/**
   HC-SR04 Distance Sensor Example
   https://wokwi.com/arduino/projects/304444938977804866
*/

#define PIN_TRIG 3
#define PIN_ECHO 2

void setup() {
  Serial.begin(115200);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  pinMode(4, OUTPUT);
}

void loop() {
  // Start a new measurement:
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  // Read the result:
  int duration = pulseIn(PIN_ECHO, HIGH);
  Serial.print("Distance in CM: ");
  Serial.println(duration / 58);
  Serial.print("Distance in inches: ");
  Serial.println(duration / 148);

  int jarak = duration / 58;

  if(jarak<=100 && jarak>50)
  {
    tone(4,500);
    delay(500);
    noTone(4);
    delay(500);
  }
  else if(jarak<=50)
  {
    tone(4,400);
    delay(200);
    noTone(4);
    delay(200);
  }
  else
  {
    noTone(4);
  }
}