Build Your Own DIY Smart Watch With NULA Mini and OLED Display

Introduction

Wearables are everywhere today: on our wrists, in gyms, on bicycles, in smart buildings, and even in industrial equipment. Smartwatches track time, weather, fitness data, notifications, and much more. Underneath all this convenience is a surprisingly simple combination of technologies: a small microcontroller board, a compact display, wireless connectivity, and an intuitive interface.

Thanks to modern development boards like the NULA Mini and accessible displays like the SSD1306 OLED, the same technology used inside commercial wearables is now available to hobbyists, makers, and students. Building your own smartwatch-like device at home is no longer a futuristic idea. It is a fun and achievable weekend project.

(INSERT IMAGE #1: NULA Mini + OLED components or assembled watch)

Why NULA Mini Is Perfect for Wearable Projects

The NULA Mini is extremely compact. Its size of 25.33 mm x 25.33 mm x 10.0 mm (roughly a one inch square footprint) makes it ideal for any project that needs to fit inside a confined space. This includes wrist-worn enclosures, small cases, or 3D printed smartwatch shells.

Even with its small size, the NULA Mini offers everything a wearable project needs:

• Wi-Fi and wireless connectivity

• Multiple GPIO pins and I2C support for displays and sensors

• Low power use suitable for battery-powered devices

• A layout that fits perfectly on small breadboards and prototyping setups

This combination of size, flexibility, and capability makes the NULA Mini a strong foundation for a DIY smartwatch.

Key Components Used in the Project

This project uses only a few parts, which keeps the build simple and accessible:

• NULA Mini as the main controller

• 0.96 inch SSD1306 OLED Display (128 x 64, I2C, Qwiic, easyC)

• One Push Button for all user interactions

• USB-C cable or battery for powering the device

• Optional: Battery, charger board, and wrist strap if you want to make it fully wearable

With this minimal hardware, you can build a powerful smartwatch-like device that feels polished and responsive.

(INSERT IMAGE #2: wiring diagram or device layout)

Featured Project: DIY Smart Watch

The DIY Smart Watch project demonstrates how much functionality you can achieve with the NULA Mini and a single-button interface. The software includes four main screens:

1. HOME: animated wallpapers created from simple one-bit bitmaps

2. CLOCK: an NTP-synchronized digital clock with date and a slow drifting effect that helps prevent OLED burn-in

3. WEATHER: current temperature and a weather icon retrieved from the Open-Meteo API

4. TIMER: a clean and readable MM:SS timer with start, pause, and reset actions

Navigation follows this pattern:

• Short press: switch to the next screen

• Long press: activate a special action (change wallpaper, sync time, refresh weather, start or pause timer)

The result feels surprisingly similar to a basic smartwatch interface.

(INSERT IMAGE #3: photos of the clock, weather, and timer screens)

How the Interface Works

Screen Navigation and User Input

The watch uses a simple state machine that changes the active screen when the button is pressed. Long-press detection is handled through an interrupt service routine and timing logic.

Accurate NTP Time Synchronization

When the device connects to Wi-Fi, the NULA Mini retrieves the current time from several NTP servers. The time is automatically refreshed every few hours so the displayed clock stays accurate.

Weather Over HTTP

The weather screen sends a small HTTP request to the Open-Meteo API. A lightweight custom parser extracts only the required fields, temperature and weather code, without relying on a full JSON library. A simple icon is then drawn based on that weather code.

Timer Functionality

The timer screen uses a clear, large font for maximum readability. The button controls whether the timer runs, pauses, or resets.

Hardware Overview and Wiring

The wiring for this smartwatch project is intentionally minimal.

The NULA Mini's extremely small size makes it easy to fit all components into compact housings or custom 3D printed designs.

Build It Yourself, Code Included

The complete project including code, wallpapers, setup instructions, and wiring overview is available on GitHub:

👉 GitHub Repository

You can customize watch faces, try different wallpapers, add sensors, or expand the project into real wearable functionality. The base system is simple, well organized, and easy to extend.

This project is ideal for anyone exploring:

• wearable UI design

• IoT development

• NTP timekeeping

• OLED graphics rendering

• simple user interfaces on microcontrollers

A Big Result From a Small Board

The DIY Smart Watch proves how much can be achieved with a device as compact as the NULA Mini. Its small size and clean design give makers the freedom to create wearable projects that feel professional while remaining simple to build and customize. This watch is only a starting point. With the NULA Mini powering your ideas, you can add sensors, build new interfaces, design custom enclosures, or create entirely new wearable concepts. When advanced hardware becomes this accessible, the distance between imagination and a finished project becomes much smaller.