A2DP Source Reconnections -> Tied to i2s.is_master?

[SamObde]

I've been banging my head on this problem for a few days now. My original test sketch worked perfectly. Now that I am integrating the ability to change between a source and a sink on reboot I run into these problems...

Short story: If I use i2s.is_master = false then a2dp reconnections do not work properly. It sometimes works if it disconnect within the first few seconds, but after a good connection is established the esp32 never actually disconnects from the speaker therefore never reconnects. I finally figured out if I simply turn on i2s,is_master = true then it works perfectly every time. Why?

Here is my code to init the bluetooth. Depending on btrole its either a sink or a source and it gets initialized based on that. After spending days going thru debug logging and all kinds of testing it comes down to one simple change, is_master = true or false. I believe this is not your library but maybe the esp-idf core but I'm not sure.

Arduino core 3.1.3 up to 3.2.0. SDK 5.3.2 up to 5.4. AudioTools up and down the range of changes over the past few months. No changes - except is_master = false/true seems to be pretty telling that's where the problem is.

  Serial << "Starting AudioTools.\n";

  // Setup Audio Stuff below.
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Warning);

  getHeap();

  Serial << "Starting I2S... i2s mode: " << (btrole ? "RX_MODE" : "TX_MODE") << " Buffers: " << i2s_buffer_count << "," << i2s_buffer_size << "\n";

  // Setup default I2S output FOR BOTH ROLES HERE
  i2s_cfg = i2s.defaultConfig(btrole ? RX_MODE : TX_MODE); // Initialize cfg based on role
  i2s_cfg.port_no = 0;                                     // Common settings
  i2s_cfg.pin_bck = 27;
  i2s_cfg.pin_ws = 26;
  i2s_cfg.use_apll = 1;
  i2s_cfg.i2s_format = I2S_STD_FORMAT; // or try with I2S_LSB_FORMAT
  i2s_cfg.sample_rate = 44100;
  i2s_cfg.channels = 2;
  i2s_cfg.bits_per_sample = 16;

  i2s_cfg.buffer_count = i2s_buffer_count; // originally expands to 6 (says not used anymore?)
  i2s_cfg.buffer_size = i2s_buffer_size;   // expands to 512 (says not used anymore?)

  if (btrole)
  {
    // SOURCE -> A2DP Bluetooth
    i2s_cfg.is_master = false; // <----- **THIS IS WHERE THE DIFFERENCE IN IF IT WORKS OR NOT.**
    i2s_cfg.pin_data = -1;     // NO OUT
    i2s_cfg.pin_data_rx = 18;  // THIS IS IN
    i2s_cfg.auto_clear = true;
  }
  else
  {
    // SINK -> I2S
    i2s_cfg.is_master = false;
    i2s_cfg.pin_data = 25;    // THIS IS OUT
    i2s_cfg.pin_data_rx = -1; // NO IN.
  }

  getHeap();

  // Start the I2S port
  i2s.begin(i2s_cfg);

  getHeap();

  // Start Bluetooth Audio Receiver
  Serial << "Initializing Bluetooth A2DP... ";

  if (btrole)
  {
    Serial << "as a SOURCE. (" << btname << ")\n";

    a2dp_source = new BluetoothA2DPSource();
    if (!a2dp_source)
    {
      Serial.println("Failed to create A2DP Source!");
      while (1)
        ; // Halt execution to catch the error
    }

    a2dp_source->set_auto_reconnect(false);
    a2dp_source->set_on_connection_state_changed(connection_state_changed);
    a2dp_source->set_data_callback_in_frames(get_sound_data);

    a2dp_source->set_ssid_callback(ssidCallback);
    a2dp_source->set_discovery_mode_callback(discoveryModeCallback);

    //a2dp_source->start(btname);
    a2dp_source->start();
  }
  else
  {
    Serial << "as a SINK. (" << btname << ")\n";
    a2dp_sink = new BluetoothA2DPSink();
    if (!a2dp_sink)
    {
      Serial.println("Failed to create A2DP Sink!");
      while (1)
        ; // Halt execution to catch the error
    }

    a2dp_sink->set_auto_reconnect(false); // doesnt seem to work as expected.

