Arduino Nano ESP32 - Button Module

Hardware Preparation

Or you can buy the following kits:

Overview of Button Module

This module is a small PCB with one momentary tactile switch and a colored cap on top. In short, it is a push button that already carries its own resistor. A pack holds five of them, one each in red, yellow, green, blue and white, so you can give every key in a project its own color.

On the edge there is a 3-pin header with 2.54mm spacing. The labels read VCC, OUT and GND, in that order:

• VCC pin: connect to the 3V3 pin of the Nano ESP32. The module accepts 3.3V to 5V, but here it must be 3.3V.
• OUT pin: connect to a digital input pin of the Arduino Nano ESP32 (D2 in this guide).
• GND pin: connect to GND (0V).

What the OUT pin reports:

• Key up (released) → the on-board pull-down resistor holds OUT at LOW.
• Key down (pressed) → OUT is tied to VCC, so it reads HIGH.

So the logic is the natural one: HIGH means pressed. No extra resistor is needed and the input pin should be set as plain INPUT. INPUT_PULLUP is the wrong choice here, because the internal pull-up would work against the resistor on the module.

Like every mechanical switch, the metal contacts inside do not close cleanly. For a few milliseconds they bounce, so one press can look like several quick presses to a fast board like the Nano ESP32. The second and third sketches below deal with that.

Wiring Diagram

Three jumper wires and no breadboard. The module's VCC goes to 3V3, OUT goes to D2, and GND goes to GND. D2 is the same pin used by the other button tutorials for this board, so you can reuse their sketches later with little change.

This image is created using Fritzing. Click to enlarge image

Pin connections between Button Module and Arduino Nano ESP32

How To Program For Button Module

All three sketches start the same way. Only the last one needs a library.

• Name the pin that reads the OUT signal:

• Make it a plain input in setup(). The module's own pull-down does the rest:

• Read the level. HIGH means the key is down, LOW means it is up:

Arduino Nano ESP32 Code - Read the Raw State

The first sketch does the simplest job: five times per second, it reads D2 and prints the level together with a short label. Use it to check the wiring before anything else.

Detailed Instructions

Follow these instructions step by step:

• If this is the first time you use Arduino Nano ESP32, see how to setup environment for Arduino Nano ESP32 on Arduino IDE.
• Make the three connections from the table above. Double-check that VCC goes to 3V3.
• Plug the Arduino Nano ESP32 into your computer with the USB Type-C cable.
• Launch the Arduino IDE on your computer.
• Select the appropriate Arduino Nano ESP32 board (e.g., Arduino Nano ESP32) and COM port.
• Paste the code above into a new sketch.
• Click the Upload button.
• Open the Serial Monitor at 9600 baud.
• Leave the key alone for a moment, then hold it down for about one second, then let go.

The output stays at 0 when nobody touches the key, without random jumps. That steady 0 is the job of the pull-down resistor. If you see 1 all the time, the OUT and VCC wires are probably swapped.

Arduino Nano ESP32 Code - Press and Release Events with delay()

Most projects do not care about the level itself. They care about the moment it changes: a doorbell rings once per press, a counter adds one per press. This sketch remembers the last state. When a new reading is different, it waits 50 milliseconds for the bouncing to end, reads D2 a second time, and only then reports the event.

Detailed Instructions

• Keep the wiring as it is.
• Upload the code above to the Arduino Nano ESP32.
• With the Serial Monitor open, press and release the key three times.

Each press gives exactly one pair of lines. The weak point is delay(): for those 50 milliseconds the Nano ESP32 does nothing else, so a sketch that also handles WiFi or a display will freeze for a short moment on every change.

Arduino Nano ESP32 Code - Button Module with the ezButton Library

The ezButton library does the same debounce, but it checks the time with millis() instead of waiting. The module has a pull-down, so the object is created with EXTERNAL_PULLDOWN, which makes HIGH count as pressed. This mode needs ezButton version 1.0.6 or newer.

The main functions:

• Button.setDebounceTime(50): set the debounce time in setup().
• Button.loop(): call it first in every loop(). It returns at once and never blocks.
• Button.isPressed() and button.isReleased(): true once per press or release.
• Button.getState(): the steady, debounced level (HIGH = pressed).

Detailed Instructions

• In the Arduino IDE, click the Library Manager icon on the left bar.
• Type "ezButton" in the search box and find the ezButton library by ArduinoGetStarted.com.
• Click Install. If an older version is installed, update it to 1.0.6 or newer.

• Search for ezButton created by ArduinoGetStarted.com and click the Install button.

• Upload the code above with the same wiring.
• Open the Serial Monitor at 9600 baud, then give the key a short tap and then a long press.

Because button.loop() returns right away, you can put other work in the same loop(), such as reading a sensor or sending data over WiFi, and the key still responds at once. To learn more about debouncing, see the Arduino Nano ESP32 - Button - Debounce tutorial. To make the key switch a light, see Arduino Nano ESP32 - Button LED.

Video Tutorial

Learn More

• Arduino Nano ESP32 - Button
• Arduino Nano ESP32 - Button - Debounce
• Arduino Nano ESP32 - Button - Long Press Short Press
• Arduino Nano ESP32 - Multiple Button
• Arduino Nano ESP32 - Switch
• Arduino Nano ESP32 - Limit Switch
• Arduino Nano ESP32 - DIP Switch
• Arduino Nano ESP32 - Button LED