#include <Adafruit_NeoPixel.h>

static const uint8_t PIN =  D0;
#define NUMPIXELS           28
Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup(){
  Serial.begin(115200);
  pixels.begin();
}
unsigned long timer=0;
unsigned int location=0;
void loop() {
  if(millis()>timer){
    timer=millis()+10;
    pixels.clear();
    for(int i=0;i<NUMPIXELS;i++){
      if(i==location)
        pixels.setPixelColor(i,pixels.Color(255, 255, 255));
      else
        pixels.setPixelColor(i,pixels.Color(0, 0, 0));
    }//for
    pixels.show();
    Serial.println(millis());
    location++;
    if(location==NUMPIXELS)
      location=0;
  }
}