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ArduinoSound

FFTAnalyzer

Description

Create an FFT analyzer with the specified length

Syntax

FFTAnalyzer(length);

Parameters

length: length to use for FFT in samples. Must be a power of 2 (64, 128, 256, etc)

Example

/*
 This example reads audio data from an Invensense's ICS43432 I2S microphone
 breakout board, and prints out the spectrum to the Serial console. The
 Serial Plotter built into the Arduino IDE can be used to plot the audio
 amplitude data (Tools -> Serial Plotter)

 Circuit:
 * Arduino/Genuino 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 21 November 2016
 by Sandeep Mistry
 */


#include <ArduinoSound.h>

// 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;

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

// create an FFT analyzer to be used with the I2S input
FFTAnalyzer fftAnalyzer(fftSize);

void setup() {
// Open serial communications and wait for port to open:
  // A baud rate of 115200 is used instead of 9600 for a faster data rate
  // on non-native USB ports
  Serial.begin(115200);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // 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() {
  // check if a new analysis is available
  if (fftAnalyzer.available()) {
    // read the new spectrum
    fftAnalyzer.read(spectrum, spectrumSize);

    // print out the spectrum
    for (int i = 0; i < spectrumSize; i++) {
      Serial.print((i * sampleRate) / fftSize); // the starting frequency
      Serial.print("\t"); //
      Serial.println(spectrum[i]); // the spectrum value
    }
  }
}

See also

Reference Home

Corrections, suggestions, and new documentation should be posted to the Forum.

The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.

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