afoht / pi_hifi_ctrl

Raspberry Pi Hi-Fi Amplifier Control

pi_hifi_ctrl

Raspberry Pi Hi-Fi Amplifier Control

This project aims to breathe new life into old Hi-Fi amplifiers/receivers, by adding network (or automatic) control via a Raspberry Pi.

Supported Amplifiers:

• 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.

Dependencies:

• 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.

Wiring:

• 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 Usage:

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 Usage:

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.