Photocell (Light Sensor)

Photocell (Light Sensor)


Simple Arduino example to print out ambient light values using a photoresistor.


1 x photoresistor
1 x 10k ohm resistor
1 x Arduino Uno
1 x breadboard
jumper wires



Arduino sketch

Inspect Serial monitor (9600) for light values.
Adapted from
Simple test of the functionality of the photo resistor

Connect the photoresistor one leg to pin 0, and pin to +5V
Connect a resistor (around 10k is a good value, higher
values gives higher readings) from pin 0 to GND. 


           PhotoR     10K
 +5     o---/\/\/--.--/\/\/---o GND
 Pin A0 o-----------


int lightPin = A0;  //define a pin for Photo resistor

void setup()
    Serial.begin(9600);  //Begin serial communcation
    pinMode( lightPin, INPUT );

void loop()
    Serial.println(analogRead(lightPin)); //Write the value of the photoresistor to the serial monitor.
    delay(10); //short delay for faster response to light.