One-Handed Text Input

Have you ever wished you could graft a text input device directly onto your arm? Well, this is about as close as it gets without surgery... Inspired by Greg Priest-Dorman's Chorder wiki, I'm using a handheld chorded keyboard based on Spaceman Spiff's Chording Keyboard Experiment (SpiffChorder) with some earlier influence from Steve Mann's septambic keyer. The subpages linked below provide explicit documentation of my efforts and, in combination with the excellent instructions on Greg's and Spiff's sites, should be more than sufficient for creating one of your own. Photos and designs published in this section are licensed under the terms of the GPL (3.0), same as the SpiffChorder project itself (since they could be considered derivative works).

Head-Mounted Display

This has traditionally been the most expensive and annoying component plaguing wearable computing enthusiasts, and I expect that will continue for some time to come (though I'm trying to stay open-minded about upcoming technologies like Google Glass and Lumus Optical). The optics and display density needed for typical computing on a HMD are still not available on the consumer market. Luckily for me, since I spend most of my time using text displays I'm able to get by with a relatively low-resolution solution. At first I wanted a monocular display as a matter of convenience and simplicity, but after reading up on binocular rivalry I'm now starting to suspect there are neurological/cognitive reasons it would be less efficient.

I've obtained a Vuzix Wrap 920 and Vuzix Wrap VGA Adapter (US$240 combined through Amazon) and removed the cosmetic sunglasses-style lenses to make the rig slightly less obtrusive. This device supports 640x480, 800x600 and 1024x768 resolutions (claimed via EDID on the VGA line) but the native resolution is closer to 640x480 so at first I thought I would stick with that. As it turns out, non-text applications like to make some assumptions about minimum screen geometry (for buttons and the like) which becomes problematic at such low resolutions. Instead, I've set my desktop environment for 1024x768 and increased font sizes where it makes sense to do so.

Single-Board Wearable Computer

At the moment I've got a BeagleBoard-xM running Debian's armhf port. Since the video output is HDMI and there's no inexpensive HDMI-supporting HMD on the market yet (might trade up to a ST1080 eventually), I'm using a High Resolution Video DVI to VGA Converter from StarTech. I've read that a similar (and cheaper) converter from fit-PC2 will work but it requires modifying the BeagleBoard (which I'd like to avoid if I can).

Portable Power Supply and Charger

The single-board wearable is currently powered from an Anker Astro3, but I may switch it to the lighter and slimmer Astro 3E once I don't need as many outputs or as much current. I already had a bunch of suitable switching power supplies on hand (Asus ADP-36EH C, replacements are available for very low cost) so I merely fashioned an appropriate adapter cable to fit the input on the Anker.

Motion-Sensing Pointer

I don't really use a mouse much (I can usually get by with the keynav utility wherever pointer interaction is absolutely required), but there are times when having one would be useful. I'll probably build something USB-based with accelerometers, but might instead do something with a small trackball:

