Add I2S_I2STest example

- Add I2S microphone input example

examples/Platforms/NRF52/NRF52_I2S_I2STest/NRF52_I2S_I2STest.ino

@@ -0,0 +1,81 @@
+#include <AutoAnalogAudio.h>
+
+AutoAnalog aaAudio;
+
+#if defined(USE_TINYUSB)
+// Needed for Serial.print on non-MBED enabled or adafruit-based nRF52 cores
+#include "Adafruit_TinyUSB.h"
+#endif
+
+#define bufferSize 320
+float volumeControl = 0.2;
+
+/*********************************************************/
+/* Tested with MAX98357A I2S breakout on XIAO 52840 Sense
+/* BCLK connected to Arduino D1 (p0.03)
+/* LRCK connected to Arduino D3 (p0.29)
+/* DIN  connected to Arduino D5 (p0.05)
+/* SD   connected to Arduino D6
+/*********************************************************/
+/* Tested with INMP441 I2S breakout on XIAO 52840 Sense
+/* SCK connected to Arduino D1 (p0.03)
+/* WS  connected to Arduino D3 (p0.29)
+/* SD  connected to Arduino D4 (p0.04)
+*/
+
+
+void setup() {
+
+
+  Serial.begin(115200);
+  aaAudio.maxBufferSize = bufferSize;
+  aaAudio.begin(1, 1, 3);           //Setup aaAudio using I2s for Mic and Output
+  aaAudio.adcBitsPerSample = 24;    // 24-bit samples input from I2S
+  aaAudio.dacBitsPerSample = 24;    // 24-bit samples output to I2S
+  aaAudio.setSampleRate(44000, 0);  // 44kHz Mono
+
+  pinMode(6, OUTPUT);  //Connected to SD pin of MAX98357A
+  digitalWrite(6, HIGH);
+}
+
+void loop() {
+
+  if (Serial.available()) {
+    char c = Serial.read();
+    if (c == '=') {
+      volumeControl += 0.1;
+    } else if (c == '-') {
+      volumeControl -= 0.1;
+      volumeControl = max(0.0, volumeControl);
+    }
+    Serial.println(volumeControl);
+  }
+
+
+  // For 24 bit samples
+  if (aaAudio.dacBitsPerSample == 24) {
+    aaAudio.getADC(bufferSize / 2);                                    // Get data from I2S microphone
+    memcpy(aaAudio.dacBuffer16, aaAudio.adcBuffer16, bufferSize * 2);  // Copy data into output buffer from input buffer
+    for (int i = 0; i < bufferSize; i += 2) {
+      int32_t test;
+      memcpy(&test, &aaAudio.dacBuffer16[i], 4);
+      test *= volumeControl;
+      memcpy(&aaAudio.dacBuffer16[i], &test, 4);
+    }
+    aaAudio.feedDAC(0, bufferSize / 2);  // Feed the data to I2S output
+
+    // For 16-bit samples
+  } else {
+    aaAudio.getADC(bufferSize);
+    memcpy(aaAudio.dacBuffer16, aaAudio.adcBuffer16, bufferSize * 2);
+    for (int i = 0; i < bufferSize; i++) {
+      int16_t test = aaAudio.dacBuffer16[i];
+      test *= volumeControl;
+      aaAudio.dacBuffer16[i] = test;
+    }
+    aaAudio.feedDAC(0, bufferSize);  // Feed the data to I2S output
+  }
+}
+
+
+