The Code

Author Gravatar Image BECKY STERN
You'll need the NeoPixel library for this project. Download by clicking the ZIP button on the NeoPixel Github repository page, and rename the resulting folder "Adafruit_NeoPixel" and move to your Arduino libraries folder.

For more information on programming your Flora board including the software you need to do so, head over to the Getting Started with Flora guide.

We got so excited about this project we made TWO Arduino sketches to meter the volume in the room (by Phil Burgess, James DeVito, and Andy Doro). You can download them both at the LED Ampli-Tie Github repo or copy from below. The first dynamically adjusts to whatever volume is happening:
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/*
LED VU meter for Arduino and Adafruit NeoPixel LEDs.

Hardware requirements:
 - Most Arduino or Arduino-compatible boards (ATmega 328P or better).
 - Adafruit Electret Microphone Amplifier (ID: 1063)
 - Adafruit Flora RGB Smart Pixels (ID: 1260)
   OR
 - Adafruit NeoPixel Digital LED strip (ID: 1138)
 - Optional: battery for portable use (else power through USB or adapter)
Software requirements:
 - Adafruit NeoPixel library

Connections:
 - 3.3V to mic amp +
 - GND to mic amp -
 - Analog pin to microphone output (configurable below)
 - Digital pin to LED data input (configurable below)
 See notes in setup() regarding 5V vs. 3.3V boards - there may be an
 extra connection to make and one line of code to enable or disable.

Written by Adafruit Industries.  Distributed under the BSD license.
This paragraph must be included in any redistribution.
*/

#include <Adafruit_NeoPixel.h>

#define N_PIXELS  16  // Number of pixels in strand
#define MIC_PIN   A9  // Microphone is attached to this analog pin
#define LED_PIN    6  // NeoPixel LED strand is connected to this pin
#define DC_OFFSET  0  // DC offset in mic signal - if unusure, leave 0
#define NOISE     10  // Noise/hum/interference in mic signal
#define SAMPLES   60  // Length of buffer for dynamic level adjustment
#define TOP       (N_PIXELS + 2) // Allow dot to go slightly off scale
#define PEAK_FALL 40  // Rate of peak falling dot

byte
  peak      = 0,      // Used for falling dot
  dotCount  = 0,      // Frame counter for delaying dot-falling speed
  volCount  = 0;      // Frame counter for storing past volume data
int
  vol[SAMPLES],       // Collection of prior volume samples
  lvl       = 10,      // Current "dampened" audio level
  minLvlAvg = 0,      // For dynamic adjustment of graph low & high
  maxLvlAvg = 512;
Adafruit_NeoPixel
  strip = Adafruit_NeoPixel(N_PIXELS, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {

  // This is only needed on 5V Arduinos (Uno, Leonardo, etc.).
  // Connect 3.3V to mic AND TO AREF ON ARDUINO and enable this
  // line.  Audio samples are 'cleaner' at 3.3V.
  // COMMENT OUT THIS LINE FOR 3.3V ARDUINOS (FLORA, ETC.):
//  analogReference(EXTERNAL);

  memset(vol, 0, sizeof(vol));
  strip.begin();
}

void loop() {
  uint8_t  i;
  uint16_t minLvl, maxLvl;
  int      n, height;

 

  n   = analogRead(MIC_PIN);                        // Raw reading from mic 
  n   = abs(n - 512 - DC_OFFSET); // Center on zero
  n   = (n <= NOISE) ? 0 : (n - NOISE);             // Remove noise/hum
  lvl = ((lvl * 7) + n) >> 3;    // "Dampened" reading (else looks twitchy)

  // Calculate bar height based on dynamic min/max levels (fixed point):
  height = TOP * (lvl - minLvlAvg) / (long)(maxLvlAvg - minLvlAvg);

  if(height < 0L)       height = 0;      // Clip output
  else if(height > TOP) height = TOP;
  if(height > peak)     peak   = height; // Keep 'peak' dot at top


  // Color pixels based on rainbow gradient
  for(i=0; i<N_PIXELS; i++) {
    if(i >= height)               strip.setPixelColor(i,   0,   0, 0);
    else strip.setPixelColor(i,Wheel(map(i,0,strip.numPixels()-1,30,150)));
    
