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Aamir Ali
09/16/14 11:46
Read: 1987 times

#190350 - PSEN outputting freq/code does not run
I am using AT89C51, & xtal freq = 15Mhz.

1. I had checked ALE pin with CRO, it outputs: 15/5 = 2.5Mhz.
2. EA pin is +5V

3. Strange problem: PSEN pin is also outputting freq same as 2.5Mhz. So my code does not run.

I had checked for some shorting between two pins but found none.
Changed several micro but same problem.

Should I pull-up PSEN to +5V with 10K

List of 7 messages in thread
PSEN outputting freq/code does not run      Aamir ALi      09/16/14 11:46      
   check EA and Pgm      Jim Granville      09/16/14 17:01      
      Done checking already      Aamir ALi      09/16/14 23:07      
   dollars to doughnots I bet      Erik Malund      09/17/14 15:10      
      any other reason/remedy      Aamir ALi      09/19/14 03:25      
         Reset circuit      Mahmood Elnasser      09/19/14 14:41      
         Have you read the datasheet?      Richard Erlacher      09/20/14 17:40      

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