int trig = 12;
int echo = 14;
int green = 0;
int red = 2;
long dauer = 0;
long entfernung = 0;

void setup() {
//  Serial.begin(115200);
pinMode(trig, OUTPUT);
pinMode(echo, INPUT);
pinMode(green, OUTPUT);
pinMode(red, OUTPUT);
}

void loop() {
digitalWrite(trig, LOW);
delay(5);
digitalWrite(trig, HIGH);
delay(10);
digitalWrite(trig, LOW);
dauer = pulseIn(echo, HIGH);
entfernung = (dauer/2) * 0.03432;

Serial.println(entfernung);

if(entfernung>=50){
  digitalWrite(green, HIGH);
  digitalWrite(red, LOW);
}else{
  digitalWrite(green, LOW);
  digitalWrite(red, HIGH);
}
delay(1000);
}