#include <Adafruit_NeoPixel.h>

const byte data_pin = 15;
const byte pir_pin  = 2 ;
const byte led_num  = 16;

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(led_num, data_pin, NEO_GRB+ NEO_KHZ800); 

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(pir_pin, INPUT);
  pixels.begin();
  pixels.show();
}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.println(digitalRead(pir_pin));
  if( digitalRead(pir_pin) ){
    generate_random_pattern();
  }
  delay(10); // this speeds up the simulation
}

void generate_random_pattern(){
  pixels.setPixelColor(0,255,0,0);
  pixels.show();
}