Position sensor code for RC Helicopter target landing game. Try to land your RC Helicopter (Syma S107 preferred) in a 10cm target. Sensor detect how far you are away from center. Three LEDs (green, orange and red) will tell your score.

helipad-distance.cpp

/*
Arduino 1 Dimensional RC Helicopter Target Center Detection
Mount sensor near a circle 10 cm across
Try to land your RC Helicopter (Syma S107 preferred)
If the Green LED lights up you are in the target zone and you get 3 points
If the Orange LED lights up you near but not in the target zone and you get 1 points
If the Red LED lights up you only get a single point

Circuit:
I used HC-SR04 Ping distance sensor
Connect Sensor VCC to Arduino 5v
Connect Sensor GND to arduino GND
Connect Sensor Echo to Arduino pin 13
Connect Sensor Trig to Arduino pin 12
Connect RedLED through 220 Ohm Resistor between to Arduino pin 6
Connect OrangeLED through 220 Ohm Resistor between to Arduino pin 5
Connect OrangeLED through 220 Ohm Resistor between to Arduino pin 5

TODO - add a second sensor for the other dimension
*/

#define trigPin 12
#define echoPin 13
#define redLED 6
#define orangeLED 5
#define greenLED 3

void setup() {
  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redLED, OUTPUT);
  pinMode(orangeLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
}

void loop() {
  long duration, distance;
  digitalWrite(trigPin, LOW); 
  delayMicroseconds(1); // Added this line
  digitalWrite(trigPin, HIGH);
  
  delayMicroseconds(1); // Added this line
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;  // may require some tuning....
  
  if (distance >= 10 && distance <= 20) {  // This is where the LED On/Off happens
    digitalWrite(greenLED,HIGH); // we are in the score zone
    digitalWrite(orangeLED,LOW);
    digitalWrite(redLED,LOW);
    Serial.print(distance);
    Serial.println(" cm for 3 points");
  }
  else if (distance > 5 && distance < 30) {  // This is where the LED On/Off happens
    digitalWrite(greenLED,LOW); // we are near the score zone
    digitalWrite(orangeLED,HIGH);
    digitalWrite(redLED,LOW);
    Serial.print(distance);
    Serial.println(" cm for 2 points");
  }
  else if (distance >= 200 || distance <= 5){
    digitalWrite(greenLED,LOW); // we are out of the score zone
    digitalWrite(orangeLED,LOW);
    digitalWrite(redLED,HIGH);
    Serial.print(distance);
    Serial.println(" cm for 1 point");
  };
  
  delay(300);  // 1000 = delay a second
}