const int trigPin = 3;
const int echoPin = 2;
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(trigPin, OUTPUT); //mengautur pin trig sebagai OUTPUT
  pinMode(echoPin, INPUT); //mengatur pin echo sebagai INPUT
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(LED_BUILTIN, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);                      // wait for a second
  long duration, distance;

  //megirim pulsa ultrasonik
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distance = duration * 0.034 / 2;
  Serial.print("jarak = ");
  Serial.print(distance);
  Serial.print(" cm"); 
  
}