ChronoWatch X2040 - a RP2040 Watch

When I was a child, I had a dream of making my own smartwatch. At that time, I had no knowledge of engineering, electronics, or 3D design, but my imagination was full of ideas. So, as a kid, I created a watch from cardboard. It was not a real working watch, but it gave me something even more valuable, joy, excitement, and the confidence to dream big. That simple cardboard watch was the beginning of my journey.

Now, the time has come to turn that childhood dream into reality and build a real watch. It may not be smart enough to count footsteps or measure heart rate, but it does something just as important — it simply shows the time.

In a world full of notifications and constant connection to the internet, this watch offers something different: simplicity, focus, and freedom from distractions. It is more than just a watch; it is a reminder that sometimes the simplest things are the most meaningful. This is my first real step toward completing the journey I started as a child.

So, I created the ChronoWatch X2040 — a custom watch powered by the Raspberry Pi RP2040 microcontroller. It features a round display and a specially designed 3D-printed case, making it comfortable to wear on the wrist like a real everyday watch.

To make it more personal and stylish, I added multiple watch faces inside the device, allowing the look of the watch to match different moods, vibes, and environments. Whether classic, modern, or minimal, the ChronoWatch X2040 can adapt with a simple change of style.

For this project, I used a WaveShare RP2040 Round Touch Display, which became the heart of theChronoWatch X2040. To give it the look and feel of a real wearable device, I designed a custom 3D-printed case using Tinkercad — a simple yet powerful software that makes 3D designing easy and accessible for creators of all skill levels.

The watch is not just about hardware; it also includes a fully functional settings interface. Users can easily adjust the time, date, and switch between 12-hour or 24-hour formats directly from the watch. It also comes with several useful features such as brightness control, a stopwatch, screen rotation options, and sleep timer settings for better battery management. Best of all, everything can be controlled through the touchscreen interface — no mobile app, no extra device, and no internet connection needed.

The modern wristwatch became popular in the late 19th century, with one of the earliest known wristwatches created in 1868 by Patek Philippe for Countess Koscowicz of Hungary. In the beginning, wristwatches were mainly worn by women as elegant fashion accessories and jewelry rather than practical timepieces. Everything changed during World War I, when soldiers needed a quick and convenient way to check time while keeping their hands free. Wristwatches proved far more practical than pocket watches, and soon became popular among men as well.

Since then, the wristwatch has continuously evolved through many generations — from mechanical watches, to quartz movements, then digital watches, and now advanced smartwatches used all around the world. From a simple tool for telling time to a symbol of style, technology, and personal identity, the wristwatch has come a long way.

Supplies

Waveshare RP2040 Round 1.28-inch Touch Display

it is a compact development board based on the Raspberry Pi RP2040 chip. It features a 1.28-inch round capacitive touch screen with 240×240 resolution. The board includes built-in accelerometer and gyroscope sensors for motion detection. It supports programming with MicroPython, Arduino IDE, and C/C++. USB Type-C and battery charging support make it suitable for portable projects. It is ideal for DIY smartwatches, mini dashboards, and IoT devices.

3D Printed Case

The 3D case design was created in Tinkercad and is made of three main parts, each serving an important purpose. The middle section forms the main body of the watch and securely holds the display module, battery, and the attachment points for the watch straps. The top section works as a locking frame that fits over the front, keeping the display firmly in place so it does not fall out while also giving the watch a clean finished look. The bottom section is fixed with screws to close the back side of the watch securely, making the overall design strong, practical, and easy to open later formaintenance, upgrades, or battery replacement if needed.

3.7V 950mAh Lipo Battery

For this project, I chose a 3.7V 950mAh battery, which fits perfectly inside the custom back cover. This battery provides a good amount of backup time, allowing the user to wear the pendant for hours without worrying about frequent recharging. In the market, there are many types of lithium batteries available in different shapes, sizes, and capacities. So depending on your design, you may find a battery that fits even better, with either lower or higher capacity, to match your specific needs.

M2 4mm screw & M2 heat inserts

These are commonly used in 3D-printed parts to create strong, reliable, and long-lasting fastening points. The heat inserts are installed into the plastic using heat, which melts them into place and forms durable metal threads inside the printed part. Once installed, the M2 4mm screws fit securely into these inserts to hold components together firmly. They are ideal for small enclosures, electronics mounts, and compact mechanical assemblies like this watch project. This combination greatly improves strength, provides a professional finish, and allows repeated assembly or disassembly without damaging the 3D-printed parts.

MX1.25 2P connector

The MX1.25 2P connector is used to connect the battery to the board. The Waveshare ESP32-S3 round display comes with a built-in 1.25 2P male connector, so the battery needs a matching female connector attached. This makes it easy to plug the battery directly into the PCB without soldering every time. Using the proper connector ensures a secure and reliable connection while also making the battery simple to replace or upgrade in the future.

Heat Shrink Sleeve Tube

A Heat Shrink Sleeve Tube (1mm) is a thin plastic tube that shrinks tightly when heated, usually with a heat gun or the side of a soldering iron. It is commonly used in electronics to cover and insulate exposed wires or solder joints, protecting them from short circuits and giving a cleaner look. For this project, the 1mm size is perfect for small battery wires and connectors. It not only improves safety but also makes the overall build look neat and professional.