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+[[attachment:ManMachine.jpg|{{attachment:ManMachineTeaser.jpg|wearable fungi}}]]
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-= Septabmic Chording Keyer =
Inspired by Greg Priest-Dorman's [[http://chorder.cs.vassar.edu/|Chorder]] wiki, I'm building a handheld [[https://en.wikipedia.org/wiki/Chorded_keyboard|chorded keyboard]] based on [[http://symlink.dk/projects/spiffchorder/|Spaceman Spiff's Chording Keyboard Experiment (SpiffChorder)]] with some earlier influence from Steve Mann's [[http://wearcam.org/septambic/|septambic keyer]]. Photos and designs published in this section are licensed under the terms of the [[http://www.gnu.org/copyleft/gpl.html|GPL (3.0)]], same as the !SpiffChorder project itself (since they could be considered derivative works).
+= One-Handed Text Input =
Have you ever wished you could graft a text input device directly onto your arm? Well, this is about as close as it gets without surgery... Inspired by Greg Priest-Dorman's [[http://chorder.cs.vassar.edu/|Chorder]] wiki, I'm using a handheld [[https://en.wikipedia.org/wiki/Chorded_keyboard|chorded keyboard]] based on [[http://symlink.dk/projects/spiffchorder/|Spaceman Spiff's Chording Keyboard Experiment (SpiffChorder)]] with some earlier influence from Steve Mann's [[http://wearcam.org/septambic/|septambic keyer]]. The subpages linked below provide explicit documentation of my efforts and, in combination with the excellent instructions on Greg's and Spiff's sites, should be more than sufficient for creating one of your own. Photos and designs published in this section are licensed under the terms of the [[http://www.gnu.org/copyleft/gpl.html|GPL (3.0)]], same as the !SpiffChorder project itself (since they could be considered derivative works).
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-== Breadboard ==
+[[/KeyerChords|{{attachment:ChordsTeaser.png|A text-terminal-friendly "modified NASA" chordset reference chart...}}]]
[[/KeyerBreadboard|{{attachment:SpiffChorderBreadboardTeaser.jpg|Prototyping a SpiffChorder on a solderless breadboard...}}]]
[[/KeyerPerfboard|{{attachment:SpiffChorderPerfboardCircuitTeaser.png|Building a SpiffChorder on perfboard...}}]]
[[/KeyerPerfboard|{{attachment:SpiffChorderPerfboardFrontTeaser.png|Building a SpiffChorder on perfboard...}}]]
[[/KeyerPCB|{{attachment:SpiffChorderSchematicTeaser.png|Designs for a SpiffChorder printed circuit board...}}]]
[[/KeyerPCB|{{attachment:SpiffChorderPaperTestTeaser.jpg|Designs for a SpiffChorder printed circuit board...}}]]
[[/KeyerHandset|{{attachment:SpiffChorderHousingInsideTeaser.jpg|Making your own SpiffChorder handset...}}]]
[[/KeyerHandset|{{attachment:SpiffChorderHousingAssembledStrapTeaser.jpg|Making your own SpiffChorder handset...}}]]
-Line 14:
+Line 23:
-[[attachment:SpiffChorderBreadboard.jpg|{{attachment:SpiffChorderBreadboardThumb.jpg|SpiffChorder breadboard}}]]
+ * [[/KeyerChords|A text-terminal-friendly "modified NASA" chordset reference chart...]]
 * [[/KeyerProgramming|Installing the SpiffChorder firmware onto an ATmega168 microcontroller from Linux...]]
 * [[/KeyerBreadboard|Prototyping a SpiffChorder on a solderless breadboard...]]
 * [[/KeyerPerfboard|Building a SpiffChorder on perfboard...]]
 * [[/KeyerPCB|Designs for a SpiffChorder printed circuit board...]]
 * [[/KeyerHandset|Making your own SpiffChorder handset...]]
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-I started on a solderless breadboard, shown above, but those really aren't suited for higher-frequency prototyping and so I was getting stray USB device resets at random (particularly if I inadvertently brushed the ground line while not grounding myself first). I used the components in Greg Priest-Dorman's Digikey bill of materials, including the suggested 9x pull-up resistor SIP array (even though I was only testing with 7 keys). I also chose poorly on a preformed bank of 3 yellow LEDs which were somewhat larger than I expected; their rather rigid leads weren't quite a multiple of 0.1" standard breadboard pitch, causing them to crack superficially upon insertion. I used the excellent [[http://www.adafruit.com/products/601|AVR ATmegaXX8 Pinout Stickers]] from [[http://www.adafruit.com/|Adafruit Industries]] to more easily keep track of what I was connecting. I also picked up a [[http://www.adafruit.com/products/46|USBtinyISP AVR Programmer Kit]], [[http://www.adafruit.com/products/174|Barebones AVR dev. board]] and [[http://www.adafruit.com/products/382|28-pin ZIF socket]] from Adafruit Industries on the theory that it would be easier to preprogram the Atmega168 on a dedicated target board. Unfortunately, I followed the !SpiffChorder instructions slightly out of order and burned the external clocking fuse before writing the firmware, thus rendering the unclocked devboard useless... so instead I programmed the microcontroller in-circuit later once the 12MHz crystal and associated components were in place to clock it correctly.
+= Head-Mounted Display =
This has traditionally been the most expensive and annoying component plaguing wearable computing enthusiasts, and I expect that will continue for some time to come (though I'm trying to stay open-minded about upcoming technologies like Google Glass and Lumus Optical). The optics and display density needed for typical computing on a [[http://en.wikipedia.org/wiki/Head-mounted_display|HMD]] are still not available on the consumer market. Luckily for me, since I spend most of my time using text displays I'm able to get by with a relatively low-resolution solution. At first I wanted a monocular display as a matter of convenience and simplicity, but after reading up on [[http://en.wikipedia.org/wiki/Binocular_rivalry|binocular rivalry]] I'm now starting to suspect there are neurological/cognitive reasons it would be less efficient.
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-== Perfboard ==

