Add PassThroughADCtoI2S example

examples/HardwareTesting/PassThroughADCtoI2S/PassThroughADCtoI2S.ino

+/*
+ * A simple hardware test which receives audio on the A2 analog pin
+ * and sends it to the audio shield (I2S digital audio)
+ *
+ * This example code is in the public domain.
+ */
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+#include <SerialFlash.h>
+
+// GUItool: begin automatically generated code
+AudioInputAnalog         adc1;           //xy=197,73
+AudioOutputI2S           i2s1;           //xy=375,85
+AudioConnection          patchCord1(adc1, 0, i2s1, 0);
+AudioConnection          patchCord2(adc1, 0, i2s1, 1);
+AudioControlSGTL5000     sgtl5000_1;     //xy=314,158
+// GUItool: end automatically generated code
+
+
+void setup() {
+  // Audio connections require memory to work.  For more
+  // detailed information, see the MemoryAndCpuUsage example
+  AudioMemory(12);
+
+  // Enable the audio shield
+  sgtl5000_1.enable();
+  sgtl5000_1.volume(0.5);
+}
+
+void loop() {
+  // Do nothing here.  The Audio flows automatically
+
+  // When AudioInputAnalog is running, analogRead() must NOT be used.
+}
+
+