Custom VEX controller

Hello, I am a newish member to my High schools robotics program and was wondering I can or if it is even legal to build a “non-vex” controller to use with my robot. I would like more buttons to be accessible if needed.

In addition, if anyone has any advise that would be very helpful.

Thanks

Replacing the primary joystick is technically possible (interface to the VEXnet key is very hard) but not competition legal.

Replacing the partner joystick is easier but not legal (AFAIK) for high school.

A couple of threads you may be interested in.
Interfacing a PS3 controller to the joystick partner port
Interfacing a multi-axis controller to the joystick partner port

For the VEX Robotics competition, it is not legal to use anything but the official VEX controller. If you need more buttons, have you considered using the partner joystick? There are almost always ways to get around the issue of not enough buttons by planning how you will use the buttons best and what is necessary, as well as possibly making key combinations (i.e. hold a trigger while pressing the button). I would just be careful with too many buttons or combinations because you can forget what they all do or get confused in a match.

Thank you,
I guess that would make things a lot easier, and I did not know you can program button combinations I am currently using EasyC but might get RobotC this season. Is button combinations possible using EasyC?

Yes.
(10 char)