// Jeff Ritchie 2 15 2026 revision- pulse
// based on adafruit neopixel example sketch
#include <Adafruit_NeoPixel.h>//pulls the Neopixel library
#ifdef __AVR__ //if an AVR board, use the library below. RP2040 is not an AVR. 
  #include <avr/power.h>
#endif
#define PIN        D0 //RP2040 uses D6 rather than pin 6
#define NUMPIXELS 16 //

Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800); //creates an instance called pixels
//third parameters indicate color in green red blue white order and the signal frequency of 800khz
#define DELAYVAL 500 //sets delay variable that makes it easier to change. Originally 500ms

void setup() {
#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000)
  clock_prescale_set(clock_div_1);
#endif
  pixels.begin();
}

void loop() {
  static int brightness = 0;
  static int direction = 1;
  pixels.setBrightness(brightness);
  for(int i=0; i<NUMPIXELS; i++) {
    pixels.setPixelColor(i, pixels.Color(255, 0, 0));
  }
  pixels.show();
  brightness += direction;
  if(brightness >= 150 || brightness <= 5) {
    direction = -direction;
  }
  delay(DELAYVAL);
}