Sandra asks:
My daughter is wanting to program some LED strip lighting using arduino so it lights up in time to music (to go with their performance for robocup).
The robotics teacher at school has already purchased an arduino and 1m of the strip lighting from your company.
In looking at the set up, however, she will need the parts to connect the lights to the arduino and to run the system on battery power. What exactly will she need? Can we purchase these items from you?
Thanks for the question Sandra!
Background
Our most popular line of LED strip lighting is the Neopixels line. Neopixels are our supplier Adafruit’s term for addressable RGB LEDs.
Parts
For this build you’re going to need an Arduino (we’ll use the Arduino Gemma), a Microphone, a Slide switch, a Lithium Polymer Battery and a NeoPixel Strip.
Arduino Gemma
MicroUSB Cable (for programming the Gemma)
Microphone
Slide Switch
Lithium Ion Battery
NeoPixel Strip
![Adafruit NeoPixel Digital RGB LED Strip - Black 30 LED - 1m [BLACK]](https://discourse.littlebird.com.au/uploads/default/original/1X/78ccd9bbc091a9d43225856d580e75a3e0bb3c61.jpeg)
Circuit Diagram
The Build
- Connect the NeoPixel’s strips “digital input” to the D0 pin on the Gemma.
- The negative wire from the strip connects to the ground pin
on the Gemma. - The positive wire from the strip connects to the VBat
pin of the Gemma (be careful not to connect it to the 3.3V pin). - The “out” pin on the Mic Amp connects to the A1/D2 pin on the Gemma (this
is also the Gemma’s analog input pin). - The positive pin on the Mic Amp will connect to the 3.3v on the Gemma.
- The negative pin on the Mic Amp shares the same ground connection as the Gemma (along with the
Neopixel strip).
Code
/* LED "Color Organ" for Adafruit Trinket and NeoPixel LEDs.
Hardware requirements:
- Adafruit Trinket or Gemma mini microcontroller (ATTiny85).
- Adafruit Electret Microphone Amplifier (ID: 1063)
- Several Neopixels, you can mix and match
o Adafruit Flora RGB Smart Pixels (ID: 1260)
o Adafruit NeoPixel Digital LED strip (ID: 1138)
o Adafruit Neopixel Ring (ID: 1463)
Software requirements:
- Adafruit NeoPixel library
Connections:
- 5 V to mic amp +
- GND to mic amp -
- Analog pinto microphone output (configurable below)
- Digital pin to LED data input (configurable below)
Written by Adafruit Industries. Distributed under the BSD license.
This paragraph must be included in any redistribution.
*/
#include <Adafruit_NeoPixel.h>
#define N_PIXELS 60 // Number of pixels you are using
#define MIC_PIN 1 // Microphone is attached to Trinket GPIO #2/Gemma D2 (A1)
#define LED_PIN 0 // NeoPixel LED strand is connected to GPIO #0 / D0
#define DC_OFFSET 0 // DC offset in mic signal - if unusure, leave 0
#define NOISE 100 // Noise/hum/interference in mic signal
#define SAMPLES 60 // Length of buffer for dynamic level adjustment
#define TOP (N_PIXELS +1) // Allow dot to go slightly off scale
// Comment out the next line if you do not want brightness control or have a Gemma
#define POT_PIN 3 // if defined, a potentiometer is on GPIO #3 (A3, Trinket only)
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() {
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
// if POT_PIN is defined, we have a potentiometer on GPIO #3 on a Trinket
// (Gemma doesn't have this pin)
uint8_t bright = 255;
#ifdef POT_PIN
bright = analogRead(POT_PIN); // Read pin (0-255) (adjust potentiometer
// to give 0 to Vcc volts
#endif
strip.setBrightness(bright); // Set LED brightness (if POT_PIN at top
// define commented out, will be full)
// 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)));
}
strip.show(); // Update strip
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);
}
}
