Audio Spectrum Analyzer Using Arduino Uno

This video will illustrate you how to visualize audio left and right signals in bar-graph on 16×2 LCD Display using Arduino.

Components Required:

1. Arduino UNO

2. 16X2 LCD Display

3. 3.5mm Audio Jack

4. Jumper Wires

Connection Diagram:

Video Link

 

Code

#include <LiquidCrystal.h>
#include <fix_fft.h>

#define DEBUG 0
#define L_IN 1 // Audio input A0 Arduino
#define R_IN 0 // Audio input A1 Arduino

const int Yres = 8;
const int gain = 3;
float peaks[64];
char im[64], data[64];
char Rim[64], Rdata[64];
char data_avgs[64];
int debugLoop;
int i;
int load;

LiquidCrystal lcd(11, 10, 7, 6, 5, 4); // pins to LCD

// Custom CHARACTERS
byte v1[8] = {
  B00000, B00000, B00000, B00000, B00000, B00000, B00000, B11111
};
byte v2[8] = {
  B00000, B00000, B00000, B00000, B00000, B00000, B00000, B11111
};
byte v3[8] = {
  B00000, B00000, B00000, B00000, B00000, B11111, B11111, B11111
};
byte v4[8] = {
  B00000, B00000, B00000, B00000, B11111, B11111, B11111, B11111
};
byte v5[8] = {
  B00000, B00000, B00000, B11111, B11111, B11111, B11111, B11111
};
byte v6[8] = {
  B00000, B00000, B11111, B11111, B11111, B11111, B11111, B11111
};
byte v7[8] = {
  B00000, B11111, B11111, B11111, B11111, B11111, B11111, B11111
};
byte v8[8] = {
  B11111, B11111, B11111, B11111, B11111, B11111, B11111, B11111
};

void setup() {
if (DEBUG) {
    Serial.begin(9600); // hardware serial
    Serial.print("Debug ON");
    Serial.println("");
  }

lcd.begin(16, 2);
  lcd.clear();
  lcd.createChar(1, v1);
  lcd.createChar(2, v2);
  lcd.createChar(3, v3);
  lcd.createChar(4, v4);
  lcd.createChar(5, v5);
  lcd.createChar(6, v6);
  lcd.createChar(7, v7);
  lcd.createChar(8, v8);

lcd.setCursor(load + 1, 1);
    lcd.write((i - i / 5 * 5) + 1);
    for (load = load + 2; load < 16; load++)
    {
      lcd.setCursor(load, 1);
      lcd.write(9);
    }
    lcd.setCursor(0, 0);
    lcd.print("LOADING.........");
    delay(50);
  }
  lcd.clear();
  delay(500);
}

void loop() {
for (int i = 0; i < 64; i++) {    // 64 bins = 32 bins of usable spectrum data
    data[i]  = ((analogRead(L_IN) / 4 ) - 128);  // chose how to interpret the data from analog in
    im[i]  = 0;   // imaginary component
    Rdata[i] = ((analogRead(R_IN) / 4 ) - 128);  // chose how to interpret the data from analog in
    Rim[i] = 0;   // imaginary component
  }

fix_fft(data, im, 6, 0);   // Send Left channel normalized analog values through fft
fix_fft(Rdata, Rim, 6, 0); // Send Right channel normalized analog values through fft

 // At this stage, we have two arrays of [0-31] frequency bins deep [32-63] duplicate

 // calculate the absolute values of bins in the array - only want positive values
  for (int i = 0; i < 32; i++) {
    data[i] = sqrt(data[i]  *  data[i] +  im[i] *  im[i]);
    Rdata[i] = sqrt(Rdata[i] * Rdata[i] + Rim[i] * Rim[i]);

// COPY the Right low-band (0-15) into the Left high-band (16-31) for display ease
    if (i < 16) {
      data_avgs[i] = data[i];
    }
    else {
      data_avgs[i] = Rdata[i - 16];
    }

// Remap values to physical display constraints... that is, 8 display custom character indexes + "_"
    data_avgs[i] = constrain(data_avgs[i], 0, 9 - gain);     //data samples * range (0-9) = 9
    data_avgs[i] = map(data_avgs[i], 0, 9 - gain, 0, Yres);  // remap averaged values
  }

Two16_LCD();
  decay(1);
}

void Two16_LCD() {
  lcd.setCursor(0, 0);
  lcd.print("L"); // Channel ID replaces bin #0 due to hum & noise
  lcd.setCursor(0, 1);
  lcd.print("R"); // ditto

for (int x = 1; x < 16; x++) {  // init 0 to show lowest band overloaded with hum
    int y = x + 16; // second display line
    if (data_avgs[x] > peaks[x]) peaks[x] = data_avgs[x];
    if (data_avgs[y] > peaks[y]) peaks[y] = data_avgs[y];

lcd.setCursor(x, 0); // draw first (top) row Left
    if (peaks[x] == 0) {
      lcd.print("_");  // less LCD artifacts than " "
    }
    else {
      lcd.write(peaks[x]);
    }

 lcd.setCursor(x, 1); // draw second (bottom) row Right
    if (peaks[y] == 0) {
      lcd.print("_");
    }
    else {
      lcd.write(peaks[y]);
    }
  }

debugLoop++;
  if (DEBUG && (debugLoop > 99)) {
    Serial.print( "Free RAM = " );
    Serial.println( freeRam(), DEC);
    Serial.println( millis(), DEC);
    debugLoop = 0;
  }
}

int freeRam () {
  extern int __heap_start, *__brkval;
  int v;
  return (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval);
}

void decay(int decayrate) {
  int DecayTest = 1;
  // reduce the values of the last peaks by 1
  if (DecayTest == decayrate) {
    for (int x = 0; x < 32; x++) {
      peaks[x] = peaks[x] - 1;  // subtract 1 from each column peaks
      DecayTest = 0;
    }
  }

DecayTest++;
}