The Use of Light Sensor

Outline The Microduino Light Sensor uses a photosensitive resistor to detect the amount of ambient light present. The sensor is effectively a resistor that changes in value as the light intensity surrounding it changes. The sensor will output a voltage value that corresponds to the amount of light detected by the sensor. Couple the sensor to an LED and you have a smart light that illuminates a room as it gets dark! Specification Electrical Specifications Analog Output Device Analog Output: 0-1023 (with Microduino Core modules) Technical Specifications Bright Resistance(up to 100Lux): 8-20kΩ Dark Resistance: 1MΩ Sensitivity: Given light intensity of 10Lux and 100Lux, with corresponding resistances (R10 and R100), the sensitivity factor is 0.8. This gives you a sense of how resistance changes with a given quantitative change in the amount of light present. Dimensions Board: 20mm x 10mm Connector: 4-Pin interface, 1.27mm-pitch Connection Interface Pins: Signal, VCC (power), GND (ground) and NC (not connected) NOTE: Sensor must be connected to analog capable ports (i.e. A0-A7) 400px Development Equipment Module Number Function mCookie-CoreUSB 1 Core board mCookie-Hub 1 Sensor pin board Microduino-Light 1 Photosensitive sensor Other Hardware Equipment One USB cable Preparation Setup 1: Connect Microduino-Light and the A0 analog port of the Hub. Setup 2: Connect the CoreUSB, Hub and Light to the computer with a USB cable. Experiment: Detect analog Brightness Value Open Arduino IDE and copy the following code into IDE. #define sensorPin A0 int state; void setup() { pinMode(sensorPin, INPUT); Serial.begin(9600); } void loop() { state = analogRead(sensorPin); Serial.print("state:"); Serial.println(state); delay(100); } Select the right board from Tools→Serial Port in Arduino IDE and download the program. After the download, you can open the serial monitor. The displayed value reflects the current light intensity. Result The stronger the light is, the greater the output value becomes. Therefore, you can build some projects controlled by light intensity change. Program Debugging "#define sensorPin A0" defines sensor interface. Use"analogRead(sensorPin);"function to read the output analog value of the sensor and therefore, to judge light intensity change. Application Couple the Light Sensor with an LED and you can automate the intensity of the LED based on how bright or dark it is in a room. Video