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Re: [avr-gcc-list] Two interrupts one function?

From: Ned Konz
Subject: Re: [avr-gcc-list] Two interrupts one function?
Date: Sun, 14 May 2006 07:13:23 -0700
User-agent: Thunderbird (Macintosh/20060308)

Ned Konz wrote:
Trampas wrote:
I have two external interrupts connected to a quadature encoder, I do the same operations when either interrupt pin is changed. I was wondering if it was possible to have one ISR that is called from both interrupts. If so how do I do it?

Seems like this would work (jump from the second handler to the first).
Look at the definition of ISR(), EMPTY_INTERRUPT(), and _VECTOR()

Here's a version with a macro called ALIAS_VECTOR() to hide much of the ugliness:

 * Shows how to share a single ISR between two or more interrupts,
* using a "jmp" instruction to get from the secondary interrupt(s) to the primary code.

avr-gcc -Os -mmcu=atmega128 -Wa,-ahlsd=twoisrs.lst -o twoisrs.elf twoisrs.c


#include <avr/io.h>
#include <avr/interrupt.h>

// Syntactic sugar:
#define ALIAS_VECTOR(fromName,toNum) \
void fromName(void) __attribute__ ((signal, naked)); \
void fromName(void) \
{ \
__asm__ __volatile__ ("jmp __vector_" #toNum ::); \

// defines __vector_1
        // your code here

// defines __vector_2 (INT1_vect) to jump to __vector_1 (INT0_vect)

int main(void)

Ned Konz

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