zhouhang shao
/
test
test
encoder.cpp
- Committer:
- szh66
- Date:
- 2017-05-07
- Revision:
- 3:34a763e93423
- Parent:
- 2:b78dfa2afe92
- Child:
- 6:9f698d1b2996
File content as of revision 3:34a763e93423:
#include "encoder.h" /* Reset both encoders */ void resetEncoders(){ leftEncoder.reset(); } /* Returns the average number of pulses across both encoders since last reset. Unit is encoder pulses; intended for straight driving only. */ int getEncoderDistance(){ return (leftEncoder) >> 1; } /* * Represents a quadrature motor encoder. Modified from mbed QEI */ Encoder::Encoder(PinName channelA, PinName channelB) : channelA_(channelA), channelB_(channelB){ pulses = 0; //Workout what the current state is. int chanA = channelA_.read(); int chanB = channelB_.read(); //2-bit state. currState_ = (chanA << 1) | (chanB); prevState_ = currState_; channelA_.rise(this, &Encoder::encode); channelA_.fall(this, &Encoder::encode); } //Internally updates the pulse count for the encoder. void Encoder::encode(void) { int chanA = channelA_.read(); int chanB = channelB_.read(); //2-bit state. currState_ = (chanA << 1) | (chanB); //11->00->11->00 is counter clockwise rotation or "forward". if ((prevState_ == 0x3 && currState_ == 0x0) || (prevState_ == 0x0 && currState_ == 0x3)) { pulses+=2; } //10->01->10->01 is clockwise rotation or "backward". else if ((prevState_ == 0x2 && currState_ == 0x1) || (prevState_ == 0x1 && currState_ == 0x2)) { pulses-=2; } prevState_ = currState_; } //Resets the encoder void Encoder::reset(void) { pulses = 0; }