/*
 * A simple program that will change the intensity of an LED based
 * on the amount of light incident on the photo resistor.
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is connected to
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}

/*
 * loop() - this function will start after setup
 * finishes and then repeat
 */
void loop()
{
  int lightLevel = analogRead(lightPin); //Read the light level
        //the photoresistor is not calibrated to any units so
        //this is simply a raw sensor value (relative light)
  lightLevel = map(lightLevel, 0, 900, 0, 255);
        //adjust the value 0 to 900 to
        //span 0 to 255

  lightLevel = constrain(lightLevel, 0, 255);//make sure the
                                           //value is between
                                           //0 and 255
  analogWrite(ledPin, lightLevel);  //write the value
}