quadcopter cufe / Mbed 2 deprecated FollowWall2

Go to goal robot with follow wall algo

Dependencies:   mbed

QEI/QEI.h@0:efef62b55c86, 2014-04-08 (annotated)

Committer:
khaledelmadawi
Date:
Tue Apr 08 13:21:17 2014 +0000
Revision:
0:efef62b55c86
Follow wall

Who changed what in which revision?

UserRevisionLine numberNew contents of line
khaledelmadawi 0:efef62b55c86 1 /**
khaledelmadawi 0:efef62b55c86 2 * @author Aaron Berk
khaledelmadawi 0:efef62b55c86 3 *
khaledelmadawi 0:efef62b55c86 4 * @section LICENSE
khaledelmadawi 0:efef62b55c86 5 *
khaledelmadawi 0:efef62b55c86 6 * Copyright (c) 2010 ARM Limited
khaledelmadawi 0:efef62b55c86 7 *
khaledelmadawi 0:efef62b55c86 8 * Permission is hereby granted, free of charge, to any person obtaining a copy
khaledelmadawi 0:efef62b55c86 9 * of this software and associated documentation files (the "Software"), to deal
khaledelmadawi 0:efef62b55c86 10 * in the Software without restriction, including without limitation the rights
khaledelmadawi 0:efef62b55c86 11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
khaledelmadawi 0:efef62b55c86 12 * copies of the Software, and to permit persons to whom the Software is
khaledelmadawi 0:efef62b55c86 13 * furnished to do so, subject to the following conditions:
khaledelmadawi 0:efef62b55c86 14 *
khaledelmadawi 0:efef62b55c86 15 * The above copyright notice and this permission notice shall be included in
khaledelmadawi 0:efef62b55c86 16 * all copies or substantial portions of the Software.
khaledelmadawi 0:efef62b55c86 17 *
khaledelmadawi 0:efef62b55c86 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
khaledelmadawi 0:efef62b55c86 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
khaledelmadawi 0:efef62b55c86 20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
khaledelmadawi 0:efef62b55c86 21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
khaledelmadawi 0:efef62b55c86 22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
khaledelmadawi 0:efef62b55c86 23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
khaledelmadawi 0:efef62b55c86 24 * THE SOFTWARE.
khaledelmadawi 0:efef62b55c86 25 *
khaledelmadawi 0:efef62b55c86 26 * @section DESCRIPTION
khaledelmadawi 0:efef62b55c86 27 *
khaledelmadawi 0:efef62b55c86 28 * Quadrature Encoder Interface.
khaledelmadawi 0:efef62b55c86 29 *
khaledelmadawi 0:efef62b55c86 30 * A quadrature encoder consists of two code tracks on a disc which are 90
khaledelmadawi 0:efef62b55c86 31 * degrees out of phase. It can be used to determine how far a wheel has
khaledelmadawi 0:efef62b55c86 32 * rotated, relative to a known starting position.
khaledelmadawi 0:efef62b55c86 33 *
khaledelmadawi 0:efef62b55c86 34 * Only one code track changes at a time leading to a more robust system than
khaledelmadawi 0:efef62b55c86 35 * a single track, because any jitter around any edge won't cause a state
khaledelmadawi 0:efef62b55c86 36 * change as the other track will remain constant.
khaledelmadawi 0:efef62b55c86 37 *
khaledelmadawi 0:efef62b55c86 38 * Encoders can be a homebrew affair, consisting of infrared emitters/receivers
khaledelmadawi 0:efef62b55c86 39 * and paper code tracks consisting of alternating black and white sections;
khaledelmadawi 0:efef62b55c86 40 * alternatively, complete disk and PCB emitter/receiver encoder systems can
khaledelmadawi 0:efef62b55c86 41 * be bought, but the interface, regardless of implementation is the same.
khaledelmadawi 0:efef62b55c86 42 *
khaledelmadawi 0:efef62b55c86 43 * +-----+ +-----+ +-----+
khaledelmadawi 0:efef62b55c86 44 * Channel A | ^ | | | | |
khaledelmadawi 0:efef62b55c86 45 * ---+ ^ +-----+ +-----+ +-----
khaledelmadawi 0:efef62b55c86 46 * ^ ^
khaledelmadawi 0:efef62b55c86 47 * ^ +-----+ +-----+ +-----+
khaledelmadawi 0:efef62b55c86 48 * Channel B ^ | | | | | |
khaledelmadawi 0:efef62b55c86 49 * ------+ +-----+ +-----+ +-----
khaledelmadawi 0:efef62b55c86 50 * ^ ^
khaledelmadawi 0:efef62b55c86 51 * ^ ^
khaledelmadawi 0:efef62b55c86 52 * 90deg
khaledelmadawi 0:efef62b55c86 53 *
khaledelmadawi 0:efef62b55c86 54 * The interface uses X2 encoding by default which calculates the pulse count
khaledelmadawi 0:efef62b55c86 55 * based on reading the current state after each rising and falling edge of
khaledelmadawi 0:efef62b55c86 56 * channel A.
