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Christoph Franck
02/21/12 08:47
Read: 417 times
Sindelfingen
Germany


 
#186110 - It's not just ESD, it's "the works"
Responding to: Kai Klaas's previous message
Kai Klaas said:
Up to now Christoph wasn't talking about such events but about ESD:


It's basically about everything Per mentioned and a bit more.

Not producing any output, or any meaningful output, is acceptable while the devices inputs are subjected to pulses of a couple of hundred volts, crazy RF interference and similar scenarios, as no one expects a useful measurement in these circumstances (quantity being measured are voltages in the sub-millivolt range).

Examples of expected external events include:

http://en.wikipedia.org/wiki/Elec..._waveforms
and
http://en.wikipedia.org/wiki/Defibrillator

However, the device should resume operation in less than ten seconds after the interference stops, and without the user having to cycle power. "Playing dead" is not acceptable.

The watchdog isn't there to cure bad electronics, it's there to cure bad external events. If electronics could be designed to handle any external events you throw at them, watchdogs wouldn't be necessary at all, would they? (Well, maybe for firmware bugs, but in a world with perfect electronics, perfect firmware shouldn't be that hard either). Of course, you could encase a satellite in a few tons of lead and water to protect it from the odd cosmic ray ... but then it wouldn't get off the ground. :)




List of 44 messages in thread
TopicAuthorDate
Pointless watchdog?      Christoph Franck      02/18/12 12:27      
   Sounds Like From What You Said...      Michael Karas      02/18/12 15:00      
      Didn't want to point fingers.      Christoph Franck      02/19/12 02:33      
         A?      JecksonS Ben      02/19/12 04:50      
            Don't forget AVR      Andy Neil      02/19/12 05:44      
               One more argument ...      Christoph Franck      02/20/12 06:14      
                  Independently testable      Per Westermark      02/20/12 11:00      
                     Slow but critical.      Christoph Franck      02/20/12 14:13      
                        Yes      Per Westermark      02/20/12 17:59      
                           ESD      Kai Klaas      02/21/12 05:38      
                               You can't      Per Westermark      02/21/12 06:04      
                                 You can...      Kai Klaas      02/21/12 06:27      
                                    But emi-filter, overvoltage protection etc may not be enough      Per Westermark      02/21/12 06:46      
                                       ESD ...      Kai Klaas      02/21/12 07:51      
                                          It's not just ESD, it's "the works"      Christoph Franck      02/21/12 08:47      
                                             I do not trust the watchdog...      Kai Klaas      02/21/12 09:44      
                                                The simpler, the more trustworthy.      Christoph Franck      02/21/12 11:08      
                                                   Less complex does not mean less probable to fail!      Kai Klaas      02/22/12 06:48      
                                                   WDT and debug breadcrumbs      Oliver Sedlacek      02/23/12 06:14      
                                                Lightning strikes      Kalpak Dabir      02/22/12 04:33      
                                                   A watchdog should never be needed - but should be there      Per Westermark      02/22/12 05:55      
                                                   A watchdog isn't a fuse...      Kai Klaas      02/22/12 07:19      
                                                      correction      Erik Malund      02/22/12 07:35      
                                                      I just can not agree with that reasoning      Per Westermark      02/22/12 08:02      
                                                         Oh please, don't...      Kai Klaas      02/22/12 17:04      
                                                            so?      Per Westermark      02/22/12 17:26      
                                                Why you need a watchdog      Oliver Sedlacek      02/23/12 04:07      
                                                   And even if you had perfect software and hardware ...      Christoph Franck      02/23/12 05:03      
                                                      Reset versus power cycle      Kai Klaas      02/23/12 05:34      
                                                         Mars Pathfinder      Christoph Franck      02/23/12 06:27      
                                                         many modern chips      Erik Malund      02/23/12 07:05      
                                                            The problem with bidirectional reset pins.      Christoph Franck      02/23/12 07:26      
                                                               The uC in question      Erik Malund      02/23/12 08:07      
                                                            Latchup      Per Westermark      02/23/12 07:29      
                                                               ONLY clocked circuits?      Erik Malund      02/23/12 08:15      
                                                                  That kitchen exhaust fan ...      Christoph Franck      02/23/12 08:42      
                                                            link...      Kai Klaas      02/24/12 05:01      
                                                               Sales talk      Per Westermark      02/24/12 05:55      
                                                   certified applications      Erik Malund      02/23/12 07:00      
                  Using external watchdog      Oliver Sedlacek      02/21/12 03:11      
                     It's a feature, actually.      Christoph Franck      02/21/12 04:16      
               Wet      JecksonS Ben      02/24/12 01:04      
   Featuritis...      Kalpak Dabir      02/20/12 19:14      
   Looking at it from another perspective      Jez Smith      02/23/12 22:38      

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