Configure Watchdog timer to pause during sleep .

RE: Configure Watchdog timer to pause during sleep .

run_ar — Wed, 17 Mar 2021 06:59:49 GMT

Hi,

The WDT timer will increment on the 32.768KHz clock. In this case, when the timer is configured to halt in sleep, and the periodic events are shorter than one 32kHz clock cycle, it will not increment, and not time out as long as the periodic events are short enough.

RE: Configure Watchdog timer to pause during sleep .

philtrinh — Thu, 11 Mar 2021 21:13:02 GMT

Hello run_ar,

Thank you for the information, as I see the periodic events generated in my system are extremely short, and the sleep period is way longer, and therefore the confusion. I did the suggestion to let the system enter endless loop and the WDT resets as expected.

All and all, this leads to another question regarding the resolution of the WDT timer. Since the WDT timer runs on the 32.768Khz clock (~30.5 uSec period), will the WDT eventually time out if the duration of every periodic event is less than this WDT resolution, say 30 uSec?

Phil.

RE: Configure Watchdog timer to pause during sleep .

run_ar — Thu, 11 Mar 2021 13:34:09 GMT

Hi,

I don't think I have seen cases where the WD did not time out. More often we see customers complaining it does time out after many hours in case of long sleep periods and having the SD run in the background.

I see that you have configured a timeout value of ~1 second and also halting the WDT while in sleep. This means you have to do spend some time not sleeping before the watchdog will trigger a reset. Can you elaborate a little on your application? what do you do when it's not sleeping? for how long is it awake? how long sleep periods do you have? i.e. are you sure the cpu has been running enough for the wdt to trigger?

As an experiment maybe you could try to enter a loop after the sleep period to see if the wdt resets as it should in that case?