Custom ergo split keyboard project, based on ErgoDox, with hot swap sockets
The ErgoMax is a split ergonomic keyboard.
It is based on the ErgoDox, a popular split ergonomic keyboard (learn more).
Its main features/differences are:
While a lot of mechanical keyboard users seem to prefer simplistic, minimal keyboards, the ErgoMax goes the opposite way.
The layout is the same as the ErgoDox, with an extra top row for F1 to F12 keys, adding more room for activities.
Here’s an example:
The keyboard PCB has been designed to use Kailh MX hotswap sockets. You won’t be able to solder the switches directly on the PCBs, you must use Kaihl MX sockets.
Switches will plug into the sockets, meaning no solder required for them, and most importantly, meaning that you can remove them and change them easily (hence the hotswap…).
Each side of the keyboard is controlled via a ProMicro, which is a cheap, small Arduino compatible board running on an ATmega32u4.
The 2 sides can be connected via a 3.5mm jack, just like the original ErgoDox. However, as the 2 sides possess their own ProMicro, that means they can also be working totally independently if needed.
There are 2 pins free on each of the ProMicros, which can be used for whatever you want. I believe it would be possible to drive a RGB strip from it, since it requires only 1 drive pin (you would need to get GND and +5V from somewhere on the PCB). I was able to use both pins to add a rotary encoder.
I tried to use the same 3.5mm TRRS jack socket as the original ErgoDox, which is a CP-43514. But it’s not super common, so I changed it for a PJ320A (same as MJ-4PP-9).
Check the guides
We are using several libraries in this project.
Kicad can generate nice 3D previews of PCBs and their components.
As we’re using components that are not included in KiCad 3d templates, you’ll need to add the next models into your KiCad template folder. On Windows, it’s C:\Users\YOURNAME\kicad\template, on OSX it’s /Users/YOURNAME/kicad/template. If the folder doesn’t exist, create it.
The 3D models of the hotswap sockets can be found there: https://github.com/qmk/qmk_hardware. Copy kailh_socket_mx.stp into your KiCad template folder.
I couldn’t find a 3D model for the PJ320A jack connector. The closest I found is this https://www.cui.com/product/resource/3dmodel/sj2-3574a-smt-tr, which gives a good preview of a real PJ320A. Copy CUI_SJ2-3574A-SMT-TR.step into your KiCad template folder.
I modified this MX Switch 3D model https://grabcad.com/library/cherry-mx-switches-mx-1 and included it in the libs/3dmodels folder of the project as MX-clean-ergomax.step.
I also modified a 2U stabilizer model that I found there https://grabcad.com/library/cherry-mx-stabilizer-mx-1. The file is also included in the libs/3dmodels folder of the project as Stabilizer-closed-ergomax.step.
I once again modified a ProMicro 3D model https://grabcad.com/library/arduino-pro-micro-1. The file is called Pro-micro-clean-ergomax.step and is stored in libs/3dmodels.
Here are some manufacturers that can print PCBs for you. They are not in any particular order and I don’t have any partnership of any sort either.
Check the guides