Rotel Amplifier Control

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

Building the Docker Container

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

git clone git@github.com:djthorpe/go-rotel.git
cd go-rotel
make docker

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

Configuring Home Assistant

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, etc

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