  }



  // Draw peak dot  
  if(peak > 0 && peak <= N_PIXELS-1) strip.setPixelColor(peak,Wheel(map(peak,0,strip.numPixels()-1,30,150)));
  
   strip.show(); // Update strip

// Every few frames, make the peak pixel drop by 1:

    if(++dotCount >= PEAK_FALL) { //fall rate 
      
      if(peak > 0) peak--;
      dotCount = 0;
    }



  vol[volCount] = n;                      // Save sample for dynamic leveling
  if(++volCount >= SAMPLES) volCount = 0; // Advance/rollover sample counter

  // Get volume range of prior frames
  minLvl = maxLvl = vol[0];
  for(i=1; i<SAMPLES; i++) {
    if(vol[i] < minLvl)      minLvl = vol[i];
    else if(vol[i] > maxLvl) maxLvl = vol[i];
  }
  // minLvl and maxLvl indicate the volume range over prior frames, used
  // for vertically scaling the output graph (so it looks interesting
  // regardless of volume level).  If they're too close together though
  // (e.g. at very low volume levels) the graph becomes super coarse
  // and 'jumpy'...so keep some minimum distance between them (this
  // also lets the graph go to zero when no sound is playing):
  if((maxLvl - minLvl) < TOP) maxLvl = minLvl + TOP;
  minLvlAvg = (minLvlAvg * 63 + minLvl) >> 6; // Dampen min/max levels
  maxLvlAvg = (maxLvlAvg * 63 + maxLvl) >> 6; // (fake rolling average)

}

// Input a value 0 to 255 to get a color value.
// The colors are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
   return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if(WheelPos < 170) {
   WheelPos -= 85;
   return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
   WheelPos -= 170;
   return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}
The second allows you to adjust the sensitivity of the VU meter:
Copy Code
/*
LED VU meter for Arduino and Adafruit NeoPixel LEDs.
 
 Hardware requirements:
 - Most Arduino or Arduino-compatible boards (ATmega 328P or better).
 - Adafruit Electret Microphone Amplifier (ID: 1063)
 - Adafruit Flora RGB Smart Pixels (ID: 1260)
 OR
 - Adafruit NeoPixel Digital LED strip (ID: 1138)
 - Optional: battery for portable use (else power through USB or adapter)
 Software requirements:
 - Adafruit NeoPixel library
 
 Connections:
 - 3.3V to mic amp +
 - GND to mic amp -
 - Analog pin to microphone output (configurable below)
 - Digital pin to LED data input (configurable below)
 See notes in setup() regarding 5V vs. 3.3V boards - there may be an
 extra connection to make and one line of code to enable or disable.
 
 Written by Adafruit Industries.  Distributed under the BSD license.
 This paragraph must be included in any redistribution.
 
 fscale function:
 Floating Point Autoscale Function V0.1
 Written by Paul Badger 2007
 Modified from code by Greg Shakar
 
 */

#include <Adafruit_NeoPixel.h>
#include <math.h>

#define N_PIXELS  16  // Number of pixels in strand
#define MIC_PIN   A9  // Microphone is attached to this analog pin
#define LED_PIN    6  // NeoPixel LED strand is connected to this pin
#define SAMPLE_WINDOW   10  // Sample window for average level
#define PEAK_HANG 24 //Time of pause before peak dot falls
#define PEAK_FALL 4 //Rate of falling peak dot
#define INPUT_FLOOR 10 //Lower range of analogRead input
#define INPUT_CEILING 300 //Max range of analogRead input, the lower the value the more sensitive (1023 = max)



byte peak = 16;      // Peak level of column; used for falling dots
unsigned int sample;

byte dotCount = 0;  //Frame counter for peak dot
byte dotHangCount = 0; //Frame counter for holding peak dot

Adafruit_NeoPixel strip = Adafruit_NeoPixel(N_PIXELS, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() 
{
  // This is only needed on 5V Arduinos (Uno, Leonardo, etc.).
  // Connect 3.3V to mic AND TO AREF ON ARDUINO and enable this
  // line.  Audio samples are 'cleaner' at 3.3V.
  // COMMENT OUT THIS LINE FOR 3.3V ARDUINOS (FLORA, ETC.):
  //  analogReference(EXTERNAL);

  // Serial.begin(9600);
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'

