SplitAnalogKeyboard

Analog-Keyboard-kmk-PiPico-NormalSplit

This is a fully analog keyboard using magnetic keys and hall sensors. I'm using a RP2040 but since it is KMK (circuitpython) based it should be compatible with other boards. I build a split keyboard, but any type form factor should work. This is my first experience with circuitpython so code might me wonky.

#TO-DO

• automatic callibration
• support all types of multiplexers (not just 16:1)
• fix mouse wheel only pressing every second turn

PCB

!DONT USE THE PCB PROVIDED! The PCB provided has some flaws that make it hard to work with. I would recommend making your own PCB and using mine as a template. In the future i might create v2 template that fixes the flaws. Also as LCSC didn't have the LEDs in stock, I build mine without them. So there is no guaranty that I did the LED wiring correctly. I did however test the code with the onboard led of the RP2040, so the code should work.

Flaws with v1

• Horizontal encoder has the wrong footprint (gnd is not in the middle)
• dont solder MCU daughter board onto PCB directly
• bigger pads for hand soldering
• more mounting holes
• if possible 2 layer PCB for cost saving

Parts

Part notes

Hall sensor:

Multiplexer: Currently any 16to1 Multiplexer should work (giving you 64 keys). If you are not hand soldering i recommend choosing a smaller sized one. Larger (32to1) should also work.

MCU: Any circuitpython compatible board should work. You just have to change the footprint on the PCB (which you should do anyway. See "Flaws with v1"

TRRS jack:

Capacitor: Capacitors are not strictly necessary but improve resolution. I tried a few and found that 100uF worked the best. Use different sensor filters

How it works

The position of the magnet in the switch is red by the hall-effect sensor. Because the pi-pico only has 4 ADCs we need multiplexers to cycle between the sensors.

Code

To install the code connect your board and install circuitpython. Then copy the content of the "code" folder into the board. For editing the code you can use Thonny or any text editor.

pins

To make life easier by not having to use "board.GP.." all the time, create (if not already present) a python file in lib/kmk/quickpin. Then add all the pins (see the other files for reference). Now when imported with

from kmk.quickpin.<boardTypeFolder>.<boardPins> import pinout as pins

into other files you can just use "pins[x]" to reference pins

kb.py:

Here you define most variables for you specific board.

Code.py

hallCali.py

analogio.py

Case