8.3 Device Model | ITV Handbook: Technologies and Standards

A distinction is made between devices and functional components . A good example of this distinction can be found in a normal TV set. Although the TV set is generally one physical box, it contains several distinct controllable entities (e.g., the tuner, display, audio amplifier , etc.). The controllable entities within a device are called functional components. All devices fall into four categories:

FAV : Full audio video devices
IAV : Intermediate audio video devices
BAV : Base audio video devices
LAV : Legacy audio video devices

HAVi-compliant devices are those in the first three categories; all other consumer electronics devices fall into the LAV category. FAVs and IAVs are controllers while BAVs and LAVs are controlled devices.

8.3.1 FAV Devices

FAV devices contain a complete set of the software elements comprising the HAVi architecture. This device class generally has a rich set of resources and is capable of supporting a complex software environment. The primary distinguishing feature of an FAV is the presence of a run-time environment for Java bytecode. This allows an FAV to upload bytecode from other devices and so provide enhanced capabilities for their control. Likely candidates for FAV devices would be set-top boxes, digital TV receivers, general purpose home control devices, and even Home PC's.

8.3.2 IAV Devices

IAV devices are generally lower in cost than FAV devices and more limited in resources. They do not provide a run-time environment for Java bytecode and so cannot act as controllers for arbitrary devices within the home network. Nevertheless, an IAV may provide native support for control of particular devices on the home network.

8.3.3 BAV Devices

These are devices that, for business or resource reasons, choose to implement future-proof behavior by providing uploadable Java bytecode, but do not host any of the software elements of the HAVi architecture. These devices can be controlled by an FAV device via the uploadable bytecode or from an IAV device via native code. The protocol between the BAV and its controller may or may not be proprietary. Communication between an FAV or IAV device and a BAV device requires that HAVi commands be translated to and from the command protocol used by the BAV device.

8.3.4 LAV Devices

LAV devices are not aware of the HAVi architecture. These devices use proprietary protocols for their control, and quite frequently have simple control-only protocols. Such devices can work in the home network but require that FAV or IAV devices act as a gateway. Communication between an FAV or IAV device and LAV device requires that HAVi commands be translated to and from the legacy command protocol.