Arduino - Light Sensor Triggers LED

In this tutorial, We are going to learn how to:

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×Light Sensor
1×220 ohm resistor
1×10 kΩ resistor
n×Jumper Wires
Please note: These are affiliate links. If you buy the components through these links, We may get a commission at no extra cost to you. We appreciate it.
Or you can order electronic components from

About LED and Light Sensor

If you do not know about LED and light sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino Light Sensor LED Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino Code

/* * Created by * * This example code is in the public domain * * Tutorial page: */ // constants won't change const int LIGHT_SENSOR_PIN = A0; // Arduino pin connected to light sensor's pin const int LED_PIN = 3; // Arduino pin connected to LED's pin const int ANALOG_THRESHOLD = 500; // variables will change: int analogValue; void setup() { pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode } void loop() { analogValue = analogRead(LIGHT_SENSOR_PIN); // read the input on analog pin if(analogValue < ANALOG_THRESHOLD) digitalWrite(LED_PIN, HIGH); // turn on LED else digitalWrite(LED_PIN, LOW); // turn off LED }

Quick Steps

  • Connect Arduino to PC via USB cable
  • Open Arduino IDE, select the right board and port
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Arduino IDE Upload Code
  • Radiates light to sensor
  • See the change of LED's state

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Video Tutorial

We are considering to make the video tutorials. If you think the video tutorials are essential, please subscribe to our YouTube channel to give us motivation for making the videos.

Light Sensor and LED on Commercial Products

  • TP-Link AC1750 Smart WiFi Router - Dual Band Gigabit Wireless Internet Routers
  • Gaming Keyboard and Mouse