just a simple i2s demo

Adafruit_UDA1334A/README.md

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+# Adafruit UDA1334A Product Examples
+
+Code to accompany this tutorial:
+https://learn.adafruit.com/adafruit-i2s-stereo-decoder-uda1334a

Adafruit_UDA1334A/SimpleTone/SimpleTone.ino

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+/*
+ This example generates a square wave based tone at a specified frequency
+ and sample rate. Then outputs the data using the I2S interface to a
+ MAX08357 I2S Amp Breakout board.
+
+ Circuit:
+ * Arduino/Genuino Zero, MKRZero or MKR1000 board
+ * MAX08357:
+   * GND connected GND
+   * VIN connected 5V
+   * LRC connected to pin 0 (Zero) or pin 3 (MKR1000, MKRZero)
+   * BCLK connected to pin 1 (Zero) or pin 2 (MKR1000, MKRZero)
+   * DIN connected to pin 9 (Zero) or pin A6 (MKR1000, MKRZero)
+
+ created 17 November 2016
+ by Sandeep Mistry
+ */
+
+#include <I2S.h>
+
+const int frequency = 440; // frequency of square wave in Hz
+const int amplitude = 500; // amplitude of square wave
+const int sampleRate = 8000; // sample rate in Hz
+
+const int halfWavelength = (sampleRate / frequency); // half wavelength of square wave
+
+short sample = amplitude; // current sample value
+int count = 0;
+
+void setup() {
+  Serial.begin(9600);
+  Serial.println("I2S simple tone");
+
+  // start I2S at the sample rate with 16-bits per sample
+  if (!I2S.begin(I2S_PHILIPS_MODE, sampleRate, 16)) {
+    Serial.println("Failed to initialize I2S!");
+    while (1); // do nothing
+  }
+}
+
+void loop() {
+  if (count % halfWavelength == 0) {
+    // invert the sample every half wavelength count multiple to generate square wave
+    sample = -1 * sample;
+  }
+
+  // write the same sample twice, once for left and once for the right channel
+  I2S.write(sample);
+  I2S.write(sample);
+
+  // increment the counter for the next sample
+  count++;
+}