Code

void setup() {
    // No need to initialize the RGB LED
    Serial.begin(115200);
}

// the loop function runs over and over again forever
void loop() {
#ifdef RGB_BUILTIN
    digitalWrite(RGB_BUILTIN, HIGH);   // Turn the RGB LED white
    delay(1000);
    digitalWrite(RGB_BUILTIN, LOW);    // Turn the RGB LED off
    delay(1000);

    neopixelWrite(RGB_BUILTIN, RGB_BRIGHTNESS, 0, 0); // Red
    delay(1000);
    neopixelWrite(RGB_BUILTIN, 0, RGB_BRIGHTNESS, 0); // Green
    delay(1000);
    neopixelWrite(RGB_BUILTIN, 0, 0, RGB_BRIGHTNESS); // Blue
    delay(1000);
    neopixelWrite(RGB_BUILTIN, 0, 0, 0); // Off / black
    delay(1000);
    Serial.println("end cycle");
#endif
}