const byte ledPins[] = {2, 4, 5};
const byte chns[] = {0, 1, 2};
void setup() {
  for(int i = 0; i < 3; i++) {
  ledcSetup(chns[i], 1000, 8);
  ledcAttachPin(ledPins[i], chns[i]);
  }
}
void loop() {
 for(int i = 0; i < 256; i++) {
   setColor(wheel(i));
   delay(20);
 }
 }

 void setColor(long rgb) {
   ledcWrite(chns[0], 255 - (rgb >> 16) & 0xFF);
   ledcWrite(chns[1], 255 - (rgb >> 8) & 0xFF);
   ledcWrite(chns[2], 255 - (rgb >> 0) & 0xFF);
    }

    long wheel(int pos) {
      long WheelPos = pos % 0xff;
      if  (WheelPos < 85) {
        return ((255 - WheelPos * 3) << 16) | ((WheelPos * 3) << 8);
      }
      else if (WheelPos < 170) { 
        WheelPos -= 85;
        return (((255 - WheelPos * 3) << 8) | (WheelPos * 3));
      }
      else {
        WheelPos -= 170;
        return ((WheelPos * 3) << 16 | (255 - WheelPos * 3));
      }
    }