How does the Watchdog work?

Question

Hi, i need to use a watchdog in my application. I read that i can use the build in one, but i thing my configuration or the usage of the watchdog is wrong. here is my config:


void WatchDogInit															(void)
{
	NRF_WDT->CONFIG =  	(WDT_CONFIG_SLEEP_Run << WDT_CONFIG_SLEEP_Pos); 
								  
	NRF_WDT->CRV = (32768 * 1); 	 
	NRF_WDT->RREN = WDT_RREN_RR0_Msk; 									
	
                    
    NRF_WDT->INTENSET=WDT_INTENSET_TIMEOUT_Msk;									
	                 
                                sd_nvic_ClearPendingIRQ(WDT_IRQn);													
	sd_nvic_SetPriority				(WDT_IRQn, APP_IRQ_PRIORITY_HIGH);		
	sd_nvic_EnableIRQ	 (WDT_IRQn);													
	NRF_WDT->TASKS_START = 1; // Watchdog start
}

when do i have to call this init method? Is tehre anything to lookfor, do i have to run it befor enabling the SD or something like that?

here is my example loop for testing it


					while (true)
					{
						NRF_WDT->RR[0] = WDT_RR_RR_Reload; ;//WDT_RR_RR_Reload;
						switch_stat_g(1);
						nrf_delay_ms(2000);
						switch_stat_g(0);
						nrf_delay_ms(2000);
					}

Do i use it in a wrong way?

Thank you for help and best regards, Nils :)

Nils Minor · Accepted Answer

Hi Hakon, Thank you for your answer and your example. I tried out what you told me and i think it doesn't work. If I run your example, the LED flashes up after init but nothing more the is no reset of the WD the LED only blinks one Time, doesn't matter if i do Relaod or not. Here is my example i don#t understand why the is no reset. The WD Counter set to 32768 that means a reset after 1 Second, is that right? And i do not reload RR[0] but after One Second is no reset. It should be Start->LED on 1 Sek->Reset and don't start while loop. But it starts the while loop. Here is my Code: #include "nrf51.h" #include "nrf_gpio.h" #include "nrf_delay.h" #include #include #include // Counter is in 32kHz ticks. (NRF_WDT->CRV + 1)/32768 seconds #define WATCHDOG_COUNTER 32768 #define MY_LED 19 void init_watchdog(void) { NRF_WDT->CONFIG = (WDT_CONFIG_SLEEP_Run << WDT_CONFIG_SLEEP_Pos); NRF_WDT->CRV = WATCHDOG_COUNTER; NRF_WDT->RREN = WDT_RREN_RR0_Enabled << WDT_RREN_RR0_Pos; NRF_WDT->TASKS_START = 1; } int main(void) { nrf_gpio_cfg_output(MY_LED); nrf_gpio_pin_set(MY_LED); nrf_delay_ms(1000); init_watchdog ( ); nrf_gpio_pin_clear(MY_LED); while (true) { //NRF_WDT->RR[0] = WDT_RR_RR_Reload; //Reload watchdog register 0 nrf_gpio_pin_set(MY_LED); nrf_delay_ms(600); nrf_gpio_pin_clear(MY_LED), nrf_delay_ms(500); } } /** *@} **/ I realy don't understand why there is no reset. I think i do a mistake but where? Thank you and best regards Nils.

How does the Watchdog work?

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