/*
  Forum: https://forum.arduino.cc/t/fastled-blend-ws2812/1420585
  Wokwi: https://wokwi.com/projects/450794513036919809

  2025/12/19
  ec2021

*/

#include <FastLED.h>

constexpr byte LED_PIN = 8;
constexpr int NUM_LEDS = 16;

CRGB leds[NUM_LEDS];

CRGB start_colour = CRGB (250,50,50);
CRGB target_colour = CRGB (50,250,50);
CRGB act_colour;

//constexpr unsigned long completeChangeTimeInMilliSeconds {3600000UL};  // 3600000 for one hour
//constexpr unsigned long completeChangeTimeInMilliSeconds {60000UL};    // 60000 is one minute = 60 seconds
constexpr unsigned long completeChangeTimeInMilliSeconds {6000UL};      //  6000 are 6 seconds
constexpr unsigned long milliSecsPerStep {completeChangeTimeInMilliSeconds/256};
unsigned long lastChange = 0;

int blendAmount = 0;

void setup() {
  Serial.begin(115200);
  Serial.println("Start");
  Serial.print("Change interval = ");
  Serial.print(milliSecsPerStep);
  Serial.println(" milliseconds");  
  FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(255);
  setColour();  // Do the first step here
}

void loop() {
  if (millis()-lastChange >= milliSecsPerStep){
    setColour();
  }
}

void setColour(){
  lastChange = millis();
  Serial.print("blendAmount = ");
  Serial.println(blendAmount);
  act_colour = blend(start_colour, target_colour, blendAmount);
  fill_solid(leds, NUM_LEDS,act_colour);
  FastLED.show();
  blendAmount++; 
  blendAmount = blendAmount % 256; 
 }