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×Micro USB Cable
1×Keypad 3x4 and 4x4 Kit
1×(Alternative) Keypad 3x4
1×(Alternative) Keypad 4x4
1×Piezo Buzzer
1×Jumper Wires
1×(Optional) 5V Power Adapter
1×(Optional) DC Power Jack
1×(Optional) ESP32 Screw Terminal Adapter

One of the following breadboard:

1×Full-sized 830-Point Breadboard
1×Half-sized 400-point Breadboard
1×Mini-sized 170-point Breadboard
1×All-sized Breadboard Kit
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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:

Wiring Diagram

ESP32 keypad piezo buzzer wiring diagram

This image is created using Fritzing. Click to enlarge image

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 23 // ESP32 pin GIOP23 connected to the buzzer's pin #define ROW_NUM 4 // four rows #define COLUMN_NUM 4 // four columns char keys[ROW_NUM][COLUMN_NUM] = { {'1', '2', '3', 'A'}, {'4', '5', '6', 'B'}, {'7', '8', '9', 'C'}, {'*', '0', '#', 'D'} }; byte pin_rows[ROW_NUM] = {19, 18, 5, 17}; // GIOP19, GIOP18, GIOP5, GIOP17 connect to the row pins byte pin_column[COLUMN_NUM] = {16, 4, 0, 2}; // GIOP16, GIOP4, GIOP0, GIOP2 connect 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.
  • On Arduino IDE, Navigate to Tools Manage Libraries
ESP32 add library
  • 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 ESP32GetStarted
  • 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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