{ "attachments": [ "0b034d6acac6.jpg" ], "title": "Making of the GameChord", "tags": [ "diy", "keyboards", "hardware", "teensy", "microcontrollers", "electronics" ], "thumbnail": "/uploads/2016/gamechord/thumbnail.jpg", "year": "2016", "month": "08", "day": "29", "isDir": true, "slug": "gamechord", "type": "entry", "date": "2016-08-29T19:00:00.000Z", "postName": "2016-08-29-gamechord", "html": "

TL;DR: I made a USB keypad that's good for gaming and typing entirely with\none hand.

\n\n\n\n\n\n\n

So, remember back in February when I said that keyboard hacking seems like\nfun? Well, I\nfinished this GameChord thing back in July after about 5 months of occasional\nwork. But, I've been too busy drinking booze\nand playing video games \nto get my butt in a chair and write about it.

\n

Let's see if I can fix that now...

\n

The design

\n

\n

I started doodling with key layouts and came up with\nthis. Only 18 switches, but enough for gaming. At the\ntime, I was putting a lot of hours into Elite\nDangerous, so this felt promising as a spaceship control pad.

\n

\n

Over on builder.swillkb.com, I plonked in the JSON from Keyboard\nLayout Editor and came up with some SVG files that printed\nup nicely.

\n

That gave me a paper mockup of a mounting plate for key switches. I had some\nclear keycaps, so I dropped them onto the paper to get a sense for how it\nwould feel under my hand.

\n

Of course, cats happen - so those keycaps didn't stay put for very long. But,\nthat's okay. Nothing wandered off too far, and I got what I needed from\nthe mess on my desk.

\n

Making the case

\n

Back when I first started thinking about building a\nkeyboard, I\nassumed I'd send off whatever design files I came up with to a place\nlike Ponoko and get the mounting plate made for me.

\n

Prices at those places were just a bit higher than I liked, though. I also\nsuspected things wouldn't work with my first attempt. I wanted to be able\nto iterate without it taking days or weeks to learn from my mistakes\nand refine.

\n

That's when I remembered i3Detroit was just down the road. I'd been\nmeaning to get over there for a couple of years: Among other things, the space\nhas nice laser cutters that I really wish I'd used back when\nI butchered some plastic to make a terrible PC monitor case.

\n

A month or so later, I'd gotten through the new member onboarding process\nand a few training sessions with the laser cutter. I had some\nacrylic sheets still on hand, so I gave my design a shot:

\n

\"Cutting

\n

Pretty sure I had the power too high and the speed too low for the run\nin this video. But, the result was not too bad for a first attempt. I had a\nfew dozen Cherry MX Clear switches to play with, so I snapped them into the\nplate and put on the keycaps I'd used in the paper mockup earlier:

\n\n\n

Still lots of work ahead, but I was feeling pretty accomplished after taking\nthis little glamour shot. I even took it into an i3Detroit member meeting\nfor show & tell.

\n

Re-making the case

\n

At this point, I'd already heard the term \"kerf\". Like a saw blade, the laser\nhas a width that destroys material while cutting. You want that on the\ninside edge of something like a key switch mounting hole, in order to keep\nthe dimensions correct. Unlike a blade, the laser is a cylindrical\nbeam that passes through a lens to form something like an\nhourglass. So, the\nkerf's shape depends on the lens focal length and the conical section that\nintersects with the material.

\n

Well, I didn't account for the kerf well enough in my first plate. All the key\nswitches were wobbly. Some would just fall out if I flipped\nthe thing over. Time for some of those iterations I\nfigured I'd have to end up doing.

\n\n\n

I know the saying is \"measure twice, cut once\" - but in this case it was\neasier to measure by cutting! I tried mounting holes with a sampling of kerf\nwidths until I found one that matched the key switch tolerances. Not so snug\nthat it cracked the plate, but not so loose that it wiggled or fell out.

\n

Once I found a good laser focus and figured out the kerf, I\nattacked another sheet of acrylic with the laser to produce another\niteration of the case.

\n

\n

Two changes you might notice: I added slots to glue in some socket\nheaders, so I could unplug or replace the Teensy without soldering. I also found some\nrelegendable keycaps on Massdrop - they have little removable covers that\ntake 14mm paper squares. I figured that would come in handy for crazy\nkey layouts I might come up with.

