Introduction to CEC
What is CEC ?
CEC stands for Consumer Electronics Control.
CEC is a set of commands that utilizes HDMI’s two-way communication to allow for single remote control of any CEC-enabled devices connected with HDMI. For example, CEC includes one-touch play, so that one touch of play on the DVD will trigger the necessary commands over HDMI for the entire system to power on and auto-configure itself to respond to the command. CEC has a variety of common commands as part of its command set, and manufacturers who implement CEC must do so in a way that ensures that these common command sets interoperate amongst all devices, regardless of manufacturer.
CEC is an optional feature within the HDMI specification, which is supported by some manufacturers under their own proprietary names for their implementation of part of the CEC command set.
CEC uses a one-wire bus running at approx. 400 Hz and is able to send around 30 bytes per second.
CEC is already available today but with a very limited multi-vendor interoperability.
|Panasonic||EZSynch / HDAVI / Viera Link|
|Sony||Bravia Theater Synch / Bravia Link|
|Toshiba||CE-Link / Regza Link|
- Request : ask another device to take an action or give information
- Informative : status messages
- Targeted : sent to a unique device
- Broadcast : sent to all the devices within the CEC networks
According to the HDMI-CEC specification, features are classified into two groups, end-user and supporting features. Some other "administrative" messages related to the general protocol are not officially classified.
- One Touch Play
- Allows a device to be played and become the active source with a single button press.
- System Standby
- Enables the user to switch all devices to standby with one button press.
- One Touch Record
- Offers a What You See Is What You Record (WYSIWYR) facility, meaning that whatever is shown on the TV screen is recorded on a selected Recording Device.
- Timer programming
- Allows the user to program the timers in a Recording Device from an EPG running on a TV or STB.
- Deck Control
- Enables a device to control (e.g. play, fast forward etc.) and interrogate a Playback Device (a deck).
- Tuner Control
- Allows a device to control the tuner of another device.
- Device Menu Control
- Enables a device to control the menu of another device by passing through user interface commands.
- Remote Control Pass Through
- Enables remote control commands to be passed through to other devices within the system.
- System Audio Control
- Allows an Audio Amplifier / Receiver to be used with the TV. The volume can be controlled using any the remote controls of any suitably-equipped devices in the system.
- Device OSD Name Transfer
- Enables devices to upload their preferred OSD name to the TV. The TV can then use this name in any menus associated with that device.
- Device Power Status
- Allows the current power status of a device to be discovered.
- OSD Display
- Enables a device to use the on-screen display of the TV to display text strings.
- Routing Control
- Allows the control of CEC Switches for streaming of a new source device.
- System Information
- Queries the system to determine device addresses and language.
- Vendor Specific Commands
- Allows a set of vendor-defined commands to be used between devices of that vendor.
- Audio Rate Control
- Allows an Amplifier to fractionally increase or decrease the playback rate of an audio source.
General protocol messages
- Abort mechanisms
- Enables messages to handle abort mechanism