#define buzzerPin 7
#define trigPin 6
#define echoPin 5 
#define greenPin 4
#define yellowPin 3
#define redPin 2
void setup()
{
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  Serial.begin(9600);
}

void loop()
{
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long waktu, jarak;
  waktu = pulseIn(echoPin, HIGH);
  jarak = (waktu * 0.0343) / 2;
  Serial.print(jarak);
  Serial.println("cm");
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, LOW);
  noTone(buzzerPin);
  if (jarak >= 50 && jarak <= 100)
  {
    digitalWrite(greenPin, HIGH);
    tone(buzzerPin, 1000);
    delay(300);
    noTone(buzzerPin);
    delay(300);
  }
  else if (jarak >= 25 && jarak <= 50)
  {
    digitalWrite(yellowPin, HIGH);
    tone(buzzerPin, 2000);
    delay(200);
    noTone(buzzerPin);
    delay(200);
  }
  else if (jarak >= 0 && jarak <= 25)
  {
    digitalWrite(redPin, HIGH);
    tone(buzzerPin, 3000);
  }
  delay(100);
}