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???
04/22/05 13:28
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 		 #92153 - The watchdog, take 3
Responding to: ???'s previous message
All this watchdog stuff is an unnecessary excersize since the toggle bit I asked Thomas to isert and check proved that no resets happened.


Yes, you did. And no, they didn't.

I will, however ask Thomas to try it again when he is rested since I was/am convinced this to be the most likely cause.


Then I'll give you the answer right away - that's what I used all morning to find.

I wrote the assembly-routine to disable the watchdog on reset and implemented it in the project. The watchdog has now been disabled for good using timed access as described on pages 36 and 37 of the DS89c420 datasheet ( http://pdfserv.maxim-ic.com/en/ds/DS89C420.pdf ).

The assembly looks like this:
Save This Code
	mov TA,#0xAA
	mov TA,#0x55
	anl WDCON,#0xFD
The timer0-interrupt occurs approx. every 48th millisecond, the main-while(1) runs for approx. 8 microseconds before relooping and the watchdog-pin is only toggled once at startup.

Strangely enough though, I still don't get any output on the second-, minute-, and hour-pins in real-world.

I'm wondering whether this would work better if I rewrote it in assembly?

/Thomas

List of 33 messages in thread
TopicAuthorDate
DS89C450 / uVision2, timer0 trouble            01/01/70 00:00      
   perhaps            01/01/70 00:00      
      nope - didn't work            01/01/70 00:00      
   never used Dallas but            01/01/70 00:00      
      I just followed orders            01/01/70 00:00      
         link, please            01/01/70 00:00      
            my apologies            01/01/70 00:00      
               try system clock            01/01/70 00:00      
                  The system clock vs. External Oscillator            01/01/70 00:00      
                     Try >=?            01/01/70 00:00      
                        good idea            01/01/70 00:00      
                           probably a watchdog or such            01/01/70 00:00      
                              about the beer ...            01/01/70 00:00      
                                 reason            01/01/70 00:00      
                                    puzzled by the simplicity            01/01/70 00:00      
                                       It's getting late in Denmark            01/01/70 00:00      
                                          the Thomas Skyt late night show ...            01/01/70 00:00      
                                             kiss            01/01/70 00:00      
                                                KISS/2            01/01/70 00:00      
   A variety of thoughts            01/01/70 00:00      
      A variety of answers            01/01/70 00:00      
         Thoughts for variety of answers            01/01/70 00:00      
            sfr's            01/01/70 00:00      
            the watchdog            01/01/70 00:00      
               The watchdog, timed access, and errata            01/01/70 00:00      
                  setting the OCR to disable the watchdog            01/01/70 00:00      
                     Timed access, take 2            01/01/70 00:00      
                        unnecessary excersize            01/01/70 00:00      
                           The watchdog, take 3            01/01/70 00:00      
                              when in doubt            01/01/70 00:00      
                                 Examining the assembly            01/01/70 00:00      
                                    get out of there            01/01/70 00:00      
                                       I got out, found a solution            01/01/70 00:00      

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