quadcopter cufe / Mbed 2 deprecated FollowWall

follow wall 1

Dependencies:   mbed

QEI/QEI.h@0:b703833f6795, 2014-04-08 (annotated)

Committer:
khaledelmadawi
Date:
Tue Apr 08 13:23:06 2014 +0000
Revision:
0:b703833f6795
follow wall 1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
khaledelmadawi 0:b703833f6795 1 /**
khaledelmadawi 0:b703833f6795 2 * @author Aaron Berk
khaledelmadawi 0:b703833f6795 3 *
khaledelmadawi 0:b703833f6795 4 * @section LICENSE
khaledelmadawi 0:b703833f6795 5 *
khaledelmadawi 0:b703833f6795 6 * Copyright (c) 2010 ARM Limited
khaledelmadawi 0:b703833f6795 7 *
khaledelmadawi 0:b703833f6795 8 * Permission is hereby granted, free of charge, to any person obtaining a copy
khaledelmadawi 0:b703833f6795 9 * of this software and associated documentation files (the "Software"), to deal
khaledelmadawi 0:b703833f6795 10 * in the Software without restriction, including without limitation the rights
khaledelmadawi 0:b703833f6795 11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
khaledelmadawi 0:b703833f6795 12 * copies of the Software, and to permit persons to whom the Software is
khaledelmadawi 0:b703833f6795 13 * furnished to do so, subject to the following conditions:
khaledelmadawi 0:b703833f6795 14 *
khaledelmadawi 0:b703833f6795 15 * The above copyright notice and this permission notice shall be included in
khaledelmadawi 0:b703833f6795 16 * all copies or substantial portions of the Software.
khaledelmadawi 0:b703833f6795 17 *
khaledelmadawi 0:b703833f6795 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
khaledelmadawi 0:b703833f6795 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
khaledelmadawi 0:b703833f6795 20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
khaledelmadawi 0:b703833f6795 21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
khaledelmadawi 0:b703833f6795 22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
khaledelmadawi 0:b703833f6795 23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
khaledelmadawi 0:b703833f6795 24 * THE SOFTWARE.
khaledelmadawi 0:b703833f6795 25 *
khaledelmadawi 0:b703833f6795 26 * @section DESCRIPTION
khaledelmadawi 0:b703833f6795 27 *
khaledelmadawi 0:b703833f6795 28 * Quadrature Encoder Interface.
khaledelmadawi 0:b703833f6795 29 *
khaledelmadawi 0:b703833f6795 30 * A quadrature encoder consists of two code tracks on a disc which are 90
khaledelmadawi 0:b703833f6795 31 * degrees out of phase. It can be used to determine how far a wheel has
khaledelmadawi 0:b703833f6795 32 * rotated, relative to a known starting position.
khaledelmadawi 0:b703833f6795 33 *
khaledelmadawi 0:b703833f6795 34 * Only one code track changes at a time leading to a more robust system than
khaledelmadawi 0:b703833f6795 35 * a single track, because any jitter around any edge won't cause a state
khaledelmadawi 0:b703833f6795 36 * change as the other track will remain constant.
khaledelmadawi 0:b703833f6795 37 *
khaledelmadawi 0:b703833f6795 38 * Encoders can be a homebrew affair, consisting of infrared emitters/receivers
khaledelmadawi 0:b703833f6795 39 * and paper code tracks consisting of alternating black and white sections;
khaledelmadawi 0:b703833f6795 40 * alternatively, complete disk and PCB emitter/receiver encoder systems can
khaledelmadawi 0:b703833f6795 41 * be bought, but the interface, regardless of implementation is the same.
