Krishna Kaushal Panduru / QuadratureEncoder

quadratureEncoder.cpp@1:52fba054be6c, 2011-07-22 (annotated)

Committer:
kaushalpkk
Date:
Fri Jul 22 15:11:28 2011 +0000
Revision:
1:52fba054be6c
Parent:
0:6b30097d9a45 

        

        
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/*





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name:                encoder.h





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date:                04-june-2011





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header description:  contains functions and external variables to interface quadrature encoder





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compiler-library:    the mbed library interface is used on the whole..





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compatability:       can also be compatable with generalised code with diffrerent hardware and software





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hardware dependency: works on rover 5 model platform interfaced with mbed controller





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indentation:         <mbed default intendation - 4 spaces>





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resources:          http://www.sparkfun.com/products/10336





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                    http://letsmakerobots.com/node/24031





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                    http://www.sparkfun.com/datasheets/Robotics/Rover%205%20Introduction.pdf





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            */





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#include "mbed.h"





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#include "quadratureEncoder.h"





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//gets a bit position by shifting 1





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#define Abit   0





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#define Bbit   1





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#define _BV(x) (1 << x)





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// sbi sets a particular bit and cbi clears the bit (target byte-word, bit position)





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#define sbi(y,x) y|=_BV(x)





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#define cbi(y,x) y&=~_BV(x)





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quadratureEncoder::quadratureEncoder(PinName pinA, PinName pinB):





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_pinA(pinA), _pinB(pinB){





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    _pinA.rise(this, &quadratureEncoder::ARise);





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    _pinA.fall(this, &quadratureEncoder::AFall);





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    _pinB.rise(this, &quadratureEncoder::BRise);





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    _pinB.fall(this, &quadratureEncoder::BFall);





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    _oldState = 0x00;





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    _nowState = 0x00;





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    _moved = 0;





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    _count = 0;





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}





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////////////////////////////////////////////////////////////////////////////////////////





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int quadratureEncoder::getCount() {





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    return _count;





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}





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void quadratureEncoder::resetCount() {





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    _count = 0;





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}





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void quadratureEncoder::setCount(int setCounter) {





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    _count = setCounter;





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}





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////////////////////////////////////////////////////////////////////////////////////////





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void quadratureEncoder::resetMoved() {





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    _moved = 0;





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}





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void quadratureEncoder::setMoved(int setMover) {





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    _moved = setMover;





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}





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int quadratureEncoder::getMoved() {





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    return _moved;





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}





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////////////////////////////////////////////////////////////////////////////////////////





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char quadratureEncoder::saveState(char nowS) {





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    return nowS;





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}





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char quadratureEncoder::getBit(char bitP, char targB) {





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    targB = targB & _BV(bitP);





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    if (targB == 0)





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        return 0;





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    else





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        return 1;





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}





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/*





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function:   the following 8 functions are ISR called by rise and fall of 4 pins





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input:      none (interupt called)





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output:     none





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functioning:interrupts are called when the pin change occours





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            sets or clears the respective bit





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            checks the previous state and increments respective direction





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            restores new state value into old state





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            increments a count value for processing    */





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void quadratureEncoder::ARise() {





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    sbi(_nowState,Abit);





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    if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==0)





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        _moved++;





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    else if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==1)





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        _moved--;





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    _oldState = saveState(_nowState);





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    _count++;





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}





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void quadratureEncoder::AFall() {





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    cbi(_nowState, Abit);





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    if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==1)





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        _moved++;





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    else if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==0)





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        _moved--;





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    _oldState = saveState(_nowState);





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    _count++;





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}





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void quadratureEncoder::BRise() {





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    sbi(_nowState,Bbit);





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    if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==0)





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        _moved++;





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    else if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==0)





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        _moved--;





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    _oldState = saveState(_nowState);





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    _count++;





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}





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void quadratureEncoder::BFall() {





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    cbi(_nowState, Bbit);





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    if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==1)





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        _moved++;





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    else if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==1)





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        _moved--;





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    _oldState = saveState(_nowState);





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    _count++;





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}





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