\n

Wiring up the key matrix

\n

I haven't learned how to design circuit boards yet, so I figured I'd just\nhandwire this like I saw in the video. Only 18 switches, so\nhow bad could it be?\nTurns out, it's rather annoying. Interesting exercise with my terrible old\nRadio Shack soldering iron.

\n\n\n\n

I think I'd much rather get over that PCB fabrication hurdle for when I try\nscaling this up to a 60% keyboard like my HHKB.

\n

The technique here involves first building up rows of diodes across the\nright-hand pin of every key switch. The diodes serve to prevent ghosting when\nmultiple keys are pressed.

\n

Then, I stripped sections of wires to\nrun as columns down the left-hand pin of the switches.

\n

The remaining\ninsulation ensures the column wires don't short against the row diodes.

\n

Wiring up the Teensy

\n\n\n

This matrix gives me 4 rows (counting the thumb switches) and 5 columns - or 9\nI/O pins to scan 18 switches.

\n

Except for magical PD6 - which is hardwired to an onboard LED - just\nabout every pin is fair game on the Teensy for rows or columns.

\n

So, I tried to pick a set that would be easiest to route wires. Since this\ncase is transparent, I wanted to keep things visually interesting with\ndifferent colored wires and a neat shape to the runs.

\n

Of course, I botched things a bit and marred the acrylic by splashing\nsolder and slipping with the iron a few times. But, maybe no one will really\nnotice.

\n

If I had to do this over again - and I still hadn't learned how to make a\nPCB - I'd probably try using something thinner like 30AWG repair\nwire. That seems like it would thread through the spaces much\nbetter, which would be even more important for a board with many more\nswitches.

\n

Programming the Teensy

\n\n

I based the GameChord firmware on the great tmk\nfirmware that seems popular on mech keyboard forums.

\n

Building the matrix was easy: The firmware scans through rows (DF0, DF1,\nDF4, and DF5) by pulling each low in turn. The columns (DB4, DB5, DB6, DF7,\nand DF6) are set as \"active low\" pins - which means keys pressed in the\ncurrent scan row get connected to ground and read as signals. So,\nI wrote the functions to manipulate & read the appropriate row & column pins,\nrespectively.

\n

It was almost too easy:

\n

Holy crap. My attempt at setting up firmware for my newly wired DIY keypad worked first time. How does this happen. https://t.co/xWESzku4Lp

— Les Orchard (@lmorchard) June 25, 2016
\n\n\n\n

From there, I built a dead simple key map with just enough\nkeys to play Overwatch:

\n
[#include](/tag/include) \"keymap_common.h\"\n\nconst uint8_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {\n    KEYMAP( ESC,   1,    2,    3,    T, \\\n            TAB,   Q,    W,    E,    R, \\\n           LSFT,   A,    S,    D,    F, \\\n             NO,  NO, LCTL,  SPC,    C),\n};\nconst uint16_t PROGMEM fn_actions[] = {};\n
\n

I got it all working and had myself a nice evening of pushing carts and taking\nobjectives.

\n\n\n

Going crazy with chording

\n

I had all these relegendable keycaps and this crazy flexible tmk\nfirmware - so I decided to try implementing a complex and fully impractical\nkeymap based on chords with the thumb keys.

\n\n\n

Given two thumb keys in combination, I can get 4 layers out of the other 15\nkeys - for a total of 60 keys. The firmware also lets me distinguish\nbetween keys held or just tapped, which gives me a few more layers or\nmodifier keys.

\n

Long story short, I can get most of the functionality of a regular keyboard\nout of just one hand. All I have to do is just get used to putting my left\nhand through some very awkward and uncomfortable contortions until I get up to\nfull typing speed!

\n

As I've written before, I do really like odd input devices.\nBut, this got old fast. This isn't so much a practical peripheral as a thing I\ndid because I could. It gave me an excuse to explore the firmware more\nand to use Inkscape to design some legends for my nifty keycaps.