Apple Watch Strap

The Apple Watch strap was used in this project to provide a comfortable, secure, and adjustable fit on the wrist. It gives the watch a modern and premium appearance while ensuring it can be worn comfortably throughout the day. The strap is lightweight, durable, and designed for long-term daily use, making it a practical choice for this build. Using a ready-made strap also saved time and effort compared to designing and manufacturing a custom band, while still giving the ChronoWatch X2040 a polished and professional look.

Designing the Case in Tinkercad

I designed a 3D-printed case for this watch to hold the battery, display, and the strap. The design was created in Tinkercad, an easy-to-use online 3D design tool.

Design is made of three main parts, each serving an important purpose. The middle section forms the main body of the watch and securely holds the display module, battery, and the attachment points for the watch straps. The top section works as a locking frame that fits over the front, keeping the display firmly in place so it does not fall out while also giving the watch a clean finished look. The bottom section is fixed with screws to close the back side of the watch securely, making the overall design strong, practical, and easy to open later formaintenance, upgrades, or battery replacement if needed.

3D Printing the Back Case

Printing Details:

• Nozzle: 0.1 mm (for fine detail and smooth finish)
• Infill: 20% (strong yet lightweight)
• Material: ABS – Black (durable, heat-resistant, and gives a professional look)

3D files : https://www.tinkercad.com/things/bg3LTt8TSza-rp2040-wristwatch

Programming the Device

This is a very simple step for the RP2040. To make programming easier, I am sharing a UF2 file that can be directly copied to the RP2040.

• Connect the display to your computer using a Type-C cable.
• Hold the BOOTSEL button on your board while plugging it into the computer.
• You will see a new drive appear on your computer.
• Drag and drop the UF2 file downloaded from my GitHubpage onto the drive.
• The board will automatically reboot, and you will see a welcome screen.

Github:https://github.com/vishalsoniindia/ChronoWatch-X2040

Full Code : https://ko-fi.com/s/90fdcc233f

Soldering the Battery Connector

In this step, we will solder the battery connector. Follow the instructions carefully.

• Carefully strip the ends of the connector wires and the battery wires.
• Slide a piece of heat shrink tube onto each battery wire.
• Solder the red wire of the connector to the red wire of the battery, and the black wire of the connector to the black wire of the battery.
• Move the heat shrink tube over the solder joints.
• Apply hot air (or briefly touch the side of the soldering iron) to shrink the tubing and secure the joints.

Heat Inserts

In this step, we are going to install the heat inserts with the help of a soldering iron.

• Take an M2 heat insert.
• Place it into the hole carefully with the help of tweezers.
• Press the heat insert gently using a heated soldering iron until it sinks into place.
• Adjust the heat insert immediately if it is not sitting flat or level before the plastic cools.

Mounting Display

Now mount the display carefully as shown in the steps below.

• Take the middle 3D-printed part of the case.
• First, insert the USB Type-C side of the display and align it with the Type-C opening in the case.
• Now carefully insert the PCB section of the display inside the case.
• The touchscreen panel will remain outside the 3D part.
• Take the top ring and carefully place it over the display.
• Now rotate the ring gently until it locks firmly in place.

Connecting Battery and Closing Back Part

After mounting the display, it is now time to install the battery and close the bottom 3D-printed part.

• Connect the battery connector carefully with the help of tweezers.
• Snap-fit the battery into its designated space inside the 3D part.
• Insert the extra wire neatly into the empty spaces provided inside the case.
• Close the bottom part and secure it in place with the help of screws.

Insert the Straps

Inserting the strap can be a little tricky because, due to the 3D print tolerances, the strap fit may be tight.

• Hold the watch body firmly in one hand and carefully insert one side of the strap, then push it toward the middle until it fits properly.
• Now flip to the other side, hold the watch securely, and carefully insert the second side of the strap into place.

Using the Watch

I divided the watch features into three main parts: Time Settings, Watch Faces, and Extra Features.

Watch Faces

On any watch face, simply slide left or right to switch between different watch faces and choose the style that matches your mood.

Time Settings

Long press on any watch face to enter the Time Settings menu. There are three setting options available, and you can go back at any time by sliding left to right.

• Set Time: Adjust the current time here. To save changes, press the right button below. To cancel and go back, slide left to right.
• Set Date: Adjust the date here. To save changes, press the right button below. To cancel and go back, slide left to right.
• Set Mode: Choose between 12-hour or 24-hour format. To save changes, press the right button below. To cancel and go back, slide left to right.
• Back: Press Back or slide left to right to return to the home screen.

Extra Features

Slide up or down to browse through the extra features of the watch. The menu works in a continuous loop, so if you keep sliding, it will cycle through all features and return to the home screen again.

• Brightness: Adjust the display brightness by increasing or decreasing the percentage level.
• Stopwatch: Press once to start the stopwatch, press again to stop it, and press once more to reset the timer.
• Rotate Screen: Rotate the watch screen orientation by pressing the rotate button.
• Sleep Time: Set the automatic sleep time of the watch or disable sleep mode completely.

Improvements & Future Ideas

The ChronoWatch X2040 is already fully functional, but there is always room for more innovation, improvements, and creativity. Here are some ideas for future upgrades:

• Optimize power consumption to significantly increase the battery life of the watch.
• Reduce battery size while maintaining the same reliable runtime.
• Decrease the overall thickness of the watch for a slimmer and more comfortable design.
• Add more smart features such as an alarm, step counter, or other useful daily tools.
• Use an RTC (Real-Time Clock) module to keep accurate time even when the battery is drained or the watch is powered of