See How Zack Freedman Built a Head-Mounted Holographic Display with the Latest Hardware
Take a look at how the YouTuber was able to replace his old display unit with a completely revamped and upgraded one
The old unit
For YouTuber and maker Zack Freedman, his smart glasses, which he affectionately refers to as the "Optagon," function as a teleprompter and are how he reads his scripts while creating a video. In recent months, however, this pair of smart glasses has fallen into a state of disrepair, and no amount glue or zip-ties would help. Even worse, the technology driving the display is ancient since the mobile device running that sends video to the glasses currently uses Android 4. With all of these problems in mind, Freedman when searching for something far better that he could incorporate into the next generation of DIY smart glasses.
Selecting better hardware
The first and primary concern was locating a set of smart glasses that simultaneously worked well enough to show text while also not costing thousands of dollars. This led Freedman to the Moverio BT-40 model of next-generation smart glasses from Epson. The headset contains a pair of 1080p displays with high contrast, a wide 34-degree field-of-view, and a wide range of sensors that could prove useful for future projects.
Along with the new set of glasses, Freedman had to find a powerful single board computer to go along with it. What he ended up choosing was the Khadas Edge-V, which is equipped with the Rockchip RK3399 SoC, 4GB of RAM, Android 9, and a plethora of interfaces for connecting almost anything.
Driving the display
In order to keep the unit light, Epson went with a standard USB-C cable interface, except in this case, it was meant to carry a Display Port (DP) signal. The standard has existed for several years, but it can be very arduous to get working correctly since both devices must perform a handshake and then rewire their buses internally first. But because the Khadas Edge-V already had a DP-compatible USB-C port, all Freedman has to do was plug in the headset and watch the Android 9 wallpaper show up in his glasses like magic.
Some disassembly required
The Moverio BT-40 is a binocular unit, meaning that each eye gets its own display. But this was a problem for Freedman since he only wanted a single lens and screen over his left eye but not his right, which meant he had to perform some mildly destructive modifications to his nearly $600 headset.
For his initial attempt, Freedman simply tried unplugging the ribbon cable connector from the right display's daughter board, but this action caused the left display to also shut off. Further snooping into the glasses' internal circuitry revealed a set of several boards, with one taking the incoming DP signal and converting it into a serial one, another that houses a microcontroller that does processing for audio and sensor data, and a pair of custom driver boards that take the serial video signal and output it to the OLED screens.
Next steps
After struggling with getting only the left display to work for several hours, Freedman decided to take a break and create his own breakout boards so he could read the signals and possibly decode them. He was also able to find a development kit that is essentially the BT-40, just with more documentation and easily-accessible pins.
For more information about the process of building the second iteration of the Optagon, you can watch Freedman's YouTube video.