Photoresistor
Youtube Video
https://www.youtube.com/watch?v=uNPaaZP4_Yo
Final Photo
Fritzing Diagram
The Source Code
/*
* A simple programme 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
//the photoresistor is not calibrated to any units so
//this is simply a raw sensor value (relative light)
//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
// lightlevel
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 betwween
//0 and 255
analogWrite(ledPin, lightLevel); //write the value
}