Download the Arduino IDE and the required libraries:

  1. FastLED
  2. Color Sensor TCS34725

The attached code can work as is. There are a few lines you may consider changing:

1. This project used 9 strands of 20 LEDs, total of 180 LEDs. If you use a different amount, change the number in this line of code:

#define NUM_LEDS  180   // Change this to reflect the number of LEDs you have

2. While working on the project, the lights might be too bright, If so, reduce the number in this line of code. 255 is the maximum for brightness:

#define BRIGHTNESS  255      // Set Brightness here 255

3. In the setup, the following code makes one of the LEDs blink 3 times to let you know that the color sensor is ready to read a color value. For this project, it made sense to light up LED #17 since it was closest to the microcontroller in the layout. You can chose the first LED instead. The counter starts with 0, so change the below to leds[0].  Also you can change the color of the blinking light. In this code, it goes from Black to White making it blink White.

for (int i=0; i<3; i++){ //this sequence flashes the first pixel three times none/white as a countdown to the color reading.
    leds[16] = CRGB::Black;; 
    leds[16] = CRGB::White;; 

The rest of the code is pretty much a combination of FastLED sample code and Color Sensor code.

In this project, it is set it up so that on restart the color sensor reads the color and the skirt fills up with a transition gradient of that color until the next reset. Similar to the Adafruit Chameleon Scarf project. You can also set it up so that it fires off the color sensor every x seconds and changes the lights according to the color it picks up. This can be achieved by moving the code starting from tcs.begin();from the setup() function to the loop() function and doing some modifications. 

Download the code by clicking the "Download Project Bundle" button below or via the link here.

To upload code you need to quickly double press the reset button on the Gemma. You know it's uploading if the green and red lights on the Gemma are on.

// SPDX-FileCopyrightText: 2021 Irete Hamdani for Adafruit Industries
// SPDX-License-Identifier: MIT
#include <FastLED.h>
#include <Wire.h>
#include "Adafruit_TCS34725.h"

#define DATA_PIN   1
#define LED_TYPE    WS2812B
#define NUM_LEDS    180     // Change this to reflect the number of LEDs you have
#define BRIGHTNESS  255     // Set Brightness here 255

// color sensor
// our RGB -> eye-recognized gamma color
byte gammatable[256];
//used to store color sensor received color
uint16_t clear, red, green, blue;

// color sensor
Adafruit_TCS34725 tcs = Adafruit_TCS34725(TCS34725_INTEGRATIONTIME_50MS, TCS34725_GAIN_4X);

void setup() {
  delay(3000); // 3 second delay for recovery

  // tell FastLED about the LED strip configuration
    .setCorrection(TypicalLEDStrip) // cpt-city palettes have different color balance
    .setDither(BRIGHTNESS < 255);
  // set master brightness control


  // helps convert RGB colors to what humans see
  for (int i=0; i<256; i++) {
    float x = i;
    x /= 255;
    x = pow(x, 2.5);
    x *= 255;
    gammatable[i] = x;      

  for (int i=0; i<3; i++){ //this sequence flashes the first pixel three times none/white as a countdown to the color reading.
    leds[16] = CRGB::Black;; 
    leds[16] = CRGB::White;; 

  // turn on LED
  delay(60);  // takes 50ms to read 
  tcs.getRawData(&red, &green, &blue, &clear);

  tcs.setInterrupt(true);  // turn off LED

void loop()
  // Figure out some basic hex code for visualization
  uint32_t sum = red;
  sum += green;
  sum += blue;
  //sum += clear; // clear contains RGB already so no need to re-add it
  float r, g, b;
  r = red; r /= sum;
  g = green; g /= sum;
  b = blue; b /= sum;
  r *= 256; g *= 256; b *= 256;
  CRGBPalette16 gTargetPalette (
   CRGB (gammatable[(int)r], gammatable[(int)g], gammatable[(int)b]));
  colorwaves( leds, NUM_LEDS, gTargetPalette);//gCurrentPalette);;
// This function draws color waves with an ever-changing,
// widely-varying set of parameters, using a color palette.
void colorwaves( CRGB* ledarray, uint16_t numleds, CRGBPalette16& palette) 
  static uint16_t sPseudotime = 0;
  static uint16_t sLastMillis = 0;
  static uint16_t sHue16 = 0;
  uint8_t sat8 = beatsin88( 87, 220, 250);
  uint8_t brightdepth = beatsin88( 341, 96, 224);
  uint16_t brightnessthetainc16 = beatsin88( 203, (25 * 256), (40 * 256));
  uint8_t msmultiplier = beat8(147); //beatsin88(147, 23, 60); - creates a more dynamic pattern [IH]
  uint16_t hue16 = sHue16;//gHue * 256;
  uint16_t hueinc16 = beatsin88(113, 300, 1500);
  uint16_t ms = millis();
  uint16_t deltams = ms - sLastMillis ;
  sLastMillis  = ms;
  sPseudotime += deltams * msmultiplier;
  sHue16 += deltams * beatsin88( 400, 5,9);
  uint16_t brightnesstheta16 = sPseudotime;
  for( uint16_t i = 0 ; i < numleds; i++) {
    hue16 += hueinc16;
    uint8_t hue8 = hue16 / 256;
    uint16_t h16_128 = hue16 >> 7;
    if( h16_128 & 0x100) {
      hue8 = 255 - (h16_128 >> 1);
    } else {
      hue8 = h16_128 >> 1;
    brightnesstheta16  += brightnessthetainc16;
    uint16_t b16 = sin16( brightnesstheta16  ) + 32768;
    uint16_t bri16 = (uint32_t)((uint32_t)b16 * (uint32_t)b16) / 65536;
    uint8_t bri8 = (uint32_t)(((uint32_t)bri16) * brightdepth) / 65536;
    bri8 += (255 - brightdepth);
    uint8_t index = hue8;
    //index = triwave8( index);
    index = scale8( index, 240);
    CRGB newcolor = ColorFromPalette( palette, index, bri8);
    uint16_t pixelnumber = i;
    pixelnumber = (numleds-1) - pixelnumber;
    nblend( ledarray[pixelnumber], newcolor, 128);
Testing with a red object
Testing with a blue object

This guide was first published on Nov 11, 2021. It was last updated on 2021-11-12 10:43:01 -0500.

This page (Coding) was last updated on Nov 27, 2021.

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