int maximumRange = 2000; // Maximum range needed
int minimumRange = 0; // Minimum range needed
long duration, distance; // Duration used to calculate distance

void setup() {
  // put your setup code here, to run once:
  Serial.begin (9600);
  pinMode(2, OUTPUT);
  pinMode(3, INPUT);
  pinMode(13, OUTPUT); // Use LED indicator (if required)
  pinMode(7, OUTPUT);
  pinMode(9, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(2, LOW);
  delayMicroseconds(2);
  digitalWrite(2, HIGH);
  delayMicroseconds(10);
  digitalWrite(2, LOW);
  duration = pulseIn(3, HIGH);

  //Calculate the distance (in cm) based on the speed of sound.
  distance = duration / 58.2;

  Serial.println(distance);  //แสดงค่าระยะทาง

  if(distance <= 250)
  // Laser rangefinder caculate effect range
  {
    digitalWrite(13,HIGH);
    Serial.println("Enemy tank is in range, fire when ready!");
    delay(5000);
    Serial.println("On the way!!");
    delay(1000);
    digitalWrite(7,HIGH);
    delay(500);
    digitalWrite(7,LOW);
    delay(500);
    digitalWrite(7,HIGH);
    delay(250);
    digitalWrite(7,LOW);
    digitalWrite(13, LOW);
    delay(2500);
    Serial.println("Enemy tank destroyed, nice shot!");

    }
  else{
    digitalWrite(9,HIGH);
    Serial.println("Enemy tank is not in range, do not expose yourself!");
    delay(5000);
    digitalWrite(9,LOW);
  }
  delay(5000);

}