#include "neopixel.h"

#define PIXEL_PIN D2
#define PIXEL_COUNT 16
#define PIXEL_TYPE WS2812

Adafruit_NeoPixel strip = Adafruit_NeoPixel(PIXEL_COUNT, PIXEL_PIN, PIXEL_TYPE);

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

}

void loop(){
    uint16_t i;
    uint32_t c = strip.Color(0, 25, 25);
    uint32_t off = strip.Color(0, 0, 0);
    
    // turn the pixel on one by one
    for(i=0; i < strip.numPixels(); i++){
        strip.setPixelColor(i, c);
        strip.show();
        delay(200);
    }
    delay(500);
    
    // reverse the sequence and turn the pixel off one by one
    for(i=strip.numPixels(); i > 0; i--){
        strip.setPixelColor(i, off);
        strip.show();
        delay(200);
    }
    delay(500);
}