commercial watch does not provide. You can use
the exact colors you’d like to wear.
And during assembly, you can also choose the
size of the battery, adapting the design to your
taste and giving it a battery lifetime far greater
than a couple of days (Figure
A
).
Open Tools
To build my watches I’ve used Blender to design
the 3D-printed cases and KiCAD to design the
PCBs. Both are free and open source software,
which means that whoever wants to take a
look at my designs and modify them can do so
without any monetary hurdles.
Making Progress (Iterations)
My first prototype, the EspWatch, was based on
a 1.54" e-paper display combined with ESP8285
microcontroller and BME280 sensor modules
(Figure
B
). I tested this setup on a breadboard
and then designed a PCB with KiCAD that
merged everything together, adding two buttons,
a switch, and a MCP73831 LiPo charging circuit
along the way (Figure
C
). This was already a
great watch, but it didn’t feel watch-like yet.
With the next iteration, the Open-SmartWatch
Light Edition, I wanted to build something
that looked closer to a wristwatch using a
round display (Figure
D
). I chose a GC9A01
TFT LCD screen with 16-bit color depth and a
resolution of 240×240 pixels. I added a BMA400
accelerometer for a step counter and for tilt/tap
detection to turn on the screen, and I switched
to an ESP32-based module, namely the TTGO
Micro-32, which provides Bluetooth in addition
to Wi-Fi. I increased the number of buttons
from two to four for better usability and added a
USB-to-serial controller to program it directly
with a serial cable (Figure
E
). I published the
project with all its sources on open-smartwatch.
github.io and it quickly got the attention of
many makers, building an amazing community
over the following year. So far there are over a
hundred forks of the OS on GitHub and dozens of
contributors behind the project.
With the release of the Light Edition I worked
in parallel on the GPS Edition, adding a Quectel
L96 GPS module and microSD card for map
data. This increased the complexity of the PCB
+
54 makezine.com
A
B
C
EMERGENCY! Open Smartwatch
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