FastLED - The Universal LED Library for Embedded and Arduino
Transform any microcontroller into an LED powerhouse.
Drive 30,000+ LEDs on high-end devices • Sub-$1 compatibility on tiny chips • Background rendering for responsive apps • Nearly every LED chipset supported • #2 most popular Arduino library
⚡ Get Blinking in 30 Seconds
#include <FastLED.h>
#define NUM_LEDS 60
CRGB leds[NUM_LEDS];
void setup() {
FastLED.addLeds<WS2812, 6>(leds, NUM_LEDS);
}
void loop() {
leds[0] = CRGB::Red; FastLED.show(); delay(500);
leds[0] = CRGB::Blue; FastLED.show(); delay(500);
}
✅ Works on Arduino, ESP32, Teensy, Raspberry Pi, and 50+ other platforms
📖 Just Getting Started?
See our Cookbook for tutorials and walkthroughs →
The FastLED Cookbook provides practical guides, step-by-step examples, and copy-paste recipes to help you create stunning LED effects - from your first blink to advanced animations.
🚀 Why FastLED?
| Massive Scale | Tiny Footprint | Background Rendering | Universal |
|---|
| Drive 30,000 LEDs on Teensy 4.1 | Runs on $0.50 ATtiny chips | ESP32/Teensy render while you code | Works on 50+ platforms |
| 50 parallel strips on Teensy | <2KB on Arduino Uno | Never miss user input | Nearly every LED chipset |
🎯 Performance: Zero-cost global brightness • High-performance 8-bit math, memory efficient on platforms that need it.
🔧 Developer Experience: Quick platform switching • Extensive examples • Active community support
📂 Source Code Directory Structure
FastLED's codebase is organized into several major areas. Each directory contains a README with detailed documentation:
| Path | Description |
|---|
| src/README.md | Overview of the FastLED source tree including public headers, core foundation, effects, platforms, sensors, and third-party integrations |
| src/fl/README.md | FastLED core library (fl::) providing cross-platform STL-like containers, graphics primitives, math, async, JSON, and I/O utilities |
| src/fx/README.md | FX library with 1D/2D effects, video playback, composition utilities, and links to effect subdirectories |
| src/platforms/readme.md | Platform directory overview with backend selection guide, controller types, board-specific documentation, and links to all platform subdirectories |
Table of Contents
📊 Detailed Build Status
The Smoke Build badge above tracks build.yml, which compiles a small
default example set across a subset of boards. Every per-board build badge
below proves compile coverage only; it does not validate hardware or timing.
The QEMU and AVR8JS badges are the explicitly labelled emulation exceptions.
Most per-board workflows compile that board's full example sweep, while a
narrower set is called out next to the affected badge. A per-board badge can
therefore be red while the smoke badge is green.
This is the beginning of the README. Read the rest at the original. Read the full README ↗
