Write in flash + re-init problem

[NicoH]

Hello,

I am currently running into an issue with nrf51822. I am trying to write in flash a flag which defines the device I use. Indeeed, the device on which the code will run can have 3 modes & a user can modify this mode with a command sent through UART. When the command has been run, the system should re-init to modify the UART, advertising or conn_params settings.

There is no particular problem with initialization but when the UART command is run, the system stops. Indeed, the write command is blocked in an infinite loop, waiting for the NRF_EVT_FLASH_OPERATION_SUCCESS event.

I join the code run at initialization & the function used to write in flash, the function run when the UART command has been received just calls the init function to re-init all settings with the new device mode.

void system_init(void)
{
    uint32_t err_code;
    
    softdevice_sys_evt_handler_set(sys_evt_handler);
    
    if (ble_device_type == DEFAULT)
    {
        ble_device_type = WBLE;
    }
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);
    
    if (ble_device_type == WBLE)
    {
        db_discovery_init();
    }
    uart_init();
    ble_stack_init();
    //Function used to write the device type flag in flash memory
    wat_write_flash_type((uint8_t )ble_device_type);
    
    else if (ble_device_type == UART_MODULE || ble_device_type == WBEACON)
    {
        gap_params_init();
        services_init();
        if (ble_device_type == UART_MODULE)
        {
            advertising_init();
            conn_params_init();
            err_code = ble_advertising_start(BLE_ADV_MODE_SLOW);
        }
        else if (ble_device_type == WBEACON)
        {
            err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
            APP_ERROR_CHECK(err_code);
        }
        
    }
}

uint8_t wat_write_flash_type(uint8_t type)
{
    uint32_t status = NRF_ERROR_BUSY;
    uint8_t d_type[4];
    
    d_type[0] = type;
    d_type[1] = 0;
    d_type[2] = 0;
    d_type[3] = 0;
    
    do
    {
        status = sd_flash_write((uint32_t *)TYPE_LOCATION, (uint32_t*)d_type, 1);
    }
    while (status == NRF_ERROR_BUSY);
    
    flashBusy = true;
    
    while(flashBusy)
    {
        sd_app_evt_wait();
    }

    if(status != NRF_SUCCESS)
    {
        return 1; // Error
    }
    
    return 0;
}

I also join the callback used to trigger the event.

void sys_evt_handler(uint32_t evt)
{
    switch(evt)
    {
        case NRF_EVT_FLASH_OPERATION_SUCCESS:
            flashBusy = false;
        break;
        
        case NRF_EVT_FLASH_OPERATION_ERROR:
        break;
        
        default:
        break;
    }
}

It seems that when I try to re-init, the system is in INVALID_STATE (that is the error code returned by the function uart_init).

Do not hesitate to ask for further information if needed.

[Jørgen Holmefjord]

Hi,

If you have already initialized UART, you will get INVALID_STATE error if you try to init it again. You either need to uninit the old initialization before re-init, or use the old initialized UART interface.

Best regards,
Jørgen

[Jørgen Holmefjord]

Most drivers/libraries have uninit functions. In most cases you should be able to reuse the initialized peripherals without re-initialization.

Are you triggering the Flash write from interrupt context or main context? Have you tried debugging the application to see if it gets past the while loop where you call sd_flash_write?

[NicoH]

I used nRFgo Studio to erase all and flasing again SoftDevice, then Keil for the application.

When I try to write in flash, I start by erasing the corresponding page first

flashBusy = true;
sd_flash_page_erase(DEVICE_TYPE_PAGE);
    
// Wait end erase flash page
while(flashBusy)
{
    sd_app_evt_wait();
}

I run this code before writing in flash, the flashBusy variable is reset by the sys_evt_handler callback on NRF_EVT_FLASH_OPERATION_SUCCESS .

It is not planned to write oftenly to flash, but for now, I cannot change the default value, it is pretty weird because I had the behaviour I wanted once but since then I cannot reproduce it anymore, really do not know why

[Jørgen Holmefjord]

What happens when you try to write flash again? Do you get any error codes etc.? What address is the location you are trying to write?

[NicoH]

Nothing really happens, the status code is ok (NRF_SUCCESS), after the write has been done I restart the device with NVIC_SystemReset, but value in flash is not modified, therefore I start again with the exact same mode.

So no particular error code, the address location is 0x00033AC0 which corresponds to the beginning of a page (page size is 1024)

[Jørgen Holmefjord]

Can you read the memory location you are writing before and after writing it? You can do this using nrfjrpog with the command --memrd <addr> 

[NicoH]

I have already kinda done that with Keil & "Memory" section while in debug mode and the value did not change. I tried it with nrfjprog but got same results, when I erase & reflash all (including SoftDevice), if I read at this address, I have FF FF FF FF which is normal. Then I run the program once and set the default value at this memory location which is 00 00 00 00, that works.

After that, I cannot change the value anymore, I try to erase it first then write the new value but that does not seems to work.

[Jørgen Holmefjord]

Are you waiting for the SUCCESS even when erasing as well? Note that erasing a page can take a long time, especially if there are BLE activity going on at the same time.

[NicoH]

Yes, I do the exact same thing when I erase a page, I wait for NRF_EVT_FLASH_OPERATION_SUCCESS, then I try to write again, waiting for the same event to be triggered, I was suspecting BLE activity could maybe interfere when I try to write in flash, could it be that ?

[Jørgen Holmefjord]

It could, but then you should not receive a SUCCESS event. Did you try reading the flash area after erase operation but before write operation?

[NicoH]

I just tried to put a breakpoint before erasing flash, I do not know why but Keil does not let me put a breakpoint there, so I think the erase is not done, maybe that could be the problem, I cannot erase => I cannot write again in flash. But I do not know why I cannot put a breakpoint there or why this part of code cannot be run

[Jørgen Holmefjord]

Put an infinite while loop (while(1)) after the erase and check the flash with nrfjprog.