HID Sensor Usage Tables - USB.org

83 HID Sensor Usages
It is up to the device to expose these as required by the particular application in which the device is used.
Note that many of these are strings, and their over-use can result in the need for very large bufffers to
handle the information represented by these report descriptors; these very large buffers may be a problem
for devices with very small amounts of internal memory.
4.2.3 Modifiers: Per-datafield Properties
A number of Properties (transferred in Feature Reports) that can be applied to Data Fields (transferred in
Input Reports) are on a per-datafield basis. This presents some options in how these per-datafield
Properties can be expressed using the definitions in this document.
One way to do so assumes there is only a single type of Data Field, and that the Property applies to all Data
Fields of that type.
.
.
.
HID_USAGE_SENSOR_PROPERTY_CHANGE_SENSITIVITY_ABS,
HID_USAGE_SENSOR_PROPERTY_MAXIMUM,
HID_USAGE_SENSOR_PROPERTY_MINIMUM,
HID_USAGE_SENSOR_PROPERTY_ACCURACY,
HID_USAGE_SENSOR_PROPERTY_RESOLUTION,
.
.
.
Even though the Data Field is not stated, it is assumed that there is only one type supported and that the
Property specified applies in the same way to all examples of that type. For example, if this were a single
Data Field for a thermometer:
HID_USAGE_SENSOR_DATA_EVNIRONMENTAL_TEMPERATURE,
then the Properties specified would apply only to that Data Field. If instead this were a tuple of Data Fields
for an accelerometer:
HID_USAGE_SENSOR_DATA_MOTION_ACCELERATION_X,
HID_USAGE_SENSOR_DATA_MOTION_ACCELERATION_Y,
HID_USAGE_SENSOR_DATA_MOTION_ACCELERATION_Z,
Then the Properties specified would apply to all the Data Fields in the same way.
A more explicit construction has been provided that is semantically equivalent. Data Fields are expressed
by means of a Data Field type and a Modifier Usage Switch.
The per-datafield properties expressed as Data Field Modifiers are defined elsewhere in the document.
Those defined in this document are repeated below for convenience:
//data type usages modifiers
//NOTE: the usage tables actually define these as two bytes, but in order
//to get the define macros to work so these are ‘or-ed’ these are defined
//here as only one byte.
#define HID_USAGE_SENSOR_DATA_MOD_NONE 0x00 //US
#define HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_ABS 0x10 //US
#define HID_USAGE_SENSOR_DATA_MOD_MAX 0x20 //US
#define HID_USAGE_SENSOR_DATA_MOD_MIN 0x30 //US
#define HID_USAGE_SENSOR_DATA_MOD_ACCURACY 0x40 //US
#define HID_USAGE_SENSOR_DATA_MOD_RESOLUTION 0x50 //US
#define HID_USAGE_SENSOR_DATA_MOD_THRESHOLD_HIGH 0x60 //US
#define HID_USAGE_SENSOR_DATA_MOD_THRESHOLD_LOW 0x70 //US
#define HID_USAGE_SENSOR_DATA_MOD_CALIBRATION_OFFSET 0x80 //US
#define HID_USAGE_SENSOR_DATA_MOD_CALIBRATION_MULTIPLIER 0x90 //US
#define HID_USAGE_SENSOR_DATA_MOD_REPORT_INTERVAL 0xA0 //US
#define HID_USAGE_SENSOR_DATA_MOD_FREQUENCY_MAX 0xB0 //US
#define HID_USAGE_SENSOR_DATA_MOD_PERIOD_MAX 0xC0 //US
#define HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_RANGE_PCT 0xD0 //US
#define HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_REL_PCT 0xE0 //US