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Interrupt handling

 
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unni.anad



Joined: 14 Aug 2009
Posts: 4
Location: India

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Interrupt handling
PostPosted: Fri Aug 14, 2009 9:49 am     Reply with quote

Whether ccs compiler itself take care of saving the W-REG and STATUS reg during when it serves an interrupt routine. In an example code provided it is shown as to be done by the programmer. (given in ALP).
Code:

  #asm
   //store current state of processor
   MOVWF save_w
   SWAPF status,W
   BCF   status,5
   BCF   status,6
   MOVWF save_status
   // Save anything else your code may change
   // You need to do something with PCLATH if you have GOTOs

   // remember to check to see what interrupt fired if using more than one!!

   // code for isr
   BCF   t0if
   INCF  counter,F
   BTFSC zero_flag
   INCF  (&counter+1),F

   // restore processor and return from interrupt
   SWAPF save_status,W
   MOVWF status
   SWAPF save_w,F
   SWAPF save_w,W
   #endasm


In an another example using C
Code:

#INT_TIMER2 //HIGH
void timer2_isr()
{
   count++;
}

What is the difference ?
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Aug 14, 2009 11:14 am     Reply with quote

See this thread for a detailed explanation of the CCS interrupt handler code:
http://www.ccsinfo.com/forum/viewtopic.php?t=29173
unni.anad



Joined: 14 Aug 2009
Posts: 4
Location: India

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PostPosted: Fri Aug 14, 2009 11:25 am     Reply with quote

Thanks for your fast and efficient reply
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