watchdog timer

[amindzo]

Hi, in my program i have some loops that the program should stock in these loops until something happens, sometimes we have some errors from sensors and the program stock in these loops for a long time. can i use the watchdog timer to reset the program after a certain time? i use picbasic pro and pic16f873a.

 

[Ian Rogers]

Just enable WDT in the config reg and then set a pre-scale to suit your application... remember, to put a "clear watchdog" in your program somewhere when its working good to stop it resetting when there is no error.

 

[amindzo]

should i enable WDT in that loop and then clear it? because i have a main loop that the program should work in it for a long time. i have two other loops that the program should work in them for maximum two minutes and if it stock in it the program should reset.

 

[Ian Rogers]

The problem we have here is the WDT times out much quicker than two minutes even with the largest prescale.. What you'll have to do is set up a local varable and count cycles with each increase of the cycle, kick the dog if you had to kick the dog "X" number of times then a reset is needed... That way you can monitor all loops independently.

 

[amindzo]

what about using timers 0 or 1?

 

[Ian Rogers]

Yes! Timer 1 with interrupt routine... Just increment the cycle counter if interrupt TM1R fires set a loop return... Good idea.