Download uC-USB-Device User`s Manual v4.05 - Doc

µC/USB Device User's Manual
transmission/reception of data to/from the device using the bulk endpoints belonging to the
Data Class Interface (DCI). Isochronous endpoints are not supported in the current
implementation. The CDC base class enables you to have several DCIs along with the CCI.
The application can communicate with the host using the communication API offered by the
CDC subclass.
As a CDC function is described by a minimum of two interfaces, when the CDC function is
used with other class functions to form a composite device, the Interface Association
Descriptor (IAD) must be present in the Configuration descriptor. IAD groups two or more
interfaces so that the host sees these interfaces as one unique class function. It allows the host
to load the same driver for all these interfaces to manage the CDC function. As soon as the
CDC class is added to a configuration during the class initialization, the µC/USB-Device stack
automatically configures the use of IAD for this CDC function. Thus, IAD will be always part
of the Configuration descriptor whatever the device type, single or composite.
IAD is supported under Mac OS X 10.7 and later. Prior versions of Mac OS X do not support IADs,
and moreover can only support non-composite, single function CDC devices. Nevertheless given that
USB device stack always uses IAD, a single CDC device won't work with Mac OS X prior to version
10.7.
Copyright 2015 Micrium Inc.
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