March 25, 2016

Hand wiring the Atreus - a step into open source hardware


The Atreus is a mechanical keyboard designed primarily to match the shape of human hands and to be as portable as possible. It consists of 42 keys in a columnar layout and has ergonomic features similar to the Ergodox, without the split aspect and scaled down in size. These traits caught my interest for traveling so I decided to build one. I opted to hand wire my keyboard matrix as I feel that it's a bit more satisfying than populating a printed circuit board. This is my venture into the open source keyboard project by Phil Hagelberg (@technomancy) documented on github.

Bill of materials

Case
Teensy 2.0
Switches (37 Cherry MX Clears, 5 Cherry MX blacks)
DSA profile keycaps (40 1x, 2 1.5x)
42 1N4148 diodes
Mini USB breakout board
Mini USB cable
Insulated copper wire
M3 machine screws and nuts

Case's bottom layer, switch plate and top layer after a few coats of satin polyurethane to protect the raw birch
Switch plate fully populated - Cherry MX Clears are used for alphas and Cherry MX Blacks are used for modifiers
Switches were then hot glued to the switch plate for additional support
Negative ends of the diodes soldered to the top left row of switches
Positive ends of the diodes soldered in parallel (positive to positive of the next diode in the row) to create the first row
Left side rows complete
Right side rows complete
Progress on the left side columns
Left side columns and left to right rows connected (staying positive end to positive end of the next diode in the row)
This tool helped drastically in cutting off the insulation for the column wires in the correct places
Matrix completed - the center switches are one column but members of the bottom two rows
Rows wired to the Teensy
Columns wired to the Teensy. I put together a mini USB to mini USB breakout board because I wanted a slimmer profile for the case, this allowed for omitting a layer of the wooden spacers. This also let me upgrade from an integrated cable to a detachable mini USB cable which helps make the keyboard travel a bit more elegantly.
After compiling the firmware and writing the hex file to the Teensy the Atreus is fully functional.