Designing CEC into your next HDMI Product There is a little-known one-wire bus snaking its way through your HDMI products. The bus, known as the consumer electronics control (CEC) bus, is the basis for a new level of automatic control in HDMI-interfaced systems. With the recent release of a CEC compliance test specification and commercial CEC test equipment, consumer electronic companies are now poised to implement CEC in their products. In fact, new CEC-enabled products are expected to begin shipping in April 2006. The basic technology of the CEC bus originated in Europe, on the SCART interface, where it’s been used with great success for many years. HDMI borrows and improves on the basic SCART technology, allowing AV products to discover and communicate with one another across a system. CEC makes possible global controls, which build on existing point-to-point E-DDC-based “plug & play” automation to minimize the number of IR remotes and key-presses required for basic operation of a system. CEC assumes that all AV source products in a system are directly or indirectly connected to a “root” display. HDMI connections form an up-side-down tree, with a display as the “root”, switches as “branches”, and various source products as “leaf” nodes. For example, CEC allows users to connect a mix of AV products as shown in Figure 1, place a DVD into the player, press PLAY, and let CEC handle the rest. Figure 1 – HDMI CEC System CEC is coming to HDMI. The CEC bus allows all products in the system to potentially discover and communicate with each other CEC enables global simplified (single remote) system control in HDMI-interfaced systems CEC will automatically power-on the appropriate produc...
