const byte buttonPin = 2;
const byte ledPin = 8;
volatile bool ledState = LOW;

void setup() {
  pinMode(buttonPin, INPUT_PULLUP);  
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);

  attachInterrupt(digitalPinToInterrupt(buttonPin), handleInterrupt, FALLING);
}

void loop() {
  Serial.println("Program sibuk, tunggu 1 detik...");
  delay(1000);
}

void handleInterrupt() {
  ledState = !ledState;
  digitalWrite(ledPin, ledState);
}