#include<Adafruit_NeoPixel.h>

#define NUMPIXELS 1
#define PIN_NEOPIXELS 4
Adafruit_NeoPixel pixels(NUMPIXELS, PIN_NEOPIXELS,  NEO_GRB +NEO_KHZ800);

void setup() {
  Serial.begin(115200);
  pixels.begin();
  pixels.setBrightness(200);
  Serial.println("HELLO, ESP32!");
}

void loop() {
 pixels.fill(0xFF0000);function();
 pixels.fill(0x00FF00);function();
 pixels.fill(0x0000FF);function();
 pixels.fill(0x000000);function();
}

void function(){
  pixels.show();
  delay(500);
}