ESP32 - Door Sensor Toggle LED

In a previous tutorial, We have learned how to turn on the LED if the door is open, and turn off LED if the door is closed. In this tutorial, We are going to learn how to toggle LED each time door is closed.

Hardware Required

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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About LED and Door Sensor

If you do not have knowledge of LED and door sensor (pinout, how they work, how to connect them to ESP32, how to program for them...), learn about them in the following tutorials:

Wiring Diagram

ESP32 Door Sensor LED Wiring Diagram

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ESP32 Code - Door Sensor Toggles LED

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-door-sensor-toggle-led */ // constants won't change const int DOOR_SENSOR_PIN = 13; // ESP32 pin connected to door sensor's pin const int LED_PIN = 3; // ESP32 pin connected to LED's pin // variables will change: 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"); // toggle state of LED ledState = !ledState; // control LED arccoding to the toggled state digitalWrite(LED_PIN, ledState); } }

Quick Steps

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE, select the right ESP32 board and COM port
  • Copy the above code and paste it to Arduino IDE
  • Click Upload button on Arduino IDE to compile and upload code to ESP32 board
  • 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

Code Explanation

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

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

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

Video Tutorial

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