I went for the iris as a portable one. Small and slightly similar to the m01 with way less keys.
I did design the keyboard myself using OpenSCAD. I then lazer cut the layers and hand wired it using a teensy and some I/o expander board. The software was the hardest because I used a teensy 3 instead of the teensy 2. The 3 requires using the teensiduino which has terrible I/o expander support. Right before I got the m01 I was able to port the keyboard to the qnk firmware but it took me a week of headaches and debugging. Because all other keyboards tend to either use two teensy 3s or a teensy 2 and the I/o extension and the real-time os has some limited support for the teensy 3 processor.
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The iris looks perfect. However I think I would want sometime more m01 like.
Just as a curiosity (Iâve got no experience with developing for microcontrollers) what is the io expander? Do 32u4 need them to make a keyboard?
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Wow, that looks great! I like that there are fewer thumb keys than the Atreus, but theyâre in a more accessible arrangement. Iâm still struggling to make efficient use of the Model 01 thumb keys - I may end up âdeprogrammingâ one to cut down on mis-presses.
You donât find the split keyboard a hassle when youâre traveling? Itâs really convenient to have the one-piece Atreus, I can use it on my lap quite easily. Just wish Iâd gotten a 62 key model, rather than the 42.
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Maybe the IO expander is needed to manage the âotherâ half of the split keyboard? Just guessing, but Iâm pretty sure the Atreus doesnât use one, just a microcontroller.
What is 32u4?
The IO expander allows you to connect the halves of the keyboard with only four wires. Mine (and as far as I know the ergodox) use a trrs cable (four wires) that communicate with the other half using i2c which is some communication protocol I donât know much about.
You need some sort of controller on the other half to detect which keys are pressed. I think You can look up âkeyboard matrixâ on google and learn how that works. Itâs a semi-complex logic of setting pins to ground and using pull-up resistors to detect current flow.
So I have a separate build thatâs one piece which I use for travel. And only a crappy photo of that one. Same layout minus two keys to make the rotation nice.
And like the Atreus this doesnât need the IO expander.
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Atmel atmega32u4 is the microcontroller used by most keyboards included the m01 and the teensy 2
Iâm doing the opposite, I brought my ergodox back from work to home and put my brand new model 01 at work 