Interfacing LDR Module with Arduino

In this project, we are going to learn about LDR and LDR Module and how to control light based of darkness outside. When darkness will come in outside the light or led will turn on automatically. Now we will make one kind darkness detector circuit using LDR module and Arduino Uno.

Component Requirement for interfacing LDR Module With Arduino:INTERFACING LDR MODULE WITH ARDUINO

LDR Module:

LDR is one kind of photoresistor and light dependent resistor that is sensitive of light. When light falls upon it then the resistance changes. Values of the resistance of the LDR may be change over many orders of magnitude the value of the resistance falling as the level of light increases. It is not uncommon for the values of resistance of an LDR to be several Megaohms in darkness and then to fall to a few hundred ohms in bright light. With such a wide variation in resistance, LDRs are easy to use.

LDR Modules are made from semiconductor materials. But one popular material for these photoresistors is cadmium sulphide. Other materials that can be used include lead sulphide, PbS and indium antimonide, InSb.

Specifications of LDR Module: 

  • Operating Voltage:3V to 5V DC
  • Operating Current: 15milli amps
  • LED indicating output and power
  • LM393 based design
  • Output Digital: 0V to 5V, Adjustable trigger level from preset
  • Output Analog:0V to 5V based on light falling on the LDR

Pinout of LDR Module:

  • VCC: Power supply
  • GND: Ground
  • D0: Digital Output
  • A0: Analog Output

Circuit Diagram of Interfacing for ldr module with arduino


Explaination on interfacing for LDR Module with arduino


Connect a LED negative to GND of arduino and positive to pin 9 with a resistance valued between 1KΩ.

How it’s works on interfacing for ldr module with arduino: 

LDR sensor module is used to detect the intensity of light. It is associated with both analog output pin and digital output pin named as AO and DO respectively. When light is presented, the resistance of LDR become low according to the intensity of light. The sensor presents a potentiometer knob that can be adjusted to change the sensitivity of LDR towards light. When darkness will come in outside the light or led will turn on automatically and other side light is presented, the led or light will turn off automatically. This project is very useful for home appliance.

Working Code:


Leave a Comment