Whistle Detector

/*

 This example reads audio data from an Invensense's ICS43432 I2S microphone

 breakout board, and uses the input to detect whistling sounds at a particular

 frequency. When a whistle is detected, it's level is used to control the

 brightness of an LED

 Circuit:

 * Arduino Zero, MKRZero or MKR1000 board

 * ICS43432:

   * GND connected GND

   * 3.3V connected 3.3V (Zero) or VCC (MKR1000, MKRZero)

   * WS connected to pin 0 (Zero) or pin 3 (MKR1000, MKRZero)

   * CLK connected to pin 1 (Zero) or pin 2 (MKR1000, MKRZero)

   * SD connected to pin 9 (Zero) or pin A6 (MKR1000, MKRZero)

 created 30 November 2016

 by Sandeep Mistry

 */

#include <ArduinoSound.h>

// the LED pin to use as output

const int ledPin = LED_BUILTIN;

// sample rate for the input

const int sampleRate = 8000;

// size of the FFT to compute

const int fftSize = 128;

// size of the spectrum output, half of FFT size

const int spectrumSize = fftSize / 2;

// frequency of whistle to detect

const int whistleFrequency = 1250;

// map whistle frequency to FFT bin

const int whistleBin = (whistleFrequency * fftSize / sampleRate);

// array to store spectrum output
int spectrum[spectrumSize];

// create an FFT analyzer to be used with the I2S input

FFTAnalyzer fftAnalyzer(fftSize);

void setup() {

  // setup the serial

  Serial.begin(9600);

  // configure the pin for output mode

  pinMode(ledPin, OUTPUT);

  // setup the I2S audio input for the sample rate with 32-bits per sample

  if (!AudioInI2S.begin(sampleRate, 32)) {

    Serial.println("Failed to initialize I2S input!");

    while (1); // do nothing

  }

  // configure the I2S input as the input for the FFT analyzer

  if (!fftAnalyzer.input(AudioInI2S)) {

    Serial.println("Failed to set FFT analyzer input!");

    while (1); // do nothing

  }
}

void loop() {

  if (fftAnalyzer.available()) {

    // analysis available, read in the spectrum

    fftAnalyzer.read(spectrum, spectrumSize);

    // map the value of the whistle bin magnitude between 0 and 255

    int ledValue = map(spectrum[whistleBin], 50000, 60000, 0, 255);

    // cap the values

    if (ledValue < 0) {

      ledValue = 0;

    } else if (ledValue > 255) {

      ledValue = 255;

    }

    // set LED brightness based on whistle bin magnitude

    analogWrite(ledPin, ledValue);

  }
}