in which a shingle is hung out

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Atreus production

Earlier this year I designed and built a small ergonomic mechanical keyboard. My original goal was just that of personal use; I wanted to take the joy of mechanical keyboards with me when I go work from coffee shops. I put the design on Github and documented my build process with photos, and once I finished my own keyboard I figured I'd be done with it. But a few of my friends were intrigued and asked me if I'd build them keyboards. I had a lot of fun constructing my first one, so I agreed to build a few more to sell to friends.

Once I got going, one thing led to another, and I started getting queries from friends-of-friends. I put up a web site with an order form, and orders started trickling in. Due to the hand-wiring approach used the construction of these boards took a good four hours of nights and weekends, so a backlog started piling up. At this point I decided I could make myself less of a bottleneck by selling kits and allowing interested customers to do the assembly themselves. This was a big help, and it seemed people really liked the hands-on approach. There's nothing quite like the satisfaction of using hardware you've constructed yourself.

Atreus wiring

The "proper" way to make a keyboard is to build it around a circuit board. But circuit board design is its own skill, and their production benefits greatly from volume discounts, so it really didn't make sense for my own personal project. But once I started to get more orders it became clear that a circuit board would help a lot since the process of hand-wiring is rather intimidating if you've never done any soldering before. I broke out KiCAD and started laying out a circuit board to hold the switches, diodes, and microcontroller after reading through some documentation and tutorials.

One side of Atreus PCB

I carefully laid out one side of the circuit board according to the row spacing and staggering used in the laser-cut case files without too much trouble. Each switch was connected to the others in the row with one pin and to the others in the column with the other, and each row and column was brought back in to the middle with the microcontroller. Then I hit a snag—the two halves of the Atreus keyboard are rotated inward at a 10° angle, but when I went to rotate the design in KiCAD rather than rotating them as a unit, it simply applied the rotation to each component individually.

At that point I was starting to think I'd have to do all this trig by hand and enter the calculated coordinates one by one into KiCAD's edit boxes, which did not sound like fun. I asked on the Freenode channel and found to my delight that the new file format for KiCAD is based on s-expressions! It can all be easily manipulated programmatically. Since the data includes symbols with leading digits in their names, the Clojure reader couldn't handle it, but Racket didn't have a problem with it. So I put together some Racket code to run the trig necessary to calculate the switch and diode positions.

Atreus PCB

Anyway, I just finished assembling my first circuit-board-based keyboard, and it works nicely. It's dramatically easier than the hand-wired variant, even such that my six-year-old son wants to build his own. I had to make one change to give clearance for the micro-USB connector, but I was able to apply this "revision" to my already-produced circuit boards with a hacksaw.

Up to this point I haven't publically promoted it much, but now that the circuit board is here I'm prepared to handle a greater volume of orders. So if you're interested in building your own mechanical travel keyboard or want to hack some hardware designed using Lisp, take a look at http://atreus.technomancy.us.

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