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???
07/06/07 22:53
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#141564 - Compiler generated IRQ vectors
Responding to: ???'s previous message
Jan Waclawek said:
the compiler&linker will spit out something like this:
   ORG   0Bh
   lcall RealISR
   reti

   ORG   somewhere else
RealISR:
... the compiled ISR code ...
   ret?

JW


Yes Jan, that is exactly what both Keil and SDCC do. What is quite nice is that they both produce: CPL P3_0 and RETI. with no extraneous register saves.

I compiled my suggestion and found that with a AT89S8252 12clocker at 18.432MHz I could achieve 85kHz in C.

replacing the LCALL RealISR in the vector table with the CPL P3_0 and RETI enabled me to get 110kHz. So unless you have a chip that can toggle a pin in hardware, a software ISR toggle is impossible with a 11MHz 12clocker.

Perhaps the OP will come back with the actual chip that he wants to use.



List of 24 messages in thread
TopicAuthorDate
How to generate 100 Khz square wave 80C51            01/01/70 00:00      
   Tips            01/01/70 00:00      
      1 KHz            01/01/70 00:00      
         that's ...            01/01/70 00:00      
         SI Units            01/01/70 00:00      
            1024 = Ki            01/01/70 00:00      
   C interrupt overhead            01/01/70 00:00      
      RE: C interrupt overhead            01/01/70 00:00      
         and listen to the guru! :-)            01/01/70 00:00      
            several reasons            01/01/70 00:00      
               Yet another reason to avoid using HLL's!            01/01/70 00:00      
               Optimizations            01/01/70 00:00      
   Use Timer0 auo reload            01/01/70 00:00      
      using            01/01/70 00:00      
      interrupt vectoring vs. latency            01/01/70 00:00      
         Then the Interupt must be in ASM            01/01/70 00:00      
            do you mean...            01/01/70 00:00      
               No            01/01/70 00:00      
               Compiler generated IRQ vectors            01/01/70 00:00      
                  OOPS we both meant LJMP REALisr            01/01/70 00:00      
                  the original problem...            01/01/70 00:00      
         Interrupt Latency + Vectoring + Service            01/01/70 00:00      
   indufficient info            01/01/70 00:00      
   use MCS52 better option            01/01/70 00:00      

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