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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 | × | Micro USB Cable | |
| 1 | × | Button | |
| 1 | × | Relay | |
| 1 | × | Warning Light Bright Waterproof | |
| 1 | × | 12V Power Adapter | |
| 1 | × | Breadboard | |
| n | × | Jumper Wires |
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Wiring Diagram between ESP32, Relay and Button
This image is created using Fritzing. Click to enlarge image
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 GIOP22 connected to button's pin
#define RELAY_PIN 27 // ESP32 pin GIOP27 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!
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