const int trigPin = 18;
const int echoPin = 17;
const int LED1 = 2;
const int LED2 = 4;
const int LED3 = 15;
#define PIEZO_PIN 5
long duration;
int distance;
void setup() {
pinMode(PIEZO_PIN, OUTPUT);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
   pinMode(LED1 , OUTPUT);
  pinMode(LED2 , OUTPUT);
  pinMode(LED3 , OUTPUT);
Serial.begin(9600);
}

void loop() 
{
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance= duration*0.034/2;
  Serial.print("Mesafe: ");
  Serial.println(distance);
  if ((distance < 30) && (distance>20)) {
    
    tone(PIEZO_PIN, 1500);
    digitalWrite(LED1, HIGH);
    delay(300);
    noTone(PIEZO_PIN);
    
    delay(300);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
  }
  else if ((distance <= 20) && (distance>10))
  {
    digitalWrite(LED2, HIGH);
     tone(PIEZO_PIN,1500);
    delay(200);
    noTone(PIEZO_PIN);
    delay(200);
    digitalWrite(LED1, LOW);
    
    digitalWrite(LED3, LOW);
  
  } 
  else if ((distance <= 10) )
  {
    digitalWrite(LED3, HIGH);
     tone(PIEZO_PIN,1500);
    delay(100);
    noTone(PIEZO_PIN);
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
    
  
  } 
  else
   digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
}