/*
    Description: Control HEX Unit to run rainbow light show
    Please install library before compiling:  
    FastLED: https://github.com/FastLED/FastLED
*/
#include <M5Stack.h>
#include "FastLED.h"

#define Neopixel_PIN    21
#define NUM_LEDS    37

CRGB leds[NUM_LEDS];
uint8_t gHue = 0;

void setup() {
  Serial.begin(115200);
  M5.Power.begin();
  M5.begin();
  M5.Lcd.clear(BLACK);
  M5.Lcd.setTextColor(YELLOW); M5.Lcd.setTextSize(2); M5.Lcd.setCursor(40, 0);
  M5.Lcd.println("HEX Example");
  M5.Lcd.setTextColor(WHITE);
  M5.Lcd.setCursor(0, 25);
  M5.Lcd.println("Display rainbow effect");

  // Neopixel initialization
  FastLED.addLeds<WS2811,Neopixel_PIN,GRB>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);
  FastLED.setBrightness(10);
}

void loop(){
    fill_rainbow( leds, NUM_LEDS, gHue, 7);
    FastLED.show();// must be executed for neopixel becoming effective
    EVERY_N_MILLISECONDS( 20 ) { gHue++; }
}