#include <Arduino.h>
#include <neopixel_blit.h>

/* red light slowly appears and disappear */

#define CPLAY_REDLED 13

static uint8_t limit;
void setup() {
  init_neopixel_blit(); /* to ensure off regardless of prior sketch. */
  pinMode(CPLAY_REDLED, OUTPUT);
  limit = 125;
}

void loop() {
  static uint8_t brightness;
  static uint8_t direction;

  delay(2000 / limit);
  analogWrite(CPLAY_REDLED, brightness);
  if(brightness == limit) { direction = -1; limit -= 1; brightness -= 1; }
  brightness += direction;
  if(brightness ==     0) { direction =  1; }
  if(limit < 5) limit = 5;
}