# Split bluetooth keyboard

Just some quick notes on something I built fairly quickly; they're published here in the hope that they might be slightly useful for others, or to help inspire others to build something better.

Parts:

* 2x Adafruit nRF52 https://www.adafruit.com/product/3406 (I got the Pro version, but you'll need a JLink to use the arduino code in this gist if you get the pro, so the link here is the non-pro version)
* 72x 1N4148 signal diodes
* 72x Cherry MX compatible keyswitches
* 6x 1.25u keycaps for modifiers
* 66x 1u keycaps
* 2x lipoly battery with JST connector.
* hot glue to secure the switches in the top plate
* 20x M3 spacers and standoffs for the case supports
* 8x M2.5 (M2 will also work) nuts and bolts to mount the controllers

## LHS - Left Hand Side

This is a bluetooth peripheral that scans its matrix and publishes the data via bleuart.

## RHS - Right Hand Side

This runs as a dual role device; it runs as a Central device that connects to
the LHS to read its matrix via bleuart, and runs a bluetooth HID peripheral to
publish the combined matrices of the two halves.

You'll want to pair your device with the RHS only!

## Wiring

This uses standard matrix wiring (which I've unhelpfully not shown here); each
switch has a diode to prevent ghosting.  The diodes are used to form the rows.
The columns are shown in matrix.svg.

The rows are connected to the A0-A5 pins on the LHS of the controller.  The
columns are connected to the pins on the other side.  Take care to avoid the
special pin 31 which is used to sample the battery voltage.

## Case

The included case.svg file is ready for use with ponoko.com.  I used a blue
matte acrylic in my build.