Arduino ile Takometre

#define trigPin 13 
  #define echoPin 12 
  #define led 11 
  #define led2 10 
   
  void setup() { 
    Serial.begin (9600); 
    pinMode(trigPin, OUTPUT); 
    pinMode(echoPin, INPUT); 
    pinMode(led, OUTPUT); 
    pinMode(led2, OUTPUT); 
  } 
   
  void loop() { 
    long duration, distance; 
    digitalWrite(trigPin, LOW);  // Added this line 
    delayMicroseconds(2); // Added this line 
    digitalWrite(trigPin, HIGH); 
  //  delayMicroseconds(1000); - Removed this line 
    delayMicroseconds(10); // Added this line 
    digitalWrite(trigPin, LOW); 
    duration = pulseIn(echoPin, HIGH); 
    distance = (duration/2) / 29.1; 
    if (distance < 4) {  // This is where the LED On/Off happens 
      digitalWrite(led,HIGH); // When the Red condition is met, the Green LED should turn off 
    digitalWrite(led2,LOW); 
  } 
    else { 
      digitalWrite(led,LOW); 
      digitalWrite(led2,HIGH); 
    } 
    if (distance >= 200 || distance <= 0){ 
      Serial.println("Out of range"); 
    } 
    else { 
      Serial.print(distance); 
      Serial.println(" cm"); 
    } 
    delay(500); 
  }