Watchdog Timer Module pulled HIGH or LOW ?

[tfoutfou]

Hi i have a question about watchdog timer module


On the QuickStart page you can read :

The input (IN) connection on the Watchdog Timer Module must be briefly pulled HIGH in order to reset the timer. You can add a simple function to your Arduino sketch which does this for you:

Ok , i understand that the INPUT pin need a pulse to reset the timer

But if for some reason the Arduino get stuck when the pin is HIGH , will the watchdog start the timer , or will it get stuck in a "RESET TIMER" state ?

Thank you

[prabbit237]

This has been a concern of mine as well and the only good solution I can think of is two watchdog circuits triggered by one pin. One would use an inverter before the timer so that when one sees a high pulse, the other sees a low one. No way for both to get stuck. However, then you have to figure out how to feed them both back into the one kill/reset output back to the MCU.