#include <Adafruit_NeoPixel.h>
#define PIN        8
#define NUMPIXELS 24
// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

int delayval = 100 ;// delay for half a second

void setup() {
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}

void loop() {
  // Forward chase
  for(int i=0; i<NUMPIXELS; i++) {
    colorWipe(strip.Color(255, 0, 0), delayval); // Red
    colorWipe(strip.Color(255, 127, 0), delayval); // Orange
    colorWipe(strip.Color(255, 255, 0), delayval); // Yellow
    colorWipe(strip.Color(0, 255, 0), delayval); // Green
    colorWipe(strip.Color(0, 0, 255), delayval); // Blue
    colorWipe(strip.Color(75, 0, 130), delayval); // Indigo
    colorWipe(strip.Color(143, 0, 255), delayval); // Violet
  }

  // Backward chase
  for(int i=NUMPIXELS-1; i>=0; i--) {
    colorWipe(strip.Color(143, 0, 255), delayval); // Violet
    colorWipe(strip.Color(75, 0, 130), delayval); // Indigo
    colorWipe(strip.Color(0, 0, 255), delayval); // Blue
    colorWipe(strip.Color(0, 255, 0), delayval); // Green
    colorWipe(strip.Color(255, 255, 0), delayval); // Yellow
    colorWipe(strip.Color(255, 127, 0), delayval); // Orange
    colorWipe(strip.Color(255, 0, 0), delayval); // Red
  }
}

// Fill the dots one after the other with a color
void colorWipe(uint32_t c, uint8_t wait) {
  for(uint16_t i=0; i<strip.numPixels(); i++) {
    strip.setPixelColor(i, c);
    strip.show();
    delay(wait);
  }
}