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how to program RGB led strip WS2812b with Arduino

Introducing the WS2812B LED Strip

The WS2812B addressable LED strip comes in several models that differ in size, sealant or LED density. Choose the one that best fits your purposes. 

Powering the WS2812B LED Strip

The LED strip should be powered using a 5V power source. At 5V, each LED draws about 50mA, when set to its full brightness.  This means that for every 30 LEDs, the strip may draw as much as 1.5 A. Make sure you select a power source that matches the strip’s needs. An AC to DC power adapter that provides 5V and 2A should do the job:

If you use an external power source, don’t forget to connect the power source ground to the Arduino ground.

Powering the WS2812B LED Strip

The LED strip should be powered using a 5V power source. At 5V, each LED draws about 50mA, when set to its full brightness.  This means that for every 30 LEDs, the strip may draw as much as 1.5 A. Make sure you select a power source that matches the strip’s needs. An AC to DC power adapter that provides 5V and 2A should do the job:

If you use an external power source, don’t forget to connect the power source ground to the Arduino ground.

Schematics

In this example, the WS2812B LED strip will be powered using the 5V Arduino pin. In my case, I’m controlling 14 LEDs. If you want to control many LEDs, you’ll need to use an external power source.

Useful tips:

  • Connect a capacitor with a capacitance between 100uF and 1000uF from power to ground to smooth out the power supply.
  • Add a 220 or 470 Ohm resistor between the Arduino digital output pin and the strip data input pin to reduce noise on that line.
  • Make your wires between the Arduino, power supply and the strip as short as possible to minimize voltage loss.
  • If your strip gets damaged and doesn’t work, check if the first LED is broken. If so, cut it, resolder the header pins, and it should work again.

Code

To control the WS2812B LED strip, you’ll need to download the FastLED library.

Installing the FastLED library

  1. Click here to download the FastLED library. You should have a .zip folder in your Downloads folder
  2. Unzip the .zip folder and you should get FastLED-master folder
  3. Rename your folder from FastLED-master to FastLED
  4. Move the FastLED folder to your Arduino IDE installation libraries folder
  5. Finally, re-open your Arduino IDE

After installing the needed library, upload the following code to your Arduino board (this is an example sketch provided in the library examples folder). Go to File > Examples > FastLED > ColorPalette or copy the code below.

#include <FastLED.h>

#define LED_PIN     5
#define NUM_LEDS    14
#define BRIGHTNESS  64
#define LED_TYPE    WS2811
#define COLOR_ORDER GRB
CRGB leds[NUM_LEDS];

#define UPDATES_PER_SECOND 100

// This example shows several ways to set up and use 'palettes' of colors
// with FastLED.
//
// These compact palettes provide an easy way to re-colorize your
// animation on the fly, quickly, easily, and with low overhead.
//
// USING palettes is MUCH simpler in practice than in theory, so first just
// run this sketch, and watch the pretty lights as you then read through
// the code.  Although this sketch has eight (or more) different color schemes,
// the entire sketch compiles down to about 6.5K on AVR.
//
// FastLED provides a few pre-configured color palettes, and makes it
// extremely easy to make up your own color schemes with palettes.
//
// Some notes on the more abstract 'theory and practice' of
// FastLED compact palettes are at the bottom of this file.



CRGBPalette16 currentPalette;
TBlendType    currentBlending;

extern CRGBPalette16 myRedWhiteBluePalette;
extern const TProgmemPalette16 myRedWhiteBluePalette_p PROGMEM;


void setup() {
    delay( 3000 ); // power-up safety delay
    FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
    FastLED.setBrightness(  BRIGHTNESS );
    
    currentPalette = RainbowColors_p;
    currentBlending = LINEARBLEND;
}


void loop()
{
    ChangePalettePeriodically();
    
    static uint8_t startIndex = 0;
    startIndex = startIndex + 1; /* motion speed */
    
    FillLEDsFromPaletteColors( startIndex);
    
    FastLED.show();
    FastLED.delay(1000 / UPDATES_PER_SECOND);
}

void FillLEDsFromPaletteColors( uint8_t colorIndex)
{
    uint8_t brightness = 255;
    
    for( int i = 0; i < NUM_LEDS; i++) {
        leds[i] = ColorFromPalette( currentPalette, colorIndex, brightness, currentBlending);
        colorIndex += 3;
    }
}


// There are several different palettes of colors demonstrated here.
//
// FastLED provides several 'preset' palettes: RainbowColors_p, RainbowStripeColors_p,
// OceanColors_p, CloudColors_p, LavaColors_p, ForestColors_p, and PartyColors_p.
//
// Additionally, you can manually define your own color palettes, or you can write
// code that creates color palettes on the fly.  All are shown here.

