Decibel_meter.ino

#include "FastLED.h"

const byte pinData = 6;
const byte pinSEN0232 = A0;
const byte pinPotentiometerMin = A1;
const byte pinPotentiometerMax = A2;

const float EMA_a = 0.6;

const byte ledCount = 24;
const byte ledBrightness = 192;
struct CRGB ledRing[ledCount];
struct CRGB ledGradient[ledCount];
CHSV gradientHueStart = CHSV(96, 255, 100);
CHSV grandientHueEnd = CHSV(0, 255, 100);

long timePeakHold = 50;

long dBValue = 0;
int dBValueEMA = 0;
byte dBMin = 0;
byte dBMax = 0;

int ledPeak = 0;
int ledPeakPrevious = 0;
long timeLastPeak = 0;

void setup()
{
  FastLED.addLeds<NEOPIXEL, pinData>(ledRing, ledCount);

  FastLED.setBrightness(ledBrightness);

  fill_gradient(ledGradient, 0, gradientHueStart, 23, grandientHueEnd, SHORTEST_HUES);
}

void loop()
{
  readSEN0232();

  readPotentiometers();

  if (ledPeak > ledPeakPrevious)
  {
    ledPeakPrevious = ledPeak;

    timeLastPeak = millis();
  }

  if (millis() > (timeLastPeak + timePeakHold))
  {
    ledPeakPrevious = ledPeakPrevious - 1;
    
    timeLastPeak = millis();
  }

  FastLED.clear();

  for ( byte i = 0; i <= ledPeak; i++)
  {
    ledRing[i] = ledGradient[i];
  }

  ledRing[ledPeakPrevious] = CHSV(0, 255, 255);

  FastLED.show();
}

void readSEN0232()
{
  float voltageValue;

  voltageValue = analogRead(pinSEN0232) / 1024.0 * 5.0;
  dBValue = voltageValue * 50.0;

  dBValueEMA = int ((EMA_a * dBValue) + ((1 - EMA_a) * dBValueEMA)) + 0.5;

  ledPeak = constrain(map(dBValueEMA, dBMin, dBMax, 0, 23), 0, 23);
}

void readPotentiometers()
{
  dBMin = constrain(map(analogRead(pinPotentiometerMin), 0, 1023, 35, 60), 35, 60);
  dBMax = constrain(map(analogRead(pinPotentiometerMax), 0, 1023, 60, 130), 60, 130);
}