Arduino - Door Sensor - LED

We are going to learn how to:

We will learn how to toggle LED each time door is closed in Arduino - Door Sensor Toggles LED tutorial.

Hardware Required

1×Arduino Uno
1×USB 2.0 cable type A/B (for USB-A PC)
1×USB 2.0 cable type C/B (for USB-C PC)
1×Door Sensor
1×LED
1×220 ohm resistor
1×Breadboard
1×Jumper Wires
1×(Recommended) Screw Terminal Block Shield for Arduino Uno
1×(Recommended) Breadboard Shield For Arduino Uno
1×(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.

About LED and Door Sensor

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

Wiring Diagram

Arduino Door Sensor LED Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-door-sensor-led */ const int DOOR_SENSOR_PIN = 9; // Arduino pin connected to the OUTPUT pin of door sensor const int LED_PIN = 3; // Arduino pin connected to LED's pin int doorState; void setup() { Serial.begin(9600); // initialize serial pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set arduino pin to input pull-up mode pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode } void loop() { doorState = digitalRead(DOOR_SENSOR_PIN); // read state if (doorState == HIGH) { Serial.println("The door is open");; digitalWrite(LED_PIN, HIGH); // turn on LED } else { Serial.println("The door is closed"); 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
  • Move the magnet close to the reed switch and them move it far from the reed switch.
  • 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.

The Best Arduino Starter Kit

※ OUR MESSAGES