USB Stack

This stack includes the USB Device Stack, USB Host Stack and common definitions.

Modules
	USB Stack Device
	This module includes USB Stack Device implementation.
	USB dual role driver
	USB low-level driver for dual role features.
	USB Stack Host
	This module includes USB Stack Host implementation.
	USB Protocol Definitions
	This module defines constants and data structures provided by the USB 2.0 specification.
	Atmel USB Identifiers
	This module defines Atmel PID and VIDs constants.