volatile int val;
	
void setup() {
  // set myFunction to be called everytime 
  // interrupt 2 is generated (everytime the pin gets from HIGH to LOW)    
  attachInterrupt(EXTERNAL_INTERRUPT_2, myFunction, FALLING); 
  
  // Starts serial to print data                                 
  Serial.begin(9600);                  
}

void loop() { 
  // sets val to 0 and polls val until reaches the value 255
  val = 0; 
  while (val!=255) 
    continue; 
	
  // prints that val changed
  Serial.println("Finally val is 255");
}

void myFunction() {
  // WARNING: you should avoid doing long procedures in interrupt routines
  val = 255;
}