Data I/O on FPGA

A NIOS configuration is nothing more than a VHDL/Verilog project that includes a NIOS CPU. In fact you have two methods of combining a NIOS and custom VHDL code:

- include a SOPC entity in your VHDL project, and add your VHDL code next to it

- make a custom component in VHDL and connect it to the CPU inside SOPC builder. You can find an example here (http://www.altera.com/literature/hb/qts/qts_qii54007.pdf).

It depends on what you want to do.