Artnet2DmxRecorder/lib/M5Stack/examples/Fire/MicrophoneSpectrumTFT/MicrophoneSpectrumTFT.ino

/************************************************************************

  M5StackFire Discovery simple Spectrum example

  The microphone signal is sampled and a frequency analysis is performed.


  Please install the arduinoFFT library.
  You will find it in the library manager or you can get it from github:
  https://github.com/kosme/arduinoFFT


  M5StackFire         September 2018, ChrisMicro

************************************************************************/
#include <M5Stack.h>

#include "arduinoFFT.h"
//#include <WiFi.h>

arduinoFFT FFT = arduinoFFT(); /* Create FFT object */

#define M5STACKFIRE_MICROPHONE_PIN 34
#define M5STACKFIRE_SPEAKER_PIN    25  // speaker DAC, only 8 Bit

#define HORIZONTAL_RESOLUTION 320
#define VERTICAL_RESOLUTION   240
#define POSITION_OFFSET_Y     20
#define SIGNAL_LENGTH         512

double oldSignal[SIGNAL_LENGTH];
double adcBuffer[SIGNAL_LENGTH];
double vImag[SIGNAL_LENGTH];

#define SAMPLINGFREQUENCY   40000
#define SAMPLING_TIME_US    (1000000UL / SAMPLINGFREQUENCY)
#define ANALOG_SIGNAL_INPUT M5STACKFIRE_MICROPHONE_PIN

void setup() {
    M5.begin();
    M5.Power.begin();
    // WiFi.mode(WIFI_OFF);
    // btStop();
    dacWrite(M5STACKFIRE_SPEAKER_PIN,
             0);  // make sure that the speaker is quite
    M5.Lcd.begin();
    M5.Lcd.fillScreen(BLACK);
    M5.Lcd.fillRect(10, 1, 150, 160, BLACK);
    M5.Lcd.setCursor(0, 0);
    M5.Lcd.setTextColor(GREEN);  // M5.Lcd.setTextSize(3);
    M5.Lcd.setTextSize(1);

    M5.Lcd.println("analog input MIC");
    M5.Lcd.print("max. frequency: ");
    M5.Lcd.print(SAMPLINGFREQUENCY / 2);
    M5.Lcd.println(" Hz");
    M5.Lcd.setTextSize(2);
}

void showSignal() {
    int n;

    int oldx;
    int oldy;
    int oldSig;
    int x, y;

    for (n = 0; n < SIGNAL_LENGTH / 2; n++) {
        x = n;
        y = map(adcBuffer[n], 0, 512, VERTICAL_RESOLUTION, POSITION_OFFSET_Y);

        if (n > 0) {
            // delete old line element
            M5.Lcd.drawLine(oldx, oldSig, x, oldSignal[n], BLACK);

            // draw new line element
            if (n < SIGNAL_LENGTH - 1)  // don't draw last element because it
                                        // would generate artifacts
            {
                M5.Lcd.drawLine(oldx, oldy, x, y, GREEN);
            }
        }
        oldx         = x;
        oldy         = y;
        oldSig       = oldSignal[n];
        oldSignal[n] = y;
    }
}

double AdcMeanValue = 0;

void loop(void) {
    int n;
    uint32_t nextTime = 0;

    // record signal
    for (n = 1; n < SIGNAL_LENGTH; n++) {
        double v = analogRead(ANALOG_SIGNAL_INPUT);
        AdcMeanValue += (v - AdcMeanValue) * 0.001;
        adcBuffer[n] = v - AdcMeanValue;

        // wait for next sample
        while (micros() < nextTime)
            ;
        nextTime = micros() + SAMPLING_TIME_US;
    }

    FFT.Windowing(adcBuffer, SIGNAL_LENGTH, FFT_WIN_TYP_HAMMING,
                  FFT_FORWARD);                                /* Weigh data */
    FFT.Compute(adcBuffer, vImag, SIGNAL_LENGTH, FFT_FORWARD); /* Compute FFT */
    FFT.ComplexToMagnitude(adcBuffer, vImag,
                           SIGNAL_LENGTH); /* Compute magnitudes */
    // int x = FFT.MajorPeak(adcBuffer, SIGNAL_LENGTH, 1000000UL /
    // SAMPLING_TIME_US);//SAMPLINGFREQUENCY
    int x = FFT.MajorPeak(adcBuffer, SIGNAL_LENGTH, SAMPLINGFREQUENCY);

    int maxAmplitudeDB = 0;
    for (n = 1; n < SIGNAL_LENGTH; n++) {
        int a = log10(adcBuffer[n]) * 20 -
                54.186;  // convert amplitude to dB scale, dB relative to
                         // log10(512samples)*20=54.186dB
        if (a > maxAmplitudeDB) maxAmplitudeDB = a;
        adcBuffer[n] = (a + 30) * 5;  // scale for TFT display
        vImag[n]     = 0;             // clear imaginary part
    }

    showSignal();

    M5.Lcd.fillRect(200, 0, 119, 40, BLUE);
    M5.Lcd.setCursor(210, 1);
    M5.Lcd.print(x);
    M5.Lcd.print(" Hz");
    M5.Lcd.setCursor(210, 21);
    M5.Lcd.print(maxAmplitudeDB);
    M5.Lcd.print(" dB");
}