Make your holiday lights dance to music!

This uses a 300 LED Adafruit Neopixel strip driven by Sparkfun Spectrum Shield (make sure you buy the stackable headers with this) and Arduino Uno. The connections are fairly simple as shown in this pic. Apart from the ground and 5v you just need to connect one data pin to the Neopixel strip to control it (refer to Adafruit Neopixel Guide). There are two standard 1/8″ audio jacks on the Shield that you can connect input audio and pass through the other to your speaker.

The code was adapted from http://michaelteeuw.nl/post/84599343577/micro-disco. (Thanks Michael!).

#include <Adafruit_NeoPixel.h> // include the Adfruit Neopixel library
 
#define PIN_NEOPIXELS 8 // connect Neopixel strip to this pin
#define PIN_STROBE 4 // spectrum shield strobe pin
#define PIN_RESET 5 // spectrum shield reset pin
#define PIN_SOUND 1 //analog input pin spectrum shield - using only one/right channel
#define NUMLEDS 300 // LEDs in Neopixel strip
 
#define MINPOWER 128 // minimum amplitude value to be considered
#define MAXPOWER 1023 // max amplitude value
 
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMLEDS, PIN_NEOPIXELS, NEO_GRB + NEO_KHZ800);
 
int soundvalue[7]; //band array to store amplitutde value for each band
 
void setup() 
{
 strip.begin(); //initialize neopixels
 strip.setBrightness(35);
 strip.show();
 //initialize spectrum shield graphic equalizer
 pinMode(PIN_RESET, OUTPUT); // reset
 pinMode(PIN_STROBE, OUTPUT); // strobe
 digitalWrite(PIN_RESET,LOW); // reset low
 digitalWrite(PIN_STROBE,HIGH); //pin 5 is RESET on the shield
}
 
void loop() {

 readMSGEQ7();
 int bColor = colorValue((soundvalue[0]+soundvalue[1])/2);
 int gColor = colorValue((soundvalue[2]+soundvalue[3]+soundvalue[4])/3);
 int rColor = colorValue((soundvalue[5]+soundvalue[6])/2);
 byte red = rColor; //convert to 0-255 byte value for Neopixel
 byte blue = bColor;
 byte green = gColor;
 
 for (int i = 0; i < NUMLEDS; i=i++) //show strip
 {
 if(i<=240) {strip.setPixelColor(i, (i<=rColor) ? red : 0,(i<=gColor) ? green : 0,(i<=bColor) ? blue : 0);}
 else {strip.setPixelColor(i, (i<=rColor) ? 255 : 0,(i<=gColor) ? 255 : 0,(i<=bColor) ? 255 : 0);} 
 } //you might have to play with this based on your setup. The if statement is to make the top LEDs show brighter
 strip.show();
 delay(5);
}
 
int colorValue(int powerValue) // calculate a a RGB color value from the sound bands
{
 return map(powerValue, MINPOWER, MAXPOWER, 0, NUMLEDS);
}
 
// Read the Analog sound data from 7 bands
void readMSGEQ7()
{
 digitalWrite(PIN_RESET, HIGH); //reset the data
 digitalWrite(PIN_RESET, LOW);
 for(int band=0; band < 7; band++) { //loop thru all 7 bands
 digitalWrite(PIN_STROBE,LOW); // go to the next band 
 delayMicroseconds(10); //gather some data
 soundvalue[band] = analogRead(PIN_SOUND); // store left band reading
 digitalWrite(PIN_STROBE,HIGH); // reset the strobe pin
 }
}