In an effort not to limit my capabilities with the keyer's software, I wanted to make sure whatever prototype I eventually built could double as a development board. To that end, I implemented all optional components of the !SpiffChorder circuit (programming header, LEDs, pull-up resistors and screw terminals for all 8 chord keys and 3 modifier keys). I tried to keep the layout as compact as possible while still working on single-sided pad-per-hole perfboard, using entirely right-angle traces so as not to make stray contact with corners of square pads. It fits in a 17x21-hole grid including a ground bus all the way around the perimeter. Here's a top-down view showing the logical supply, ground and signal paths colored for easy identification,the front showing just silkscreen markings and jumpers, one with the traces on the back (mirrored for easier visual reference), and finally photographs of the finished board for comparison:

[[attachment:SpiffChorderPerfboardCircuit.png|{{attachment:SpiffChorderPerfboardCircuitThumb.png|SpiffChorder perfboard circuit}}]]
[[attachment:SpiffChorderPerfboardLayoutFront.png|{{attachment:SpiffChorderPerfboardLayoutFrontThumb.png|SpiffChorder perfboard front}}]]
[[attachment:SpiffChorderPerfboardLayoutBack.png|{{attachment:SpiffChorderPerfboardLayoutBackThumb.png|SpiffChorder perfboard back}}]]
[[attachment:SpiffChorderPerfboardFront.jpg|{{attachment:SpiffChorderPerfboardFrontThumb.jpg|SpiffChorder perfboard front}}]]
[[attachment:SpiffChorderPerfboardBack.jpg|{{attachment:SpiffChorderPerfboardBackThumb.jpg|SpiffChorder perfboard back}}]]

I was going to try laying it out with [[http://fritzing.org/|Fritzing]], but got sidetracked when I couldn't find a resistor array in its parts library. Instead I wound up just sketching the layout on graph paper and transferring it into [[https://live.gnome.org/Dia|Dia]] by hand. [[attachment:spiffchorder.dia|Here's the multi-layer original from which the above graphics were exported.]] The same pathing could be used for a custom double-sided PCB, which I'll probably create before I build the next one since installing all those tiny traces without accidentally shorting any together was painfully time-consuming. You'll notice this layout uses an 8-resistor array instead of Greg Priest-Dorman's 9x (to save on space). I also show couple of 3-resistor arrays (R5-7, R16-18)... Digikey has no such beast, but I bussed individual resistors mounted vertically by soldering the common leads together above the board (only passing one of the three through the board). For further customization, I sourced appropriately-sized green, yellow and red LEDs to fit into the thumb switches and drilled corresponding holes at the tops of those three keycaps. I also got a mini-USB-B connector and 5x 0.1" pitch through-hole 4-line right-angle screw terminals (these need a 2mm jeweler's screwdriver) to connect leads for all the switches, LEDs and USB (CON2-4), and a keyed through-hole 2x3 right-angle shrouded header of the correct size for the USBtinyISP AVR Programmer (CON1)...

