#define trigPin 7
#define echoPin 6
#define led 13
#define buzzer 11

int frekuensi = 250;
long jarak, waktu;

void setup() {
  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode (echoPin, INPUT);
  pinMode (led, OUTPUT);
  pinMode (buzzer, OUTPUT);
  }

void loop () {
  digitalWrite (trigPin,LOW);
  delayMicroseconds(2);
  digitalWrite (trigPin,HIGH);
  delayMicroseconds(10);
  digitalWrite (trigPin,LOW);
  waktu = pulseIn (echoPin, HIGH);
  jarak = (waktu/2) / 29.1;

  if (jarak <= 150) {
    digitalWrite (led, HIGH);
    tone(buzzer, frekuensi);   
    Serial.print (jarak);
    Serial.print ("  cm \n");
    }
    else if (jarak > 150){
      digitalWrite (led, LOW);
      noTone (buzzer);
       Serial.print("Jarak diluar jangkauan!\n");
      }
 
delay(500);
  }