The code here is for bridging a Rotel Amplifier to MQTT, for integration into Home Assistant, where the Rotel Amplifier is connected to the serial port of a host machine. The requirements are:

• A Linux host connected to the Rotel Amplifier via a RS232 port
• A MQTT broker running on the same machine or on the network
• Docker installed on the host machine

To run the docker container on an ARM64 host,

docker run --rm --name rotel --device=/dev/ttyUSB1 \
  ghcr.io/djthorpe/rotel-linux-aarch64:1.0.7 \
  rotel -mqtt localhost:1883 -tty /dev/ttyUSB1

This assumes that the serial port is /dev/ttyUSB1 and the MQTT broker is running on the same machine. The command line arguments for the rotel command are:

Usage of rotel:
  -mqtt string
    	MQTT broker address (default "localhost:1833")
  -qos int
    	MQTT quality of service
  -topic string
    	Topic for messages (default "homeassistant")
  -tty string
    	TTY for Rotel device (default "/dev/ttyUSB0")
  -version
    	Print version and exit

To build the docker container, ensure you are logged into docker. The Makefile contains some parameters you'll want to change. Then,

git clone [email protected]:djthorpe/go-rotel.git
cd go-rotel
make docker

This will make the container and upload it to the registry.

Assuming you have the MQTT integratiion installed, you can create a card in Home Assistant to control the amplifier, that looks like this:

The card can be created using the following YAML:

type: entities
entities:
  - entity: switch.rotel_amp00
  - entity: number.rotel_amp00
  - entity: select.rotel_amp00
title: Rotel
show_header_toggle: false
state_color: true

Contributions are welcome. Please raise an issue or pull request on the GitHub repository. The limitations at the me moment are,

• A -name parameter should uniquely identify the amplifier (at the moment it's hard-coded to "amp00")
• Only the power, volume and source are exposed (it wouldn't be difficult to expose more controls). These are the other controls which could be added:
  • ROTEL_FLAG_MUTE
  • ROTEL_FLAG_BASS
  • ROTEL_FLAG_TREBLE
  • ROTEL_FLAG_BALANCE
  • ROTEL_FLAG_BYPASS
  • ROTEL_FLAG_SPEAKER
  • ROTEL_FLAG_DIMMER
• Implement the following push buttons: play, stop, pause, track_next, track_prev, mute_toggle, vol_up, vol_down, bass_up, bass_down, bass_reset, treble_up, treble_down, treble_reset, balance_left, balance_right, balance_reset, speaker_a_toggle, speaker_b_toggle, dimmer_toggle, power_toggle
• Code is only tested on an A12 amplifier, but should work on other models
• A github workflow should be used to build the containers on different platforms and architectures
• Only one amplifier and serial port can be controlled per host