This is an X-Plane plugin that offers subscriptions to Datarefs via an USB connection. Datarefs can also be written and commands sent via USB. Note that this project is work in progress and neither finished nor fully tested.
There is an example Arduino project demonstrating how the Master light of the pilot's flight director switch can be mapped to the built-in LED of the Arduino board.
Contributions are appreciated. Please, start a pull request to contribute.
There is right now no build system for the plugin. However, the project configuration files for Visual Studio 2017 are included (taken over from the example plugin project in the X-Plane SDK). Moreover, the simplest way of building and changing the plugin is by importing the project into Visual Studio 2017.