int ECHO = 8;
int TRIG = 9;
int green = 6;
int yellow = 5;
int red = 4;
int BUZ = 7;

void setup() {
  // put your setup code here, to run once:
pinMode(ECHO, INPUT);
pinMode(TRIG, OUTPUT);
pinMode(green, OUTPUT);
pinMode(yellow, OUTPUT);
pinMode(red, OUTPUT);
pinMode(BUZ, OUTPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(TRIG, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG, LOW);
int waktu;
waktu = pulseIn(ECHO, HIGH);
int jarak;
jarak = waktu/2*0.034; //kecepatan cahaya dalam cm/microsecond

if (jarak>300){
  digitalWrite(green, LOW);
  digitalWrite(yellow, LOW);
  digitalWrite(red, LOW);
  noTone(BUZ);//buzzer mati
}
else if(jarak >200 && jarak<=300){
  digitalWrite(green, HIGH);
  digitalWrite(yellow, LOW);
  digitalWrite(red, LOW);
  noTone(BUZ);//buzzer mati
}
else if(jarak >100 && jarak <=200){
  digitalWrite(yellow, HIGH);
  digitalWrite(green, LOW);
  digitalWrite(red, LOW);
  noTone(BUZ);//buzzer mati
}
else{
  digitalWrite(yellow, LOW);
  digitalWrite(green, LOW);
  digitalWrite(red, HIGH);
  tone(BUZ, 100);//buzzer nyala. You can change the value of buzzer to make different sound
}
Serial.println(jarak);
delay(1000);
}