Wristwatches, and smartwatches in particular, are a great way for makers to test their skills. By necessity, smartwatches need to be very compact and energy efficient. That means you have to plan out how you’ll fit all of the necessary components inside the enclosure very carefully. And, once you’ve planned it, you have to be able to actually execute your plan flawlessly. Samsonmarch’s DIY smartwatch is the perfect example of that, and has the kind of craftsmanship we rarely see in homemade devices.
The first thing you’ll notice about this design is the round screen that’s used for the watch face. Round LCDs certainly aren’t unheard of, but they’re uncommon and more difficult to work with. But Samson preferred the aesthetics of a traditional round watch over the squircles and squares that are so popular today. The second thing that stands out about this design is that it’s remarkably thin, which is very hard to achieve when you’re making a smartwatch yourself.
The case of the smartwatch is made in two pieces that are 3D-printed in a wood fill PLA. That material contains sawdust mixed in with the plastic, and actually behaves a lot like wood. It can be sanded and stained, which gives the watch a sophisticated look. Those parts were first cleaned up and sanded. Then they were stained a dark walnut color, which pairs well with the brown leather wristband.
Inside of the smartwatch case is a custom-designed four-layer PCB that contains all of the electronic components to make the device work. The brain of the operation is a Dialog Semiconductor DA14683, which has an Arm Cortex-M0 CPU and built-in BLE connectivity. In addition, there is an accelerometer for detecting the watch’s orientation, a charging and protection circuit for the lithium-ion battery, and a vibration motor for notifications.
All of those components are SMT (surface-mount technology) and soldered onto the PCB in a reflow oven. Samson programmed all of the watch’s function himself, including notification forwarding from his iPhone over Bluetooth. Interestingly, all of the letters and numbers for those messages are sliced out of a single image, similar to how a video game engine loads sprites. With that all working, Samson’s final step was to build a beautiful matching charging dock, which the watch snaps into magnetically.