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???
07/14/06 16:53
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 		 #120263 - Marketing trick
Responding to: ???'s previous message
Erik said:
The purpose of watchdog is NOT to pernit you to be sloppy, it is there to prevent dangerous happenings when ESD or other impossible to protect against events happen.

Yes, and then you HOPE that the watchdog will reset the micro to make it work properly again.

I don't like watchdogs very much. And sometimes I even think that the watchdog is nothing more than a marketing trick: If you have between two micros to choose, then you will choose the one with watchdog, which is promised to do soooo healthy things for you...

The issue is, if I want to add something to make my device failsafe, then I need to trust it 100%-ly. "Safety" is always a 100% safety. Like being pregnant: Either you are pregnant or you are not. But the watchdog cannot bring you 100% saftey.
So, why using it at all?

I'm not better, I also use this damned watchdog. Why? Because my boss would not understand that I don't use a watchdog while others do...

I have experimented with all kinds of noise and interference to test how to make a micro to run ill. And I can tell you, that there were numberous situations, where the watchdog did not do the right job!! Yes, it can even decrease the safety, when stupid engineers think they can neglect needed decoupling and filtering measures, because they have this wonderful watchdog.

So, how to proceed? I don't rely on the benefits of this wonderful watchdog. I prefer to enhance the filtering, so that a watchdog will never be "needed". On the other hand, I use a watchdog, of course, but only to calm my boss...

Kai

List of 30 messages in thread
TopicAuthorDate
processor fault            01/01/70 00:00      
   Use Watchdog            01/01/70 00:00      
      Not necessarily            01/01/70 00:00      
         Spec of AT89S51            01/01/70 00:00      
            Still too specific            01/01/70 00:00      
   There is no one such thing!            01/01/70 00:00      
   Undefined state !            01/01/70 00:00      
      processor fault            01/01/70 00:00      
         RTFM            01/01/70 00:00      
            reset            01/01/70 00:00      
               Read the data sheet            01/01/70 00:00      
                  WD with indication            01/01/70 00:00      
                     I, too, can visualize some exotic conditions where            01/01/70 00:00      
                        to bite or not to bite            01/01/70 00:00      
                           the REAL issue            01/01/70 00:00      
                              Marketing trick            01/01/70 00:00      
                                 to be dramatic            01/01/70 00:00      
                                    It is helpful, of course.            01/01/70 00:00      
                                 let's put it this way:            01/01/70 00:00      
                           I doubt that it's 10 transistors ...            01/01/70 00:00      
                              the context            01/01/70 00:00      
                     Can you name an example of this sort?            01/01/70 00:00      
                  reset            01/01/70 00:00      
                     AT89S51 WD            01/01/70 00:00      
         How do you propose to make the processor "illumina            01/01/70 00:00      
   Software hang-up, hardware lock-up            01/01/70 00:00      
      How about redundancy?            01/01/70 00:00      
         paranoia            01/01/70 00:00      
            ... but it WILL detect a processor fault!            01/01/70 00:00      
               The ultimate misconception            01/01/70 00:00      

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