CODEWITHSUNDEEP
bluetoothesp32a2dp
Jeeper1974
Jeeper1974

Reputation: 11

ESP32 A2DP Headphones bonding issue

I am fairly new to working with Bluetooth and the ESP32 Bluetooth stack, so forgive me if I don't use the right terminology.

I can get the ESP-IDF Development example "A2DP_Source" working perfect only if I enable the headphones pairing mode first. After it is paired, and the bonding is stored in the Bluetooth, it will reconnect to the headphones without issue, but it then does not notify the app through the call back functions that it has connected. The app then continues to search for a bluetooth device and the audio streams sporadically, or not at all.

I've tried multiple speakers, and headphones, all with the same results.

I can see the bonded device list also and the device is there.

Is there callback function in the bluetooth stack that needs to be initialized to notify the app that the bluetooth connected to a previously paired device instead of just a device in pairing mode?

These are the three callback functions setup currently that run when connected through pairing mode, but don't run when the bluetooth connects in non-pairing mode.

...
/* register GAP callback function */
        esp_bt_gap_register_callback(bt_app_gap_cb);
        
         /* initialize AVRCP controller */
        esp_avrc_ct_init();
        esp_avrc_ct_register_callback(bt_app_rc_ct_cb);
        
        /* initialize A2DP source */
        esp_a2d_register_callback(&bt_app_a2d_cb);
        esp_a2d_source_register_data_callback(bt_app_a2d_data_cb);
      ...

Any help or pointers would be appreciated. Thanks.

Upvotes: 1

Views: 1972

Answers (2)

Natsuki
Natsuki

Reputation: 45

Did you mean ESP32 A2DP cannot connect a device without the push of a PAIR button?

The example "A2DP_Source" does not seem to connect the bonded device. It just tries to discover the device with the certain name ("ESP_SPEAKER" in the original code) calling the function esp_bt_gap_start_discovery. If the device is found, bt_app_gap_cb is called and then the connect to peer will start via esp_a2d_source_connect.

So I suggest fixing the code so as to connect peer instead of calling esp_bt_gap_start_discovery if there is any bonded device. You can use the function esp_bt_gap_get_bond_device_list and find out the address of the bonded device which is required by esp_a2d_source_connect.

The API reference is available in https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/bluetooth/esp_gap_bt.html and https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/bluetooth/esp_a2dp.html.

Upvotes: 1

Jeeper1974
Jeeper1974

Reputation: 11

Working through this problem more, I found that using C++ to call the native C code was the issue. I don't have a strong enough background in coding to understand the "why" it did not work, but once I returned all the code back to "C" it started working without issue. Hope this helps someone else who may make the same mistake.

Upvotes: 0

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