KNOW THE LINGO – WHAT IS A CEC?

By: Joseph D. Cornwall, CTS-D, CTS-I
AV Technology Evangelist — Legrand

This is one installment in a series of articles in which we'll lift the veils of misunderstanding from the lingo of the AV industry. You can see the rest of our Know the Lingo series in AV University, where you can earn AVIXA CTS certification renewal credits while you learn!

Technical lingo is a kind of shorthand that's used to express concepts common to a specialized area of focus. Technical lingo is important because it provides a precise or unique "shorthand" description of a device, effect or concept. Unfortunately, if you aren't comfortable and familiar with the lingo of a topic it can be a tall hurdle to communicate efficiently with folks who consider the jargon of their field to be "self-explanatory." 

What is a CEC?

Consumer Electronic Control, often referred to simply as CEC, is a feature that is part of the HDMI standard. CEC is designed to allow one device to control up to 15 other connected CEC-enabled devices using an HDMI interface. For example, a Blu-ray DVD player may be able to control an attached display such as a flat panel LCD TV. CEC allows two forms of control—user initiated, and device initiated.

An example of user-initiated control would be pressing the volume button on a Chromecast with Google TV remote control and controlling the display as a result. It's important to understand this isn't the same as a "universal" remote control as the controlling signals are actually traveling through the HDMI cable from the streaming player to the display. 

An example of a device-initiated control would be automatically changing the input of the attached display to "DVD" when the play button is pressed on the BluRay player. Again, the control signal is sent via the HDMI cable.

CEC is a one-wire bidirectional serial bus. One conductor in the HDMI cable is designated to carry the CEC signal. While CEC wiring is mandatory in all HDMI connections beginning with the very first HDMI 1.0 release in 2004, the actual implementation of CEC capability is not mandatory. Each manufacturer is free to include or exclude CEC functionality in particular products.

Manufacturing companies often give proprietary names to their implementation of CEC functionality in a family of products. Trade names for CEC include Samsung's Anynet+, Sharp's Aquos Link, Sony's BRAVIA Link and Panasonic's VIERA Link. Despite these copyrighted names, all of these systems are implementations of the CEC standard.

As might be expected, Consumer Electronics Control (CEC) is often not implemented on products designed expressly for the commercial market. For example, an LG commercial display may not respond to CEC commands, while the corresponding model from the consumer line does. Typically, this is because the CEC functionality has the ability to be turned on or off via a menu selection on a device's service menu.

The following is a list of the most common HDMI-CEC commands:
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• One Touch Play allows devices to switch the TV to use it as the active source when playback starts
• System Standby enables users to switch multiple devices to standby mode with the press of one button
• One Touch Record allows users to record whatever is currently being shown on the HDTV screen on a selected recording device
• Timer Programming allows users to use the electronic program guides (EPGs) that are built into many HDTVs and set-top boxes to program the timer in recording devices like PVRs and DVRs
• System Information checks all components for bus addresses and configuration
• Deck Control allows a component to interrogate and control the operation (play, pause, rewind etc.), of a playback component (Blu-ray or HD DVD player, or a Camcorder, etc.)
• Device Menu Control allows a component to control the menu system of another component by passing through the user interface (UI) commands
• Routing Control controls the switching of signal sources
• Device OSD Name Transfer transfers the preferred device names to the TV set
• System Audio Control allows the volume of an AV receiver, integrated amplifier or pre-amplifier to be controlled using any remote control from a suitably-equipped device(s) in the system