An AVR external interrupt example
#include<avr/io.h>
#include<avr/interrupt.h> // interrupt header file
#include<util/delay.h>
/**
External Interrupt Program
*/
// Interrupt service Routine for INTO
ISR(INT0_vect)
{
//_delay_ms(50); // Software Debounce delay
PORTB ^= 1<<PINB0;
_delay_ms(50);
}
int main (void)
{
DDRB |= 1<< PINB0 | 1<< PINB2; // setn PINB0 and PINB1 as output
PORTB &= ~(1<< PINB0 | 1<< PINB2);
DDRD &= ~(1<<PIND2); // PIND2 set as input.. This is the INT0 pin to which button is connected
PORTD |= 1 << PIND2; // push PIND2 to high - internal pull up resisitor- short when button is pressed
GIMSK = 1<<INT0; // enable interrupt on INTO pinD2
MCUCR = 1<<ISC01 | 1 << ISC00; // Trigger INTO on rising edge
// enable global interrupts
sei();
while(1)
{
PORTB ^= 1 << PINB2;
_delay_ms(50);
}
}