HID Sensor Usage Tables - USB.org

45 HID Sensor Usages
2. Sensor Backgrounder
This section describes Sensor terminology and the conceptual object model associated with the HID Sensor
Usages. This section is Informative, which means it is only for orientation and guidance.
2.1 Glossary
A number of terms specific to the Sensor subject matter are used in the context of this document. The
following table provides a list of those terms, and the intended meaning.
Accelerometer A device that measures acceleration along one or more linear axes
(traditionally called X, Y, and Z). When the device is still, it can
measure the acceleration of the Earth’s gravity, and can be used to
calculate the device’s orientation (expressed in angles
traditionally called Pitch and Roll). When the device is in motion,
can also measure the speed ups and slow downs. Note that an
accelerometer cannot detect the difference between perfectly still
and a perfectly constant speed.
Actuator A device that causes an output. Technically not a true Sensor
(which acquires an input), but some actuators are represented as
Sensors for convenience.
Altimeter Another name for Barometer.
Altitude Height with respect to some reference level of the Earth. The
most common reference levels are the Geoid (especially when
reported by a GPS) and mean sea level (when reported by a
Barometer).
Ambient Light Sensor Measures the amount of light striking the sensor, from which can
be deduced the amount of ambient light in the local environment.
Ambient Temperature Sensor Another name for Thermometer.
Atmospheric Pressure Sensor Another name for Barometer.
Anemometer Measures wind speed. Also called a Wind Speed sensor.
Barometer A sensor that measures the pressure exerted by the weight of the
atmosphere. Also called an Atmospheric Pressure sensor. The
output can be affected by local weather conditions. Cold weather
results in low pressure; warm weather results in high pressure.
The output is also affected by Altitude; the higher you are, the less
weight of atmosphere is pressing down. As a result, barometers
can also be used to calculate Altitude and therefore are also called
Altimeters.
Category A first-order level of description of a Sensor’s Type. The
Categories of Sensors are: All, Biometric, Electrical,
Environmental, Light, Location, Mechanical, Motion,
Orientation, Scanner, Time, Custom, and Generic. The
Application Programming Interfaces (APIs) of modern operating
systems may provide a way of searching for sensors (for example,
by scanning all of the HID Top Level Collections and/or all of the
Logical sub-Collections) based on the Category description. This
may be convenient and adequate based on application
programmer needs. A more comprehensive search technique is to