I think it’s fair to say that none of us know where we’re going anymore. Thanks to the proliferation of GPS technology, we no longer have to memorize the streets and layout of our city. That’s not necessarily a bad thing when you’re just driving around, but it is less than ideal when you’re walking. Aside from the potential danger of strolling into a light post, oncoming traffic, or an open manhole, staring at your phone while you walk prevents you from enjoying the sights your city has to offer. That’s why Sam March designed DIY smart glasses that unobtrusively provide turn-by-turn GPS navigation instructions.
To passersby, this device just looks like some trendy sunglasses. They will have no idea that you’re actually sashaying with the confidence that comes wearing a computer that tells you exactly where to go. From the wearer’s perspective, the view isn’t any more obstructed than it is by any other pair of glasses. But when they reach an intersection where they need to turn, an LED will turn on at the edge of their peripheral vision to indicate which direction to go. A blue light means they should turn, while a green light indicates which side of the road their destination is located. The GPS navigation is handled by the user’s smartphone, which ensures accuracy while also keeping the glasses themselves as lightweight as possible.
March’s write-up provides a lot of detail about how he used a CNC router to fabricate the frame of the glasses and even the lenses, but the real magic comes from the custom control board that he developed. That board is built around a chip we don’t see often: the Dialog DA14531 SoC. In small quantities, this chip only costs about $1.50, but it packs a lot of hardware into a tiny package. It has an Arm Cortex M0+ processor, 48kB of RAM, up to 12 GPIO pins, and a built-in BLE (Bluetooth Low Energy) radio. The board also contains an accelerometer, IO expander for controlling the LEDs, and a Microchip MCP73831T-2ACI/MC-based power circuit paired with a small rechargeable LIR1220 lithium-ion coin cell battery.
This circuit board can’t do much on its own, but comes to life when it’s paired with an iPhone via Bluetooth. It doesn’t, unfortunately, work with Android devices at this time. March programmed an app using Apple's fantastic Swift language that users can open when they need to enter a destination. Like most map apps, it understands natural language like “coffee shop near me.” After selecting a destination, users can pocket their phone and it will communicate the turn-by-turn instructions to the smart glasses. Best of all, March has made this project open source so that you can build your own glasses! Everything from the code to the mechanical design files are available on GitHub for you to take advantage of.