Difference between revisions of "Sensor-Light-A1"

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Download the above example:  
Download the above example:  
*Open the Serial Monitor (magnifier glass on top right) and set 9600 baud. This will display the serial output data.

Revision as of 19:12, 18 August 2017

Language: English  • 中文

The product number of Sensor-Light-A1 is: MSDT42

Sensor-Light-A1 is a photosensitive brightness detection sensor module.

The light sensor transforms the light signal into electric signal with the photosensitive resistance. Its sensitive wavelength is near that of the visible light, including the infrared and the ultraviolet.

Description of the Sensor Pin

Sensor backpin.png

Light A1 Sensor
General Pin Out Sensor / Trinket's Pin Out
PIN3 (SIGNAL-A) Analog Input
PIN4 (SIGNAL-B) Not Connected
  • General Pin Out is the standard pin out of a Sensor / Trinket connector.
  • Sensor / Trinket's Pin Out is this specific Sensor / Trinket's wiring in relation to the General Pin Out.
  • SIGNAL-A / SIGNAL-B are signals that could be digital input, digital output, analog input or analog output. Or special signals such as serial communication (SoftwareSerial, IIC (I2C), etc) or other special signals.
  • Not Connected refers to the Pin not being used for this particular Sensor / Trinket.
  • Read more about the hub module.


  • Resistance photosensitive element, with high sensitivity.


  • Sensor voltage
    • 3.3V~5V working voltage
  • Size of the sensor
    • Size of the board: 23.5mm*13mm;
    • 1.27mm-spacing 4Pin interface connected with sensorhub;
    • CAD drawing of the sensor: File:Sensor CAD.zip
  • Function description
    • The sensor outputs the corresponding voltage according to the detected light intensity.
  • Connection
    • This sensor can be connected to the following interfaces of core: A0~A7


  • Schematic diagram:
  • Main sensor:


Basic Functionality

The Light Sensor is an analog input sensor. It is able to detect light levels by using a photoresistor. A photoresistor is sensitive to the amount of light and changes its resistance based on light levels. When used in a voltage divider, different voltage levels will be produced based on the amount of light. A Core module can read the voltage value.

Light Sensor State Table
Light Amount Value Produced
No Light < 200
Finger Covering the Sensor 200~300
Ambient Light 700~900
10 Inches from the Sun 1023



The Light Sensor is used as an analog input pin. Therefore, the pinMode and analogRead functions will be used.

Key Functions

  • Required Libraries: None
  • Key Functions:
    • pinMode(pin_number, pin_mode) - sets the mode for the pin
      • pin_number - is the pin number that the sensor is connected to
      • pin_mode - is the mode to set the pin to. Either INPUT or OUTPUT
    • analogRead(pin_number) - Reads the value of the pin, between 0 and 1023
      • pin_number - is the pin number that the sensor is connected to


This is a simple example which outputs the state of the Light Sensor to the serial port terminal.

Note: Important lines of code are highlighted.

//Define the pin the sensor is connected to
//Note: This sensor uses analog read, which means only pins denoted with an 'A' prefix will work.
const int LIGHT_SENSOR_PIN = A0;

void setup(){
  // put your setup code here, to run once:

  //Initial serial communication port at 9600 baud

  //Configure the pin into input mode

void loop(){
  // put your main code here, to run repeatedly:

  //Perform a digital read and store the value into pin_state variable
  int pin_value = analogRead(LIGHT_SENSOR_PIN);

  //Print out the current value of the sensor

  //delay 10ms between loops

Copy and paste the code above to the Arduino IDE or

Download the above example:

  • Open the Serial Monitor (magnifier glass on top right) and set 9600 baud. This will display the serial output data.

Program Download


  • Follow the Software Getting Started Guide.
  • Select the Board, Processor and Port.
  • Click [File]->[Open], browse to the project program address, and click "Microduino_Light_A1.ino" to open the program.
  • After confirming all these items are correct, click "→" to download the program to the development board.

Hardware Setup

  • Referring to the following diagram, connect the Sensor-Light_A1 to the analog port A0/A1 of Microduino-Sensorhub.

Microduino-sLight A1.JPG


  • After download, open the serial monitor.
  • The value displayed on serial monitor reflects the current light intensity detected by the sensor.


It can feel the intensity of light around us. It can be used to detect the light intensity, and control the indoor lighting and object shading and so on.





  • Front
Sensor-Light Front
  • Back
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