Changes

=== USB joystick ===

Before learning final platform and its embedded controlers (USB joystick with a controler, is just 7 wires : left right up down buttonX buttonY buttonZ), and after having destroyed 12 collector original joysticks during tests... I did some research about simply connecting a modern USB joystick into FPGA. It was a part of my Agile Method run, I worked about two months on it.

==== Sniffing USB frames ====

===== USB mode: USB1 or USB2; low speed, full speed or high speed =====

For sampling, I speed up five times the saving speed on RAM. I succeed sampling an USB1 transmission: "Logitech dual action USB joystick", and an USB2: "Sony PS3 USB joystick". PS3 joystick is not stable enough with my FPGA, but Logitech joystick is correct.

===== pull up and pull down =====

If you respect USB protocol, you have to plug some pull-up and pull-down resistors and some capacitors. But as I am a bad electrician, I just simulate then in VHDL, they are important because they cause USB speed negotiations. You also have an electronic mechanism in order to detect presence of joystick plug, I don't care about it.