Setting Up the Beagleboard Miniature Computer

June 25, 2010Tagged Cyborg, Martin

I'm trying to replace the iPhone with a general purpose computer. After some research I discovered the beagleboard:

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It's a fan-less miniature single board computer that can run Linux from an SDcard. Importantly, for my purposes, it features s-video and an USB port. Setup was not trivial, so I thought I'd share my solutions to some problems that others might also run into.

First, you need to communicate with the card through a serial port. None of my computers are sufficiently ancient to have a serial port. I bought aMac-compatible USB to RS232 adapter. It did not come with required drivers, but these open source drivers worked for me.

Second, running screen in the OS X terminal produced nothing but garbage output and junk characters. The problem was the wiring of the DB9 connector that Mariusz kindly provided me with. This meant I finally got to do some soldering:

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The beagleboard FAQ includes an image to compare the wiring with:

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Third, there were some instructions for using a Mac to format the SD card using the fuse-ext2 driver. This did not work for me. Instead I used the script provided in these instructions on another laptop running Ubuntu Linux.

Fourth, booting the card failed with a mysterious "Kernel panic - not syncing: Fatal exception in interrupt" error. This turned out to be caused by insufficient current when powering the beagleboard through USB. Powering the board through an external power source fixed the problem.

Fifth, and finally (phew!), s-video out can be enabled by adding "omapdss.def_disp=tv omapfb.mode=tv:ntsc" to the bootargs environment variable. My head-mounted display accepts composite video, so I plugged in ans-video to RCA adapter. But the picture quality was horrible. Text was impossible to read on the fuzzy, flickering, bleeding, and snowing screen. I was about ready to give up when I discovered another bootargs parameter "omapdss.tvcable=composite". This did wonders, as demonstrated using my Dell monitor's composite video input:

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Connecting an Apple keyboard and mouse worked flawlessly, resulting in the following setup:

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iPhone-based Wearable Computer

June 08, 2010Tagged Cyborg

My friend Tommy lend me his NokiaSU-8W folding bluetooth keyboard. After jail breaking my iPhone (sigh), buying BTstack Keyboard, and configuring TVoutTVOut2 Mirror to enable TV-out for any iPhone app, I have a complete wearable computing rig:

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I'm very happy with the system's compact size:

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However, I've discovered a number of problems when using it:

Overcoming these problems will be the next big step.


Second-Hand Glasses

June 05, 2010Tagged Cyborg, Martin

Finding a pair of glasses to mount the display on was not easy. But Sanna had the idea to visit a second-hand store. It was a veritable gold mine, and I bought five pairs of glasses! I ended up using these:

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The display is simply strapped on with a cable tie and some electric tape:

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First Attempt at Modding a Head-Mounted Display

June 03, 2010Tagged Cyborg, Martin

In my search for a head-mounted display I bought the Vuzix Wrap 920. It looks like this with the lenses removed:

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My plan is to modify them into a monocular display that doesn't block your entire view. With some prying, the glasses come apart to reveal the circuit board, a 640x480 micro display, and the magnifying lens:

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I figured the right part of the frame could be cut off and used:

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Thinning down the plastic:

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The resulting right hand side frame:

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The lens elements, glued directly on the micro display using epoxy:

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Gluing the display elements onto the frame:

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Despite my abuse, the display still works after connecting the tiny cables to the circuit board:

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The circuit board runs along the inside of the frame:

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I was considering mounting the unit on a pair of protective glasses with clear lenses:

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But I decided to try to find some better glasses, here using Velcro straps and a pair of regular sunglasses:

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Connecting the iPhone to a Head-Mounted Display

June 03, 2010Tagged Cyborg, Martin

The first step of building myself an iPhone-based wearable computer is connecting the phone to an external display.

Using an iPhone TV-out cable:

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Connecting a head-mounted display:

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Wearing the display:

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