Hi Yann,

First, let me say that your english is better than my [insert your native language here], so there are no excuses or apologies necessary. Trust me when I say that if your shortcomings in english lead to an ambiguity, we'll ask for clarification.

Now, just in case you haven't already gotten it, the data sheet for your chip can be found here.

http://www.atmel.com/dyn/resou...oc4109.pdf

The USB description begins on page 82, and the required configuration details begin on page 86. I'm pretty sure that you're going to need a driver loaded in the PC to talk to this unit through the USB, though you will likely be able to use one of the standard drivers that comes in Windows. Also the chip is going to require initialization (setting the address, defining endpoints, etc.) before it will communicate with the USB firmware/drivers. That the hardware is already there is indeed a big help, but USB is a very software/firmware and protocol intensive scheme. The "user friendliness" comes at quite a price.

Finally, do you know if Atmel has updated FLIP to use the USB connection? This is something else that will need verification.