WHEEL_TICK
What it is
Reports wheel ticks
The first element in the vector is a reset count. A reset indicates previous tick counts are not comparable with this and future ones. Some sort of discontinuity in tick counting has occurred.
The next four elements represent ticks for individual wheels in the following order: front left, front right, rear right, rear left. All tick counts are cumulative. Tick counts increment when the vehicle moves forward, and decrement when vehicles moves in reverse. The ticks should be reset to 0 when the vehicle is started by the user.
int64Values[0] = reset count int64Values[1] = front left ticks int64Values[2] = front right ticks int64Values[3] = rear right ticks int64Values[4] = rear left ticks
configArray is used to indicate the micrometers-per-wheel-tick value and which wheels are supported. configArray is set as follows:
configArray[0], bits [0:3] = supported wheels. Uses enum Wheel. For example, if all wheels are supported, then configArray[0] = VehicleAreaWheel::LEFT_FRONT | VehicleAreaWheel::RIGHT_FRONT | VehicleAreaWheel::LEFT_REAR | VehicleAreaWheel::RIGHT_REAR configArray[1] = micrometers per front left wheel tick configArray[2] = micrometers per front right wheel tick configArray[3] = micrometers per rear right wheel tick configArray[4] = micrometers per rear left wheel tick
NOTE: If a wheel is not supported, its value shall always be set to 0.
VehiclePropValue.timestamp must be correctly filled in.
How the ID is built
A property ID is a 32-bit value packing four fields. Reading 0x11510306 apart:
| Field | Mask | Value | Means |
|---|---|---|---|
| Group | 0xf0000000 | 0x10000000 | SYSTEM |
| Area | 0x0f000000 | 0x01000000 | GLOBAL |
| Type | 0x00ff0000 | 0x00510000 | INT64_VEC |
| Ordinal | 0x0000ffff | 0x00000306 | 0x306 |
Reading it from an app
CarPropertyManager mgr = (CarPropertyManager)
car.getCarManager(Car.PROPERTY_SERVICE);
mgr.registerCallback(callback,
VehiclePropertyIds.WHEEL_TICK,
CarPropertyManager.SENSOR_RATE_ONCHANGE);This property is read-only — writes are rejected. It changes continuously, so subscribe at a sample rate rather than polling.