#include <Adafruit_NeoPixel.h>
const byte pir_pin=2;
const byte data_pin=15;
const byte led_num=16;
Adafruit_NeoPixel pixel= Adafruit_NeoPixel(led_num,data_pin,NEO_GRB+NEO_KHZ800);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(pir_pin, INPUT);
  pixel.begin();
  pixel.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(){
  pixel.setPixelColor(0,255,0,0);
  pixel.show();
}