Arduino random blink

randomblink.ino

const int LED_PIN= 3;

int cur_millis, wait_millis, brightness;
void setup() {
  Serial.begin(9600);  
  cur_millis = millis();
  wait_millis = random(1000);
  brightness = random(255);
}

void loop() {
   
  int ellapse_millis = millis() - cur_millis;
  if(ellapse_millis > wait_millis ){
    wait_millis = random(1000);
    brightness = random(255);
    cur_millis = millis();
  }
    
  unsigned long coefficient = millis() % 2000;
  coefficient = ( coefficient <= 1000 ? coefficient : 2000 - coefficient  );
  int out_brightness = (int)( coefficient / 1000.0 * brightness );
  Serial.println(out_brightness);

  analogWrite( LED_PIN, out_brightness );
}