This Pebble-Inspired Smartwatch Is On Its Fifth PCB Revision

The Pebble was, for a while, the closest thing the smartwatch world had to a genuinely open, hackable platform — simple hardware, an easily programmable interface, and a community that actually built things for it. After it was acquired by Fitbit and effectively wound down, Matthew James Bellafaire set out to build something with the same spirit.

What They Built

The watch is built around an ESP32 in its WROOM module configuration, taking advantage of the chip’s dual-core processor and simultaneous WiFi and Bluetooth support. Bellafaire’s board, now on its fifth revision, includes onboard battery charging and power management, an ADXL337 accelerometer, an LCD controller, and a touch controller, with each module switched through its own MOSFET so unused subsystems can be powered down to save battery.

How They Did It

A custom Android app acts as the watch’s bridge to the outside world, handling Bluetooth Low Energy notifications by streaming text to the watch in small chunks and terminating each message with a marker the firmware watches for. The watch can also control Spotify playback over Bluetooth, displaying the current track and exposing play/pause and skip controls, and the firmware itself is built to be modular enough that other developers can add their own features without redesigning the whole thing.

Why It’s Worth Your Time

The fifth-revision PCB is the real story here — this isn’t a single weekend prototype, it’s a hardware platform that’s been iterated on repeatedly in response to real use, which is a different kind of DIY smartwatch story than most one-off builds.

Go See It

Matthew James Bellafaire’s design files and firmware are on GitHub, with additional background from Hackster.