SimpleTone

/*

 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 Zero, MKR family and Nano 33 IoT

 * MAX08357:

   * GND connected GND

   * VIN connected 5V

   * LRC connected to pin 0 (Zero) or 3 (MKR) or A2 (Nano)

   * BCLK connected to pin 1 (Zero) or 2 (MKR) or A3 (Nano)

   * DIN connected to pin 9 (Zero) or A6 (MKR) or 4 (Nano)

 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++;
}