Looking for an open source smartwatch you’re in total control of? If so, check out the Bangle.js 2 which is currently crowdfunding on Kickstarter.

This hacker-friendly piece of horological hardware is the brainchild of Espruino developer Gordon Williams. Much like Williams’ earlier efforts in this area, the Bangle.js 2 runs on JavaScript.

Yup, JavaScript; it seems JS really can run everywhere! 😉

Specifically the Bangle.js uses the open source Espruino JavaScript interpreter. This is custom designed software for devices with extremely low hardware resources, like microcontrollers.

New apps can be written in JavaScript without an SDK, or compiling, or additional software. They can be sent wirelessly (via Web Bluetooth) to the watch to run. In fact, to hack, connect to, and/or install apps on this smartwatch all you need is a modern web browser.

Not in building apps? An open-source online “app store” is also available where you can browse apps created by others, and quickly ‘download’ them to the watch itself wirelessly. If you make a cool app and you want to share with others you can open a pull request on Github to submit it to the store.

Bangle.js 2 hardware specs

bangle.js 2 colour options
Bangle.js 2 is available in three colours

I won’t like: from the outside the Bangle.js 2 looks like your average, run-of-the-mill smartwatch. Y’know, the sort you find on cheap electronics sites (usually with a photoshopped Apple Watch face). And this is partly by design; the watch is an off-the-shelf model from China. However, all of the software and firmware that runs on it is open source, having been reverse engineered and retro-fitted to it.

The focal point of the watch is the 1.2-inch 3-bit colour always on LCD (176×176) with backlight and full-size touchscreen that’s readable even in direct sunlight. It’s housed in a 36mm x 43mm x 12mm watch body (which connects to standard 20mm watch straps). It is available in three distinct colours.

Inside, the Bangle.js 2 is powered by an 64MHz nRF52840 ARM Cortex-M4 with Bluetooth LE, 256 KB RAM, 1 MB on-chip flash, and 8 MB external flash. it also a heart rate monitor, an air pressure/temperature sensor, and a vibration motor.

A 3 axis accelerometer, 3 axis magnetometer, and a GPS/Glonass receiver are also included. For proper tinkering, a full SWD debug port is located on the rear of the watch.

And don’t think the Bangle.js 2’s tiny 200mAh battery small. It is able to deliver around 4 weeks standby time on a single charge!

‘Truly hackable, totally open source’

Bangle.js 2 pitch video

But what brings it to live is the open source software environment and the low barrier to entry it offers in terms of developing and tinkering with the device.

In summary, the Bangle.js 2 is fully hackable, totally open source, and the only limits to its capabilities are the limits of your imagination.

JavaScript is often uses as a byword for bloat on the web but Espruino proceeds it can run like a champ on embedded microcontrollers to make tiny development platforms capable of doing pretty big things.

The Bangle.js 2 crowdfunding campaign runs until 12 October. Although it has already smashed its initial crowdfunding goal new stretch goals have been announced. You can pledge without a reward, or support from £59 to get a watch when shipping begins in mid-November.

Visit the Bangle.js 2 on Kickstarter

Gordon Williams has run 4 crowdfunding campaigns before and delivered on all of them, which should offer some reassurance should you need it. That said, crowdfunding campaigns are not pre-orders; you’re not guaranteed to receive a product regardless of which tier you back.

Finally, you may have noticed that this smartwatch doesn’t run Linux, and has no direct connection to Ubuntu (that I’m aware of). So why have I written about it? Mainly because its ethos and development model appeal to me, and no doubt many others the free software community. Fostering projects like the Bangle.js is important to the overall health of the FOSS ecosystem as a whole, regardless of whether it directly benefits desktop Linux or otherwise.

crowdfunding JavaScript open source smartwatch