Datasheet

You may want to try different pulldown resistors depending on the light level range you want to detect!

Simple Code for Analog Light Measurements

This code doesn't do any calculations, it just prints out what it interprets as the amount of light in a qualitative manner.

For most projects, this is pretty much all thats needed!

/* Photocell simple testing sketch.

Connect one end of the photocell to 5V, the other end to Analog 0.

Then connect one end of a 10K resistor from Analog 0 to ground

Connect LED from pin 11 through a resistor to ground

For more information see http://learn.adafruit.com/photocells */

int photocellPin = 0; // the cell and 10K pulldown are connected to a0

int photocellReading; // the analog reading from the sensor divider

int LEDpin = 11; // connect Red LED to pin 11 (PWM pin)

int LEDbrightness; //

void setup(void) {

// We'll send debugging information via the Serial monitor

Serial.begin(9600);

}

void loop(void) {

photocellReading = analogRead(photocellPin);

Serial.print("Analog reading = ");

Serial.println(photocellReading); // the raw analog reading

// LED gets brighter the darker it is at the sensor

// that means we have to -invert- the reading from 0-1023 back to 1023-0

photocellReading = 1023 - photocellReading;

//now we have to map 0-1023 to 0-255 since thats the range analogWrite uses

LEDbrightness = map(photocellReading, 0, 1023, 0, 255);

analogWrite(LEDpin, LEDbrightness);

delay(100);

}