TinkerKit LDR Sensor Overview LDR (or Light Dependant Resistor, or Photoresistor) is a variable resistor. Light falling on the sensor decreases its resistance. Output: This module outputs 5v when the sensor receives no light (the circuit is open) and 0v when exposed to bright light (the circuit is closed). When connected to an input on the Arduino using the TinkerKit Shield, you can expect to read values from 0 to 1023. Module Description: This module features a Light Dependent Resistor, a signal amplifier, the standard TinkerKit 3pin connector, a green LED that signals that the module is correctly powered and a yellow LED whose brightness changes according to the amount of lightness. This module is a SENSOR. The connector is an OUTPUT which must be connected to one of the INPUT connectors on the TinkerKit Shield. Code Example /* Analog input, analog output, serial output Reads an analog input pin, and T000090 LDR Analog Sensor connected to I0, maps the result to a range from 0 to 255 and uses the result to set the pulsewidth modulation (PWM) on a T010111 LED Module connected on O0. Also prints the results to the serial monitor. created 29 Dec. 2008 Modified 4 Sep 2010 by Tom Igoe modified 7 dec 2010 by Davide Gomba This example code is in the public domain. */ define O0 11 define O1 10 define O2 9 define O3 6 define O4 5 define O5 3 define I0 A0 define I1 A1 define I2 A2 define I3 A3 define I4 A4 define I5 A5 // These constants won t change. They re used to give names // to the pins used: const int analogInPin = I0 // Analog input pin that the LDR is attached to const int analogOutPin= O0 // Analog output pin that the LED is attached to int sensorValue = 0 // value read from the pot int outputValue = 0 // value output to the PWM (analog out) void setup() // initialize serial communications at 9600 bps: Serial.begin(9600) void loop() // read the analog in value: sensorValue = analogRead(analogInPin)