ESP32 - Keypad - Beep

This tutorial instructs you how to use generate a beep each time a key on keypad is pressed using ESP32, keypad and piezo buzzer.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×USB Cable Type-C
1×Keypad 3x4 and 4x4 Kit
1×(Alternative) Keypad 3x4
1×(Alternative) Keypad 4x4
1×Piezo Buzzer
1×Jumper Wires
1×(Optional) DC Power Jack
1×(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
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Introduction to Keypad and Piezo Buzzer

We have specific tutorials about keypad and Piezo Buzzer. 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:

Please note that this tutorial use 3-5V buzzer, but you can adapt it for 12v buzzer. you can learn about ESP32 - Buzzer tutorial

Wiring Diagram

ESP32 keypad piezo buzzer wiring diagram

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 * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit */ #include <Keypad.h> #include <ezBuzzer.h> #define BUZZER_PIN 19 // ESP32 pin GPIO19 connected to the buzzer #define ROW_NUM 4 // keypad four rows #define COLUMN_NUM 3 // keypad three columns char keys[ROW_NUM][COLUMN_NUM] = { {'1', '2', '3'}, {'4', '5', '6'}, {'7', '8', '9'}, {'*', '0', '#'} }; byte pin_rows[ROW_NUM] = {12, 14, 27, 26}; // ESP32 pin: GPIO12, GPIO14, GPIO27, GPIO26 connected to the row pins byte pin_column[COLUMN_NUM] = {25, 33, 32}; // ESP32 pin: GPIO25, GPIO33, GPIO32 connected to the column pins Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM ); ezBuzzer buzzer(BUZZER_PIN); // create ezBuzzer object that attach to a pin; void setup() { Serial.begin(9600); } void loop() { buzzer.loop(); // MUST call the buzzer.loop() function in loop() char key = keypad.getKey(); if (key) { Serial.print(key); // prints key to serial monitor buzzer.beep(100); // generates a 100ms beep } }

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.
  • Click to the Libraries icon on the left bar of the Arduino IDE.
  • Type “keypad” on the search box, then look for the keypad library by Mark Stanley, Alexander Brevig
  • Click Install button to install keypad library.
ESP32 keypad library
  • Type “ezBuzzer” on the search box, then look for the buzzer library by ArduinoGetStarted
  • Click Install button to install ezBuzzer library.
ESP32 buzzer library
  • Copy the above code and paste it to Arduino IDE.
  • Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
Arduino IDE Upload Code
  • Press several keys on the keypad
  • Listen to the beep and see the result in Serial Monitor

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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