\n

Showing it off

\n

And just to wrap things up, this happened:

\n

I even have a project out in the @i3Detroit tent at #MakerFaireDetroit ! pic.twitter.com/v0goD3DCBk

— Les Orchard (@lmorchard) July 30, 2016
\n\n\n\n

This was the first summer I went to Maker Faire Detroit as a Maker. I\nhelped for a bit at the i3Detroit tent, mainly just standing and smiling\nat the front table as folks walked in. But, I had my little keyboard out there\non a table, with a project card and everything.

\n

It and I were only there for a handful of hours, but it's pretty satisfying to\nhave actually gotten this thing done!

\n\n\n\n\n", "body": "**TL;DR**: I made a USB keypad that's good for gaming and typing entirely with\none hand.\n\n\n\n\n\nSo, remember back in February when I said that [keyboard hacking seems like\nfun][keyboardhacking]? Well, I\nfinished this GameChord thing back in July after about 5 months of occasional\nwork. But, I've been too busy [drinking booze\nand playing video games](https://twitter.com/lmorchard/status/770771394816729088) \nto get my butt in a chair and write about it.\n\nLet's see if I can fix that now...\n\n[keyboardhacking]: http://blog.lmorchard.com/2016/02/06/keyboard-hacking/\n\n## The design\n\n[][layoutpermalink]\n\nI started doodling with key layouts and [came up with\nthis][layoutpermalink]. Only 18 switches, but enough for gaming. At the\ntime, I was putting a lot of hours into Elite\nDangerous, so this felt promising as a spaceship control pad. \n[](https://www.flickr.com/photos/deusx/24872268889/)\n\n[](https://www.flickr.com/photos/deusx/24781232904/in/datetaken-public/)\n\nOver on [builder.swillkb.com][builder], I plonked in the JSON from [Keyboard\nLayout Editor][layoutpermalink] and came up with some SVG files that printed\nup nicely.\n\nThat gave me a paper mockup of a mounting plate for key switches. I had some\nclear keycaps, so I dropped them onto the paper to get a sense for how it\nwould feel under my hand.\n\nOf course, cats happen - so those keycaps didn't stay put for very long. But,\nthat's okay. Nothing wandered off too far, and I got what I needed from\nthe mess on my desk.\n\n[builder]: http://builder.swillkb.com/\n\n## Making the case\n\nBack when [I first started thinking about building a\nkeyboard][keyboardhacking], I\nassumed I'd send off whatever design files I came up with to a place\nlike [Ponoko](https://www.ponoko.com/) and get the mounting plate made for me.\n\nPrices at those places were just a bit higher than I liked, though. I also\nsuspected things wouldn't work with my first attempt. I wanted to be able\nto iterate without it taking days or weeks to learn from my mistakes\nand refine.\n\nThat's when I remembered [i3Detroit][] was just down the road. I'd been\nmeaning to get over there for a couple of years: Among other things, the space\nhas [nice laser cutters][lasercutters] that I really wish I'd used [back when\nI butchered some plastic to make a terrible PC monitor case][monitorcase]. \n\n[lasercutters]: https://www.i3detroit.org/wiki/Category:Laser_Cutter\n[monitorcase]: http://blog.lmorchard.com/2013/02/10/building-my-couch-computing-station/\n[i3Detroit]: https://i3detroit.org\n\nA month or so later, I'd gotten through the new member onboarding process\nand a few training sessions with the laser cutter. I had some\nacrylic sheets still on hand, so I gave my design a shot:\n\n\"Cutting\n\nPretty sure I had the power too high and the speed too low for the run\nin this video. But, the result was not too bad for a first attempt. I had a\nfew dozen Cherry MX Clear switches to play with, so I snapped them into the\nplate and put on the keycaps I'd used in the paper mockup earlier:\n\n\n\nStill lots of work ahead, but I was feeling pretty accomplished after taking\nthis little glamour shot. I even took it into an [i3Detroit][] member meeting\nfor show & tell.