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Chapter 15 described how to use USB device controllers designed specifically

for virtual COM-port applications. USB virtual COM-port devices can also use

just about any generic full- or high-speed USB device controller with support-

ing firmware. As with any USB device, the descriptors returned by the device

determine which INF file the PC uses to identify drivers for the device. A USB

virtual COM-port device can use drivers provided by Windows or vendor-spe-

cific drivers.

USB virtual COM-port devices that use the drivers provided by Windows

belong to the USB communication devices class. This chapter introduces the

class and its use in virtual COM-port devices.

 



 
 

The USB communication devices class (CDC) encompasses a variety of

devices, including telephones and “medium-speed” networking devices. The

telephones group includes generic virtual COM port devices as well as analog