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???
11/06/07 18:55
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Msg Score: +1
 +1 Informative		 #146695 - yes it is
Responding to: ???'s previous message
but under certain conditions a heavy EMI can lock the CPU in such a way that only a power-off can reset it. Is it normal?
yes it is,

ANY electronic circuit will fail if the components are exposed to strong enough EMI. How much EMI the device can withstand is a matter of design (see the FAQs).

Which are the 10% of the recommendations you have not followed?

I do believe that you have an additional problem when the watchdog does not bite, I am fortunately not familar with the Atmel chips, but if there is ANY method to disable the watchdog or the feeding is anything else that two specific consequtive writes the chance that runaway code will feed it or disable it is there.

The watchdog implementations across the spectrum of '51 derivatives ranges from truly miserable to less than one in amillion chance for a missed reset when code runs away. If you need a chip with a purebred puppy do the research.

Someone may chime in and suggest an external watchdog, I would never use one such. It is waaaaay too easy for runaway code to toggle the pin that tickles an external watchdog.

Erik

List of 88 messages in thread
TopicAuthorDate
Atmel 89 Series and EMI            01/01/70 00:00      
   FAQ            01/01/70 00:00      
      Thanks, but...            01/01/70 00:00      
         yes it is            01/01/70 00:00      
            EMI design consideration...            01/01/70 00:00      
               reset pulses?            01/01/70 00:00      
                  Finally a note to the OP            01/01/70 00:00      
                     well, sometimes...            01/01/70 00:00      
                     Fire Extinguisher            01/01/70 00:00      
                        extinguisher            01/01/70 00:00      
                  Latched-up CMOS!            01/01/70 00:00      
                     logic, and beyond            01/01/70 00:00      
                     not a cure            01/01/70 00:00      
   EMI Design            01/01/70 00:00      
      restated in one sentence            01/01/70 00:00      
         Don't jump to the conclusion...            01/01/70 00:00      
            then just say "outside the specs, no can do"            01/01/70 00:00      
      Thanks...            01/01/70 00:00      
   What PCB do you use?            01/01/70 00:00      
      Two Layer            01/01/70 00:00      
         No surprise, then!            01/01/70 00:00      
            Ground...            01/01/70 00:00      
               About naked firefighters...            01/01/70 00:00      
               Absolutely it is fair            01/01/70 00:00      
   Some advice            01/01/70 00:00      
      Yes, it's a bunch of measures...            01/01/70 00:00      
      Good points.            01/01/70 00:00      
         No, no, no,....            01/01/70 00:00      
            Remember            01/01/70 00:00      
         CMOS Latch up            01/01/70 00:00      
         NOPE            01/01/70 00:00      
            You think so...            01/01/70 00:00      
               No, it is not            01/01/70 00:00      
               A proper design would stand it!            01/01/70 00:00      
                  Proper design            01/01/70 00:00      
                     some of my definitions            01/01/70 00:00      
                     Me thinks...            01/01/70 00:00      
                        the real point            01/01/70 00:00      
            More advice            01/01/70 00:00      
               Does that mean, that...            01/01/70 00:00      
                  It's the designers responsibility            01/01/70 00:00      
                     No joke, but...            01/01/70 00:00      
                  EMI and 2 layers            01/01/70 00:00      
                     Yes, for tiny projects...            01/01/70 00:00      
               that something is possible/done succesfully            01/01/70 00:00      
   Show us your design...            01/01/70 00:00      
      Why? You want to make fun of it? :)            01/01/70 00:00      
         Or            01/01/70 00:00      
            You mean...            01/01/70 00:00      
               I do not know what Steve ment            01/01/70 00:00      
               Yes !            01/01/70 00:00      
         how about a schematic            01/01/70 00:00      
            Relays            01/01/70 00:00      
               Even then...            01/01/70 00:00      
         From what I can see            01/01/70 00:00      
            Mostly agree.            01/01/70 00:00      
               Layers, layouts...            01/01/70 00:00      
                  are you serious, or did you forget            01/01/70 00:00      
                     Sorry, I forgot...            01/01/70 00:00      
                     Is it good?            01/01/70 00:00      
                        Just a few points.            01/01/70 00:00      
                           I believe you!            01/01/70 00:00      
                        No harm, usually            01/01/70 00:00      
                  Separate Ground Planes            01/01/70 00:00      
                     Inter-plane coupling            01/01/70 00:00      
                     Cable entry point            01/01/70 00:00      
                        Thanks            01/01/70 00:00      
            what I do ..            01/01/70 00:00      
            half measures            01/01/70 00:00      
            Taking notes...            01/01/70 00:00      
               the downfall of many            01/01/70 00:00      
               Do some tests            01/01/70 00:00      
                  This can be deadly!            01/01/70 00:00      
                     Deadly?            01/01/70 00:00      
                        I'm sorry...            01/01/70 00:00      
         Farshad, I would never make fun of it!            01/01/70 00:00      
            Very Informative            01/01/70 00:00      
               Decoupling            01/01/70 00:00      
                  Thank you!            01/01/70 00:00      
               and not a word about 4 layers            01/01/70 00:00      
   paralelling            01/01/70 00:00      
      Why not using 10µF/10V/X5S ceramics?            01/01/70 00:00      
   more information?            01/01/70 00:00      
      Schematics would not be very "helpfil"            01/01/70 00:00      
      More information            01/01/70 00:00      
      The best stuff I have ever seen is...            01/01/70 00:00      
         Sorry, I forgot, that you must suscribe first...            01/01/70 00:00      
      John, I have seen....            01/01/70 00:00      

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