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???
10/26/05 06:20
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 		 #102954 - one caution
Responding to: ???'s previous message
hi,
Sarang Patki said:

For Timer 2 interrupt the vector address is 002BH

Unlike timers 0 and 1, timer 2 has its interrupt vector shared with interrupt produced with Timer/Counter 2 capture/reload trigger and direction control via pin T2EX. Even you have disabled this feature by EXEN2=0 nevertheless it is good practice to check the source of interrupt when come to ISR which vector is shared.
The another effect of that I said above, is that hardware does not clear TF2 flag. Hardware clears TF0/TF1 flags of timers 0/1 but timer 2 requires to clear the flag by software. This bahaviour allows user to determine the source of interrupt. So do not forget to clear TF2 flag yourself inside ISR.

Regards,
Oleg

List of 27 messages in thread
TopicAuthorDate
Timer 2 in AT89S8252            01/01/70 00:00      
   most often, a '51 datasheet does not            01/01/70 00:00      
      continuing the above            01/01/70 00:00      
   Timer 2 for PWM...            01/01/70 00:00      
      one caution            01/01/70 00:00      
   PWM example code:            01/01/70 00:00      
   Time 2 problem            01/01/70 00:00      
      you are missing this one            01/01/70 00:00      
         I think I have covered that            01/01/70 00:00      
            RCAP2            01/01/70 00:00      
               Program with changes but still problem            01/01/70 00:00      
                  RCAP2 wrong            01/01/70 00:00      
                     Still no good            01/01/70 00:00      
                        So where do you expect the interrupt to            01/01/70 00:00      
                           why enable UART interrupt??            01/01/70 00:00      
                              sorry, early morning here            01/01/70 00:00      
                                 Is it still too early?            01/01/70 00:00      
                                    no and, please read the datasheet            01/01/70 00:00      
            I highlighted "must be cleared by            01/01/70 00:00      
   Has anyone used it ?            01/01/70 00:00      
      the biggest sin            01/01/70 00:00      
         Are you sure?            01/01/70 00:00      
            Jan is right            01/01/70 00:00      
               so am I            01/01/70 00:00      
            No, of course the datsheets are just nov            01/01/70 00:00      
            the third sin            01/01/70 00:00      
               Does this work on anyone's simulator?            01/01/70 00:00      

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