HDMI-CEC MQTT adapter

This is a simple connector to expose an HDMI-CEC adapter (e.g. PulseEight, possibly Raspberry PI) via MQTT.

Usage

This tool is primarily meant to be run from a docker container.

docker run --privileged -e MQTT_URL=tcp://localhost:1883 -v /dev/ttyACM0:/dev/ttyACM0 tobiasha/hdmi-cec:latest

Note that privileged mode is required to be able to use the HDMI CEC device and the device needs to be mounted into the container. Depending on the type of CEC adapter you might need to change the device name.

Kubernetes

A sample Kubernetes deployment file is provided in the deploy subdirectory, it can also be used as a kustomize base.

Manual build

If you want to build the tool yourself or use it without docker, check the Dockerfile for build details. CGO is required!

Compile dependencies:

• libcec-dev
• udev-dev
• p8-platform-dev

Raspberry PI

It should be possible to build and use this for a Raspberry PI, but I haven't tested that yet and do not have a pre-made Docker image for it at this time. PRs welcome!

Configuration

Configuration is exclusively done via environment variables:

Name	Default	Description
MQTT_URL		MQTT Endpoint URL
MQTT_USERNAME		MQTT Username
MQTT_PASSWORD		MQTT Password
MQTT_TOPIC	cec	MQTT Topic prefix
CEC_DEVICE	/dev/ttyACM0	CEC device file

Topics

The prefix /cec is the default and can be switched by specifying the CEC_DEVICE environment variable. Some operations require you to specify a device logical address, it can be determined by reading from the /cec/list topic. Usually the TV seems to have logical address 0.

/cec/list

The tool will continuously poll the list of HDMI devices and push it to this topic. It should be treated as read-only for users. The list will also contain the logical address of the connected devices that is required for some operations.

/cec/transmit

Publishing to this topic will transmit the given payload as arbitrary HDMI-CEC command. See for example cec-o-matic for details.

/cec/mute

Publishing to this topic (payload is irrelevant) will toggle the mute status.

/cec/key/<addr>

Publishing to this topic sends the key specified in the payload to the HDMI device with the logical address. See the cec library for valid key names.

/cec/power/<addr>

Publishing the payload on to this topic will turn the device with the given logical address on, publishing any other value will turn it off.

/cec/volume

Publishing the payload up will turn the volume up, publishing any other value will turn it down.