#define TRIG_PIN 13
#define ECHO_PIN 14
#define GREEN_LED 15
#define ORANGE_LED 16
#define RED_LED 17

void setup(){
  pinMode(TRIG_PIN,OUTPUT);
  pinMode(ECHO_PIN,INPUT);
  pinMode(GREEN_LED,OUTPUT);
  pinMode(ORANGE_LED,OUTPUT);
  pinMode(RED_LED,OUTPUT);

  Serial.begin(9600);

}

void loop() {

  long duration;
  int distance;


  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration=pulseIn(ECHO_PIN,HIGH);
  distance=duration*0.034/2;

  Serial.print("distance:");
  Serial.print(distance);
  Serial.print("cm");

  if(distance>300){

    digitalWrite(GREEN_LED, HIGH);
    digitalWrite(ORANGE_LED, LOW);
    digitalWrite(RED_LED, LOW);
  }

  else if(distance>200 && distance<=300) {

    digitalWrite(GREEN_LED,LOW);
    digitalWrite(ORANGE_LED, HIGH);
    digitalWrite(RED_LED, LOW);
  }

  else if(distance<=200) {

    digitalWrite(GREEN_LED,LOW);
    digitalWrite(ORANGE_LED, LOW);
    digitalWrite(RED_LED, HIGH);
  }

  delay(500);
}