#include <FastLED.h>

#define LED_PIN     8
#define NUM_LEDS    16
#define BRIGHTNESS  255
#define LED_TYPE    WS2812
#define COLOR_ORDER GRB
CRGBArray<NUM_LEDS>leds;

void setup() {
  FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
  FastLED.setBrightness(  BRIGHTNESS );
}


void loop () {

    cd77_sinelon_oneway(50, CRGB::Red, 5);

} 
 
// Functions ======================


// Modification of sinelon() in FastLED's DemoReel100 example
void cd77_sinelon_oneway(uint8_t BPM, CRGB color, uint8_t fadeby)
{
  // a colored dot going in one direction with fading tail
  fadeToBlackBy( leds, NUM_LEDS, fadeby);  //change fadeby to smaller or larger number to adjust the length of the tail.
  uint8_t u= beat8(BPM,0); //BPM will allow you to adjust the speed the dot is moving.
  uint16_t pos=map(u,0,255,0,NUM_LEDS);
 leds[pos] = color;
 FastLED.show();
}