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Continuous interrupt

 
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Lykos1986



Joined: 26 Nov 2005
Posts: 68

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Continuous interrupt
PostPosted: Sun Dec 07, 2008 11:01 am     Reply with quote
Hi! May I have your help? I am trying to set up an interrupt from the serial port using a PIC 16F877. The problem is that the PIC always goes to the interrupt service routine…

What I have to do?


Code:

#include <16f877A.h>
#FUSES XT, NOWDT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay (clock = 4000000)
#use rs232(baud=9600, xmit=PIN_C6,rcv=PIN_C7,stream=module)

#int_rda
void serial_isr()
{
disable_interrupts(int_rda);
disable_interrupts(global);

output_high(led3);
delay_ms(1000);
output_low(led3);
delay_ms(1000);

enable_interrupts(int_rda);
enable_interrupts(global);
return;
}

void main()
{
........

enable_interrupts(global);
enable_interrupts(int_rda);

   while(1)
   {
   sleep();
   }   
}
dyeatman



Joined: 06 Sep 2003
Posts: 1968
Location: Norman, OK

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PostPosted: Sun Dec 07, 2008 11:25 am     Reply with quote
For why it constantly goes to interrupt routine...

http://www.ccsinfo.com/forum/viewtopic.php?t=36800


Also, in the int_rda routine
remove enable and disable interrupt lines, already taken care of by the compiler..
remove the return, already taken care of by the compiler.
Remove the delay, set a flag instead and process in the main loop

Example main loop pseudocode:

Code:

main()
{
   Enable_interrupts(int_rda)
   Enable_interrupts(global)
   set flag false

   While (1)
       {
   
        if flag from interrupt set
            {
               set flag false
               blink LED here
             }

       }
}



Last edited by dyeatman on Sun Dec 07, 2008 2:54 pm; edited 1 time in total
FvM



Joined: 27 Aug 2008
Posts: 2337
Location: Germany

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PostPosted: Sun Dec 07, 2008 1:58 pm     Reply with quote
Basically, the interrupt flag has to be reset in the ISR by reading from the UART, otherwise it must repeat continuously
Code:
c = getc();

Why don't you simply try the CCS programming examples?
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