RotaryEncoder.cpp

/*
  Rotary Encoder Lib for Arduino
  by Watterott electronic (www.watterott.com)
  
  reading routine by Peter Dannegger
  http://www.mikrocontroller.net/articles/Drehgeber
 */

#include <inttypes.h>
#if (defined(__AVR__) || defined(ARDUINO_ARCH_AVR))
# include <avr/io.h>
#endif
#if ARDUINO >= 100
# include "Arduino.h"
#else
# include "WProgram.h"
#endif
#include "digitalWriteFast.h"
#include "RotaryEncoder.h"


#define STEPS           4 //1, 2 or 4 steps

#define RE_SW_PIN       5
#define RE_PHA_PIN      6
#define RE_PHB_PIN      7

#define RE_SW_READ()    digitalReadFast(RE_SW_PIN)
#define RE_PHA_READ()   digitalReadFast(RE_PHA_PIN)
#define RE_PHB_READ()   digitalReadFast(RE_PHB_PIN)


//-------------------- Constructor --------------------


RotaryEncoder::RotaryEncoder(void)
{
  return;
}


//-------------------- Public --------------------


void RotaryEncoder::init(void)
{
  //init pins
  pinMode(RE_SW_PIN, INPUT);
  digitalWrite(RE_SW_PIN, HIGH); //pull-up
  pinMode(RE_PHA_PIN, INPUT);
  digitalWrite(RE_PHA_PIN, HIGH); //pull-up
  pinMode(RE_PHB_PIN, INPUT);
  digitalWrite(RE_PHB_PIN, HIGH); //pull-up

  //init global vars
  re_sw    = 0;
  re_delta = 0;
  re_last  = 0;
  if(RE_PHA_READ())
  {
    re_last = 3;
  }
  if(RE_PHB_READ())
  {
    re_last ^= 1;
  }

  return;
}


void RotaryEncoder::service(void) //called every 1ms
{
  int_least8_t re_new, re_diff;
  static int_least16_t re_pressed=0;

  re_new = 0;
  if(RE_PHA_READ())
  {
    re_new = 3;
  }
  if(RE_PHB_READ())
  {
    re_new ^= 1;                //convert gray to binary
  }
  re_diff = re_last-re_new;     //difference last - new
  if(re_diff & 1)               //bit 0 = value (1)
  {
    re_last   = re_new;         //store new as next last
    re_delta += (re_diff&2)-1;  //bit 1 = direction (+/-)
  }

  if(RE_SW_READ())
  {
    if(re_pressed > 800) //800 ms
    {
      if(re_sw == 0)
      {
        re_sw = SW_PRESSEDLONG;
      }
    }
    else if(re_pressed > 80) //80 ms
    {
      if(re_sw == 0)
      {
        re_sw = SW_PRESSED;
      }
    }
    re_pressed = 0;
  }
  else
  {
    re_pressed++;
  }

  return;
}


int_least8_t RotaryEncoder::step(void)
{
  int_least8_t val;

  cli();
  val      = re_delta;
#if STEPS == 1
  re_delta = 0;      //1step:0 / 2step:val&1 / 4step:val&3
#elif STEPS == 2
  re_delta = val&1;  //1step:0 / 2step:val&1 / 4step:val&3
#elif STEPS == 4
  re_delta = val&3;  //1step:0 / 2step:val&1 / 4step:val&3
#endif
  sei();

#if STEPS == 1
  val = val>>0;      //1step:val / 2step:val>>1 / 4step:val>>2
#elif STEPS == 2
  val = val>>1;      //1step:val / 2step:val>>1 / 4step:val>>2
#elif STEPS == 4
  val = val>>2;      //1step:val / 2step:val>>1 / 4step:val>>2
#endif

  if(val < 0)
  {
    return +1;
  }
  else if(val > 0)
  {
    return -1;
  }

  return 0;
}


int_least8_t RotaryEncoder::sw(void)
{
  int_least8_t val;

  val   = re_sw;
  re_sw = 0;

  return val;
}