Communication between NIOSII core and HDL (Verilog) module- Cyclone IVGX

No, you don´t need PIO´s.

I mean, that you can use the PIO code as reference, to write your own.

Than you can create your own component in QSYS and let it communicate via the Avalon Interface with your NIOSII.

Or you can have a look at this tutorial:

ftp://ftp.altera.com/up/pub/altera_material/12.0/tutorials/making_qsys_components.pdf

It describes creating custom components in Verilog or VHDL.

I have createt my first component with this tutorial.

Greets

Olaf