#include <FastLED.h>

const int numLeds = 30;
const int ledStripPin = 6;

CRGB leds[numLeds];

void setup() {
  FastLED.addLeds<NEOPIXEL, ledStripPin>(leds, numLeds);
  FastLED.setMaxPowerInVoltsAndMilliamps(5, 400);
  FastLED.setBrightness(8);
}


void loop() {
  for (int light=0; light<30; light++) {
    leds[light] = CRGB::Red;
    FastLED.show();
    delay(10);
    leds[light] = CRGB::Black;
  }
  for (int light=30; light>0; light--) {
    leds[light] = CRGB::Red;
    FastLED.show();
    delay(10);
    leds[light] = CRGB::Black;
  }
}