#include Adafruit_NeoPixel.h

      // Pin connected to the NeoPixels (WS2812B)
      #define LED_PIN 15
      
      // Number of NeoPixels
      #define LED_COUNT 1
      
      // Create NeoPixel object
      Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
      
      void setup() {
        // Initialize NeoPixel strip
        strip.begin();
        strip.show(); // Initialize all pixels to 'off'
      }
      
      void loop() {
        // Cycle through different colors
        rainbow(20); // Change colors every 20ms
      }
      
      // Function to cycle through rainbow colors
      void rainbow(uint8_t wait) {
        for (uint16_t i = 0; i < 256; i++) {
          uint32_t color = Wheel((i + strip.numPixels()) & 255);
          for (int j = 0; j < strip.numPixels(); j++) {
            strip.setPixelColor(j, color);
          }
          strip.show();
          delay(wait);
        }
      }
      
      // Input a value 0 to 255 to get a color value.
      // The colors are a transition r - g - b - back to r.
      uint32_t Wheel(byte WheelPos) {
        WheelPos = 255 - WheelPos;
        if (WheelPos < 85) {
          return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
        }
        if (WheelPos < 170) {
          WheelPos -= 85;
          return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
        }
        WheelPos -= 170;
        return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
      }