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	×	Breadboard
1	×	Jumper Wires
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 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

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-keypad-beep */ #include <Keypad.h> #include <ezBuzzer.h> #define BUZZER_PIN 23 // ESP32 pin GPIO23 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}; // GPIO19, GPIO18, GPIO5, GPIO17 connect to the row pins byte pin_column[COLUMN_NUM] = {16, 4, 0, 2}; // GPIO16, GPIO4, GPIO0, GPIO2 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

Type “keypad” on the search box, then look for the keypad library by Mark Stanley, Alexander Brevig
Click Install button to install keypad library.

Type “ezBuzzer” on the search box, then look for the buzzer library by ESP32GetStarted
Click Install button to install ezBuzzer 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

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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