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NeoPixel Rainbow (WS2812 + Arduino)

Animate a flowing rainbow across an addressable LED strip. Learn the Adafruit_NeoPixel library and HSV color.

Beginner20 min

What you need

Wiring

Arduino Uno
NeoPixel strip

Hover a pin or a wire to trace the connection.

Code

neopixel_rainbow.ino
// Flowing rainbow across a NeoPixel (WS2812) strip.
// Install "Adafruit NeoPixel".
#include <Adafruit_NeoPixel.h>

const int PIN = 6;
const int NUM = 8;   // set to your strip's LED count
Adafruit_NeoPixel strip(NUM, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  strip.begin();
  strip.setBrightness(40);  // keep current draw sane
  strip.show();
}

void loop() {
  for (long j = 0; j < 65536; j += 256) {
    for (int i = 0; i < NUM; i++) {
      long hue = (i * 65536L / NUM + j) & 0xFFFF;
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue)));
    }
    strip.show();
    delay(20);
  }
}

Steps

  1. Wire DIN to D6 through a ~330Ω resistor; 5V and GND to power (external 5V for long strips, shared ground).
  2. Set NUM to your strip's LED count and install "Adafruit NeoPixel".
  3. Upload to see a flowing rainbow. Lower setBrightness if the strip draws too much current.