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???
02/21/12 13:27
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 		 #186101 - You can...
Responding to: ???'s previous message
Per said:
You can't make a circuit immune to external events. Only adjust the amount of electromagnetic interference it takes to produce an error or kill the electronics.

With todays filtering components you can filter out ESD to nearly any desired level. And you must do that, just because you cannot trust any actively running circuitry like watchdogs and µC.

You MUST make the circuit immune to external events, at least to a level where the likelyhood of a failure is acceptable. But using a watchdog to cure an imporperly immunized circuit will straightaway run into disaster!!

Kai Klaas



List of 44 messages in thread
TopicAuthorDate
Pointless watchdog?            01/01/70 00:00      
   Sounds Like From What You Said...            01/01/70 00:00      
      Didn't want to point fingers.            01/01/70 00:00      
         A?            01/01/70 00:00      
            Don't forget AVR            01/01/70 00:00      
               One more argument ...            01/01/70 00:00      
                  Independently testable            01/01/70 00:00      
                     Slow but critical.            01/01/70 00:00      
                        Yes            01/01/70 00:00      
                           ESD            01/01/70 00:00      
                               You can't            01/01/70 00:00      
                                 You can...            01/01/70 00:00      
                                    But emi-filter, overvoltage protection etc may not be enough            01/01/70 00:00      
                                       ESD ...            01/01/70 00:00      
                                          It's not just ESD, it's "the works"            01/01/70 00:00      
                                             I do not trust the watchdog...            01/01/70 00:00      
                                                The simpler, the more trustworthy.            01/01/70 00:00      
                                                   Less complex does not mean less probable to fail!            01/01/70 00:00      
                                                   WDT and debug breadcrumbs            01/01/70 00:00      
                                                Lightning strikes            01/01/70 00:00      
                                                   A watchdog should never be needed - but should be there            01/01/70 00:00      
                                                   A watchdog isn't a fuse...            01/01/70 00:00      
                                                      correction            01/01/70 00:00      
                                                      I just can not agree with that reasoning            01/01/70 00:00      
                                                         Oh please, don't...            01/01/70 00:00      
                                                            so?            01/01/70 00:00      
                                                Why you need a watchdog            01/01/70 00:00      
                                                   And even if you had perfect software and hardware ...            01/01/70 00:00      
                                                      Reset versus power cycle            01/01/70 00:00      
                                                         Mars Pathfinder            01/01/70 00:00      
                                                         many modern chips            01/01/70 00:00      
                                                            The problem with bidirectional reset pins.            01/01/70 00:00      
                                                               The uC in question            01/01/70 00:00      
                                                            Latchup            01/01/70 00:00      
                                                               ONLY clocked circuits?            01/01/70 00:00      
                                                                  That kitchen exhaust fan ...            01/01/70 00:00      
                                                            link...            01/01/70 00:00      
                                                               Sales talk            01/01/70 00:00      
                                                   certified applications            01/01/70 00:00      
                  Using external watchdog            01/01/70 00:00      
                     It's a feature, actually.            01/01/70 00:00      
               Wet            01/01/70 00:00      
   Featuritis...            01/01/70 00:00      
   Looking at it from another perspective            01/01/70 00:00      

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