pinchange.ino

// This module uses PIN CHANGE INTERRUPT INT3

#include <avr/interrupt.h>
#include <avr/io.h>
#include "timer_1.h"

//initialize pin change interrupt and data directions
inline void init_pc(void) {
  // enable/ setup output port
  DDRA = 0xff; // all out
  PORTA = 0x00; // all low

  // enable input port
  // enable interrupt
  EICRA |= (1<<ISC30)|(1<<ISC31);
  EIMSK |= (1<<INT3);
}

ISR(INT3_vect) {
  Serial.println(timer_stop());
}