Arduino - Rotary encoder using Neopixel ring indicator

rotary_encoder_and_neopixel_ring.ino

#include <Adafruit_NeoPixel.h>

 /* Read Quadrature Encoder
  * Connect Encoder to Pins encoder0PinA, encoder0PinB, and +5V.
  *
  * Sketch by max wolf / www.meso.net
  * v. 0.1 - very basic functions - mw 20061220
  *
  */  

#define PIN            9
#define NUMPIXELS      16  
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);


 int val; 
 int encoder0PinA = 2;
 int encoder0PinB = 3;
 int encoder0Pos = 0;
 int encoder0PinALast = LOW;
 int n = LOW;

 void setup() { 
   pinMode (encoder0PinA,INPUT);
   pinMode (encoder0PinB,INPUT);
   pinMode (5, OUTPUT);
   pinMode (6, OUTPUT);
   digitalWrite (5, HIGH);
   digitalWrite (6, LOW );
   Serial.begin (9600);   
   pixels.begin(); // This initializes the NeoPixel library.
 } 

 void loop() { 
   n = digitalRead(encoder0PinA);
   if ((encoder0PinALast == LOW) && (n == HIGH)) {
     if (digitalRead(encoder0PinB) == LOW) {
       encoder0Pos--;
     } else {
       encoder0Pos++;
     }
     Serial.print (encoder0Pos);
     Serial.print ("\n");

     for (byte i=0; i<16; i++) {
        if (encoder0Pos == 0) {
          pixels.setPixelColor(i, pixels.Color(0, 0, 0));
        } else if (encoder0Pos > 0) {
          uint32_t pixelColor = (encoder0Pos > i)? Wheel((15-i)*16) : 0;
          pixels.setPixelColor(i,pixelColor);
        } else {
           uint32_t pixelColor = (encoder0Pos < -i)? Wheel((i+1)*16) : 0;
           pixels.setPixelColor(15-i, pixelColor);
        }
        
        
       
     }
     pixels.show();
   } 
   encoder0PinALast = n;
 } 

 // 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) {
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) {
    return pixels.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return pixels.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return pixels.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}