ESP32 - Button - Relay

This tutorial instructs you how to use ESP32 to control LED based on the pressing state of button. In detail:

If a button is being pressed, ESP32 activates a relay
If a button is NOT being pressed, ESP32 deactivates a relay

We also have another tutorial: ESP32 - Button Toggles Relay, which toggle relay's state between ON and OFF when the button is pressed.

We can extend this tutorial to use button to control a led strip, siren, light bulb, or motor... by connnecting them to the relay.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	Button
1	×	Relay
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) Solenoid Lock
1	×	(Optional) 12V Power Adapter
1	×	(Optional) DC Power Jack
1	×	(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Introduction to Relay and Button

We have specific tutorials about relay and button. 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 between ESP32, Relay and Button

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 Code

/* * 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-button-relay */ #define BUTTON_PIN 22 // ESP32 pin GPIO22 connected to button's pin #define RELAY_PIN 27 // ESP32 pin GPIO27 connected to relay's pin void setup() { Serial.begin(9600); // initialize serial pinMode(BUTTON_PIN, INPUT_PULLUP); // set ESP32 pin to input pull-up mode pinMode(RELAY_PIN, OUTPUT); // set ESP32 pin to output mode } void loop() { int buttonState = digitalRead(BUTTON_PIN); // read new state if (buttonState == LOW) { Serial.println("The button is being pressed"); digitalWrite(RELAY_PIN, HIGH); // turn on } else if (buttonState == HIGH) { Serial.println("The button is unpressed"); digitalWrite(RELAY_PIN, LOW); // turn off } }

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

Press and keep pressing the button several seconds
See the change on the relay's state

Line-by-line Code Explanation

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

Video Tutorial

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