WhistleDetector.ino

/*
 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

 CCircuit:
 * Arduino/Genuino Zero, MKR family and Nano 33 IoT
 * ICS43432:
   * GND connected GND
   * 3.3V connected to 3.3V (Zero, Nano) or VCC (MKR)
   * WS connected to pin 0 (Zero) or 3 (MKR) or A2 (Nano)
   * CLK connected to pin 1 (Zero) or 2 (MKR) or A3 (Nano)
   * SD connected to pin 9 (Zero) or A6 (MKR) or 4 (Nano)

 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);
  }
}