const byte ledPin = 5;
const byte interruptPin = 2;
volatile byte state = LOW;


void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin,OUTPUT);
  pinMode(interruptPin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(interruptPin),blink,CHANGE);

}

void loop() {
  // put your main code here, to run repeatedly:
  while(1){
    digitalWrite(ledPin,state);
  }
}



void blink(){
  state = !state;
}