What an RP2040 Smartwatch Is and Why Build One
An RP2040 smartwatch is a wrist-worn device built around the Raspberry Pi RP2040 microcontroller that combines a low-power processor, a compact display, and a rechargeable battery into a custom wearable for showing time and other sensor data directly on your wrist. In this RP2040 smartwatch build, you are not limited to commercial layouts or features; you can choose your own form factor, watch faces, and controls. The RP2040 offers low power consumption and enough processing power for a microcontroller watch project, especially when paired with a round touch display that includes an accelerometer and gyroscope. According to the ChronoWatch X2040 project, a Waveshare RP2040 round 1.28-inch touch display makes an ideal Raspberry Pi wearable core, with USB Type‑C and battery charging on board. Compared to most commercial options, this DIY custom watch approach can reduce costs while giving you full control over hardware and firmware.
Planning the Design and Choosing Core Components
Before you print anything or upload firmware, decide what your RP2040 smartwatch build should do: always-on time display, multiple watch faces, stopwatch, or brightness control. List features, then pick components to support them. The Waveshare RP2040 round touch display is well suited because it integrates the Raspberry Pi RP2040 chip, a 1.28-inch round capacitive touch screen at 240×240 resolution, motion sensors, USB Type‑C, and battery charging support. Add a 3.7 V lithium battery; the ChronoWatch X2040 uses a 950 mAh LiPo that fits neatly inside a compact case. For a professional, serviceable enclosure, plan for M2 heat inserts and M2 4 mm screws in your 3D design, plus an MX1.25 2P connector between board and battery so you can unplug power without resoldering. Finally, select a comfortable off-the-shelf strap, such as an Apple Watch strap, to save design time and improve wearability for your DIY custom watch.
Designing and 3D Printing the Custom Watch Case
The enclosure turns a bare Raspberry Pi wearable board into something you can wear daily. In the ChronoWatch X2040, the case is modeled in Tinkercad as three separate parts that assemble into a strong, serviceable shell. The middle section is the main body: it holds the RP2040 display module, the battery, and the mounting points for the watch straps. The top section is a thin locking frame that snaps or screws over the front, securing the round display so it cannot fall out while giving a clean bezel. The bottom section is a back cover that closes with M2 screws into heat inserts, allowing repeated opening for maintenance or battery replacement. When exporting from Tinkercad, check clearances around the USB Type‑C port and side buttons (if any), and leave room for the MX1.25 connector and cable bends inside your microcontroller watch project.
Assembling Hardware and Power System Safely
Once your parts are printed, begin assembly by installing M2 heat inserts into the relevant holes of the middle and bottom sections using a soldering iron and gentle pressure. Place the RP2040 round display into the middle section, aligning the touch screen with the opening and verifying that the USB Type‑C port is accessible. Solder the MX1.25 2P female connector to the LiPo battery leads, insulate the joints with 1 mm heat shrink sleeve tube, and plug it into the board’s male connector. This creates a neat power path without exposed metal. Seat the 3.7 V 950 mAh battery behind or under the module, depending on your layout, making sure wires do not press against the display. Add the bottom cover and fasten it with M2 4 mm screws. Finally, attach the Apple Watch strap to the side mounts so the finished RP2040 smartwatch build sits comfortably on your wrist.
Programming Watch Faces, Settings, and Everyday Use
With hardware complete, move on to firmware. The Waveshare RP2040 round board supports MicroPython, Arduino IDE, and C/C++, so choose a stack you know. Start by coding a basic digital clock that reads the internal timekeeping variables and draws hours, minutes, and seconds onto the 240×240 round display. Then add multiple watch faces, switching styles from classic to minimal with a tap or long press. The ChronoWatch X2040 firmware includes a settings interface to set time and date, choose 12-hour or 24-hour formats, control brightness, rotate the screen, and configure a sleep timer for better battery life through the touchscreen alone. You can also use the built-in accelerometer and gyroscope to wake the display on wrist movement or add gesture controls. Over time, extend your DIY custom watch with features like a stopwatch or motion-based animations, and enjoy a distraction-free Raspberry Pi wearable tailored to your needs.