FastLED Platform: ARM SAMD51 (d51)

SAMD51 (Feather/Itsy M4, Wio Terminal) support.

Files (quick pass)

• fastled_arm_d51.h: Aggregator; includes fastpin_arm_d51.h, clockless_arm_d51.h, and SPI core where applicable.
• fastpin_arm_d51.h: Pin helpers for SAMD51.
• led_sysdefs_arm_d51.h: System defines for SAMD51.
• clockless_arm_d51.h: Clockless WS281x driver for SAMD51.
• README.txt: Historical notes on tested boards.

Notes:

• Higher clock speeds and interrupt policy can affect jitter; prefer short critical sections.
• Typical settings: FASTLED_USE_PROGMEM=0; consider enabling interrupts with careful ISR timing.

Optional feature defines

• FASTLED_USE_PROGMEM: Default 0.
• FASTLED_ALLOW_INTERRUPTS: Default 1. Enables FASTLED_ACCURATE_CLOCK when 1.

Define before including FastLED.h.