This project aims to breathe new life into old Hi-Fi amplifiers/receivers, by adding network (or automatic) control via a Raspberry Pi.
- Cambridge Audio azur 540A/640A v2, 840A v2, CXA60 (CXA81?)
If you have another Cambridge Audio amplifier, please contact me, I'll do my best to find the relevant documentation and add support for it.
- Python 3 (apt-get install python3)
- pigpio library, with pigpiod running (see https://github.com/joan2937/pigpio/ or http://abyz.co.uk/rpi/pigpio/).
- cec-utils (apt-get install cec-utils) if /usr/bin/cec-client is not already installed.
- Pick an unused GPIO pin on your Pi (the default is GPIO 4).
- Connect your pin to the signal wire of an RCA cable, and a ground to the shield.
- Plug the RCA cable in to the "Ctrl In" socket on your Cambridge Audio amplifier.
ca_amp_ctrl.py is used to send a command to the amplifier.
ca_amp_ctrl.py [-h] [--pin [GPIO number]] [--repeat [positive integer]] [--model [model number]] command
Exactly one command must be specified. Commands differ between amplifier models, for the 540A/640A they are:
| Command | Function |
|---|---|
| ampon | power on |
| ampoff, standby | power off |
| aux, av, cd, dvd, tapemon, tuner | source selections ("av" is the "DMP/MP3" input) |
| source+, source- | select next/previous source |
| tapemon | toggle tape monitoring |
| vol+, vol- | increase/decrease volume (a small increment) |
| mute, muteon, muteoff | mute toggle/on/off |
| clipon, clipoff | probably turns on/off clipping protection (untested) |
| bright | maybe display brightness? |
The other optional arguments are:
-h merely shows brief usage help (including a full list of available commands and amplifier models)
--pin [GPIO number] to specify the GPIO pin to transmit on (default: 4)
--repeat [positive integer] to repeat the command (e.g. vol+/vol- only move the volume a very small amount)
--model [model number] to select your amplifier model, available choices are: CXA60, 840A, or 540A.
The default is 540A, which should also be compatible with the 640A.
CXA60 may also be compatible with CXA81.
cec_stream.py is used to receive commands from a TV via HDMI and forward them on to the amplifier.
The amplifier will turn on & off when the TV does, and will respond to the TV's volume & mute buttons.
Copy cec_stream.py into /home/pi/cec/ and startup_cec into /etc/init.d/, then run:
sudo update-rc.d startup_cec defaults
It will then start/stop when you boot/shutdown. Plug an HDMI cable from your pi into the TV, preferably via the "ARC" HDMI port.