cec-mqtt-bridge

A HDMI-CEC and IR to MQTT bridge written in Python 3 for connecting your AV-devices to your Home Automation system. You can control and monitor power status and volume.

Features

• HDMI-CEC
  • Power control and feedback
  • Volume control (up/down/specific) and feedback
  • Relay HDMI-CEC messages from HDMI to broker (RX)
  • Relay HDMI-CEC messages from broker to HDMI (TX)
• IR
  • Relay IR keypresses from IR to broker (RX)
  • Relay IR keypresses from broker to IR (TX)

Dependencies

• MQTT (required)

  • MQTT broker (like Mosquitto)

• HDMI-CEC (optional)

  • libcec4 with python bindings (https://github.com/Pulse-Eight/libcec)
    • You can compile the bindings yourself, or use precompiled packages from my libcec directory.
  • HDMI-CEC interface device (like a Pulse-Eight device, or a Raspberry Pi)

• IR (optional)

  • lirc + hardware to receive and send IR signals
  • python-lirc (https://pypi.python.org/pypi/python-lirc/)

Install on Raspbian bullseye

apt-get update
apt-get install build-essential git lirc python3 python3-dev python3-setuptools python3-pip python3-wheel python3-build python3-venv python3-paho-mqtt python3-cec
git clone https://github.com/michaelarnauts/cec-mqtt-bridge.git
cd cec-mqtt-bridge/
./contrib/debian-ubuntu-install.sh
sudo vi /etc/cec-mqtt-bridge.ini

to update

cd cec-mqtt-bridge/
git pull
sudo pip install .

MQTT Topics

The bridge subscribes to the following topics:

topic	body	remark
prefix/cec/device/laddr/power/set	on / standby	Turn on/standby device with with logical address laddr (0-14).
prefix/cec/device/laddr/active/set	yes / no	Turn on/standby device with with logical address laddr (0-14).
prefix/cec/audio/volume/set	integer (0-100) / up / down	Sets the volume level of the audio system to a specific level or up/down.
prefix/cec/audio/mute/set	on / off	Mute/Unmute the the audio system.
prefix/cec/tx	commands	Send the specified commands to the CEC bus. You can specify multiple commands by separating them with a space. Example: cec/tx 15:44:41,15:45.
prefix/ir/remote/tx	key	Send the specified key of remote to the IR transmitter.

The bridge publishes to the following topics:

topic	body	remark
prefix/bridge/status	online / offline	Report availability status of the bridge.
prefix/cec/device/laddr/type	on / off	Report type of device with logical address laddr (0-14).
prefix/cec/device/laddr/address	on / off	Report physical address of device with logical address laddr (0-14).
prefix/cec/device/laddr/active	yes / no	Report active source status of device with logical address laddr (0-14).
prefix/cec/device/laddr/vendor	string	Report vendor of device with logical address laddr (0-14).
prefix/cec/device/laddr/osd	string	Report OSD of device with logical address laddr (0-14).
prefix/cec/device/laddr/cecver	string	Report CEC version of device with logical address laddr (0-14).
prefix/cec/device/laddr/power	on / standby / toon / tostandby / unknown	Report power status of device with logical address laddr (0-14).
prefix/cec/device/laddr/language	string	Report langauge of device with logical address laddr (0-14).
prefix/cec/audio/volume	integer (0-100) / unknown = 127	Report volume level of the audio system.
prefix/cec/mute/status	on / off	Report mute status of the audio system.
prefix/cec/rx	command	Notify that command was received.
prefix/ir/remote/rx	key	Notify that key of remote was received. You have to configure key AND remote as config in the lircrc file.
prefix/ir/rx	key	Notify that key was received. You have to configure key in the lircrc file. This format is used if the remote is not given in the config file.

id is the address (0-15) of the device on the CEC-bus.

Examples

• mosquitto_pub -t media/cec/volup -m ''
• mosquitto_pub -t media/cec/tx -m '15:44:42,15:45'

Configuration

You can either copy config.default.ini to config.ini and adjust its properties, or alternatively declare any of those as environment variables using the format SECTION_KEY (e.g., MQTT_USER).

Lirc

You need a lircrc config file. This can be generated from the lircd.conf of your lirc daemon using the script create_lircrc.py. Simply call this script with the lircd.conf path as first argument. It will print the lircrc contents to stdout and can be easily written to a file:

$ ./create_lircrc.py /etc/lirc/lircd.conf > lircrc

If you write your own lircrc file, notice that the config parameter for each configuration is what is given to the bridge. It is assumed that it is in the format <remote>,<key>. If only one value is given, the remote is expected to be omitted.

The lircrc format (that would be generated by the create_lircrc.py script) should look like:

begin
  remote = <remote-name>
  button = <key-name>
  prog = cec-ir-mqtt
  config = <remote-name>,<key-name>
end

To only get the key (without the remote name in the MQTT topic) use the format without the remote in the config:

begin
  remote = <remote-name>
  button = <key-name>
  prog = cec-ir-mqtt
  config = <key-name>
end

Interesting links

• https://github.com/nvella/mqtt-cec
• http://www.cec-o-matic.com/
• https://kwikwai.com/knowledge-base/the-hdmi-cec-bus/
• https://www.hdmi.org/docs/Hdmi13aSpecs
• https://github.com/Pulse-Eight/libcec/blob/master/include/cec.h
• https://github.com/Pulse-Eight/libcec/blob/master/src/pyCecClient/pyCecClient.py