I took one of my past Arduino projects and updated the code to work directly with the underlying architecture on an ATmega328P. The project was originally controlled by code that utilized various Arduino libraries. I rewrote the code to use avr-libc, a C library for the AVR family of microcontrollers.
The Rock Band guitar-controller is a form of Human Interface Device (HID). Many USB game controllers follow an HID-compliant standard. This standard allows us to read digital and analog inputs easily from any program.
My past work with this guitar-shaped controller was back in 2014 when I drove a robot around using the buttons on this controller.
This is a quick prototype robot designed to test certain mechanisms before spending my time building a more polished robot. It has two wheels and drives them forwards or backwards as the body tilts in order to keep the robot balanced upright.