The repo contains the VHDL code and some C++ code that interfaces with the board and displays the results. If you have that particular board, it would be a good basis for a different project.

This code is intended to run on an FPGA and includes a software-only version of the AVR 8-bit microcontroller core. Essentially, you’ll simulate VHDL code that simulates AVR hardware.

Design and Simulation of 8255 Programmable Peripheral Interface Adapter Using VHDL The 8255A Programmable Peripheral Interface (PPI) implements a general-purpose I/O interface to connect ...

The simulation of the system proves all the features mention above. They have designed the system using VHDL codes in Xilinx & analog filter simulation in Matlab.