rs232 uart ip :: user guide

No - you don't need any C code to send characters to the UART.

However, you mention a 'Hello World' program as your 'reference'. This will be in C and will be for use on, typically, a Nios processor core. So, I'm a little confused as to what you're trying to do.

You can either connect the UART IP directly in your Verilog - as you showed in your first post (no c code required), or you connect the UART IP to a Nios soft processor, via Avalon, and run software (C code) on the Nios - which is where the 'Hello World' programs comes in.

Which one are you're trying to do?

Cheers,

Alex