khaledelmadawi 0:b703833f6795 42 *
khaledelmadawi 0:b703833f6795 43 * +-----+ +-----+ +-----+
khaledelmadawi 0:b703833f6795 44 * Channel A | ^ | | | | |
khaledelmadawi 0:b703833f6795 45 * ---+ ^ +-----+ +-----+ +-----
khaledelmadawi 0:b703833f6795 46 * ^ ^
khaledelmadawi 0:b703833f6795 47 * ^ +-----+ +-----+ +-----+
khaledelmadawi 0:b703833f6795 48 * Channel B ^ | | | | | |
khaledelmadawi 0:b703833f6795 49 * ------+ +-----+ +-----+ +-----
khaledelmadawi 0:b703833f6795 50 * ^ ^
khaledelmadawi 0:b703833f6795 51 * ^ ^
khaledelmadawi 0:b703833f6795 52 * 90deg
khaledelmadawi 0:b703833f6795 53 *
khaledelmadawi 0:b703833f6795 54 * The interface uses X2 encoding by default which calculates the pulse count
khaledelmadawi 0:b703833f6795 55 * based on reading the current state after each rising and falling edge of
khaledelmadawi 0:b703833f6795 56 * channel A.
khaledelmadawi 0:b703833f6795 57 *
khaledelmadawi 0:b703833f6795 58 * +-----+ +-----+ +-----+
khaledelmadawi 0:b703833f6795 59 * Channel A | | | | | |
khaledelmadawi 0:b703833f6795 60 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:b703833f6795 61 * ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 62 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:b703833f6795 63 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:b703833f6795 64 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:b703833f6795 65 * ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 66 * ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 67 * Pulse count 0 1 2 3 4 5 ...
khaledelmadawi 0:b703833f6795 68 *
khaledelmadawi 0:b703833f6795 69 * This interface can also use X4 encoding which calculates the pulse count
khaledelmadawi 0:b703833f6795 70 * based on reading the current state after each rising and falling edge of
khaledelmadawi 0:b703833f6795 71 * either channel.
khaledelmadawi 0:b703833f6795 72 *
khaledelmadawi 0:b703833f6795 73 * +-----+ +-----+ +-----+
khaledelmadawi 0:b703833f6795 74 * Channel A | | | | | |
khaledelmadawi 0:b703833f6795 75 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:b703833f6795 76 * ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 77 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:b703833f6795 78 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:b703833f6795 79 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:b703833f6795 80 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 81 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 82 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
khaledelmadawi 0:b703833f6795 83 *
khaledelmadawi 0:b703833f6795 84 * It defaults
khaledelmadawi 0:b703833f6795 85 *
khaledelmadawi 0:b703833f6795 86 * An optional index channel can be used which determines when a full
khaledelmadawi 0:b703833f6795 87 * revolution has occured.
khaledelmadawi 0:b703833f6795 88 *
khaledelmadawi 0:b703833f6795 89 * If a 4 pules per revolution encoder was used, with X4 encoding,
khaledelmadawi 0:b703833f6795 90 * the following would be observed.
khaledelmadawi 0:b703833f6795 91 *
khaledelmadawi 0:b703833f6795 92 * +-----+ +-----+ +-----+
khaledelmadawi 0:b703833f6795 93 * Channel A | | | | | |
khaledelmadawi 0:b703833f6795 94 * ---+ +-----+ +-----+ +-----
khaledelmadawi 0:b703833f6795 95 * ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 96 * ^ +-----+ ^ +-----+ ^ +-----+
khaledelmadawi 0:b703833f6795 97 * Channel B ^ | ^ | ^ | ^ | ^ | |
khaledelmadawi 0:b703833f6795 98 * ------+ ^ +-----+ ^ +-----+ +--
khaledelmadawi 0:b703833f6795 99 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 100 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 101 * ^ ^ ^ +--+ ^ ^ +--+ ^
khaledelmadawi 0:b703833f6795 102 * ^ ^ ^ | | ^ ^ | | ^
khaledelmadawi 0:b703833f6795 103 * Index ------------+ +--------+ +-----------
khaledelmadawi 0:b703833f6795 104 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
khaledelmadawi 0:b703833f6795 105 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
khaledelmadawi 0:b703833f6795 106 * Rev. count 0 1 2
khaledelmadawi 0:b703833f6795 107 *
khaledelmadawi 0:b703833f6795 108 * Rotational position in degrees can be calculated by:
khaledelmadawi 0:b703833f6795 109 *
khaledelmadawi 0:b703833f6795 110 * (pulse count / X * N) * 360
khaledelmadawi 0:b703833f6795 111 *
khaledelmadawi 0:b703833f6795 112 * Where X is the encoding type [e.g. X4 encoding => X=4], and N is the number
khaledelmadawi 0:b703833f6795 113 * of pulses per revolution.
