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/*
  WARMER COOLER GAME

  Use a ping sensor to determine distance and then depending on the distance,
  show warmer or cooler colours.

  Built using a ping))) Sensor and connected to a RGB display.

  Uses the ping))) example in the base Arduino install, written by David Mellis & Tom Igoe
  http://www.arduino.cc/en/Tutorial/Ping

 */

#define PING_PIN 7
#define RED 9
#define GREEN 10
#define BLUE 11

#define BLUE_LONG 400
#define BLUE_SHORT 175
#define GREEN_LONG 225
#define GREEN_SHORT 75
#define RED_LONG 125
#define RED_SHORT 0

void setup() {
  // initialize serial communication:
  Serial.begin(9600);

  // set the LED off
  pinMode(RED, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(BLUE, OUTPUT);

  // uses a common anode RGB LED (so +5v turns them off)
  digitalWrite(RED, HIGH);
  digitalWrite(GREEN, HIGH);
  digitalWrite(BLUE, HIGH);
}

void loop()
{

  long distance;
  distance = ping();

  // now depending on the distances we map the colours on the LED.
  // BLUE will be bright at about 350 cm fading out to 175cm
  // GREEN will be bright about 225cm fading out to about 75cm
  // RED will be faded at about 125cm getting bright to 0cm

  if (distance > RED_LONG) {
    digitalWrite(RED, HIGH);
  } else {
    analogWrite(RED, map(distance, RED_LONG, RED_SHORT, 255, 0));
  }

  if ((distance > GREEN_LONG) || (distance < GREEN_SHORT)) {
      digitalWrite(GREEN, HIGH);
  } else {
      analogWrite(GREEN, map(distance, GREEN_LONG, GREEN_SHORT, 255, 0));
  }

  if ((distance > BLUE_LONG) || (distance < BLUE_SHORT)) {
      digitalWrite(BLUE, HIGH);
  } else {
      analogWrite(BLUE, map(distance, BLUE_LONG, BLUE_SHORT, 255, 0));
  }

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

  delay(100);
}

long ping() {
  // returns the distance to the nearest object.
  // establish variables for duration of the ping,
  // and the distance result in inches and centimeters:
  long duration, cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
  pinMode(PING_PIN, OUTPUT);
  digitalWrite(PING_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(PING_PIN, HIGH);
  delayMicroseconds(5);
  digitalWrite(PING_PIN, LOW);

  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(PING_PIN, INPUT);
  duration = pulseIn(PING_PIN, HIGH);

  // convert the time into a distance
  return (microsecondsToCentimeters(duration));

}

long microsecondsToCentimeters(long microseconds)
{
  // The speed of sound is 340 m/s or 29 microseconds per centimeter.
  // The ping travels out and back, so to find the distance of the
  // object we take half of the distance travelled.
  return microseconds / 29 / 2;
}