How can I prevent system reset?

[purgoufr]

Hello, I created a timer that runs the scan_start function at certain intervals.And I put this timer in the for loop.

static void scan_timeout_handler(void * p_context)
{
	scan_start();
}

static void timers_init(void)
{
	uint32_t err_code;

  // Create timers.   
	err_code = app_timer_create(&start_scan_timer_id,
															APP_TIMER_MODE_SINGLE_SHOT,
															scan_timeout_handler);
	APP_ERROR_CHECK(err_code);
}

When the timer completes the time I have defined, the system restarts each time the program flow arrives at the end of the For loop.

int main(void)
{
    uint32_t err_code;
	
		// Initialize the application timer module.
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
	
    ble_stack_init();
    
    err_code = ble_db_discovery_init();
    APP_ERROR_CHECK(err_code);
    
    nus_c_init();
	timers_init();

	nrf_gpio_cfg_output(LED1);
	nrf_gpio_cfg_output(LED2);
	
	nrf_gpio_pin_set(LED1);			
	nrf_gpio_pin_set(LED2);			
	nrf_delay_ms(1000);
	nrf_gpio_pin_clear(LED1);
	nrf_gpio_pin_clear(LED2);
		
    for (;;)
    {	
		err_code = app_timer_start(start_scan_timer_id, APP_TIMER_TICKS(START_SCAN_INTERVAL, APP_TIMER_PRESCALER), NULL);
		APP_ERROR_CHECK(err_code);
			
    }
}

My aim is to constantly measure rssi on the backplane. Then connect to the device when it reaches a certain rssi value and do not reconnect until the rssi value is below a certain value.

case BLE_GAP_EVT_ADV_REPORT:
    {
        const ble_gap_evt_adv_report_t *p_adv_report = &p_gap_evt->params.adv_report;    					
					
	    if(p_adv_report->rssi >= -70 && enter_region==false)	
	    {
	       if (is_uuid_present(&m_normalMode_uuids, p_adv_report))	
	       {		
		   err_code = sd_ble_gap_connect(&p_adv_report->peer_addr,&m_scan_params,&m_connection_param);	
		  }					
	  }    											
           break;	

case BLE_GAP_EVT_CONNECTED:
		APPL_LOG("Connected to target\r\n");
		err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
		APP_ERROR_CHECK(err_code);
		
		m_ble_nus_c.conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
		
		// start discovery of services. The NUS Client waits for a discovery result
		err_code = ble_db_discovery_start(&m_ble_db_discovery, p_ble_evt->evt.gap_evt.conn_handle);
		APP_ERROR_CHECK(err_code);
		sd_ble_gap_rssi_start(p_ble_evt->evt.gap_evt.conn_handle, 0 , 0);

		break;

    case BLE_GAP_EVT_RSSI_CHANGED:						 
    	rssi_value = p_ble_evt->evt.gap_evt.params.rssi_changed.rssi;
    				
    	if(rssi_value>-70 && rssi_value < -61)
    	{
    		enter_region=false;
    	}
    	else if(rssi_value > -60 && rssi_value < -30)		
    	{
    		enter_region=true;
    	}
    break;

The problem is that the system restarts itself every time the timer expires(According to my prediction SoftDeviceHandler is causing this). Thus, all variables are reset to default regardless of program flow(such as rssi_value, enter_region).

How can I always stay in the for loop? Or is there an alternative solution?

[MartinBL]

Why do you call app_timer_start() over and over in an endless for() loop?

The system resets itself by default if a function returns an error which is then checked by APP_ERROR_CHECK(err_code);. You should debug it like this.

[purgoufr]

Because I want to do continuous rssi measurement. And I do not know if I have any other way to do this.(Theoritically, Timeslot can solve the problem, but I do not have enough knowledge about it yet.)

On th other hand, I do not think the system has restarted itself because of a APP_ERROR_CHECK. I think it has been reset cause of ble_stack_init function (I mean softdevice). I read this link The system seems to be running a watchdog, and when it is finished, the program starts again from stack_init. But I'm not sure about the possibilities.

[MartinBL]

So where inside ble_stack_init() do things go wrong? Have you stepped through the function with a debugger?

[purgoufr]

I can not follow it with the Debugger(Usually freezes in "ble_nus_c_on_ble_evt(&m_ble_nus_c,p_ble_evt);" function). But every time the program is restarted I can reach the result that the device is reset because the led is on.

int main(void)
{
    uint32_t err_code;

    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
	
    ble_stack_init();
    
    err_code = ble_db_discovery_init();
    APP_ERROR_CHECK(err_code);
    
    nus_c_init();
    timers_init();

    nrf_gpio_cfg_output(LED0);
    nrf_gpio_pin_set(LED0);	
    nrf_delay_ms(1000);
    nrf_gpio_pin_clear(LED0);
for(;;)
{}

[MartinBL]

There are many lines of code inside ble_nus_c_on_ble_evt(). Please put a breakpoint in it and see if you can step through the function. There is probably also a function called ble_nus_c_evt_handler(), or similar, in your main.c file. It might be worth setting a breakpoint in there too, and see if any of the function calls inside it return any errors.