#define LED_PIN 9
#define BUTTON_PIN 3

byte ledState = LOW;

unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 0;    

void setup() {
  Serial.begin(9600);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT);
  digitalWrite(LED_PIN, LOW);

  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), blinkLed, CHANGE);

}

void loop() {
  Serial.println(digitalRead(BUTTON_PIN));

}

void blinkLed() {
  if ((millis() - lastDebounceTime) > debounceDelay) {
    lastDebounceTime = millis();
    ledState = !ledState;
    digitalWrite(LED_PIN, ledState);
  }
}