:40:47 GMT

Please follow the debug guide here. The code never "freezes" it only end up being in a dead loop or it resets.

How do you call the function ? Have you removed wait_for_flash_ready()

RE: Flash Storage not working in ble_evt_handler

Ameer Usman — Thu, 10 Oct 2019 13:03:00 GMT

I connect and the logger shows me that it is Connected but when I update the value of the characteristic, which will cause the event handler to initiate, the program freezes. But if I remove line 12-56 (of first code pasted) it works fine. This is the same code that handles the flash storage.

Like even before coming into the evt_handler the code freezes.

RE: Flash Storage not working in ble_evt_handler

Hung Bui — Thu, 10 Oct 2019 12:57:51 GMT

What exactly not working ? How do you call it out side of ble_evt_handler?

RE: Flash Storage not working in ble_evt_handler

Ameer Usman — Thu, 10 Oct 2019 12:25:04 GMT

No its not working even when i secluded it from the ble_evt_handler.

Any further information I can provide regarding this for diagnosis?

RE: Flash Storage not working in ble_evt_handler

Hadi Deknache — Thu, 10 Oct 2019 12:05:22 GMT

Do you check the flag inside the loop? I assume that the code you posted above on main is not the one you used?

e.g.,

for (;;)
{   
    if(flash_ready)
    {
        flash_Test(); 
    }
    
    idle_state_handle();
}

EDIT:

Does the code also freeze if you call these in the ble_evt_handler

err_code = nrf_fstorage_init(&fstorage, p_fs_api, NULL);
APP_ERROR_CHECK(err_code);             

NRF_LOG_INFO("Initializing nrf_fstorage_sd implementation...");

/* Let's write to flash. */
NRF_LOG_INFO("Writing \"%x\" to flash.", p_data);
err_code = nrf_fstorage_write(&fstorage, 0x3e100, &p_data, length, NULL);
APP_ERROR_CHECK(err_code);

and then perform the next read function calls in the fstorage_evt_handler when it triggers NRF_FSTORAGE_EVT_WRITE_RESULT and vice versa

/Hadi

RE: Flash Storage not working in ble_evt_handler

Hung Bui — Thu, 10 Oct 2019 11:51:59 GMT

I agree with Hadi. You shouldn't call fstorage init and especially wait_for_flash_ready() inside the event handler.

wait_for_flash_ready() is a blocking function and the MCU will stuck inside that event handler waiting for the fstorage event. But the event can't be handled because you are already on the same context priority so the event will not be fetched and you will end up in a dead loop.

In stead you should check for the event inside fstorage_evt_handler().

RE: Flash Storage not working in ble_evt_handler

Ameer Usman — Thu, 10 Oct 2019 10:20:22 GMT

I tried changing a flag that would initiate a snip in the main loop but the code seems to stay under

idle_state_handle();

So I am unable to run it in the main loop.

But I tried it in a timer, but again the program froze and gave no errors.

RE: Flash Storage not working in ble_evt_handler

Hadi Deknache — Thu, 10 Oct 2019 09:59:21 GMT

Hi Ameer,

My guess is that the flash storage functions are blocking in the event handler which therefore cause it to freeze. Generally events should be very short and call as few functions as possible in the event handler. A good idea would be to either add app_scheduler in you application or change a flag which you check in a loop if it has been changed and perform the function calls there.

/Hadi