khaledelmadawi 0:efef62b55c86 57 *
khaledelmadawi 0:efef62b55c86 58 * +-----+ +-----+ +-----+
khaledelmadawi 0:efef62b55c86 59 * Channel A | | | | | |
khaledelmadawi 0:efef62b55c86 60 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:efef62b55c86 61 * ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 62 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:efef62b55c86 63 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:efef62b55c86 64 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:efef62b55c86 65 * ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 66 * ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 67 * Pulse count 0 1 2 3 4 5 ...
khaledelmadawi 0:efef62b55c86 68 *
khaledelmadawi 0:efef62b55c86 69 * This interface can also use X4 encoding which calculates the pulse count
khaledelmadawi 0:efef62b55c86 70 * based on reading the current state after each rising and falling edge of
khaledelmadawi 0:efef62b55c86 71 * either channel.
khaledelmadawi 0:efef62b55c86 72 *
khaledelmadawi 0:efef62b55c86 73 * +-----+ +-----+ +-----+
khaledelmadawi 0:efef62b55c86 74 * Channel A | | | | | |
khaledelmadawi 0:efef62b55c86 75 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:efef62b55c86 76 * ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 77 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:efef62b55c86 78 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:efef62b55c86 79 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:efef62b55c86 80 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 81 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 82 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
khaledelmadawi 0:efef62b55c86 83 *
khaledelmadawi 0:efef62b55c86 84 * It defaults
khaledelmadawi 0:efef62b55c86 85 *
khaledelmadawi 0:efef62b55c86 86 * An optional index channel can be used which determines when a full
khaledelmadawi 0:efef62b55c86 87 * revolution has occured.
khaledelmadawi 0:efef62b55c86 88 *
khaledelmadawi 0:efef62b55c86 89 * If a 4 pules per revolution encoder was used, with X4 encoding,
khaledelmadawi 0:efef62b55c86 90 * the following would be observed.
khaledelmadawi 0:efef62b55c86 91 *
khaledelmadawi 0:efef62b55c86 92 * +-----+ +-----+ +-----+
khaledelmadawi 0:efef62b55c86 93 * Channel A | | | | | |
khaledelmadawi 0:efef62b55c86 94 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:efef62b55c86 95 * ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 96 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:efef62b55c86 97 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:efef62b55c86 98 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:efef62b55c86 99 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 100 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 101 * ^ ^ ^ +--+ ^ ^ +--+ ^
khaledelmadawi 0:efef62b55c86 102 * ^ ^ ^ | | ^ ^ | | ^
khaledelmadawi 0:efef62b55c86 103 * Index ------------+ +--------+ +-----------
khaledelmadawi 0:efef62b55c86 104 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:efef62b55c86 105 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
khaledelmadawi 0:efef62b55c86 106 * Rev. count 0 1 2
khaledelmadawi 0:efef62b55c86 107 *
khaledelmadawi 0:efef62b55c86 108 * Rotational position in degrees can be calculated by:
khaledelmadawi 0:efef62b55c86 109 *
khaledelmadawi 0:efef62b55c86 110 * (pulse count / X * N) * 360
khaledelmadawi 0:efef62b55c86 111 *
khaledelmadawi 0:efef62b55c86 112 * Where X is the encoding type [e.g. X4 encoding => X=4], and N is the number
khaledelmadawi 0:efef62b55c86 113 * of pulses per revolution.
khaledelmadawi 0:efef62b55c86 114 *
khaledelmadawi 0:efef62b55c86 115 * Linear position can be calculated by:
khaledelmadawi 0:efef62b55c86 116 *
khaledelmadawi 0:efef62b55c86 117 * (pulse count / X * N) * (1 / PPI)
khaledelmadawi 0:efef62b55c86 118 *
khaledelmadawi 0:efef62b55c86 119 * Where X is encoding type [e.g. X4 encoding => X=44], N is the number of
khaledelmadawi 0:efef62b55c86 120 * pulses per revolution, and PPI is pulses per inch, or the equivalent for
khaledelmadawi 0:efef62b55c86 121 * any other unit of displacement. PPI can be calculated by taking the
khaledelmadawi 0:efef62b55c86 122 * circumference of the wheel or encoder disk and dividing it by the number
khaledelmadawi 0:efef62b55c86 123 * of pulses per revolution.
