How does the Watchdog work?

[Nils Minor]

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 :)

[Håkon Alseth]

You are setting up the watchdog to reset every 1 sec (CRV register = 32768) if to reloaded. In your main you are reloading the watchdog every >4 seconds. This will cause the watchdog to do a system reset.

Is that what you are seeing?

-H

[Nils Minor]

Hi, Thanks for your answer. So do i understand it wrong how to use it? I want to make a reset in this Method, after 1 Second. But the Loop is runing and the device doesn't do a reset.

Best regards Nils

[John Kelley]

I've never set the INTENSET register before, maybe that just causes an interrupt rather than trigger a reset?

Try commenting out your four lines dealing with IRQ and try again.

[Nils Minor]

Hi,

Thanks for your Help. I tried out your comment but i didn't work. I found in an other question an example how to use watchdog with Softdevice -> devzone.nordicsemi.com/.../another-nrf51822-watchdog-question

So i tried out and came to this piece of code in my application: NRF_WDT->CONFIG = ( WDT_CONFIG_SLEEP_Run << WDT_CONFIG_SLEEP_Pos); NRF_WDT->CRV = 3*32768; //ca 3 sek. timout NRF_WDT->RREN |= WDT_RREN_RR0_Msk; //Enable reload register 0

				NRF_WDT->TASKS_START = 1; // Watchdog start
				while (true)
				{
					//NRF_WDT->RR[0] = 3*32768;;  //Reload watchdog register 0
					switch_stat_g(1);
					nrf_delay_ms(2000);
					switch_stat_g(0);
					nrf_delay_ms(2000);
				}

I set wdt to reset the device after 3 Seconds is this right?

But nothing happens when i enter the while loop, i do not reload the RR0 but nothing happens.

What am i doing wrong?Is there something to lookfor?

Thank you , Nils Minor

[Håkon Alseth]

Hi Nils,

I do not see why your application should not do a WD-reset. How do you detect the WD-reset?

I usually use a LED blinking sequence in init to see if the device resets. If you run the attached firmware, do you then see a watchdog reset?

-Håkon

wd_example_main.c