Simple Interrupt

Interrupt.ino

// Pin 13 has an LED connected on most Arduino boards.
const byte ledPIN = 13;
const byte interruptPIN = 2;
volatile boolean enabled;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(ledPIN, OUTPUT);
  pinMode(interruptPIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(interruptPIN), first_ISR, FALLING);
  enabled=true;
}

// the loop routine runs over and over again forever:
void loop() {
  if(enabled)
  digitalWrite(ledPIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(100);              // wait for a second
  digitalWrite(ledPIN, LOW);    // turn the LED off by making the voltage LOW
  delay(100);               // wait for a second
}

void first_ISR() {
  if(enabled){
    enabled=false;
    }else{
      enabled=true;
      }
}