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libraries/audio-tools/examples/examples-communication/a2dp/basic-i2s-a2dp/README.md

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+
+# Stream I2S Input to A2DP Bluetooth
+
+## General Description:
+We implement a A2DP source: We stream the sound input which we read in from the I2S interface to a A2DP sink. We can use any device which provides the sound data via I2S. In order to test the functionality we use the INMP441 microphone.
+
+![INMP441](https://pschatzmann.github.io/Resources/img/inmp441.jpeg)
+
+The INMP441 is a high-performance, low power, digital-output, omnidirectional MEMS microphone with a bottom port. The complete INMP441 solution consists of a MEMS sensor, signal conditioning, an analog-to-digital converter, anti-aliasing filters, power management, and an industry-standard 24-bit I²S interface. The I²S interface allows the INMP441 to connect directly to digital processors, such as DSPs and microcontrollers, without the need for an audio codec in the system.
+
+## Pins
+ 
+| INMP441 |  ESP32
+| --------| ---------------
+| VDD     |  3.3
+| GND     |  GND
+| SD      |  IN (GPIO32)
+| L/R     |  GND
+| WS      |  WS (GPIO15)
+| SCK     |  BCK (GPIO14)
+
+
+SCK: Serial data clock for I²S interface
+WS: Select serial data words for the I²S interface
+L/R: Left / right channel selection
+        When set to low, the microphone emits signals on one channel of the I²S frame.
+        When the high level is set, the microphone will send signals on the other channel.
+ExSD: Serial data output of the I²S interface
+VCC: input power 1.8V to 3.3V
+GND: Power groundHigh PSR: -75 dBFS.
+
+### Dependencies
+
+- https://github.com/pschatzmann/ESP32-A2DP.git
+

libraries/audio-tools/examples/examples-communication/a2dp/basic-i2s-a2dp/basic-i2s-a2dp.ino

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+/**
+ * @file basic-i2s-a2dp.ino
+ * @author Phil Schatzmann
+ * @brief We use a INMP441 I2S microphone as input and send the data to A2DP
+ * Unfortunatly the data type from the microphone (int32_t)  does not match with
+ * the required data type by A2DP (int16_t), so we need to convert.
+ * @copyright GPLv3
+ */
+
+#include "AudioTools.h"
+#include "AudioTools/Communication/A2DPStream.h"
+
+AudioInfo info32(44100, 2, 32);
+AudioInfo info16(44100, 2, 16);
+BluetoothA2DPSource a2dp_source;
+I2SStream i2s;
+FormatConverterStream conv(i2s);
+const int BYTES_PER_FRAME = 4;
+
+
+int32_t get_sound_data(Frame* data, int32_t frameCount) {
+  return conv.readBytes((uint8_t*)data, frameCount*BYTES_PER_FRAME)/BYTES_PER_FRAME;
+}
+
+// Arduino Setup
+void setup(void) {
+  Serial.begin(115200);
+  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);
+
+  // setup conversion
+  conv.begin(info32, info16);
+
+  // start i2s input with default configuration
+  Serial.println("starting I2S...");
+  auto cfg = i2s.defaultConfig(RX_MODE);
+  cfg.i2s_format = I2S_STD_FORMAT; // or try with I2S_LSB_FORMAT
+  cfg.copyFrom(info32);
+  cfg.is_master = true;
+  i2s.begin(cfg);
+
+  // start the bluetooth
+  Serial.println("starting A2DP...");
+  // a2dp_source.set_auto_reconnect(false);
+  a2dp_source.set_data_callback_in_frames(get_sound_data);
+  a2dp_source.start("LEXON MINO L");
+
+  Serial.println("A2DP started");
+}
+
+// Arduino loop - repeated processing
+void loop() { delay(1000); }