When designing little computers, one of the most interesting aspects is the dimension and functionality of the keyboard. Do you want to use it rarely and the screen real estate doesn’t matter? You can use an on screen keyboard. With little devices such as the PocketPi, it is okay to have a small keyboard, but that’s not for writing code, it’s okay for messages etc. Recently I bought a Psion Series 5 mx pro, that is a keyboard with 17cm length and a phantastic trade-off between usability and size. But I was also experimenting with self-built keyboards for a while and discovered that I’m not alone.

For building a sub-notebook or netbook powered by a Raspberry Pi, I was looking into 40% keyboards, my first experiment was a NIU PCB with Kailh Choc low profile switches just to find out that the NIU doesn’t support this form factor. I kind of hacked it by modifying the switches and soldering on the back side:

And it kind of worked. But it’s not beautiful and you have to mirror the default keyboard mapping. For my taste, the key caps are also too far apart, on the plus side, it has LEDs (the key caps are the “natural” color, i.e. semi-transparent which is also good for lights):

But then, after posting this on reddit, another forum member hinted that there would be the Pancake PCB that would “natively” support the low profile switches, so I ordered the pancake PCB together with the white key caps.

To save some more height, I decided to solder the Arduino Micro Pro directly on the PCB without a socket or pins, luckily, there’s also a QMK layout for it already and flashing with the QMK tool is a breeze (just press the button WHILE plugging in the USB cable to the computer).

That yields a total height of 18mm which is, in notebook terms, still quite a lot, but for mechanical keyboards it’s the best I can achieve for the moment.

The alternative would be to design and print a switch holder grid and connect the switches directly without a PCB. Whatever, this is the end result:

A much cleaner and tighter look compared to the NIU:

To learn how to type on an ortholinear keyboard, I practise on this sensational website. I was not very fast after 30min practise but improving fast:

So just as an outlook for the sub-notebook (10.1 inch screen, 21x15cm), here’s the hardware collection that I had half a year ago (yes, that’s a dedicated touchpad with mouse buttons in the middle). I’ll change the LiPo for a dual 18650 UPS I recently found which is way more compact.