#define ECHO_PIN 2
#define TRIG_PIN 3 

void setup() {
  Serial.begin(115200);
  pinMode (LED_BUILTIN, OUTPUT);
  pinMode (TRIG_PIN, OUTPUT);
  pinMode (ECHO_PIN, INPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration  = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void loop () {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration  = pulseIn(ECHO_PIN, HIGH);
  float distance = duration * 0.034 / 2;

  Serial.print("Jarak: ");
  Serial.println(readDistanceCM());
}