Freescale Semiconductor TWR-MCF52259-Ethenet - page 101

TM
Software – General Concepts
The General USB Process
How Does the Host Know a Device’s Requirements?
Interface
Descriptor
//------------------------------------------------------------
// Sample Standard Interface Descriptor Type
// Definition Fields
//------------------------------------------------------------
Length (9 bytes)
Descriptor Type (INTERFACE)
Interface Number (interface number, zero based, and
incremented once for each new interface descriptor.)
Alternate Setting (value used to select alternative
setting)
Number of Endpoints (number of Endpoints used for
this interface)
Interface Class (e.g., HID, mass storage))
Interface Sub Class (subclass Code - assigned by
USB Org)
Interface Protocol (Protocol Code assigned by USB
Org)
Index (Index of String Descriptor Describing this
interface)
The interface descriptor groups
endpoints into functional groups
that perform a single feature of
the device.