Bangle.js 2 Offers an Open and Refreshing Break From Expensive Smartwatches with JavaScript

Program an Arm Cortex-M4 with JavaScript or load free apps developed by others.

James Lewis
3 years ago β€’ Wearables
Bangle.js 2 (πŸ“·: Bangle.js 2 Kickstarter Campaign)

JavaScript is well known for its role in modern web applications. However, it also runs on embedded microcontrollers, thanks to a UK-based software engineer who has brought multiple hardware products to market over the past eight years. Gordon Williams is kickstarting the Bangle.js 2, a new version of the already successful JavaScript-based open smartwatch. If this feature-packed yet tiny development platform interests you, you better hurry because only a few more devices are available in its campaign!

From the outside, Bangle.js 2 looks like any other modern smartwatch. It even supports standard 20 millimeter watch bands. But, inside of the 36 by 43 by 12 millimeter case is a system-on-chip (SoC) module that runs JavaScript code, several sensors, and a port for programming.

The Nordic nRF52840 SoC combines an Arm Cortex-M4 running at 64 MHz with a Bluetooth Low Energy radio. The CPU has 256 kilobytes of RAM with over 200 kilobytes available free for program and variable usage! On-chip there is one megabyte of flash memory with an additional eight megabytes available external to the SoC.

Compared to the previous Bangle.js, the new display supports an always-on mode. In addition, there are 176 x 176 pixels 3-bit color inside of a 1.3" illuminated screen. Williams says the battery should last up to two weeks and can be re-charged with the included magnetic charging cable.

Bangle.js 2 offers an air pressure and a temperature sensor in addition to the standard smartwatch sensing elements like a GPS, accelerometer, and heart rate monitor.

While the intended development language is JavaScript, an exposed serial-wire debug (SWD) interface opens the platform to virtually any language. Additionally, the Cortex-M4 in the nRF52840 could also target machine learning applications using TensorFlow Lite for Microcontrollers. Bangle.js 2's campaign description does not mention the nRF52840's other 2.4 GHz applications, like ZigBee or Thread, but presumably, it would be possible to write applications for those with languages other than JavaScript.

Getting software onto the Bangle.js 2 is not just limited to JavaScript, nor does it require programming. The Bangle.js App Store makes finding and loading apps easy. Although, it might be more proper to call it an "App Loader" since all apps are free!

There is good news and potentially bad news if you are interested in buying a Bangle.js 2. The good news is that Williams has run successful hardware crowdfunding campaigns in the past. Most of which delivered within one month of the estimated delivery. With an eye on the 2021 component situation, Williams already has 2500 Bangle.js 2 in production. So, delivery could happen as early as late November 2021. The potentially bad news is that a limited number of watches remain available in the Bangle.js 2 Kickstarter Campaign. So, if you're interested, you better act fast!

James Lewis
Electronics enthusiast, Bald Engineer, and freelance content creator. AddOhms on YouTube. KN6FGY.
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