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???
03/16/07 14:32
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 		 #135106 - It's obvious I need to learn about WDT
Responding to: ???'s previous message
Hi Everyone,

I was (apparently errantly) under the impression that the WDT was just a counter that you program with some interval and it counts down. Then, if it ever gets to zero it reboots the µ-controller. Being a hardware implementation it isn't subject to hanging if the program locks up, thus insuring that the µ-controller won't just freeze and sit there. The trick then becomes that the program must reset the counter periodically (before it gets to zero) in order to keep the µ-controller running.

Am I just wrong? Do I have the basic idea but with an incomplete understanding? Why would the WDT care which loop or ISR is executing when the reset instruction is given? Doesn't it just start counting down from the beginning again? Or is this one of those "all you need is a capacitor for the power on reset" situations?

Joe


List of 23 messages in thread
TopicAuthorDate
Where to kick the watchdog            01/01/70 00:00      
   Not being the consummate embedded guy, ...            01/01/70 00:00      
   Be kind to animals            01/01/70 00:00      
      I thought that as well, stray main loop =badness            01/01/70 00:00      
      Sort of            01/01/70 00:00      
   There are watchdogs and the there are WATCHDOGS            01/01/70 00:00      
   I doubt the usefulness of normal watchdog            01/01/70 00:00      
      watchdog IS expensive...            01/01/70 00:00      
         i suppose arguments for and against having a dog            01/01/70 00:00      
            bugs happen...            01/01/70 00:00      
               Not having quite the same budget as NASA            01/01/70 00:00      
                  the case for the internal dog            01/01/70 00:00      
   It's obvious I need to learn about WDT            01/01/70 00:00      
      the WD would not care, but if you reset it in e.g.            01/01/70 00:00      
      if your main function goes of to play in the weeds            01/01/70 00:00      
      I wouldn't have thought about that.            01/01/70 00:00      
         one more reason to KISS            01/01/70 00:00      
      there is nothing like "frozen" microcontroller...            01/01/70 00:00      
         You would be surprised...            01/01/70 00:00      
            Apply ESD to your micro and look what happens...            01/01/70 00:00      
            I am not surprised...            01/01/70 00:00      
               be reasonable            01/01/70 00:00      
                  therac            01/01/70 00:00      

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