ESP32 - Door Sensor Toggle LED

This tutorial instructs you how to use ESP32 to toggle LED each time door is closed.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Door Sensor
1×LED
1×220 ohm resistor
1×Breadboard
4×Jumper Wires
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Introduction to LED and Door Sensor

We have specific tutorials about LED and door sensor. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

Wiring Diagram

wiring diagram between esp32 door sensor led

This image is created using Fritzing. Click to enlarge image

ESP32 Code - Door Sensor Toggles LED

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-door-sensor-toggle-led */ #define DOOR_SENSOR_PIN 23 // ESP32 pin GIOP23 connected to the OUTPUT pin of door sensor #define LED_PIN 17 // ESP32 pin GIOP17 connected to LED's pin // The below are variables, which can be changed int ledState = LOW; // the current state of LED int lastDoorState; // the previous state of door sensor int currentDoorState; // the current state of door sensor void setup() { Serial.begin(9600); // initialize serial pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set ESP32 pin to input pull-up mode pinMode(LED_PIN, OUTPUT); // set ESP32 pin to output mode currentDoorState = digitalRead(DOOR_SENSOR_PIN); } void loop() { lastDoorState = currentDoorState; // save the last state currentDoorState = digitalRead(DOOR_SENSOR_PIN); // read new state if (lastDoorState == HIGH && currentDoorState == LOW) { // state change: HIGH -> LOW Serial.println("The door-closing event is detected, toggles the state of LED"); // toggle state of LED ledState = !ledState; // control LED arccoding to the toggled state digitalWrite(LED_PIN, ledState); } }

Quick Instructions

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
  • Do the wiring as above image.
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE on your PC.
  • Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
  • Copy the above code and paste it to Arduino IDE.
  • Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
  • Move the magnet close to the reed switch and them move it far from the reed switch. Repeat this several times
  • See the change of LED's state

Line-by-line Code Explanation

The above ESP32 code contains line-by-line explanation. Please read the comments in the code!

In the code, ledState = !ledState is equivalent to the following code:

if(ledState == LOW) ledState = HIGH; else ledState = LOW;

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