RotaryEncoder.cpp

// -----
// RotaryEncoder.cpp - Library for using rotary encoders.
// This class is implemented for use with the Arduino environment.
//
// Copyright (c) by Matthias Hertel, http://www.mathertel.de
//
// This work is licensed under a BSD 3-Clause style license,
// https://www.mathertel.de/License.aspx.
//
// More information on: http://www.mathertel.de/Arduino
// -----
// Changelog: see RotaryEncoder.h
// -----

#include "RotaryEncoder.h"
#include "Arduino.h"

#define LATCH0 0 // input state at position 0
#define LATCH3 3 // input state at position 3


// The array holds the values �1 for the entries where a position was decremented,
// a 1 for the entries where the position was incremented
// and 0 in all the other (no change or not valid) cases.

const int8_t KNOBDIR[] = {
    0, -1, 1, 0,
    1, 0, 0, -1,
    -1, 0, 0, 1,
    0, 1, -1, 0};


// positions: [3] 1 0 2 [3] 1 0 2 [3]
// [3] is the positions where my rotary switch detends
// ==> right, count up
// <== left,  count down


// ----- Initialization and Default Values -----

RotaryEncoder::RotaryEncoder(int pin1, int pin2, LatchMode mode)
{
  // Remember Hardware Setup
  _pin1 = pin1;
  _pin2 = pin2;
  _mode = mode;

  // Setup the input pins and turn on pullup resistor
  pinMode(pin1, INPUT_PULLUP);
  pinMode(pin2, INPUT_PULLUP);

  // when not started in motion, the current state of the encoder should be 3
  int sig1 = digitalRead(_pin1);
  int sig2 = digitalRead(_pin2);
  _oldState = sig1 | (sig2 << 1);

  // start with position 0;
  _position = 0;
  _positionExt = 0;
  _positionExtPrev = 0;
} // RotaryEncoder()


long RotaryEncoder::getPosition()
{
  return _positionExt;
} // getPosition()


RotaryEncoder::Direction RotaryEncoder::getDirection()
{
  RotaryEncoder::Direction ret = Direction::NOROTATION;

  if (_positionExtPrev > _positionExt) {
    ret = Direction::COUNTERCLOCKWISE;
    _positionExtPrev = _positionExt;
  } else if (_positionExtPrev < _positionExt) {
    ret = Direction::CLOCKWISE;
    _positionExtPrev = _positionExt;
  } else {
    ret = Direction::NOROTATION;
    _positionExtPrev = _positionExt;
  }

  return ret;
}


void RotaryEncoder::setPosition(long newPosition)
{
  switch (_mode) {
  case LatchMode::FOUR3:
  case LatchMode::FOUR0:
    // only adjust the external part of the position.
    _position = ((newPosition << 2) | (_position & 0x03L));
    _positionExt = newPosition;
    _positionExtPrev = newPosition;
    break;

  case LatchMode::TWO03:
    // only adjust the external part of the position.
    _position = ((newPosition << 1) | (_position & 0x01L));
    _positionExt = newPosition;
    _positionExtPrev = newPosition;
    break;
  } // switch

} // setPosition()


void RotaryEncoder::tick(void)
{
  int sig1 = digitalRead(_pin1);
  int sig2 = digitalRead(_pin2);
  int8_t thisState = sig1 | (sig2 << 1);

  if (_oldState != thisState) {
    _position += KNOBDIR[thisState | (_oldState << 2)];
    _oldState = thisState;

    switch (_mode) {
    case LatchMode::FOUR3:
      if (thisState == LATCH3) {
        // The hardware has 4 steps with a latch on the input state 3
        _positionExt = _position >> 2;
        _positionExtTimePrev = _positionExtTime;
        _positionExtTime = millis();
      }
      break;

    case LatchMode::FOUR0:
      if (thisState == LATCH0) {
        // The hardware has 4 steps with a latch on the input state 0
        _positionExt = _position >> 2;
        _positionExtTimePrev = _positionExtTime;
        _positionExtTime = millis();
      }
      break;

    case LatchMode::TWO03:
      if ((thisState == LATCH0) || (thisState == LATCH3)) {
        // The hardware has 2 steps with a latch on the input state 0 and 3
        _positionExt = _position >> 1;
        _positionExtTimePrev = _positionExtTime;
        _positionExtTime = millis();
      }
      break;
    } // switch
  } // if
} // tick()


unsigned long RotaryEncoder::getMillisBetweenRotations() const
{
  return (_positionExtTime - _positionExtTimePrev);
}

unsigned long RotaryEncoder::getRPM()
{
  // calculate max of difference in time between last position changes or last change and now.
  unsigned long timeBetweenLastPositions = _positionExtTime - _positionExtTimePrev;
  unsigned long timeToLastPosition = millis() - _positionExtTime;
  unsigned long t = max(timeBetweenLastPositions, timeToLastPosition);
  return 60000.0 / ((float)(t * 20));
}


// End