Automatic subtle colour changing on ws2812b with arduino

Question

I'm creating a wordclock and I'd like to change the ws2812b led strip color slowly, so that it fades from one colour to another. However, I'm new to arduino and I can't get it done and I also could not find anything on this anywhere (probably because of using the wrong keywords)

Currently I have a colour hardcoded like this:

void SwitchLED(int MyArray[], int n) {
     for (i = MyArray[0]; i < MyArray[0]+n; i++) {
          leds[i].setRGB((161,57,0); 
     }
}

(The array in this code are the LEDs that will light up depending on the time I get from a ds3231).

So I would like a (random) starting colour to slowly change to another colour and so on. This in such a way that you will notice it only after a couple of minutes, so very slow and subtle.

I'm using the FastLED libary. I bit of help on this would be appreciated very much.

Answer 1

For the color, you can use the time (millis()) as a hue parameter.

void SwitchLED(int MyArray[], int n) {
    CRGB color = CHSV(millis()/1024, 255, 255);
    for (i = MyArray[0]; i < MyArray[0]+n; i++) {
        leds[i] = color; 
    }
}

I used 1024 here to scale the time, so it takes 4 min 22 sec, to go through the hue cycle. And a power of two, should solve a visual glitch on millis() overflow.