khaledelmadawi 0:efef62b55c86 124 */
khaledelmadawi 0:efef62b55c86 125
khaledelmadawi 0:efef62b55c86 126 #ifndef QEI_H
khaledelmadawi 0:efef62b55c86 127 #define QEI_H
khaledelmadawi 0:efef62b55c86 128
khaledelmadawi 0:efef62b55c86 129 /**
khaledelmadawi 0:efef62b55c86 130 * Includes
khaledelmadawi 0:efef62b55c86 131 */
khaledelmadawi 0:efef62b55c86 132 #include "mbed.h"
khaledelmadawi 0:efef62b55c86 133
khaledelmadawi 0:efef62b55c86 134 /**
khaledelmadawi 0:efef62b55c86 135 * Defines
khaledelmadawi 0:efef62b55c86 136 */
khaledelmadawi 0:efef62b55c86 137 #define PREV_MASK 0x1 //Mask for the previous state in determining direction
khaledelmadawi 0:efef62b55c86 138 //of rotation.
khaledelmadawi 0:efef62b55c86 139 #define CURR_MASK 0x2 //Mask for the current state in determining direction
khaledelmadawi 0:efef62b55c86 140 //of rotation.
khaledelmadawi 0:efef62b55c86 141 #define INVALID 0x3 //XORing two states where both bits have changed.
khaledelmadawi 0:efef62b55c86 142
khaledelmadawi 0:efef62b55c86 143 /**
khaledelmadawi 0:efef62b55c86 144 * Quadrature Encoder Interface.
khaledelmadawi 0:efef62b55c86 145 */
khaledelmadawi 0:efef62b55c86 146 class QEI {
khaledelmadawi 0:efef62b55c86 147
khaledelmadawi 0:efef62b55c86 148 public:
khaledelmadawi 0:efef62b55c86 149
khaledelmadawi 0:efef62b55c86 150 typedef enum Encoding {
khaledelmadawi 0:efef62b55c86 151
khaledelmadawi 0:efef62b55c86 152 X2_ENCODING,
khaledelmadawi 0:efef62b55c86 153 X4_ENCODING
khaledelmadawi 0:efef62b55c86 154
khaledelmadawi 0:efef62b55c86 155 } Encoding;
khaledelmadawi 0:efef62b55c86 156
khaledelmadawi 0:efef62b55c86 157 /**
khaledelmadawi 0:efef62b55c86 158 * Constructor.
khaledelmadawi 0:efef62b55c86 159 *
khaledelmadawi 0:efef62b55c86 160 * Reads the current values on channel A and channel B to determine the
khaledelmadawi 0:efef62b55c86 161 * initial state.
khaledelmadawi 0:efef62b55c86 162 *
khaledelmadawi 0:efef62b55c86 163 * Attaches the encode function to the rise/fall interrupt edges of
khaledelmadawi 0:efef62b55c86 164 * channels A and B to perform X4 encoding.
khaledelmadawi 0:efef62b55c86 165 *
khaledelmadawi 0:efef62b55c86 166 * Attaches the index function to the rise interrupt edge of channel index
khaledelmadawi 0:efef62b55c86 167 * (if it is used) to count revolutions.
khaledelmadawi 0:efef62b55c86 168 *
khaledelmadawi 0:efef62b55c86 169 * @param channelA mbed pin for channel A input.
khaledelmadawi 0:efef62b55c86 170 * @param channelB mbed pin for channel B input.
khaledelmadawi 0:efef62b55c86 171 * @param index mbed pin for optional index channel input,
khaledelmadawi 0:efef62b55c86 172 * (pass NC if not needed).
khaledelmadawi 0:efef62b55c86 173 * @param pulsesPerRev Number of pulses in one revolution.
khaledelmadawi 0:efef62b55c86 174 * @param encoding The encoding to use. Uses X2 encoding by default. X2
khaledelmadawi 0:efef62b55c86 175 * encoding uses interrupts on the rising and falling edges
khaledelmadawi 0:efef62b55c86 176 * of only channel A where as X4 uses them on both
khaledelmadawi 0:efef62b55c86 177 * channels.
khaledelmadawi 0:efef62b55c86 178 */
khaledelmadawi 0:efef62b55c86 179 QEI(PinName channelA, PinName channelB, PinName index, int pulsesPerRev, Encoding encoding = X2_ENCODING);
khaledelmadawi 0:efef62b55c86 180
khaledelmadawi 0:efef62b55c86 181 /**
khaledelmadawi 0:efef62b55c86 182 * Reset the encoder.
