12-Key Mini Pad – ESP32-S3 Zero

This is a compact 12-key mini keyboard designed to be easy to assemble. It requires no screws and only basic soldering skills.

The keypad is configured with numbers 0 to 9, plus dot (.) and Enter.

It also features:

A potentiometer to control sound/volume on your device

A 0.91 inch OLED display (I²C, 4 pins) where you can display custom information

An ESP32-S3 Zero as the main controller

All components were purchased from AliExpress for around 10€ total (if you don’t already have them).

Required Components

-12 mechanical switches

-1 × ESP32-S3 Zero

-1 × Potentiometer

-1 × 0.91" OLED screen (4-pin I²C version)

3D Printing Settings

Any standard print settings will work for the main parts (case, cover, key support).

For better detail:

Use 0.1 mm layer height for the keycaps and the knurled parts.

Assembly Instructions

1️⃣ Switch Matrix

Create a matrix of rows and columns by wiring the switches together (as shown in the photos, using the red wires).

Connect each row and column end to GPIO pins on the ESP32-S3 Zero.

2️⃣ OLED Screen Wiring

Connect VCC to the 3.3V pin of the ESP32

Connect GND to ESP32 GND

Connect SDA and SCL to two available GPIO pins (I²C)

3️⃣ Potentiometer Wiring

Connect one outer pin to 5V

Connect the other outer pin to GND

Connect the middle pin to an analog GPIO on the ESP32

4️⃣ Ground

Make sure the OLED screen and the potentiometer share the same ground as the ESP32.

To make the board more stable, you can solder header pins underneath the ESP32 as shown in the photos.

Software Notes

Don’t forget to update the GPIO pin configuration in the program to match your wiring.

You can find the ESP32-S3 Zero pinout diagram here:

https://www.espboards.dev/img/zCH2tgb8GF-1000.webp

You can customize the OLED display output however you like (for example using AI tools to generate display ideas or graphics).

If you upload the program and the board is no longer detected in your IDE, press and hold the BOOT button while connecting it to your computer.

mini pad 12 keys and sound control with 0.91" oled screen