\n\n## Re-making the case\n\nAt this point, I'd already heard the term \"kerf\". Like a saw blade, the laser\nhas a width that destroys material while cutting. You want that on the\n*inside* edge of something like a key switch mounting hole, in order to keep\nthe dimensions correct. Unlike a blade, the laser is a cylindrical\nbeam that passes through a lens to form [something like an\nhourglass][beamshape]. So, the\nkerf's shape depends on the lens focal length and the conical section that\nintersects with the material.\n\n[beamshape]: http://www.buildlog.net/blog/2013/05/why-are-my-laser-cut-edges-not-straight/\n\nWell, I didn't account for the kerf well enough in my first plate. All the key\nswitches were wobbly. Some would just fall out if I flipped\nthe thing over. Time for some of those iterations I\nfigured I'd have to end up doing.\n\n\n\nI know the saying is \"measure twice, cut once\" - but in this case it was\neasier to measure by cutting! I tried mounting holes with a sampling of kerf\nwidths until I found one that matched the key switch tolerances. Not so snug\nthat it cracked the plate, but not so loose that it wiggled or fell out. \n\nOnce I found a good laser focus and figured out the kerf, I\nattacked another sheet of acrylic with the laser to produce another\niteration of the case.\n\n[](https://www.flickr.com/photos/deusx/26975072884/)\n\nTwo changes you might notice: I added slots to glue in some socket\nheaders, so I could unplug or replace the Teensy without soldering. I also found some\n[relegendable keycaps][] on Massdrop - they have little removable covers that\ntake 14mm paper squares. I figured that would come in handy for crazy\nkey layouts I might come up with.\n\n[relegendable keycaps]: http://dro.ps/b/x3g0KCy\n\n## Wiring up the key matrix\n\nI haven't learned how to design circuit boards yet, so I figured I'd just\nhandwire this [like I saw in the video][handwirevideo]. Only 18 switches, so\nhow bad could it be?\nTurns out, it's rather annoying. Interesting exercise with my terrible old\nRadio Shack soldering iron. \n\n\n\n\nI think I'd much rather get over that PCB fabrication hurdle for when I try\nscaling this up to a 60% keyboard like my HHKB.\n\nThe technique here involves first building up rows of diodes across the\nright-hand pin of every key switch. The diodes serve to prevent [ghosting when\nmultiple keys are pressed][ghosting]. \n\nThen, I stripped sections of wires to\nrun as columns down the left-hand pin of the switches. \n\nThe remaining\ninsulation ensures the column wires don't short against the row diodes.\n\n[handwirevideo]: https://www.youtube.com/watch?v=MrokZ1afnVg\n[ghosting]: https://deskthority.net/wiki/Rollover,_blocking_and_ghosting\n\n## Wiring up the Teensy\n\n\n\nThis matrix gives me 4 rows (counting the thumb switches) and 5 columns - or 9\nI/O pins to scan 18 switches.\n\nExcept for [magical PD6][pd6] - which is hardwired to an onboard LED - just\nabout every pin is fair game on the Teensy for rows or columns. \n\nSo, I tried to pick a set that would be easiest to route wires. Since this\ncase is transparent, I wanted to keep things visually interesting with\ndifferent colored wires and a neat shape to the runs.\n\nOf course, I botched things a bit and marred the acrylic by splashing\nsolder and slipping with the iron a few times. But, maybe no one will really\nnotice.\n\nIf I had to do this over again - and I *still* hadn't learned how to make a\nPCB - I'd probably try using something thinner like [30AWG repair\nwire][30awg]. That seems like it would thread through the spaces much\nbetter, which would be even more important for a board with many more\nswitches. \n\n[30awg]: https://www.adafruit.com/product/1446\n\n[pd6]: https://geekhack.org/index.php?topic=72804.0\n\n

