void setup() {       
    attachInterrupt(digitalPinToInterrupt(3),stopper,RISING); //interruptpins nur 2 oder 3!!!!!!
    Serial.begin(9600);
    pinMode(4, OUTPUT);
    pinMode(7, OUTPUT);
    pinMode(3,INPUT);
}

void loop() {
         
    digitalWrite(4, HIGH);



}

void stopper()
{
  int Schalterzustand = digitalRead(3);
  while (Schalterzustand == HIGH) {
    digitalWrite(4, LOW);
    digitalWrite(7, HIGH);
     Serial.println(Schalterzustand);
  }
}