#include <Adafruit_NeoPixel.h>

#define LED_PIN PB3
#define LED_COUNT 60

Adafruit_NeoPixel pixels(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  pixels.begin();
}

void loop() {
  rainbowChase(20, 50); // Change the values as per your preference
}

void rainbowChase(int delayTime, int trailLength) {
  for (int j = 0; j < 256; j++) {
    for (int i = 0; i < pixels.numPixels() + trailLength; i++) {
      pixels.setPixelColor(i, Wheel(((i * 256 / pixels.numPixels()) + j) & 255));
      pixels.show();
      delay(delayTime);
      if (i >= trailLength) {
        pixels.setPixelColor(i - trailLength, 0);
      }
    }
  }
}

uint32_t Wheel(byte WheelPos) {
  if (WheelPos < 85) {
    return pixels.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if (WheelPos < 170) {
    WheelPos -= 85;
    return pixels.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
    WheelPos -= 170;
    return pixels.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}