Difference between revisions of "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)

Development

Equipment

• 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