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Legacy I2S API
Espressif is retiring the legacy I2S API. So with Arduino ESP32 3.0.0 (which is based on IDF 5.1) this legacy API will not be available any more.
You can still use it in older releases.
This can be used e.g. to build your own Bluetooth Speaker.
Here is the simplest example which just uses the proper default settings:
#include "BluetoothA2DPSink.h"
BluetoothA2DPSink a2dp_sink;
void setup() {
a2dp_sink.start("MyMusic");
}
void loop() {
}
This creates a new Bluetooth device with the name “MyMusic” and the output will be sent to the following default I2S pins which need to be conected to an external DAC:
- bck_io_num = 26
- ws_io_num = 25
- data_out_num = 22
You can define your own pins easily by calling the set_pin_config
method in the setup before the start
.
#include "BluetoothA2DPSink.h"
BluetoothA2DPSink a2dp_sink;
void setup() {
i2s_pin_config_t my_pin_config = {
.mck_io_num = I2S_PIN_NO_CHANGE,
.bck_io_num = 26,
.ws_io_num = 25,
.data_out_num = 22,
.data_in_num = I2S_PIN_NO_CHANGE
};
a2dp_sink.set_pin_config(my_pin_config);
a2dp_sink.start("MyMusic");
}
void loop() {
}
In some cases you might want to use your specific i2s_config settings. E.g. to request a different bits_per_sample (e.g. 32) or to use the use_apll or to optimize the dma buffer...
#include "BluetoothA2DPSink.h"
BluetoothA2DPSink a2dp_sink;
void setup() {
static i2s_config_t i2s_config = {
.mode = (i2s_mode_t) (I2S_MODE_MASTER | I2S_MODE_TX),
.sample_rate = 44100, // updated automatically by A2DP
.bits_per_sample = (i2s_bits_per_sample_t)32,
.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
.communication_format = (i2s_comm_format_t) (I2S_COMM_FORMAT_STAND_I2S),
.intr_alloc_flags = 0, // default interrupt priority
.dma_buf_count = 8,
.dma_buf_len = 64,
.use_apll = true,
.tx_desc_auto_clear = true // avoiding noise in case of data unavailability
};
a2dp_sink.set_i2s_config(i2s_config);
a2dp_sink.start("MyMusic");
}
void loop() {
}
You can also send the output directly to the internal DAC of the ESP32 by providing the corresponding i2s_config:
#include "BluetoothA2DPSink.h"
BluetoothA2DPSink a2dp_sink;
void setup() {
static const i2s_config_t i2s_config = {
.mode = (i2s_mode_t) (I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN),
.sample_rate = 44100, // corrected by info from bluetooth
.bits_per_sample = (i2s_bits_per_sample_t) 16, /* the DAC module will only take the 8bits from MSB */
.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
.communication_format = (i2s_comm_format_t)I2S_COMM_FORMAT_STAND_MSB,
.intr_alloc_flags = 0, // default interrupt priority
.dma_buf_count = 8,
.dma_buf_len = 64,
.use_apll = false
};
a2dp_sink.set_i2s_config(i2s_config);
a2dp_sink.start("MyMusic");
}
void loop() {
}
The output goes now to the DAC pins GPIO25 (Channel 1) and GPIO26 (Channel 2).
Here is the link to the legacy information