PC - Uart communication

Greetings,

I'm a new Nios (I) user. I'm working in my final project about video coding and I've had problems with the communication between the pc and the board.

Until now, the idea is that I could send many bytes to Nios uart, corresponding to pixels from an image, and I could see them with a "printf". However, when I run my Nios sw code (in C), it waits and waits for receiving data and it blocks the serial port; so, my another program (which sends pixels from a file) in Java says "Port is busy". Besides, if I run first the program in Java, bytes are sent but the program in C doesn't work, it finishes inmediately.

Any help?? http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif

Is it neccesary using interrupts?

Thanks in advance.