#include <FastLED.h>
#define NUM_LEDS 100  // LED 數量
#define DATA_PIN 3

const int buttonPin = 4;
int buttonState = 0;
int i,j;
int Delay;
long Previous;

CRGB leds[NUM_LEDS];

void setup() {
  pinMode(buttonPin, INPUT_PULLUP); // 按鍵輸入
  pinMode(A0, INPUT);               // 速度調整
  
  FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);  // GRB ordering is assumed
}

void loop() {
  
  Previous = millis();
  j = analogRead(A0);
  Delay = map(j, 0, 1024, 24, 120); //T = 1200/wpm; 24 = 50wpm, 120 = 10wpm
  
  for (i = NUM_LEDS - 1; i > 0; i--) {
    leds[i] = leds[i - 1];              //移位
  }
  
  buttonState = digitalRead(buttonPin);
  if (buttonState == LOW)
    leds[0] = CRGB::Green;
  else
    leds[0] = CRGB::Black;

  FastLED.show();

  while(millis()- Previous < Delay);
}