Max published a video on designing and building his 26-key minimalistic split, the LHM keyboard.
KBD.news Published June 24, 2022
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The LHM is a handwired split keyboard sporting an esp32 Bluetooth controller – the term "handwired wireless" haunts me… :D
While designing his board, the main goals of Max aka OkSet6700 were to keep his hands at shoulder width (to eliminate ulnar deviation) and also eliminate pronation by means of tenting.
I designed the case and the layout for the keys based more on how it feels rather than science. I wanted to feel comfortable using it and reduce the movement of the arms and fingers as much as possible – Max.
Another design goal was simplicity, so the author got rid of diodes, which is feasible with this small number of keys but required a small hack with the NodeMCU esp32 controller (pins 34, 35, 36, 39 don't have internal pullup resistors).
By the way, Max runs a Youtube channel dubbed "LifeHackerMax" – in case you were wondering about the name of the keyboard.
Specs
26 keys (10 keys + 3 thumb keys per half)
10 degree tenting angle
NodeMCU esp32 development board
no diodes
handwired
custom firmware
After using it for a while, Max uploaded a well-edited video on the design and building process, as well on the custom keymap and firmware.
I built my very own split keyboard and I have been using it for the past 3 weeks. I will share with you the whole build process, my experience using the keyboard and how it works considering it has only 26 keys.
The video is aimed at a more general audience so you can skip to about 2:30 if you know full well that standard keyboards suck. :D
Max used the Arduino IDE to program and upload his own firmware, using the BleKeyboard library (designed specially for the esp32 and turning it into a Bluetooth keyboard) and the JC Button library for debouncing.
With regards to the logical layout, the 26-key LHM keyboard uses layers but also button combinations similar to steno machines, however, this board is not for stenography.