#define pinTring 8
#define pinEcho 9
#define pinLED 3
void setup() {
  // put your setup code here, to run once:
  pinMode(pinTring, OUTPUT);
  pinMode(pinEcho, INPUT);
  pinMode(pinLED, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int jarak, waktu;
  digitalWrite(pinTring, LOW);
  delay(2);
  digitalWrite(pinTring, HIGH);
  delay(10);
  digitalWrite(pinTring, LOW);

  waktu = pulseIn(pinEcho, HIGH);
  jarak = (waktu/2)/29.1;
  Serial.print("jarak = ");
  Serial.print(jarak);
  Serial.println(" cm");
  if(jarak <50){
    digitalWrite(pinLED, HIGH);
    }else{
      digitalWrite(pinLED, LOW);
    }
  
  delay(2000);
}