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libraries/audio-tools/examples/examples-stream/streams-i2s_pdm-serial/README.md

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+
+# Stream PDM Input to CSV Output
+
+## General Description:
+
+To use a PDM microphone you need to have a microcontroller that supports PDM input or a dedicated library.
+
+The ESP32 supports PDM via the I2S API: We stream the sound input from a PDM microphone (PDM Digital MEMS MP34DT01) which we read in from the I2S interface and displays it on the Arduino Serial Plotter. 
+
+
+## Pins
+
+![i2s-adc](https://pschatzmann.github.io/Resources/img/pdm-mic.jpg)
+
+| i2s-mic  |  ESP32
+| ---------| ---------------
+| 3V       |  3V
+| GND      |  GND
+| SEL      |  GND  (GND or 3.3V)
+| CLK      |  WS (GPIO15)
+| DAT      |  IN (GPIO32)
+| -        |  BCK (GPIO14)
+
+
+## Additional Comments
+
+You can select if you receive only data on the left or right by setting SEL to high or low.
+
+Please note that in the 2.x realease of the Arduino ESP core, the WS pin is used as CLK. Prior to this it was BCK
+

libraries/audio-tools/examples/examples-stream/streams-i2s_pdm-serial/streams-i2s_pdm-serial.ino

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+/**
+ * @file streams-i2s_pdm-serial.ino
+ * @author Phil Schatzmann
+ * @brief see https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-stream/streams-i2s_pdm-serial/README.md
+ * 
+ * @author Phil Schatzmann
+ * @copyright GPLv3
+ */
+
+
+#include "AudioTools.h"
+
+AudioInfo info(44100, 1, 16);
+I2SStream i2sStream; // Access I2S as stream
+CsvOutput<int16_t> csvOutput(Serial);
+StreamCopy copier(csvOutput, i2sStream); // copy i2sStream to csvOutput
+
+// Arduino Setup
+void setup(void) {
+    Serial.begin(115200);
+    AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);
+    
+    auto cfg = i2sStream.defaultConfig(RX_MODE);
+    cfg.copyFrom(info);
+    cfg.signal_type = PDM;
+    //cfg.use_apll = false;  
+    //cfg.auto_clear = false;
+    cfg.pin_bck = -1; // not used depending on ESP32 core version
+    i2sStream.begin(cfg);
+
+    // make sure that we have the correct channels set up
+    csvOutput.begin(info);
+
+}
+
+// Arduino loop - copy data
+void loop() {
+    copier.copy();
+}