HID Sensor Usage Tables - USB.org

58 HID Sensor Usages
See Also
For more information about USB bus operation concepts and terminology; please refer to the Universal
Serial Bus Specification (Reference Document [1]).
For more information on Human Interface Device concepts, terminology, and technical details; please refer
to the Device Class Definition for Human Interface Devices specification (Reference Document [2]),
including particularly Section 4.4.
3.3 HID Logical Devices
Upon first connection and/or detection, the Host Computer queries the Sensor Device for identification
information. The device returns a HID Report Descriptor as defined by the HID Specification.
See Also
For more information about HID Report Descriptors; please refer to Section 6.2.2 of the Device Class
Definition for Human Interface Devices specification (Reference Document [2]).
The HID Report Descriptor contains metadata describing the layout of one or more logical devices, the
Reports that each logical device can transfer along with their Report IDs, and the characteristics of Report
Items within each Report.
Important components of the HID Report Descriptor are one or more elements called Collections. A
Collection can be used to describe a Sensor logical device.
Collections may be nested within other collections, and such are declared as either
Collection(Physical) or Collection(Logical).
The un-nested Collections (those not contained within any other Collection) are known as Top Level
Collections (or “TLC” for short) and are customarily declared as Collection(Application).
Top Level Collections are unique because most modern Operating Systems treat them as a logical device
object; they expect and attempt to load a device driver to service the device.
There are two strategies that can be used to organize the definitions of sensors into Collections.