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???
07/13/06 10:32
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 		 #120167 - Not necessarily
Responding to: ???'s previous message
Onyau Chan said:
I think you need to use the watchdog to detect the processor fault.

That depends on the nature of the "processor fault"!
See: http://www.8052.com/forum/read.phtml?id=120166

Watchdogs are most useful for recovering from software bugs that cause infinite waits - but there are very many other possible "processor faults" that would not trigger a watchdog!

Without further diagnostics, a watchdog itself will not tell you what fault occurred!

Please have a look at page 8 of the spec.

What spec?!

If the proccessor is hanging, it can not feed the watchdog. As a result, the watchdog will reset the MCU.

Unless you have something like a timer interrupt feeding the watchdog...!
Or some other bug that somehow manages to keep the dog fed...#


Again, "hanging" is often not a fault in the processor itself.




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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