Markus Opitz's "Data Glasses" Turn a Seeed XIAO nRF52840 Into a Smart, Wearable Display

Artist, maker, and teacher Markus Opitz has written a guide to building a low-cost pair of wearable "Data Glasses," which can be controlled over Bluetooth Low Energy via a Seeed Studio XIAO BLE nRF52840 Sense board.

"Long before I published on Instructables, a great project caught my eye in 2018: Alain's data glasses," Opitz explains, referring to a project by maker Alain Mauer to build a head-up display. "I was fascinated by the idea. Alain used the glasses to display his voltage meter via Bluetooth. Although I didn't have such a measuring device, I tried to replicate it and built in a few gadgets: compass with circuit board, crosshairs, countdown. The device was controlled via an app on my cell phone. This way I had to learn how to use the MIT App Inventor 2."

Sadly, Opitz's original prototype was never finished — but his discovery of the compact Seeed Studio XIAO BLE nRF52840 Sense, a compact yet complete development board built around Nordic Semiconductors' eponymous microcontroller of the same name, turned out to be the missing piece of the puzzle. The result: a fully-functional 3D-printed pair of "Data Glasses," which uses the board's integrated sensors to drive a range of head-up display functions, from an artificial horizon to a simple clock.

"There are two approaches to DIY data glasses," Opitz explains of the final design. "The display beams its image forwards parallel to the frame, where it is directed towards the eye by two mirrored surfaces. The second mirror in DIY data glasses is often a foil or Plexiglas. I found the second mirror particularly problematic: the projection surface was not flat enough (distortion) and the image was not bright enough, especially outside in the sun. A further development seemed more logical to me: projection directly into the eye using just one mirror. Although the eyepiece seems to be in the way, in practice the restriction of the field of view is only minimal."

It's this second approach which is used for Opitz's guide, which places an 0.49" OLED 64×32 display, the XIAO board, a 150mAh battery, plastic lens, and plastic mirror into a 3D-printed housing suitable for wearing. The firmware on the microcontroller links to a smartphone app for control via Bluetooth Low Energy, though Opitz suggests this could in theory be swapped for on-device voice control using the board's integrated microphone.

The project is detailed in full on Instructables.