Overview

CEC (Consumer Electronics Control) is an HDMI feature that allows devices to send control commands over the HDMI cable. In a simple point-to-point setup, this allows a TV remote to control a connected source device.

CEC works well when a single source is connected directly to a single display. In an HDMI over IP system, however, a single source may be routed to multiple displays simultaneously. Allowing native HDMI CEC to pass through the system could unintentionally send commands to multiple displays or sources at once.

To prevent this, Just Add Power devices isolate native HDMI CEC communication and instead allow CEC commands to be intentionally passed to a specific Encoder or Decoder.

CEC over IP

In a Just Add Power system, the physical CEC link between the source and display is interrupted at the Encoder and Decoder.

• CEC commands from a source stop at the Encoder.
• CEC commands from a display stop at the Decoder.

CEC is then treated similarly to IR over IP or Serial over IP. A control system sends a CEC command to a specific Just Add Power device, which then forwards the command to the connected source or display.

This ensures CEC commands are delivered only to the intended zone, providing predictable behavior in distributed AV systems.

Access

CEC commands can be sent using either the Command Line Interface (CLI) through Telnet or the HTTP API, depending on the control system being used.

All commands are case-sensitive.

Built-In Commands

The following CEC commands are built into Just Add Power devices and are supported in standard drivers:

cec_tv_on.sh

POST /command/cec/tv on

cec_tv_off.sh

POST /command/cec/tv off

cec_watch_me.sh

POST /command/cec/bytes EF 82 10 00

cec_audio_off.sh

POST /command/cec/bytes E0 72 01

cec_audio_on.sh

POST /command/cec/bytes E0 72 00

Firmware Requirements

The cec_mode options described in this article require the following minimum firmware versions:

• Omega Series / Ultra Series: justOS B3.2.0 or later
• MaxColor Series: MAX v4.5.0 or later

CEC Mode Behavior Modification (cec_mode)

A configurable parameter called cec_mode changes how certain built-in CEC commands are handled by the device.

Depending on the selected option, cec_mode can add an input selection command before or after a power command, or change how CEC button press and release commands are transmitted.

These options are useful for displays or AVRs that require additional CEC behavior beyond a standard power command.

Available Options

Multiple options may be applied simultaneously. When more than one is set, all selected behaviors will execute.

wake_on

watch_on

wake_off

extra

Applying the Setting

Use the following syntax in the CLI:

Apply one option:

astparam s cec_mode wake_on

Apply two options:

astparam s cec_mode wake_on wake_off

Apply all options:

astparam s cec_mode wake_on wake_off watch_on

Apply Press & Release option:

astparam s cec_mode extra

Save Settings to Memory

astparam save

Reboot the Device

After saving the configuration, reboot the device for the changes to take effect.

reboot

Custom Commands

If the hexadecimal command sequence is known, any valid CEC command can be transmitted through a Just Add Power device.

Format

CEC commands consist of hexadecimal byte pairs.

The first byte specifies the source and destination logical addresses, while the remaining bytes contain the CEC opcode and any required parameters.

Example:

EF 82 10 00

To send a custom command:

CEC_SEND_BYTES EF 82 10 00

Finding CEC Codes

Because CEC is part of the HDMI specification, many codes are standardized. However, manufacturer implementation varies. Always test commands before deployment.

A commonly used CEC lookup tool is:

www.cec-o-matic.com

CEC-O-Matic is published and maintained by INCYMA. All credit for that tool belongs to its respective owners.

Common Custom Codes

Begin all entries below with CEC_SEND_BYTES