#include "FastLED.h"                                          // FastLED library.

#if FASTLED_VERSION < 3001000
#error "Requires FastLED 3.1 or later; check github for latest code."
#endif

// Fixed definitions cannot change on the fly.
#define LED_DT 2                                          // Serial data pin
#define LED_CK                                            // Clock pin for WS2801 or APA102
#define COLOR_ORDER BGR                                       // It's GRB for WS2812B and GBR for APA102
#define LED_TYPE WS2812B                                    // What kind of strip are you using (APA102, WS2801 or WS2812B)?
#define NUM_LEDS 120                            // Number of LED's
#define BRIGHTNESS 200

// Initialize changeable global variables.                                 // Overall brightness definition. It can be changed on the fly.

struct CRGB leds[NUM_LEDS];                                   // Initialize our LED array.



void setup() {

  Serial.begin(115200);

LEDS.addLeds<LED_TYPE, LED_DT, COLOR_ORDER>(leds, NUM_LEDS);         // For WS2812B


  FastLED.setBrightness(BRIGHTNESS);
  set_max_power_in_volts_and_milliamps(5, 1000);              // FastLED 2.1 Power management set at 5V, 500mA

} // setup()



void loop () {

  rainbow_march(200, 10);
  FastLED.show();

} // loop()



void rainbow_march(uint8_t thisdelay, uint8_t deltahue) {     // The fill_rainbow call doesn't support brightness levels.

  uint8_t thishue = millis()*(255-thisdelay)/255;             // To change the rate, add a beat or something to the result. 'thisdelay' must be a fixed value.

// thishue = beat8(50);                                       // This uses a FastLED sawtooth generator. Again, the '50' should not change on the fly.
// thishue = beatsin8(50,0,255);                              // This can change speeds on the fly. You can also add these to each other.

  fill_rainbow(leds, NUM_LEDS, thishue, deltahue);            // Use FastLED's fill_rainbow routine.

} // rainbow_march()