PC software for FPGA control through USB port

Thanks everybody for your suggestions and comments.

The facts are :

- My final objective is to develop a commercial product prototyped and based on the Cyclone III DSP dev. kit design. The provision of an USB port for PC control seems the unavoidable choice for any commercial product nowadays.

- I like the idea of a simple separate USB to RS232 or RS485 converter, but unfortunately the Dev. kit doesn't provide such a simple serial port.

- It's true that the USB port of the Dev. kit is mainly intended for USB-blaster use but the USB fifo chip is fully interfaced to the FPGA which made me think it was also planned for user application purposes.

- Using Ethernet instead of USB is a possibility, but this would appear as a normal choice for the end-user only if it provides the benefits of an embedded web-server. Otherwise, in the case of a simple PC software, USB choice appears as obvious.

To conclude and further to the thoughts you inspired me, I am hesitating between 2 solutions :

1. Continue with an USB + PC software based approach, knowing that no simple pre-made solution exist for low-level communication and that I will have to take care of drivers mostly by myself.

2. Move to an Ethernet + embedded web-server approach.

Does anybody has an opinion on which could be the most simple overall ?

Do you know if an embedded web-server solution (free or paying IP) i.e. based on NIOS core already exists ? (I intend to start a new topic about that).

Whatsoever, I am quite surprised that the control of an FPGA based product from a PC is not a more covered area. I assume this should be a basic common requirement for many companies. This could be an interesting opportunity to provide some new IPs and make money of it...