First release is working. Source code is available at the project repository.
And the first controller integrated to the project is a boomerang PC gamepad by unknown manufacturer.
The D-Pad provides discrete resistances on X and Y axes (0, ~50k, ~100k).
Buttons A and B have a TURBO function and are mapped to buttons 1 and 2 of the Joystick 1 (pins 2 and 7).
Shoulder buttons Right and Left are mapped to buttons 1 and 2 of the Joystick 2 (pins 10 and 14).