void ChangePalettePeriodically()
{
    uint8_t secondHand = (millis() / 1000) % 60;
    static uint8_t lastSecond = 99;
    
    if( lastSecond != secondHand) {
        lastSecond = secondHand;
        if( secondHand ==  0)  { currentPalette = RainbowColors_p;         currentBlending = LINEARBLEND; }
        if( secondHand == 10)  { currentPalette = RainbowStripeColors_p;   currentBlending = NOBLEND;  }
        if( secondHand == 15)  { currentPalette = RainbowStripeColors_p;   currentBlending = LINEARBLEND; }
        if( secondHand == 20)  { SetupPurpleAndGreenPalette();             currentBlending = LINEARBLEND; }
        if( secondHand == 25)  { SetupTotallyRandomPalette();              currentBlending = LINEARBLEND; }
        if( secondHand == 30)  { SetupBlackAndWhiteStripedPalette();       currentBlending = NOBLEND; }
        if( secondHand == 35)  { SetupBlackAndWhiteStripedPalette();       currentBlending = LINEARBLEND; }
        if( secondHand == 40)  { currentPalette = CloudColors_p;           currentBlending = LINEARBLEND; }
        if( secondHand == 45)  { currentPalette = PartyColors_p;           currentBlending = LINEARBLEND; }
        if( secondHand == 50)  { currentPalette = myRedWhiteBluePalette_p; currentBlending = NOBLEND;  }
        if( secondHand == 55)  { currentPalette = myRedWhiteBluePalette_p; currentBlending = LINEARBLEND; }
    }
}

// This function fills the palette with totally random colors.
void SetupTotallyRandomPalette()
{
    for( int i = 0; i < 16; i++) {
        currentPalette[i] = CHSV( random8(), 255, random8());
    }
}

// This function sets up a palette of black and white stripes,
// using code.  Since the palette is effectively an array of
// sixteen CRGB colors, the various fill_* functions can be used
// to set them up.
void SetupBlackAndWhiteStripedPalette()
{
    // 'black out' all 16 palette entries...
    fill_solid( currentPalette, 16, CRGB::Black);
    // and set every fourth one to white.
    currentPalette[0] = CRGB::White;
    currentPalette[4] = CRGB::White;
    currentPalette[8] = CRGB::White;
    currentPalette[12] = CRGB::White;
    
}

// This function sets up a palette of purple and green stripes.
void SetupPurpleAndGreenPalette()
{
    CRGB purple = CHSV( HUE_PURPLE, 255, 255);
    CRGB green  = CHSV( HUE_GREEN, 255, 255);
    CRGB black  = CRGB::Black;
    
    currentPalette = CRGBPalette16(
                                   green,  green,  black,  black,
                                   purple, purple, black,  black,
                                   green,  green,  black,  black,
                                   purple, purple, black,  black );
}


// This example shows how to set up a static color palette
// which is stored in PROGMEM (flash), which is almost always more
// plentiful than RAM.  A static PROGMEM palette like this
// takes up 64 bytes of flash.
const TProgmemPalette16 myRedWhiteBluePalette_p PROGMEM =
{
    CRGB::Red,
    CRGB::Gray, // 'white' is too bright compared to red and blue
    CRGB::Blue,
    CRGB::Black,
    
    CRGB::Red,
    CRGB::Gray,
    CRGB::Blue,
    CRGB::Black,
    
    CRGB::Red,
    CRGB::Red,
    CRGB::Gray,
    CRGB::Gray,
    CRGB::Blue,
    CRGB::Blue,
    CRGB::Black,
    CRGB::Black
};



// Additionl notes on FastLED compact palettes:
//
// Normally, in computer graphics, the palette (or "color lookup table")
// has 256 entries, each containing a specific 24-bit RGB color.  You can then
// index into the color palette using a simple 8-bit (one byte) value.
// A 256-entry color palette takes up 768 bytes of RAM, which on Arduino
// is quite possibly "too many" bytes.
//
// FastLED does offer traditional 256-element palettes, for setups that
// can afford the 768-byte cost in RAM.
//
// However, FastLED also offers a compact alternative.  FastLED offers
// palettes that store 16 distinct entries, but can be accessed AS IF
// they actually have 256 entries; this is accomplished by interpolating
// between the 16 explicit entries to create fifteen intermediate palette
// entries between each pair.
//
// So for example, if you set the first two explicit entries of a compact 
// palette to Green (0,255,0) and Blue (0,0,255), and then retrieved 
// the first sixteen entries from the virtual palette (of 256), you'd get
// Green, followed by a smooth gradient from green-to-blue, and then Blue.

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