}

void loop() 
{
  unsigned long startMillis= millis();  // Start of sample window
  float peakToPeak = 0;   // peak-to-peak level

  unsigned int signalMax = 0;
  unsigned int signalMin = 1023;
  unsigned int c, y;


  // collect data for length of sample window (in mS)
  while (millis() - startMillis < SAMPLE_WINDOW)
  {
    sample = analogRead(MIC_PIN);
    if (sample < 1024)  // toss out spurious readings
    {
      if (sample > signalMax)
      {
        signalMax = sample;  // save just the max levels
      }
      else if (sample < signalMin)
      {
        signalMin = sample;  // save just the min levels
      }
    }
  }
  peakToPeak = signalMax - signalMin;  // max - min = peak-peak amplitude
 
  // Serial.println(peakToPeak);


  //Fill the strip with rainbow gradient
  for (int i=0;i<=strip.numPixels()-1;i++){
    strip.setPixelColor(i,Wheel(map(i,0,strip.numPixels()-1,30,150)));
  }


  //Scale the input logarithmically instead of linearly
  c = fscale(INPUT_FLOOR, INPUT_CEILING, strip.numPixels(), 0, peakToPeak, 2);

  


  if(c < peak) {
    peak = c;        // Keep dot on top
    dotHangCount = 0;    // make the dot hang before falling
  }
  if (c <= strip.numPixels()) { // Fill partial column with off pixels
    drawLine(strip.numPixels(), strip.numPixels()-c, strip.Color(0, 0, 0));
  }

  // Set the peak dot to match the rainbow gradient
  y = strip.numPixels() - peak;
  
  strip.setPixelColor(y-1,Wheel(map(y,0,strip.numPixels()-1,30,150)));

  strip.show();

  // Frame based peak dot animation
  if(dotHangCount > PEAK_HANG) { //Peak pause length
    if(++dotCount >= PEAK_FALL) { //Fall rate 
      peak++;
      dotCount = 0;
    }
  } 
  else {
    dotHangCount++; 
  }
}

//Used to draw a line between two points of a given color
void drawLine(uint8_t from, uint8_t to, uint32_t c) {
  uint8_t fromTemp;
  if (from > to) {
    fromTemp = from;
    from = to;
    to = fromTemp;
  }
  for(int i=from; i<=to; i++){
    strip.setPixelColor(i, c);
  }
}


float fscale( float originalMin, float originalMax, float newBegin, float
newEnd, float inputValue, float curve){

  float OriginalRange = 0;
  float NewRange = 0;
  float zeroRefCurVal = 0;
  float normalizedCurVal = 0;
  float rangedValue = 0;
  boolean invFlag = 0;


  // condition curve parameter
  // limit range

  if (curve > 10) curve = 10;
  if (curve < -10) curve = -10;

  curve = (curve * -.1) ; // - invert and scale - this seems more intuitive - postive numbers give more weight to high end on output 
  curve = pow(10, curve); // convert linear scale into lograthimic exponent for other pow function

  /*
   Serial.println(curve * 100, DEC);   // multply by 100 to preserve resolution  
   Serial.println(); 
   */

  // Check for out of range inputValues
  if (inputValue < originalMin) {
    inputValue = originalMin;
  }
  if (inputValue > originalMax) {
    inputValue = originalMax;
  }

  // Zero Refference the values
  OriginalRange = originalMax - originalMin;

  if (newEnd > newBegin){ 
    NewRange = newEnd - newBegin;
  }
  else
  {
    NewRange = newBegin - newEnd; 
    invFlag = 1;
  }

  zeroRefCurVal = inputValue - originalMin;
  normalizedCurVal  =  zeroRefCurVal / OriginalRange;   // normalize to 0 - 1 float

  // Check for originalMin > originalMax  - the math for all other cases i.e. negative numbers seems to work out fine 
  if (originalMin > originalMax ) {
    return 0;
  }

  if (invFlag == 0){
    rangedValue =  (pow(normalizedCurVal, curve) * NewRange) + newBegin;

  }
  else     // invert the ranges
  {   
    rangedValue =  newBegin - (pow(normalizedCurVal, curve) * NewRange); 
  }

  return rangedValue;
}


// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
    return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } 
  else if(WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } 
  else {
    WheelPos -= 170;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}
Last updated on 2014-04-15 at 01.54.03 PM Published on 2013-02-27 at 12.05.44 PM