encoder.cpp

00001 /*
00002 #include "encoder.h"
00003 
00004 
00005 void resetEncoders(){
00006     leftEncoder.reset();
00007 }
00008 
00009 int getEncoderDistance(){
00010     return (leftEncoder) >> 1;
00011 }
00012 
00013 Encoder::Encoder(PinName channelA, PinName channelB) : 
00014     channelA_(channelA), 
00015     channelB_(channelB){
00016     pulses = 0;
00017 
00018     //Workout what the current state is.
00019     int chanA = channelA_.read();
00020     int chanB = channelB_.read();
00021 
00022     //2-bit state.
00023     currState_ = (chanA << 1) | (chanB);
00024     prevState_ = currState_;
00025 
00026     channelA_.rise(this, &Encoder::encode);
00027     channelA_.fall(this, &Encoder::encode);
00028 }
00029 
00030 //Internally updates the pulse count for the encoder.
00031 void Encoder::encode(void) {
00032     int chanA  = channelA_.read();
00033     int chanB  = channelB_.read();
00034 
00035     //2-bit state.
00036     currState_ = (chanA << 1) | (chanB);
00037 
00038     //11->00->11->00 is counter clockwise rotation or "forward".
00039     if ((prevState_ == 0x3 && currState_ == 0x0) ||
00040             (prevState_ == 0x0 && currState_ == 0x3)) {
00041         pulses+=2;
00042     }
00043     //10->01->10->01 is clockwise rotation or "backward".
00044     else if ((prevState_ == 0x2 && currState_ == 0x1) ||
00045              (prevState_ == 0x1 && currState_ == 0x2)) {
00046         pulses-=2;
00047     }
00048     
00049     prevState_ = currState_;
00050 }
00051 
00052 //Resets the encoder
00053 void Encoder::reset(void) {
00054     pulses = 0;
00055 }*/