#include <FastLED.h>
#define pin 0
#define led 1

CRGB leds[led];

void setup() {
  FastLED.addLeds<WS2812, pin, GRB>(leds, led);
  FastLED.clear();
  FastLED.setBrightness(255);
  FastLED.show();
}

void loop() {
  uint8_t speed = 20;
  uint8_t change = 10;
  uint8_t hue = beat8(speed, 255);
  fill_rainbow(leds, led, hue, change);
  FastLED.show();
}