Problem with implementation of the watchdog interrupt

[AndrzejB]

I ran watchdog with this code:

void wdt_init(void)
{
	NRF_WDT->CONFIG = (WDT_CONFIG_HALT_Pause << WDT_CONFIG_HALT_Pos) | ( WDT_CONFIG_SLEEP_Run << WDT_CONFIG_SLEEP_Pos);
	NRF_WDT->CRV = 1*32768;   //1 sec. timeout
	NRF_WDT->RREN |= WDT_RREN_RR0_Msk;  //Enable reload register 0
	NRF_WDT->TASKS_START = 1; //triggering of watchdog
}

Because I want to save some data to flash before the nrf51822 reset, I tried to use WDT_IRQn (generated on the TIMEOUT event). Unfortunately, my code doesn't work.

APP_TIMER_DEF(wdt_timer_id);

//some code

static void WDT_IRQHandler(void * p_context) 
{
	LEDS_OFF(BSP_LED_4_MASK);
	LEDS_OFF(BSP_LED_3_MASK);
	LEDS_OFF(BSP_LED_2_MASK);
	LEDS_OFF(BSP_LED_1_MASK);
	LEDS_OFF(BSP_LED_0_MASK);
	while(1)
	{
	}
}

void wdt_interrupt_init(void)
{
	uint32_t err_code;
	NRF_WDT->INTENSET = WDT_INTENSET_TIMEOUT_Msk;
	sd_nvic_SetPriority(WDT_IRQn, 1);
	sd_nvic_EnableIRQ(WDT_IRQn);
	err_code = app_timer_create(&wdt_timer_id,
										APP_TIMER_MODE_SINGLE_SHOT,
										WDT_IRQHandler);
	APP_ERROR_CHECK(err_code);
}

Adding WDT_IRQ doesn't change behavior of MCU, it restarts without executing of the WDT_IRQHandler.

I am not sure where I should place app_timer_start(wdt_timer_id, NRF_WDT->CRV, NULL) function. Up to now it is placed right beneath the place where the watchdog is being reloaded.

[John]

I'm a bit confused as to why you would want to call the WDT IRQ handler out of a timer. The system should invoke that function itself without it being in a timer. I'd suggest using Nordic's WDT driver as it already implements all of this for you. All you need to do is set up a configuration structure and call their init function. You can find it in SDK 11 components\drivers_nrf\wdt.

[AndrzejB]

I just didn't understand how to implement event handler, after analyzing the code of the wdt example I did it in the right way. I didn't simply use the wdt example because I had problem with adding nrf_drv_wdt.c to my project. Besides, I wanted to learn how it works.