Nucleus USB Stack
Nucleus USB stack supports
USB 1.1 and
USB 2.0 and
On-The-Go (OTG) supplement to USB 2.0
specification.
- USB 1.1 supports full
speed (12Mb/s) and low speed (1.5Mb/s) data
rates.
- USB 2.0 is backward
compatible with USB 1.1 and supports high
speed (480 Mb/s) data rate.
- USB OTG supports
portable devices to be able to communicate
with each other as the culture of technology
moves away from a PC-centric world.
Nucleus USB stack is available
as either a Nucleus USB Host stack, a Nucleus
USB Function stack or a Nucleus USB OTG stack.
The Nucleus USB Host stack is
the main framework and set of services that
manages a Nucleus USB Host System. It is
responsible for enumerating various devices
that are connected to the Host. It provides
data transfer mechanisms and presents to its
class drivers an abstraction of a USB device
that can be manipulated for configuration and
state management
The Nucleus USB Function stack
is the main framework and set of services that
manages a Nucleus USB Function System. It
manages multiple function controllers. It
implements the standard USB control requests.
It is responsible for notifying the class
drivers of any data transfers initiated by the
Host. It provides the necessary USB
abstraction to the class drivers. It interacts
closely with the function controller hardware
driver to provide data transfer services over
USB to the class drivers
The Nucleus USB Function stack
comes with a descriptor utility that can
automatically create endpoint descriptors
required by Function stack. This utility is
found to be very useful when dealing with a
composite device which consists of multiple
functions on the same device. For example a
camera with a camera and dual audio channels
and a microphone. Because the descriptors are
hierarchical in nature and the data structures
of the he descriptors can be fairly large and
quite cryptic. See
more
The Nucleus USB OTG stack is
the main framework and set of services that
manages a Nucleus USB OTG System. It consists
of Nucleus USB Host stack and Nucleus USB
Function stack with necessary OTG protocols
(Host Negotiation Protocol (HNP), Session
Request Protocol (SRP)) support to allow
connected portable devices to automatically
determine which device is the host and which
is the function.
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See Also:
Applications,
Benefits,
Collateral, and
Overview
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