kicad-kbplacer

KiCad plugin for mechanical keyboard design. It features automatic key placement based on popular layout description from keyboard-layout-editor

Motivation

All PCB's for mechanical keyboards shares common properties which creates great opportunity for scripting. Although this project does not aim to provide complete automatic PCB generation tool it speeds up development process by reducing tedious element placement task.

Features

• Automatic keys and diodes placement
• Support for different annotation schemes
• Basic track routing
• Key rotation support
• User selectable diode position in relation to key position

Some examples can be found in examples directory.

Installation

To install release version of this plugin, use KiCad's Plugin and Content Manager (available since version KiCad 6.0).

In order to work with latest version of plugin, checkout this repository and copy (or link) content of kbplacer directory to one of the KiCad's plugin search paths. For more details see this guide.

For KiCad 5.1 compatible version see tag v0.1

How to use?

Direct usage

• Create switch matrix schematic which meets following requirements:

  • Each switch has dedicated diode with same annotation number
  • Symbols are ordered by Y position
  • Diodes are column-to-row configuration (COL = Anode, ROW = Cathode)

  

• Create new PCB and load netlist

• Obtain kle-serial compatible layout json file (note: this is not json which can be downloaded directly from keyboard-layout-editor website. Expected json format can be seen in examples directory.

  For conversion you can use https://adamws.github.io/kle-serial or keyboard-tools.xyz/kle-converter

• Run kicad-kbplacer plugin

• Select json layout file and plugin options and click OK.

  

Diode placement and routing

By default diodes are placed like shown below. This placement may not work for all switch and diode footprints combinations.

Before	After

To use custom diode position, manually place D1 diode and run plugin with Use first switch-diode pair as reference for relative position option enabled. Remaining switch-diode pairs will be placed same as the first one.

Before	After

Some custom diodes positions may be to difficult for router algorithm. In the above example it managed to connect diodes to switches but failed to connect diodes together.

Switch-to-diode routing is not done with proper auto-routing algorithm and it is very limited. It attempts to create track in the shortest way (using 45° angles) and doesn't look for other options if there is a collision, leaving elements unconnected.

If first switch-diode pair is routed before plugin execution, as shown below, kicad-kbplacer instead of using it's built in routing algorithm, will copy user's track. This allow to circumvent plugin's router limitations.

Before	After

Demo project

For example demo project see demo directory. This project contains 4x4 switch matrix with already generated layout json file (kle_internal.json) in expected by plugin format. It requires keyswitch-kicad-library to be installed. Use this project to validate plugin installation.

As a service

This plugin is part of my another project. See keyboard-tools

Troubleshooting

• See stacktrace
• See created kbplacer.log file (in PCB directory)