The simplest, most lightweight WS2812B RGB LED library for SAMD21-based Arduino boards (Arduino Zero, MKR family, Adafruit M0, etc.). For single RGB control, this library saves program, memory space, and CPU cycles compared to popular RGB LED control libraries.

• Ultra-minimal - Uses direct PORT register access and cycle-accurate bit-banging
• Simple API - Just two functions: begin() and set()
• 8 predefined colors - Common colors built-in

Connect your WS2812B LED to your SAMD21 board:

WS2812B Pin  →  SAMD21
-----------     ------
VDD (5V)     →  5V or VIN
VSS (GND)    →  GND
DIN          →  Any GPIO pin (e.g., pin 6)

1. Download or clone this repository
2. Move the SAMD21_WS2812B folder to your Arduino libraries folder:
   • macOS: ~/Documents/Arduino/libraries/
   • Windows: Documents\Arduino\libraries\
   • Linux: ~/Arduino/libraries/
3. Restart Arduino IDE

#include <SAMD21_WS2812B.h>

#define LED_PIN 6  // GPIO pin for WS2812B data (DIN)

WS2812B led;

void setup() {
  // Initialize with GPIO pin number
  led.begin(LED_PIN);
}

void loop() {
  // Flash red with a 1 second interval
  led.set("red", 255); // Brightness value optional, defaults to full brightness
  delay(1000);
  led.set("black");
  delay(1000);
}

Initialize the WS2812B controller on the specified GPIO pin.

• Parameters: pin - GPIO pin number (e.g., 5)
• Returns: true on success, false on failure

Set the LED color and brightness.

• Parameters:
  • color - Color name (see below)
  • brightness - Brightness level from 1-255 (255 = full brightness)
    • Use "black" to turn the LED off
• Returns: None

The library uses CPU cycle-accurate bit-banging calibrated for 48 MHz SAMD21 boards. Interrupts are disabled during transmission to prevent timing jitter.

• SAMD21-based Arduino board (Arduino Zero, MKR Zero, MKR1000, Adafruit Feather M0, Adafruit M0 Express, etc.)
• Single WS2812B LED

LED doesn't light up:

• Check power connections (WS2812B needs both 5V and GND)
• Verify data pin connection
• Ensure your board runs at 48 MHz (standard for SAMD21)
• Try a different GPIO pin

LED shows wrong colors:

• Some WS2812B variants use RGB instead of GRB - check your LED's datasheet
• If needed, change the byte order in SAMD21_WS2812B.cpp:

    // Standard WS2812B expects GRB order
    sendByte(g);
    sendByte(r);
    sendByte(b);

Timing issues or flickering:

• This library is calibrated for 48 MHz SAMD21. Other clock speeds would require adjusting the NOP counts
• Ensure no high-priority interrupts are running too frequently (USB, timers, etc.)

Compilation errors:

• Ensure your board is properly configured in Arduino IDE (Tools > Board > Arduino SAMD Boards)