SimpleTone

This example shows you how to generate a simple tone using a SAMD21 based board (MKRZero, MKR1000 or Zero) and an I2S DAC like the adafruit MAX98357A.

Hardware Required

Circuit

To run this example you simply have to connect the board and the I2S DAC using the I2S bus as shown in the image. The image is for MKRZero; you find the proper pins for Zero and MKR1000 at the beginning of the sketch, in the comments.

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Code

/*
 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++;
}

See Also:


Last revision 2016/12/02 by AG

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