neopixel-rainbow-organ/neopixel-rainbow-organ.ino

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
#include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif


#define DEBUG true

#define LED_COUNT 9 // Number of LEDs in strip
#define BUFFSIZE 72 // at least LED_COUNT!
#define HUESTEP ((65536/LED_COUNT)+23)
#define BASELINE_FACTOR 0.5
#define DECAY_FACTOR 0.2

#define MICPIN   A7 // microphone
#define LED_PIN    4
// Declare our NeoPixel strip object:
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_RGB + NEO_KHZ800);
// Argument 1 = Number of pixels in NeoPixel strip
// Argument 2 = Arduino pin number (most are valid)
// Argument 3 = Pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
//   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)


#define AVGSIZE 4
int rawBuff[BUFFSIZE] = {0};
int avgBuff[BUFFSIZE] = {0};
int index = 0, hue = 0;

unsigned long lastTime, thisTime;

void setup() {
  if (DEBUG) {
    Serial.begin(230400);
  }
  lastTime = millis();
  index = 0;
  strip.begin(); // Initialize pins for output
  strip.show();  // Turn all LEDs off ASAP
}

void loop() {
  thisTime = millis();
  rawBuff[index] = analogRead(MICPIN);
  int nextIndex = (index + 1) % BUFFSIZE;
  int minVal = 1024, maxVal = -1;
  for (int i = 0; i < BUFFSIZE; i++) {
    avgBuff[i] = 0;
    for (int j = 0; j < AVGSIZE ; j++) {
      avgBuff[i] += rawBuff[(i + BUFFSIZE - j) % BUFFSIZE];
    }
    avgBuff[i] /= AVGSIZE;
    minVal =   min(minVal, avgBuff[i]);
    maxVal =   max(maxVal, avgBuff[i]);
  }

  int baseline;
  for (int i = 0;  i < LED_COUNT; i++) {
    int value = 0;
    if (i) {
      value = (BASELINE_FACTOR * baseline) +
              ((1.0 - BASELINE_FACTOR) *
               constrain(
                 map(avgBuff[(index + BUFFSIZE - i) % BUFFSIZE], minVal, maxVal , -255, 255),
                 0, 255) *
               pow(1.0 - DECAY_FACTOR, i));
    } else {
      baseline = constrain(
                   map(avgBuff[(index + BUFFSIZE - i) % BUFFSIZE], minVal, maxVal , -255, 255),
                   0, 255);
      value =  baseline;
    }
    strip.setPixelColor(i, strip.ColorHSV(hue  , 255, value));
    hue = (hue + HUESTEP) % 65536;
    if (DEBUG) {
      Serial.print(minVal);
      Serial.print(' ');
      Serial.print(maxVal);
      Serial.print(' ');
      Serial.print(baseline);
      Serial.print(' ');
      Serial.print(value);
      Serial.print('\n');
    }
  }
  strip.show();
  index = nextIndex;
  lastTime = thisTime;
  delay(10);
}