{{attachment:CherryMXWithLEDs.jpg|Cherry MX with LEDs}}
{{attachment:MiniUSBBConnector.jpg|mini-USB-B connector}}
{{attachment:RightAngleScrewTerminals.jpg|right-angle screw terminals}}
{{attachment:RightAngleShroudedHeader.jpg|Cherry MX Clears with LEDs}}

A revised Digikey bill of materials including all the parts I used:

||<style="background-color: green;">'''index'''||<style="background-color: green;">'''quantity'''||<style="background-color: green;">'''part number'''||<style="background-color: green;">'''description'''||<style="background-color: green;">'''customer reference'''||
||1||2||490-3709-ND||CAP CER 22PF 50V 5% RADIAL||C1-2||
||2||2||399-4328-ND||CAP CER 0.1UF 100V 10% RADIAL||C3,5||
||3||1||493-1767-ND||CAP ALUM 10UF 16V 20% RADIAL||C4||
||4||1||609-2846-ND||CONN HEADER 6POS DUAL R/A PCB||CON1||
||5||5||A98335-ND||TERM BLOCK 4POS SIDE ENT 2.54MM||CON2-4||
||6||1||26022-ND||TOOL SCREWDRVR SLOT 2.0MM 145MM||screwdriver for CON2-4||
||7||2||1N5227BDICT-ND||DIODE ZENER 3.6V 500MW DO-35||D1-2||
||8||1||ATMEGA168-20PU-ND||IC AVR MCU 16K 20MHZ 28DIP||IC1||
||9||1||ED90054-ND||IC SOCKET 28PIN MS TIN/TIN .300||socket for IC1||
||10||1||OD222JE-ND||RESISTOR 2.2K OHM .25W CARB COMP||R1||
||11||1||OD472JE-ND||RESISTOR 4.7K OHM .25W CARB COMP||R2||
||12||2||OD820JE-ND||RESISTOR 82 OHM .25W CARB COMP||R3-4||
||13||3||OD102JE-ND||RESISTOR 1.0K OHM .25W CARB COMP||R5-7||
||14||1||CSC10KW-ND||RES ARRAY 10K OHM 8 RES 9-SIP||R8-15||
||15||3||OD103JE-ND||RESISTOR 10K OHM .25W CARB COMP||R16-18||
||16||1||XC1380-ND||CRYSTAL 12.000 MHZ 18PF CYL||X1||
||17||1||WM17115-ND||CONN USB RECEPTACLE 5POS RT ANG||mini-USB-B port||
||18||7||CH196-ND||SWITCH PUSH SPST-NO 0.01A 12V||key switches||
||19||1||67-1062-ND||LED 3MM 5V SHORT LENS GREEN DIFF||near thumb lamp||
||20||1||67-1080-ND||LED 3MM 5V SHORT LENS YEL DIFF||center thumb lamp||
||21||1||67-1068-ND||LED 3MM 5V SHORT LENS RED DIFF||far thumb lamp||
||22||1||V2025-ND||BOARD 2-SIDE PPH 2.0X3.0||project board||

== Handset ==

I hacked up an old telephone handset from my junk pile so I could have something vaguely ergonomic into which to mount the keys. Once I'd separated the front and back of the handset, I opened up tracks for the keys using a small cutting wheel on a Dremmel. Epoxy was added in a few places and sanded to get the tolerances just right. I ordered 7x [[http://www.wasdkeyboards.com/index.php/row-2-size-1x1-cherry-mx-keycap.html|Row 2, Size 1x1 Cherry MX Keycaps]] from [[http://www.wasdkeyboards.com/|WASD Keyboards]] and popped them onto the stems.

