At start, some frames are employed for "next frame description", they can generally be ignored, as our USB architecture is fixed and minimal (one USB joystick, that's all)
==== go further with USB sniffer ====
A better way to snif USB could be generation of TCP/IP packets encapsuling USB packets, and record them directly on PC from a RJ45 plug, using this way I could save more than 10 seconds of information transmission (RAM size is limited on FPGA platfoms)
=== Why NEXYS2 500kgates starter kit ===