File content as of revision 0:88b904c4ffbb:

/********************************************************/
/*          Library untuk pembacaan Encoder             */
/*                  Adopsi dari QEI                     */
/*  Bismillahirahmanirrahim                             */
/*  Encoder yang sudah dicoba :                         */
/*  1. Autonics                                         */
/*  2. Encoder bawaan Motor                             */
/*                                                      */
/*  ______________________                              */
/*  |______Autonics______|                              */
/*  | Out A = Input 1    |                              */
/*  | Out B = Input 2    |                              */
/*  | 5V                 |                              */
/*  |_Gnd________________|                              */
/*                                                      */
/********************************************************/

#include "mbed.h"
#include "encoderKRAI.h"

encoderKRAI::encoderKRAI(PinName channelA,
                         PinName channelB,
                         int pulsesPerRev,
                         Encoding encoding) : channelA_(channelA), channelB_(channelB)
{
    pulses_       = 0;
    revolutions_  = 0;
    pulsesPerRev_ = pulsesPerRev;
    encoding_     = encoding;

    //Workout what the current state is.
    int chanA = channelA_.read();
    int chanB = channelB_.read();

    //2-bit state.
    currState_ = (chanA << 1) | (chanB);
    prevState_ = currState_;

    //X2 encoding uses interrupts on only channel A.
    //X4 encoding uses interrupts on      channel A,
    //and on channel B.
    channelA_.rise(this, &encoderKRAI::encode);
    channelA_.fall(this, &encoderKRAI::encode);

    //If we're using X4 encoding, then attach interrupts to channel B too.
    if (encoding == X4_ENCODING) {
        channelB_.rise(this, &encoderKRAI::encode);
        channelB_.fall(this, &encoderKRAI::encode);
    }
}

void encoderKRAI::reset(void) {

    pulses_      = 0;
    revolutions_ = 0;

}

int encoderKRAI::getPulses(void) {

    return pulses_;

}

int encoderKRAI::getRevolutions(void) {

    revolutions_ = pulses_ / pulsesPerRev_;
    return revolutions_;

}

/***************************************
 *  Perhitungan Pulse Encoder
 ***************************************/

void encoderKRAI::encode(void) {

    int change = 0;
    int chanA  = channelA_.read();
    int chanB  = channelB_.read();

    //2-bit state.
    currState_ = (chanA << 1) | (chanB);

    if (encoding_ == X2_ENCODING) {

        //11->00->11->00 is counter clockwise rotation or "forward".
        if ((prevState_ == 0x3 && currState_ == 0x0) ||
                (prevState_ == 0x0 && currState_ == 0x3)) {

            pulses_++;

        }
        //10->01->10->01 is clockwise rotation or "backward".
        else if ((prevState_ == 0x2 && currState_ == 0x1) ||
                 (prevState_ == 0x1 && currState_ == 0x2)) {

            pulses_--;

        }

    } else if (encoding_ == X4_ENCODING) {

        //Entered a new valid state.
        if (((currState_ ^ prevState_) != INVALID) && (currState_ != prevState_)) {
            //2 bit state. Right hand bit of prev XOR left hand bit of current
            //gives 0 if clockwise rotation and 1 if counter clockwise rotation.
            change = (prevState_ & PREV_MASK) ^ ((currState_ & CURR_MASK) >> 1);

            if (change == 0) {
                change = -1;
            }

            pulses_ -= change;
        }

    }

    prevState_ = currState_;

}