// Nama : Rika Rahmawati
// NIM : 21210005
long duration;
int distance;
#define echoPin 3
#define trigPin 4
int merah = 12;
int hijau = 2;
const int buzzer =5;
void setup() {
  // put your setup code here, to run once:
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(merah, OUTPUT);
pinMode(hijau, OUTPUT);
pinMode(buzzer, OUTPUT);
Serial.begin(9600);
Serial.println("Ultrasonic Sensor HC-SR04 Test");
Serial.println("with Arduino UNO R3");
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin,HIGH);
distance = duration *0.034/2;
Serial.println("Distance");
Serial.println(distance);
Serial.println("cm");
delay(1000);

if(distance <50) {
  digitalWrite(merah,HIGH);
  digitalWrite(hijau, LOW);
}else{
  digitalWrite(hijau, HIGH); // ...for 1 sec 
  digitalWrite(merah, LOW);
  if (distance >100){
    digitalWrite(merah, LOW);
    digitalWrite(hijau, LOW);
    tone(buzzer,2000); //Send 1KHz sound signal...
    delay(1000);
    noTone(buzzer); // Stop Sound...
    delay(1000);
}
}
}