zhouhang shao / Mbed 2 deprecated test

test

Dependencies:   RemoteIR mbed

encoder.cpp@3:34a763e93423, 2017-05-07 (annotated)

Committer:
szh66
Date:
Sun May 07 01:31:52 2017 +0000
Revision:
3:34a763e93423
Parent:
2:b78dfa2afe92
Child:
6:9f698d1b2996
motor circuit test

Who changed what in which revision?

UserRevisionLine numberNew contents of line
szh66 3:34a763e93423 1 #include "encoder.h"
szh66 3:34a763e93423 2 /*
szh66 3:34a763e93423 3 Reset both encoders
szh66 3:34a763e93423 4 */
szh66 3:34a763e93423 5 void resetEncoders(){
szh66 3:34a763e93423 6 leftEncoder.reset();
szh66 3:34a763e93423 7 }
szh66 3:34a763e93423 8
szh66 3:34a763e93423 9 /*
szh66 3:34a763e93423 10 Returns the average number of pulses across both encoders since last reset. Unit is encoder pulses; intended for straight driving only.
szh66 3:34a763e93423 11 */
szh66 3:34a763e93423 12 int getEncoderDistance(){
szh66 3:34a763e93423 13 return (leftEncoder) >> 1;
szh66 3:34a763e93423 14 }
szh66 3:34a763e93423 15
szh66 3:34a763e93423 16 /*
szh66 3:34a763e93423 17 * Represents a quadrature motor encoder. Modified from mbed QEI
szh66 3:34a763e93423 18 */
szh66 3:34a763e93423 19 Encoder::Encoder(PinName channelA, PinName channelB) :
szh66 3:34a763e93423 20 channelA_(channelA),
szh66 3:34a763e93423 21 channelB_(channelB){
szh66 3:34a763e93423 22 pulses = 0;
szh66 3:34a763e93423 23
szh66 3:34a763e93423 24 //Workout what the current state is.
szh66 3:34a763e93423 25 int chanA = channelA_.read();
szh66 3:34a763e93423 26 int chanB = channelB_.read();
szh66 3:34a763e93423 27
szh66 3:34a763e93423 28 //2-bit state.
szh66 3:34a763e93423 29 currState_ = (chanA << 1) | (chanB);
szh66 3:34a763e93423 30 prevState_ = currState_;
szh66 3:34a763e93423 31
szh66 3:34a763e93423 32 channelA_.rise(this, &Encoder::encode);
szh66 3:34a763e93423 33 channelA_.fall(this, &Encoder::encode);
szh66 3:34a763e93423 34 }
szh66 3:34a763e93423 35
szh66 3:34a763e93423 36 //Internally updates the pulse count for the encoder.
szh66 3:34a763e93423 37 void Encoder::encode(void) {
szh66 3:34a763e93423 38 int chanA = channelA_.read();
szh66 3:34a763e93423 39 int chanB = channelB_.read();
szh66 3:34a763e93423 40
szh66 3:34a763e93423 41 //2-bit state.
szh66 3:34a763e93423 42 currState_ = (chanA << 1) | (chanB);
szh66 3:34a763e93423 43
szh66 3:34a763e93423 44 //11->00->11->00 is counter clockwise rotation or "forward".
szh66 3:34a763e93423 45 if ((prevState_ == 0x3 && currState_ == 0x0) ||
szh66 3:34a763e93423 46 (prevState_ == 0x0 && currState_ == 0x3)) {
szh66 3:34a763e93423 47 pulses+=2;
szh66 3:34a763e93423 48 }
szh66 3:34a763e93423 49 //10->01->10->01 is clockwise rotation or "backward".
szh66 3:34a763e93423 50 else if ((prevState_ == 0x2 && currState_ == 0x1) ||
szh66 3:34a763e93423 51 (prevState_ == 0x1 && currState_ == 0x2)) {
szh66 3:34a763e93423 52 pulses-=2;
szh66 3:34a763e93423 53 }
szh66 3:34a763e93423 54
szh66 3:34a763e93423 55 prevState_ = currState_;
szh66 3:34a763e93423 56 }
szh66 3:34a763e93423 57
szh66 3:34a763e93423 58 //Resets the encoder
szh66 3:34a763e93423 59 void Encoder::reset(void) {
szh66 3:34a763e93423 60 pulses = 0;
szh66 3:34a763e93423 61 }