khaledelmadawi 0:efef62b55c86 183 *
khaledelmadawi 0:efef62b55c86 184 * Sets the pulses and revolutions count to zero.
khaledelmadawi 0:efef62b55c86 185 */
khaledelmadawi 0:efef62b55c86 186 void reset(void);
khaledelmadawi 0:efef62b55c86 187
khaledelmadawi 0:efef62b55c86 188 /**
khaledelmadawi 0:efef62b55c86 189 * Read the state of the encoder.
khaledelmadawi 0:efef62b55c86 190 *
khaledelmadawi 0:efef62b55c86 191 * @return The current state of the encoder as a 2-bit number, where:
khaledelmadawi 0:efef62b55c86 192 * bit 1 = The reading from channel B
khaledelmadawi 0:efef62b55c86 193 * bit 2 = The reading from channel A
khaledelmadawi 0:efef62b55c86 194 */
khaledelmadawi 0:efef62b55c86 195 int getCurrentState(void);
khaledelmadawi 0:efef62b55c86 196
khaledelmadawi 0:efef62b55c86 197 /**
khaledelmadawi 0:efef62b55c86 198 * Read the number of pulses recorded by the encoder.
khaledelmadawi 0:efef62b55c86 199 *
khaledelmadawi 0:efef62b55c86 200 * @return Number of pulses which have occured.
khaledelmadawi 0:efef62b55c86 201 */
khaledelmadawi 0:efef62b55c86 202 int getPulses(void);
khaledelmadawi 0:efef62b55c86 203
khaledelmadawi 0:efef62b55c86 204 /**
khaledelmadawi 0:efef62b55c86 205 * Read the number of revolutions recorded by the encoder on the index channel.
khaledelmadawi 0:efef62b55c86 206 *
khaledelmadawi 0:efef62b55c86 207 * @return Number of revolutions which have occured on the index channel.
khaledelmadawi 0:efef62b55c86 208 */
khaledelmadawi 0:efef62b55c86 209 int getRevolutions(void);
khaledelmadawi 0:efef62b55c86 210
khaledelmadawi 0:efef62b55c86 211 private:
khaledelmadawi 0:efef62b55c86 212
khaledelmadawi 0:efef62b55c86 213 /**
khaledelmadawi 0:efef62b55c86 214 * Update the pulse count.
khaledelmadawi 0:efef62b55c86 215 *
khaledelmadawi 0:efef62b55c86 216 * Called on every rising/falling edge of channels A/B.
khaledelmadawi 0:efef62b55c86 217 *
khaledelmadawi 0:efef62b55c86 218 * Reads the state of the channels and determines whether a pulse forward
khaledelmadawi 0:efef62b55c86 219 * or backward has occured, updating the count appropriately.
khaledelmadawi 0:efef62b55c86 220 */
khaledelmadawi 0:efef62b55c86 221 void encode(void);
khaledelmadawi 0:efef62b55c86 222
khaledelmadawi 0:efef62b55c86 223 /**
khaledelmadawi 0:efef62b55c86 224 * Called on every rising edge of channel index to update revolution
khaledelmadawi 0:efef62b55c86 225 * count by one.
khaledelmadawi 0:efef62b55c86 226 */
khaledelmadawi 0:efef62b55c86 227 void index(void);
khaledelmadawi 0:efef62b55c86 228
khaledelmadawi 0:efef62b55c86 229 Encoding encoding_;
khaledelmadawi 0:efef62b55c86 230
khaledelmadawi 0:efef62b55c86 231 InterruptIn channelA_;
khaledelmadawi 0:efef62b55c86 232 InterruptIn channelB_;
khaledelmadawi 0:efef62b55c86 233 InterruptIn index_;
khaledelmadawi 0:efef62b55c86 234
khaledelmadawi 0:efef62b55c86 235 int pulsesPerRev_;
khaledelmadawi 0:efef62b55c86 236 int prevState_;
khaledelmadawi 0:efef62b55c86 237 int currState_;
khaledelmadawi 0:efef62b55c86 238
khaledelmadawi 0:efef62b55c86 239 volatile int pulses_;
khaledelmadawi 0:efef62b55c86 240 volatile int revolutions_;
khaledelmadawi 0:efef62b55c86 241
khaledelmadawi 0:efef62b55c86 242 };
khaledelmadawi 0:efef62b55c86 243
khaledelmadawi 0:efef62b55c86 244 #endif /* QEI_H */