PC to DE2-115 USB Communication

It is difficult to interface JTAG UART with a custom C/C++ program. I prefer to use USB to UART module in this case.

External modules are board that you can connect to DE2, like UM232H: http://www.ftdichip.com/support/documents/datasheets/modules/ds_um232h.pdf.

If you use USB to UART like UM232R http://www.ftdichip.com/support/documents/datasheets/modules/ds_um232r.pdf you can use "altera avalon uart" IP core after doing right connections with DE2.

With UM232H you have to write your IP core to interface module to system.