"Xinput" protocol started in XboX 360. Now it has been pushed as "de facto" standart for input in Windows games, games on Steam. Thing is, many games (especially small games from individual developers) are made with only Xinput controls in mind, and many old, classic joysticks (with DirectInput) not working properly.
I have plenty information on that, has been investigating control config problems in recent games. I can write more about it in private messages, or here open, as you wish.
My point is: there are almost none flightsticks with Xinput standart (there was Saitek "AV8r" (Aviator)). Would be nice to have DIY customizable project that makes that kind of output.
And, here are DIY versions that I mentioned:
http://www.zlittell.com/2015/07/fightstick/ (Teensy)
https://engenhariaegambiarras.wordpress.com/2017/02/04/racing-wheel-xinput-controller/ (STM32F103)
Both open source codes. I actually started to edit that "wheel" source in Keil, compiles and runs okay.
I recently bought used Logitech dual-standart gamepad (switchable Xinput - DirectInput), just in case, to be ready for any game. BUT - I want to make flightstick with dual protocols.
Sure, I can disassemble that gamepad, and use electronics for flightstick, but I better make some DIY electronics ;-)
So, the reason is - recently there are a lot of games (also flying games), that have only Xinput for controlling it.