DIY : How to Make Your Own Smartwatch – Ryan Siu – Medium

A guide to building a $200 smartwatch for less

In July, I got my first smartwatch as a present for making it to college.

It’s a Mobvoi Ticwatch Pro, a premium $250 smartwatch, and has all the features I could reasonably ask for in a smartwatch. I use it for the same reasons most people use a smartwatch — for notifications, health tracking, and, well, for the fact that it’s a watch.

It hasn’t disappointed me, but something in my head kept nagging at me. Do these features really merit a $250 price tag? Couldn’t I build the same thing for much less?

When I took ENTR 390, an entrepreneurship design class, in the fall of 2018, I was given the chance to turn this thought into reality in the form of a final project. I call it Chron-x.

About Chron-x

Chron-x is an open source, Arduino-based, Bluetooth-enabled smartwatch that can receive notifications from your Android phone once connected via an app. Unlike the smartwatches currently on the market, Chron-x can be completely customized for your needs.

Chron-x has similar functionality as market smartwatches: in addition to notifications, it has a screen and buttons for UX, can track footsteps, and, naturally, displays the date and time.

I’m not aiming to reinvent the smartwatch with Chron-x, but I’m making its creation more accessible to everyone.

How to Build

What You’ll Need

  • Adafruit ItsyBitsy (3.3V) — $9.95
  • Monochrome OLED display — $19.95
  • LiPo Backpack — $4.95
  • LiPo Battery (350mAh) — $7.95
  • Slide Pot (small) — $1.95
  • Vibrating Motor Disk — $1.95
  • HC-05 Bluetooth Module — $7.69
  • Sparkfun Triple Axis Accelerometer Breakout — $14.95
  • SPDT Slide Switch — $0.95
  • Tactile Button Switch (note that we’ll only use 2) — $2.50
  • Snappable Perfboard (for structure) — $7.95
  • Breadboard and jumper wires (optional — if you want to ensure your circuits work before soldering)
  • Stranded/solid-core wire (your preference)
  • Soldering iron and solder
  • Glue gun (optional)
  • 3D printer and filament

Total: $81.69

Pre-assembly (optional, but recommended)

Before you assemble the watch with solder, which is relatively hard to undo if you make a mistake, try building the watch on a breadboard, and use jumper wires to connect the components.

A Fritzing file of the circuits can be found here. Note that you may have to download Fritzing parts from Adafruit.

The pre-assembly circuit I used to test the software.

Software

Once the pre-assembly is complete, you can test the software on the watch. This should work even if all the components are not attached, as long as the microcontroller, screen, slide pot, and Bluetooth module are connected.

All of the source code for Chron-x can be found in this GitHub repo. Upload the code for the watch to the microcontroller and download the Android app onto your phone. After you pair your watch with your phone (the device name will likely be “HC-05” — see screenshot below), any notifications your phone receives should be sent to your watch.

Screenshot of the Android app — pairing with the smartwatch

If you would like to play around with the software or write your own functionality, you can look at the GitHub repo for documentation. Feel free to open issues and submit pull requests!

Assembly

This part is left to the maker, you.

There’s no one way to assemble this watch. Each watch will look and be different, due to the free-form way we’re putting this together. I started with soldering components to the microcontroller, and progressively built up to the final product by soldering other components to the growing core of electronics. You may choose to assemble the watch differently.

A couple of recommendations:

  1. Test the circuits/microcontroller/code at the end of every step. This is what I did to ensure my soldering was correct. It’s hard to keep track of wires sometimes with a project with a lot of wires (like this one!), and I caught a few mistakes before they became irreversible.
  2. Plan out the assembly once you have all the parts. Decide which parts to solder first and which to save for later, especially if you aren’t soldering this in one sitting. Start inside, and work your way out. Which components do you envision in the middle, and which on the outside?
  3. Use the perfboard as support material for your buttons, and also use it to connect GND/3V components in parallel. (It gives you a much larger space to work with than the one 3V and three GND pins on the ItsyBitsy!)
  4. Be wary of exposed wires, which can cause a short circuit and hard-to-debug problems with the watch.
  5. A glue gun can be useful for securing loose components (vibration motor) or components with small wires (also vibration motor). I also used it to hold the screen to the perfboard.

Happy soldering!

Post-assembly

Once you have the electronics assembled, you can 3D print a case for your new smartwatch to protect the electronics. This part is also up to you — feel free to be creative with the design!

Note that you may want to incorporate a watch band into the design. I found a couple of velcro watch bands on Amazon for a reasonable price, and incorporating them was as simple as creating two slits towards the bottom of the case.

Notes

If you attempted to make this project, please let me know at ryansiu@umich.edu! I appreciate any feedback to make Chron-x a better product. This is a work-in-progress and I hope to continue making updates!

If you would like to read my other blog posts about Chron-x:

Thanks for checking out this project!

LEAVE A REPLY

Please enter your comment!
Please enter your name here