Thursday, February 2, 2017

2017-02-01 (W) Head-Mounted Display

A head-mounted computer display has been the dream of many hackers and makers. Google Glass made it seem like it was just on the horizon. Many people have copied the idea but they still cost as much as a mid-range computer and to my knowledge, none of them are open-source. So much for buying a commercial product.
Reading and walking are two of my favorite activities for relaxing. By combining them I get twice as much done with none of the relaxation. Engineer'd!
~Brian McEvoy

This project only requires a handful of items. The easy-to-find items are a pair of plastic glasses, a Raspberry Pi Zero, an acrylic case, a tie block, a few zip ties, and a USB cable with a mini-USB plug on one end. The hard-to-find item is a video display that attaches to glasses. These tend to be expensive or difficult to work with or both.

Easy-to-find items

Every version of the Raspberry Pi except the Pi Zero has a common plug for the analog video output. This project uses analog video output but it simple to connect with some solder. A mini USB cable was harvested for the display connector. The display used a mini USB connector but only because it was a convenient 4-position connector, it didn't provide any digital connectivity. Power wires were soldered to the 5V GPIO pins and the video wires were soldered to the "TV" terminals. The video signal wire was closer to the center of the board.

Wires soldered to the Pi Zero

A standard install of Raspbian was put on a card and run on the Pi Zero. The display worked as well as hoped. A wireless keyboard and mouse confirmed that the display worked with no noticeable latency. Computer display resolution was much higher than the analog display could reasonably handle. Web pages had to be zoomed to several hundred percent in order to be legible.

Working display showing the desktop

The Pi Zero was installed in the acrylic case after threading the modified cable through the GPIO hole. A tie block was installed on top of the case and the intact portion of the cable was fastened with a pair of zip ties. Keeping the fragile wires fastened should make this rugged enough to be carried in a pocket until a more permanent solution can be made.

Assembled computer module

The display was attached to a pair of glasses without lenses. The cheap plastic glasses were pretty dorky. A USB battery charger powered the device. It was easily small enough to fit inside a pocket while wearing. Near the hinge of the glasses a couple zip ties were added to keep the modified USB wire in place. At this point the equipment was working. Refinements were needed.

Me wearing a ridiculous orange hoodie. And a head-mounted computer display

The config.txt file was changed to output a 320x240 video. To demonstrate how absurd this looks it was put on a 55" television with a banana for scale. At this point the mouse pointer is the size of a household rodent.

 Low resolution video displayed on a large television

Improvements need to be made. The resolution needs to be turned up even if some clarity is lost. A better solution for input devices need to be found, particularly a mouse with a scroll-wheel that can be operated while walking. Something needs to be done to align the display more precisely. When the display is tilted, which happens easily, it becomes illegible.

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2.
Completed projects from year 3.



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2017-01-12 (Th)

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