Volumio Version: 2.779
Hardware: RPi 3B+, blackhat GPIO breakout, AlloDigiOne feeding SPDIF to DAC
DAC: Khadas Toneboard feeding Allo Relay Attenuator for Hardware Volume Control.
The analog left and right outputs from the KTB feed into an Allo Relay Attenuator (ARA) for hardware volume control, which I wish to control from the volumio web UI. The ARA gets its inputs from an RPi breakout board which feeds 5v, grd, SDA, SCK and RPIO 17 to the ARA.
This configuration is supposed to work – see Volumio website https://volumio.org/product/allo-relay-attenuator/ point 5 – “Please note: to use the Allo Relay Attenuator directly on the Raspberry PI you need GPIO spacers, since the Allo Relay Volume Attenuator is not HAT compliant”.
The only two Volumio plugins installed are DSP for Volumio v1.8.5 and Allo Relay Attenuator Plugin v1.3.0.
Both plug-ins say they are installed correctly, and both are enabled. The DRC plugin works fine. The ARA plugin reports no errors, but under playback options / volume options, there is no hardware volume control. Also the ARA also does not appear in a list of ALSA devices.
When I use the r_attenuc client program from an SSH command line session, I can correctly get the current value of volume on the ARA, and set the ARA volume down or up to any value between 0 and 63. So the basic wiring to and from the ARA is working, but it is not detected as a hardware volume control by Volumio.
Any hints as to how to debug this would be much appreciated. What are the key settings I should be checking? What logs might give any clues?
From looking at the Volumio architecture diagrams, it seems that the ARA plugin takes inputs from the Volumio Web UI, pass them through the Websocket interface, and through the command router possibly to the ARA as an ALSA device.