File content as of revision 0:d510e8063ad1:

#ifndef ENCODER_H_INCLUDED
#define ENCODER_H_INCLUDED

/** Class to handle a rotary encoder
 *  The lib is interrupt based, therefore no update functions have to be called.
 *  Example usage:
 *  @code
 *
 *  #include "mbed.h"
 *  #include "Encoder.h"
 *
 *  RotaryEncoder encoder(D3, D4);
 *
 *  int main()
 *  {
 *      while(1)
 *      {
 *          int pos = encoder.position();
 *          wait(1.0f);
 *      }
 *  }
 *  @endcode
 */
class RotaryEncoder {
public:
    RotaryEncoder(PinName outa, PinName outb)
        : position_(0), delta_(0),
          inta_(outa), intb_(outb), outa_(outa), outb_(outb) {
        outa_.mode(PullUp);
        outb_.mode(PullUp);
        inta_.rise(this, &RotaryEncoder::handleIntA);
        inta_.fall(this, &RotaryEncoder::handleIntA);
        intb_.rise(this, &RotaryEncoder::handleIntB);
        intb_.fall(this, &RotaryEncoder::handleIntB);
    }

    /** Returns the overall position of the encoder
     */
    int position() {
        return position_;
    }

    /** Returns the encoders change since the last call to this function
     */
    int delta() {
        int d = delta_;
        delta_ = 0;
        return d;
    }

private:

    // A  = B --> Clockwise
    // A /= B --> Counter clockwise
    void handleIntA() {
        if (outa_ == outb_) {
            increment(1);
        } else {
            increment(-1);
        }
    }

    // A  = B --> Counter clockwise
    // A /= B --> Clockwise
    void handleIntB() {
        if (outa_ == outb_) {
            increment(-1);
        } else {
            increment(1);
        }
    }

    void increment(int i) {
        position_ += i;
        delta_ += i;
    }

    int position_;
    int delta_;

    InterruptIn inta_;
    InterruptIn intb_;
    DigitalIn outa_;
    DigitalIn outb_;
};

#endif /* ENCODER_H_INCLUDED */