Diagnostics & OBD2

VHAL_HEARTBEAT

What it is

Defines an event that VHAL signals to car watchdog as a heartbeat.

If VHAL supports this property, VHAL should write system uptime to this property at every 3 second. Car watchdog subscribes to this property and checks if the property is updated at every 3 second. With the buffer time of 3 second, car watchdog waits for a heart beat to be signaled up to 6 seconds from the last heart beat. If it isn’t, car watchdog considers VHAL unhealthy and terminates it. If this property is not supported by VHAL, car watchdog doesn't check VHAL health status.

How the ID is built

A property ID is a 32-bit value packing four fields. Reading 0x11500f33 apart:

Field	Mask	Value	Means
Group	0xf0000000	0x10000000	SYSTEM
Area	0x0f000000	0x01000000	GLOBAL
Type	0x00ff0000	0x00500000	INT64
Ordinal	0x0000ffff	0x00000f33	0xf33

Reading it from an app

CarPropertyManager mgr = (CarPropertyManager)
        car.getCarManager(Car.PROPERTY_SERVICE);

CarPropertyValue<Long> value =
        mgr.getProperty(VehiclePropertyIds.VHAL_HEARTBEAT, 0);

This property is read-only — writes are rejected. It fires a callback whenever the value changes.