ESP32 LED Strip. tutorial: https://help.sinric.pro/pages/tutorials/light/LED-Stripe-5050.html

ESP32-LED-Strip.ino

// Red, green, and blue pins for PWM control
const int ledR = 14;   
const int ledG = 12;   
const int bluePin = 27;
 
uint8_t color = 0;          // a value from 0 to 255 representing the hue
uint32_t R, G, B;           // the Red Green and Blue color components
uint8_t brightness = 255;  // 255 is maximum brightness, but can be changed.  Might need 256 for common anode to fully turn off.
bool invert = false;

void hueToRGB(uint8_t hue, uint8_t brightness);

void setup() {
  Serial.begin(115200);
  delay(10); 

  ledcAttachPin(ledR, 1);
  ledcAttachPin(ledG, 2);
  ledcAttachPin(ledB, 3); 

  // Initialize channels 
  // channels 0-15, resolution 1-16 bits, freq limits depend on resolution
  // ledcSetup(uint8_t channel, uint32_t freq, uint8_t resolution_bits);
  ledcSetup(1, 12000, 8); // 12 kHz PWM, 8-bit resolution
  ledcSetup(2, 12000, 8);
  ledcSetup(3, 12000, 8);
}

void loop(){
   for (color = 0; color < 255; color++) { // Slew through the color spectrum
    hueToRGB(color, brightness);  // call function to convert hue to RGB

    // write the RGB values to the pins
    ledcWrite(1, R); // write red component to channel 1, etc.
    ledcWrite(2, G);   
    ledcWrite(3, B); 
  
    delay(100); // full cycle of rgb over 256 colors takes 26 seconds
 }  
}

// Courtesy http://www.instructables.com/id/How-to-Use-an-RGB-LED/?ALLSTEPS
// function to convert a color to its Red, Green, and Blue components.

void hueToRGB(uint8_t hue, uint8_t brightness) {
    uint16_t scaledHue = (hue * 6);
    uint8_t segment = scaledHue / 256; // segment 0 to 5 around the
                                            // color wheel
    uint16_t segmentOffset =
      scaledHue - (segment * 256); // position within the segment

    uint8_t complement = 0;
    uint16_t prev = (brightness * ( 255 -  segmentOffset)) / 256;
    uint16_t next = (brightness *  segmentOffset) / 256;

    if(invert)
    {
      brightness = 255 - brightness;
      complement = 255;
      prev = 255 - prev;
      next = 255 - next;
    }

    switch(segment ) {
    case 0:      // red
        R = brightness;
        G = next;
        B = complement;
    break;
    case 1:     // yellow
        R = prev;
        G = brightness;
        B = complement;
    break;
    case 2:     // green
        R = complement;
        G = brightness;
        B = next;
    break;
    case 3:    // cyan
        R = complement;
        G = prev;
        B = brightness;
    break;
    case 4:    // blue
        R = next;
        G = complement;
        B = brightness;
    break;
   case 5:      // magenta
    default:
        R = brightness;
        G = complement;
        B = prev;
    break;
    }
}