I have just uploaded a new version of the firmware.

• Some bugs have been corrected, specially the deadlock condition caused by pin change interrupt on pin 9 of 5200 port (Cav control).
• Using Classic controller library >0.8.1 . From version 0.8.1 the axes values are always returned in the range 0-255, even for knockoff controllers that can only operate in low resolution mode.
• Added a non-linear curve, that in practice provides a sort of dead band on the center and gets steep at the extremes. The curve saturate close to the edges to compensate some controllers that can not return in full range, even in high resolution mode.

• Corrected the code that adds the movement of left and right sticks in single controller mode.

The resistor R1 shall be the value changed to 1K ohm so the LED on pin 13 of some Arduino Nanos does not interfere with Cav control.

Thanks  @Chris Belcher for the feedbacks!