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configs.gg23.audio: Bluetooth A2DP receiver into the hub
acheron gets BlueZ (adapter "gg23", UB500 dongle) as an A2DP sink only;
WirePlumber's bluez monitor targets received streams at the "hub" sink,
like roc-lan and AirPlay. A bt-agent (NoInputNoOutput) accepts pairing
without PIN. A Home Assistant button (MQTT discovery) opens a 120s
discoverable/pairable window; afterwards bonded devices are trusted so they
reconnect any time, and a binary_sensor shows the window state.
author
Hermes
committer
lassulus
date
(Oct 16, 2026, 10:47 PM CEST)
commit
49f39a5a
49f39a5acc0448620f419d8d820f9e37bd381801
parent
d48ef870
d48ef870c48d4c9098e3a2479747a7dd7969ebac
+120
-1
+120
-1
configs/gg23/audio/hub.nix
+120
-1
configs/gg23/audio/hub.nix
···
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# virtual "hub" sink, whose monitor is linked to the ROC sinks of the rooms
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# selected with `audio-room` or from Home Assistant (MQTT). Senders: any LAN
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# machine via ROC (while `gg23-audio` from tools/gg23-audio runs), barnacle
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# via AirPlay 2 (shairport-sync + nqptp). Rooms run ./room.nix.
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# via AirPlay 2 (shairport-sync + nqptp), phones via Bluetooth A2DP (paired
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# during the window opened by the "Bluetooth pairing" button). Rooms run
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# ./room.nix.
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{
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self,
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config,
···
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icon = "mdi:speaker-multiple";
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};
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}) choices;
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# seconds acheron stays discoverable and pairable after the button press
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pairingTimeout = 120;
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bluetoothDiscovery = [
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{
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topic = "homeassistant/button/bluetooth_pairing/config";
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config = {
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name = "Bluetooth pairing";
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unique_id = "acheron_bluetooth_pairing";
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command_topic = "gg23/bluetooth-pairing/set";
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icon = "mdi:bluetooth-connect";
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};
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}
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{
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topic = "homeassistant/binary_sensor/bluetooth_pairing/config";
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config = {
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name = "Bluetooth pairing";
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unique_id = "acheron_bluetooth_pairing_state";
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state_topic = "gg23/bluetooth-pairing/state";
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icon = "mdi:bluetooth-connect";
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};
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}
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];
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in
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{
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services.pipewire = {
···
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"sink.props"."node.description" = "${r} (ROC)";
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};
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}) rooms;
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};
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# phones play into the hub: acheron is only an A2DP sink (no headset or
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# LE audio roles), and the received stream targets "hub"
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wireplumber.extraConfig."10-bluetooth-hub" = {
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"monitor.bluez.properties"."bluez5.roles" = [ "a2dp_sink" ];
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"monitor.bluez.rules" = [
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{
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matches = [ { "node.name" = "~bluez_input.*"; } ];
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actions.update-props."target.object" = "hub";
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}
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];
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};
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};
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# The UB500 dongle (RTL8761BU) firmware comes from linux-firmware.
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# Discoverable and pairable only after the "Bluetooth pairing" button.
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hardware.bluetooth = {
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enable = true;
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settings.General = {
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Name = "gg23";
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# audio/video major class, loudspeaker, so phones show a speaker
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Class = "0x200414";
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DiscoverableTimeout = pairingTimeout;
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PairableTimeout = pairingTimeout;
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# a phone that forgot acheron can pair again during the window
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JustWorksRepairing = "always";
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};
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};
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# Accepts pairing without PIN (NoInputNoOutput is just works) and service
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# connections of paired devices.
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systemd.services.bluetooth-agent = {
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wantedBy = [ "bluetooth.service" ];
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bindsTo = [ "bluetooth.service" ];
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after = [ "bluetooth.service" ];
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serviceConfig = {
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ExecStart = "${pkgs.bluez-tools}/bin/bt-agent -c NoInputNoOutput";
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DynamicUser = true;
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Restart = "always";
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RestartSec = 2;
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};
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};
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···
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serviceConfig = {
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DynamicUser = true;
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SupplementaryGroups = [ "pipewire" ];
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Restart = "always";
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RestartSec = 2;
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};
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};
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# MQTT button -> pairing window. BlueZ itself turns discoverable/pairable
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# off after pairingTimeout; then devices bonded in the window get trusted,
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# so they reconnect without the agent, and the state goes back to OFF.
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systemd.services.bluetooth-pairing = {
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wantedBy = [ "bluetooth.service" ];
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bindsTo = [ "bluetooth.service" ];
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after = [
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"bluetooth.service"
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"mosquitto.service"
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];
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path = [
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pkgs.mosquitto
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config.systemd.package
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];
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script = ''
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${lib.concatMapStrings (d: ''
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mosquitto_pub ${mqtt} -r -t ${d.topic} -m ${lib.escapeShellArg (builtins.toJSON d.config)}
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'') bluetoothDiscovery}
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adapter() {
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busctl set-property org.bluez /org/bluez/hci0 org.bluez.Adapter1 "$1" b "$2"
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}
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state() {
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mosquitto_pub ${mqtt} -r -t gg23/bluetooth-pairing/state -m "$1"
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}
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trust() {
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for d in $(busctl tree --list org.bluez | grep '/dev_[0-9A-F_]*$'); do
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if [ "$(busctl get-property org.bluez "$d" org.bluez.Device1 Bonded)" = "b true" ]; then
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busctl set-property org.bluez "$d" org.bluez.Device1 Trusted b true
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fi
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done
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}
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adapter Discoverable false
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adapter Pairable false
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trust
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state OFF
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mosquitto_sub ${mqtt} -t gg23/bluetooth-pairing/set | while read -r _; do
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if [ -n "''${window-}" ] && kill -0 "$window" 2>/dev/null; then
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continue
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fi
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adapter Pairable true
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adapter Discoverable true
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state ON
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(sleep ${toString pairingTimeout}; trust; state OFF) &
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window=$!
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done
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'';
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serviceConfig = {
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DynamicUser = true;
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Restart = "always";
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RestartSec = 2;
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};