/* interrupt routine for Rotary Encoders





   The average rotary encoder has three pins, seen from front: A C B

   Clockwise rotation A(on)->B(on)->A(off)->B(off)

   CounterCW rotation B(on)->A(on)->B(off)->A(off)



   and may be a push switch with another two pins, pulled low at pin 8 in this case

  



*/



// usually the rotary encoders three pins have the ground pin in the middle

enum PinAssignments {

  encoderPinA = 2,   // right (labeled DT on our decoder, yellow wire)

  encoderPinB = 3,   // left (labeled CLK on our decoder, green wire)

  clearButton = 8    // switch (labeled SW on our decoder, orange wire)

// connect the +5v and gnd appropriately

};



volatile unsigned int encoderPos = 0;  // a counter for the dial

unsigned int lastReportedPos = 1;   // change management

static boolean rotating=false;      // debounce management



// interrupt service routine vars

boolean A_set = false;              

boolean B_set = false;





void setup() {



  pinMode(encoderPinA, INPUT_PULLUP); // new method of enabling pullups

  pinMode(encoderPinB, INPUT_PULLUP); 

  pinMode(clearButton, INPUT_PULLUP);

 // turn on pullup resistors (old method)

  //digitalWrite(encoderPinA, HIGH);

 // digitalWrite(encoderPinB, HIGH);

 // digitalWrite(clearButton, HIGH);



// encoder pin on interrupt 0 (pin 2)

  attachInterrupt(0, doEncoderA, CHANGE);

// encoder pin on interrupt 1 (pin 3)

  attachInterrupt(1, doEncoderB, CHANGE);



  Serial.begin(9600);  // output

}



// main loop, work is done by interrupt service routines, this one only prints stuff

void loop() { 

  rotating = true;  // reset the debouncer



  if (lastReportedPos != encoderPos) {

    Serial.print("Index:");

    Serial.println(encoderPos, DEC);

    lastReportedPos = encoderPos;

  }

  if (digitalRead(clearButton) == LOW )  {

    encoderPos = 0;

  }

}



// Interrupt on A changing state

void doEncoderA(){

  // debounce

  if ( rotating ) delay (1);  // wait a little until the bouncing is done



  // Test transition, did things really change? 

  if( digitalRead(encoderPinA) != A_set ) {  // debounce once more

    A_set = !A_set;



    // adjust counter + if A leads B

    if ( A_set && !B_set ) 

      encoderPos += 1;



    rotating = false;  // no more debouncing until loop() hits again

  }

}



// Interrupt on B changing state, same as A above

void doEncoderB(){

  if ( rotating ) delay (1);

  if( digitalRead(encoderPinB) != B_set ) {

    B_set = !B_set;

    //  adjust counter - 1 if B leads A

    if( B_set && !A_set ) 

      encoderPos -= 1;



    rotating = false;

  }

}