[[attachment:SpiffChorderHousingPieces.jpg|{{attachment:SpiffChorderHousingPiecesThumb.jpg|SpiffChorder housing, pieces}}]]
[[attachment:SpiffChorderHousingInside.jpg|{{attachment:SpiffChorderHousingInsideThumb.jpg|SpiffChorder housing, inside}}]]
[[attachment:SpiffChorderHousingAssembledTop.jpg|{{attachment:SpiffChorderHousingAssembledTopThumb.jpg|SpiffChorder housing, assembled, top}}]]
[[attachment:SpiffChorderHousingAssembledUnderside.jpg|{{attachment:SpiffChorderHousingAssembledUndersideThumb.jpg|SpiffChorder housing, assembled, underside}}]]

= Monocular Headmount Display =
As I begin work on a wearable display, I'll flesh out this section. Here are some interesting links for components I'm considering:
 * http://wearcomp.wikia.com/wiki/Myvu_Crystal
 * http://blog.makezine.com/2009/03/17/myvu-crystal-as-a-wearable-hea/
 * http://blog.makezine.com/2009/01/12/myvu-display-in-a-wearable-computer/
+I've obtained a Vuzix Wrap 920 and Vuzix Wrap VGA Adapter (US$240 combined through Amazon) and removed the cosmetic sunglasses-style lenses to make the rig slightly less obtrusive. This device supports 640x480, 800x600 and 1024x768 resolutions (claimed via EDID on the VGA line) but the native resolution is closer to 640x480 so at first I thought I would stick with that. As it turns out, non-text applications like to make some assumptions about minimum screen geometry (for buttons and the like) which becomes problematic at such low resolutions. Instead, I've set my desktop environment for 1024x768 and increased font sizes where it makes sense to do so.
-Line 77:
+Line 36:
-Right now I just go everywhere with an [[http://eeepc.asus.com/|Asus Eee PC]] netbook running [[http://www.debian.org/|Debian GNU/Linux]], but intend to transition soon to a low-power single-board computer. Some links for reference:
 * http://beagleboard.org/
 * http://www.raspberrypi.org/
 * http://www.cs.vassar.edu/people/priestdo/wearables/top
+At the moment I've got a [[http://beagleboard.org/hardware-xM/|BeagleBoard-xM]] running [[http://wiki.debian.org/ArmHardFloatPort|Debian's armhf port]]. Since the video output is HDMI and there's no inexpensive HDMI-supporting HMD on the market yet (might trade up to a [[http://www.siliconmicrodisplay.com/|ST1080]] eventually), I'm using a High Resolution Video DVI to VGA Converter from !StarTech. I've read that a similar (and cheaper) converter from fit-PC2 will work but it requires [[http://blog.galemin.com/2011/03/dvi-d-to-vga-converter-for-beagleboard-xm/|modifying the BeagleBoard]] (which I'd like to avoid if I can).
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-Portable power will also be critical:
 * http://www.sparkfun.com/products/8290
 * http://www.adafruit.com/products/280
 * http://www.adafruit.com/products/353
+The single-board wearable is currently powered from an [[http://www.ianker.com/anker-astro-external-battery-backup-charger/product/79UN5V2-B16P100A|Anker Astro3]], but I may switch it to the lighter and slimmer [[http://www.ianker.com/anker-astro-external-battery-backup-charger/product/79ANS1052-BA|Astro 3E]] once I don't need as many outputs or as much current. I already had a bunch of suitable switching power supplies on hand (Asus ADP-36EH C, replacements are available for very low cost) so I merely fashioned an appropriate adapter cable to fit the input on the Anker.

= Motion-Sensing Pointer =
I don't really use a mouse much (I can usually get by with the [[http://www.semicomplete.com/projects/keynav/|keynav]] utility wherever pointer interaction is absolutely required), but there are times when having one would be useful. I'll probably build something USB-based with accelerometers, but might instead do something with a small trackball:
 * http://www.ladyada.net/make/usbgamepad/
 * http://www.sparkfun.com/products/9320