/***
 *** slow colour fade for a short strip of ws2812 LEDs
 ***
 *** runs on 8MHz interneal-clock ATtiny85
 ***
 ***/

#include <Adafruit_NeoPixel.h>

#define PIN 	0
#define PIXELS 	5

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(PIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup()
{
  pixels.begin();
}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
   return pixels.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if(WheelPos < 170) {
   WheelPos -= 85;
   return pixels.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
   WheelPos -= 170;
   return pixels.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}

uint8_t  col = 0;

void loop()
{
  for (int i=0; i<PIXELS; i++) {
    pixels.setPixelColor(i, Wheel(col));
  }
  col++;
  pixels.show();
  delay(500);
}