Interfacing LDR Sensor with Arduino | led dimmer LDR Sensor Arduino Code for Analog Output

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Hello friends! Welcome back to ElectroDuino. This tutorial is base on Interfacing LDR Sensor with Arduino | LDR Sensor Arduino Code for Analog Output Read. Here we will learn how to connect the LDR Sensor module to the Arduino circuit diagram, and LDR Sensor Arduino code for Analog Output. Also, we will make a dark & light detector project using the analog output of the sensor..

Components Required

Components NameQuantity
Arduino UNO or you can use other types of Arduino like Arduino NANO, MEGA, pro mini, etc.1
LDR Sensor Module1
LED (Green & Red)1 pcs each color
220ohm Resistor2
Connecting wiresAs required in the circuit diagram

LDR Sensor Module or Photoresistor sensor Pin Diagram

LDR Sensor module pinout pin diagram
LDR Sensor module pinout pin diagram

How to use LDR Sensor with Arduino to Read Analog Output

Here we will connect the LDR sensor module with Arduino to read the Analog Output of the sensor. First of all, we connected the sensor Vcc pin to the Arduino 5v pin and the GND pin is connected to the GND pin. The analog output pin is connected to the Arduino analog pin to read the analog output value from the LDR sensor module.

Arduino LDR Sensor Circuit diagram for Analog Output

Arduino LDR Sensor Circuit diagram for Analog Output
Arduino LDR Sensor Circuit diagram for Analog Output

Circuit Wiring

Components PinArduino Pin
LDR sensor Vcc pin+ 5v Pin
LDR sensor GND pinGND (ground) pin
LDR sensor  AO (Digital Out) pinAnalog pin A5
LED1 (Green) positive terminalDigital pin D5
LED1 (Green) negative terminalGND pin through the 220ohm resistor.
LED2 (Red) positive terminalDigital pin D4
LED2 (Red) positive terminalGND pin through the 220ohm resistor.

How the LDR Sensor Works as a Dark & Light Detector using Sensor Digital Output value

In this circuit, the Sensor Analog Output pin is connected to the Arduino analog pin “A5”. LDR Sensor Analog Output change according to the changes of light intensity on the surface of the LDR. The sensor gives analog output value ranges from 0 to 1023 (0v to 5v), and prints this value on Arduino IDE serial monitor window. The LDR sensor gives a maximum analog output (1023) when no light falls on the surface of the LDR, and it will a minimum analog output(0) when light falls on the surface of the LDR.

The LED1(Green) and LED2(Red) are indicators, these are indicated light and dark respectively.

In the Arduino code, we need to take two analog values, one for the maximum analog value and another one for the minimum analog value. Here we will take 800 for maximum analog value and 300 for minimum analog value.

 If Arduino reads analog value greater than or equal to 800 from the sensor output pin, LED2(Red) will turn ON, and LED1(Green) will turn OFF, It means that it is dark. Else if Arduino reads analog value less than or equal to 300 from the sensor output pin, LED1(Green) will turn ON, and LED2(Red) will turn OFF, It means that it is Light.

LDR Sensor with Arduino Code

Code Analysis

Code Line

Description

 int LDRSensor = A5;

It is declared that your LDR sensor’s analog output (A0) pin connected to Arduino analog pin “A5” and named as LDRSensor.

int LED1 = 5;

int LED2 = 4;

It is declared that the Green LED pin connected to the “D5” pin and named as LED1, and the Red LED pin connected to “D4” pin and named as LED2.

pinMode (LDRSensor, INPUT);

Initialize Arduino analog pin “A5”, as an INPUT. That will read the analog output from your LDR Sensor.

pinMode (LED1, OUTPUT);

pinMode (LED2, OUTPUT);

Initialize “D5” and “D4” pins, asOUTPUT.

Serial.begin(9600);

This function starts serial communication, at 9600 bits of data per second, between your board and your computer with the line.

int Sensordata = analogRead (LDRSensor);

The function analogRead() is used to read the Analog output value come from the sensor and store this value in the variable Sensordata.

Serial.print("Sensor value:");
Serial.println(Sensordata);

This command used to print the sensor value on your serial monitor window.

 if (Sensordata <= 300)

{

digitalWrite(LED1, HIGH); digitalWrite(LED2, LOW);

}

If Arduino reads the analog value “less than or equal to 300” from the sensor, then Arduino provides commands to turn ON the LED1 and turn OFF the LED2.

else if (Sensordata == 1)

{

digitalWrite(LED1, LOW); digitalWrite(LED2, HIGH);

}

Else if Arduino reads the analog value greater than or equal to 800″ from the sensor, then Arduino provides commands to turn ON the LED2 (Red) and turn OFF the LED1.

Output

  • When high light intensity falls on the LDR, then LED1(Green) will turn ON and LED 2(Red) will turn OFF, It means that it is Light.
  • When no light falls on the LDR sensor, then LED2(Red) will turn ON, and LED1(Green) will turn OFF, It means that it is dark.
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