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

[Ned Konz]

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
ISR(INT0_vect)
{
        // your code here
}

// defines __vector_2 (INT1_vect) to jump to __vector_1 (INT0_vect)
ALIAS_VECTOR(INT1_vect,1)

int main(void)
{
}



Thanks,
--
Ned Konz
address@hidden
http://bike-nomad.com