{"id":4405,"date":"2022-02-01T21:39:20","date_gmt":"2022-02-01T20:39:20","guid":{"rendered":"https:\/\/www.pschatzmann.ch\/home\/?p=4405"},"modified":"2024-03-21T07:55:44","modified_gmt":"2024-03-21T06:55:44","slug":"building-an-esp32-audio-bluetooth-receiver-with-output-to-spdif-with-just-a-few-lines-of-code","status":"publish","type":"post","link":"https:\/\/www.pschatzmann.ch\/home\/2022\/02\/01\/building-an-esp32-audio-bluetooth-receiver-with-output-to-spdif-with-just-a-few-lines-of-code\/","title":{"rendered":"Building an Arduino ESP32 Audio Bluetooth Receiver with output to SPDIF with just a few lines of code."},"content":{"rendered":"

The last couple of days I have spent to add SDIF<\/a> audio output support to my Arduino AudioTools<\/a> library and I would like to thank joba-1 for testing the solution<\/a>.<\/p>\n

Together with my ESP32-A2DP Bluetooth library<\/a> we can build now a Bluetooth receiver that outputs the audio signals as SPDIF with just a few lines of code:<\/p>\n

The Arduino Sketch<\/h2>\n

Here is the Arduino Sketch<\/p>\n

#define USE_A2DP\n#include \"AudioConfigLocal.h\"\n#include \"AudioTools.h\"\n\nBluetoothA2DPSink a2dp_sink;\nSPDIFStream spdif;\n\n\/\/ Write data to SPDIF in callback\nvoid read_data_stream(const uint8_t *data, uint32_t length) {\n    spdif.write(data, length);\n}\n\nvoid setup() {\n  Serial.begin(115200);\n  AudioLogger::instance().begin(Serial, AudioLogger::Warning);\n\n  \/\/ register callback\n  a2dp_sink.set_stream_reader(read_data_stream, false);\n\n  \/\/ Start Bluetooth Audio Receiver\n  a2dp_sink.set_auto_reconnect(false);\n  a2dp_sink.start(\"a2dp-spdif\");\n\n  \/\/ setup SPDIF output\n  auto cfg = spdif.defaultConfig();\n  cfg.pin_data = 23;\n  cfg.sample_rate = a2dp_sink.sample_rate();\n  cfg.channels = 2;\n  cfg.bits_per_sample = 16;\n  spdif.begin(cfg);\n\n}\n\nvoid loop() {\n  delay(100);\n}\n<\/code><\/pre>\n
The regular output of the BluetoothA2DPSink goes to I2S, but we can alternatively send the output to a callback methods<\/strong>: This is done with the set_stream_reader(read_data_stream, false)<\/code>. In the callback method we just need to write the audio data to the SPDIFStream.<\/p>\n
Before starting the Bluetooth Sink, I deactivate the automatic reconnect – so that I can easily switch my feeding devices.<\/p>\n
With the #include “AudioConfigLocal.h” you have the possibility to define some sketch specific configuration<\/strong>. In my example I use this mechanism to define some specific I2S_BUFFER_COUNT<\/em> and I2S_BUFFER_SIZE<\/em> values.<\/p>\n
Source Code<\/h2>\n
The (potentially updated) source code<\/a> can be found on Github<\/p>\n
Dependencies<\/h2>\n
The following libraries need to be installed<\/p>\n