    a2dp_sink->set_avrc_metadata_attribute_mask(ESP_AVRC_MD_ATTR_TITLE | ESP_AVRC_MD_ATTR_ARTIST | ESP_AVRC_MD_ATTR_ALBUM | ESP_AVRC_MD_ATTR_PLAYING_TIME);
    a2dp_sink->set_avrc_metadata_callback(avrc_metadata_callback);
    a2dp_sink->set_avrc_rn_playstatus_callback(avrc_rn_playstatus_callback);
    a2dp_sink->set_avrc_rn_play_pos_callback(avrc_rn_play_pos_callback);
    // a2dp_sink->set_avrc_rn_track_change_callback();
    a2dp_sink->set_on_connection_state_changed(connection_state_changed);
    a2dp_sink->set_on_audio_state_changed(audio_state_changed);
    a2dp_sink->set_avrc_rn_volumechange(volume_change_callback);
    a2dp_sink->set_stream_reader(read_data_stream, false);

    a2dp_sink->start(btname);
  }

  getHeap();

  // Get our mac address for later use.
  getDeviceAddress(btmac); // Now btmac contains our MAC address, e.g., "01:23:45:67:89:ab"

  Serial.println("Setup() Complete...");

Theres nothing going on in loop() other than delay(10).

After wusing the debug logging I don't even see an attempt to disconnect from a speaker that disappears. There is nothing. Here is output from normal working conditions where you can see connections and disconnections working great if is_master = false. As soon as I turn on is_master = true the backend never sees the speaker disconnect therefore it never even tries to scan and reconnect. I can reproduce the problem simply by changing the is_master property.

<!-- STARTUP of GroupTooth Source (#99), Firmware: GTS25040610 Compile Time: Apr  6 2025 10:23:04 --->
<!-- SDK firmware is v5.3.2-584-g489d7a2b3a-dirty --->
Heap: +189548 bytes. (189548)
Starting Wire.
Heap: -5684 bytes. (183864)
Starting AudioTools.
Starting I2S... i2s mode: RX_MODE Buffers: 6,512
Heap: -19476 bytes. (164388)
Initializing Bluetooth A2DP... as a SOURCE. (Job Rocker Max)
Heap: -93836 bytes. (70552)
Setup() Complete...
Scan started.
Found [Job Rocker Max], waiting 2 seconds to connect...
Found [Job Rocker Max], done waiting.
Scan stopped.
Scanned Devices:
Name: Job Rocker Max | MAC: 0C:FC:83:87:B6:60 | RSSI: -71 | Last Seen: 0s ago.
Connecting
Connected
Heap: -10824 bytes. (59728)
Heap: -2936 bytes. (56792)
Heap: -592 bytes. (56200)
Heap: -49800 bytes. (6400) <--- I do wonder why this goes so low sometimes... it seems to recover always but sheesh!
Disconnected
Connecting
Heap: +54312 bytes. (60712)
Disconnected
Heap: +3208 bytes. (63920)
Connecting
Heap: -3972 bytes. (59948)
Connected
Heap: -3768 bytes. (56180)
Heap: -48 bytes. (56132)

I'm testing this on a dev wroom not on my pcb with another clock present - so I don't know if the underlying idf framework is looking for a clock and can't find one so it gets confused ... but I need a way to determine this at runtime so I can compensate for it. I have 8 wrooms on a pcb sharing i2s audio (working perfectly) but need the ability to change the roles from sink to source between them. Obviously one needs to be the clock which I will handle - but I think this is going to be a problem either way.

PS - Phil your libraries are great. I cannot believe how much work you have put into this and still have time in the day to do anything else.

[pschatzmann]

I would not know why that would be.
I am always using the ESP32 as master both when attaching an external DAC and ADC!

Are you sure that you provide proper data to A2DP: if A2DP would not get proper audio data, then it would automatically disconnect...

[SamObde]

This is on a wroom programmer with no i2s hooked up... so no clock or no data. It stays connected if I use 'i2s.is_master = true'. The weird part is that if its not the master it stays connected and never disconnects. I wonder if the underlying i2s bus is locking things up because its not able to sync. I'll do some more debug log comparing and post more here shortly.

[pschatzmann]

If I remember right: even if no i2s is hooked up, you will get data with i2s.is_master = true, but no data with i2s.is_master = false, so it will hang up...