Programming the Teensy

\n\nI based [the GameChord firmware][gamechordfirmware] on the great [tmk\nfirmware][] that seems popular on mech keyboard forums.\n\nBuilding [the matrix][] was easy: The firmware scans through rows (DF0, DF1,\nDF4, and DF5) by pulling each low in turn. The columns (DB4, DB5, DB6, DF7,\nand DF6) are set as \"active low\" pins - which means keys pressed in the\ncurrent scan row get connected to ground and read as signals. So,\nI wrote the functions to manipulate & read the appropriate row & column pins,\nrespectively. \n\nIt was almost *too* easy:\n\n

Holy crap. My attempt at setting up firmware for my newly wired DIY keypad worked first time. How does this happen. https://t.co/xWESzku4Lp

— Les Orchard (@lmorchard) June 25, 2016
\n\nFrom there, I built [a dead simple key map][plainmap] with just enough\nkeys to play [Overwatch][]:\n\n```c\n#include \"keymap_common.h\"\n\nconst uint8_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {\n KEYMAP( ESC, 1, 2, 3, T, \\\n TAB, Q, W, E, R, \\\n LSFT, A, S, D, F, \\\n NO, NO, LCTL, SPC, C),\n};\nconst uint16_t PROGMEM fn_actions[] = {};\n```\n\nI got it all working and had myself a nice evening of pushing carts and taking\nobjectives.\n\n\n\n[the matrix]: https://github.com/lmorchard/gamechord/blob/863295d2cbdbc7052a25e989a77c3448796e67a6/matrix.c\n[plainmap]: https://github.com/lmorchard/gamechord/blob/863295d2cbdbc7052a25e989a77c3448796e67a6/keymap_plain.c\n[gamechordfirmware]: https://github.com/lmorchard/gamechord\n[tmk firmware]: https://github.com/tmk/tmk_keyboard\n[overwatch]: https://playoverwatch.com/en-us/\n\n## Going crazy with chording\n\nI had all these [relegendable keycaps][] and this crazy flexible [tmk\nfirmware][] - so I decided to try implementing [a complex and fully impractical\nkeymap based on chords with the thumb keys][halfqwerty].\n\n[halfqwerty]: https://github.com/lmorchard/gamechord/blob/863295d2cbdbc7052a25e989a77c3448796e67a6/keymap_halfqwerty.c\n\n\n\nGiven two thumb keys in combination, I can get 4 layers out of the other 15\nkeys - for a total of 60 keys. The firmware also [lets me distinguish\nbetween keys held or just tapped][taps], which gives me a few more layers or\nmodifier keys.\n\n[taps]: https://github.com/lmorchard/gamechord/blob/863295d2cbdbc7052a25e989a77c3448796e67a6/keymap_halfqwerty.c#L43\n\nLong story short, I can get most of the functionality of a regular keyboard\nout of just one hand. All I have to do is just get used to putting my left\nhand through some very awkward and uncomfortable contortions until I get up to\nfull typing speed!\n\n[As I've written before][steamcontroller], I do really like odd input devices.\nBut, this got old fast. This isn't so much a practical peripheral as a thing I\ndid because I could. It gave me an excuse to explore the firmware more\nand to use Inkscape to design some legends for my nifty keycaps.\n\n[steamcontroller]: http://blog.lmorchard.com/2016/02/05/steam-controller/\n\n## Showing it off\n\nAnd just to wrap things up, this happened:\n\n

I even have a project out in the @i3Detroit tent at #MakerFaireDetroit ! pic.twitter.com/v0goD3DCBk

— Les Orchard (@lmorchard) July 30, 2016
\n\nThis was the first summer I went to [Maker Faire Detroit][] as a Maker. I\nhelped for a bit at the [i3Detroit][] tent, mainly just standing and smiling\nat the front table as folks walked in. But, I had my little keyboard out there\non a table, with a project card and everything.\n\nIt and I were only there for a handful of hours, but it's pretty satisfying to\nhave actually gotten this thing done!\n\n[maker faire detroit]: http://www.makerfairedetroit.com/\n[laservideo]: https://www.flickr.com/photos/deusx/25839524664/\n[layoutpermalink]: http://www.keyboard-layout-editor.com/##@_name=gamechord&author=lmorchard;&@=1&=2&=3&=4&=5;&@=1&=2&=3&=4&=5;&@=1&=2&=3&=4&=5;&@_r:35&rx:2.5&ry:3.5&y:-1&x:1;&=a&=b&=c\n\n\n\n\n\n", "parentPath": "./content/posts/archives/2016/2016-08-29-gamechord", "path": "2016/08/29/gamechord", "summary": "TL;DR: I made a USB keypad that's good for gaming and typing entirely with\none hand.", "needsBuild": true, "prevPostPath": "2016/04/17/spreadsheets-in-space", "prevPostTitle": "How I learned to love spreadsheets in space", "nextPostPath": "2016/08/31/yak-shaving-habits", "nextPostTitle": "On the Yak Shaving Habits of a Writer" }