#include <Mouse.h>

#define ENCA 2
#define ENCB 3

volatile int counter;
volatile uint8_t pre;
int preCount;

void setup()
{
  pinMode(ENCA, INPUT_PULLUP);
  pinMode(ENCB, INPUT_PULLUP);
  
  //マウス初期化
  Mouse.begin();

  counter = 0;
  preCount = 0;
  pre = 0;
  
  attachInterrupt(digitalPinToInterrupt(ENCA), pulse, CHANGE);
}

void pulse()
{
  uint8_t a, b;

  a = digitalRead(ENCA);
  b = digitalRead(ENCB);

  if(pre == a) // チャタリング除去
    return;
    
  if(a == 1)
  {
    if(b == 1)
      ++counter;
    else
      --counter;
  }
  else
  {
    if(b == 1)
      --counter;
    else
      ++counter;
  }

  pre = a;
}

void loop()
{
  int diff;

  diff = counter - preCount;

  if(diff != 0)
  {
    Mouse.move(diff << 4, 0, 0);
    preCount = counter;
  }
}