khaledelmadawi 0:b703833f6795 114 *
khaledelmadawi 0:b703833f6795 115 * Linear position can be calculated by:
khaledelmadawi 0:b703833f6795 116 *
khaledelmadawi 0:b703833f6795 117 * (pulse count / X * N) * (1 / PPI)
khaledelmadawi 0:b703833f6795 118 *
khaledelmadawi 0:b703833f6795 119 * Where X is encoding type [e.g. X4 encoding => X=44], N is the number of
khaledelmadawi 0:b703833f6795 120 * pulses per revolution, and PPI is pulses per inch, or the equivalent for
khaledelmadawi 0:b703833f6795 121 * any other unit of displacement. PPI can be calculated by taking the
khaledelmadawi 0:b703833f6795 122 * circumference of the wheel or encoder disk and dividing it by the number
khaledelmadawi 0:b703833f6795 123 * of pulses per revolution.
khaledelmadawi 0:b703833f6795 124 */
khaledelmadawi 0:b703833f6795 125
khaledelmadawi 0:b703833f6795 126 #ifndef QEI_H
khaledelmadawi 0:b703833f6795 127 #define QEI_H
khaledelmadawi 0:b703833f6795 128
khaledelmadawi 0:b703833f6795 129 /**
khaledelmadawi 0:b703833f6795 130 * Includes
khaledelmadawi 0:b703833f6795 131 */
khaledelmadawi 0:b703833f6795 132 #include "mbed.h"
khaledelmadawi 0:b703833f6795 133
khaledelmadawi 0:b703833f6795 134 /**
khaledelmadawi 0:b703833f6795 135 * Defines
khaledelmadawi 0:b703833f6795 136 */
khaledelmadawi 0:b703833f6795 137 #define PREV_MASK 0x1 //Mask for the previous state in determining direction
khaledelmadawi 0:b703833f6795 138 //of rotation.
khaledelmadawi 0:b703833f6795 139 #define CURR_MASK 0x2 //Mask for the current state in determining direction
khaledelmadawi 0:b703833f6795 140 //of rotation.
khaledelmadawi 0:b703833f6795 141 #define INVALID 0x3 //XORing two states where both bits have changed.
khaledelmadawi 0:b703833f6795 142
khaledelmadawi 0:b703833f6795 143 /**
khaledelmadawi 0:b703833f6795 144 * Quadrature Encoder Interface.
khaledelmadawi 0:b703833f6795 145 */
khaledelmadawi 0:b703833f6795 146 class QEI {
khaledelmadawi 0:b703833f6795 147
khaledelmadawi 0:b703833f6795 148 public:
khaledelmadawi 0:b703833f6795 149
khaledelmadawi 0:b703833f6795 150 typedef enum Encoding {
khaledelmadawi 0:b703833f6795 151
khaledelmadawi 0:b703833f6795 152 X2_ENCODING,
khaledelmadawi 0:b703833f6795 153 X4_ENCODING
khaledelmadawi 0:b703833f6795 154
khaledelmadawi 0:b703833f6795 155 } Encoding;
khaledelmadawi 0:b703833f6795 156
khaledelmadawi 0:b703833f6795 157 /**
khaledelmadawi 0:b703833f6795 158 * Constructor.
khaledelmadawi 0:b703833f6795 159 *
khaledelmadawi 0:b703833f6795 160 * Reads the current values on channel A and channel B to determine the
khaledelmadawi 0:b703833f6795 161 * initial state.
khaledelmadawi 0:b703833f6795 162 *
khaledelmadawi 0:b703833f6795 163 * Attaches the encode function to the rise/fall interrupt edges of
khaledelmadawi 0:b703833f6795 164 * channels A and B to perform X4 encoding.
khaledelmadawi 0:b703833f6795 165 *
khaledelmadawi 0:b703833f6795 166 * Attaches the index function to the rise interrupt edge of channel index
khaledelmadawi 0:b703833f6795 167 * (if it is used) to count revolutions.
khaledelmadawi 0:b703833f6795 168 *
khaledelmadawi 0:b703833f6795 169 * @param channelA mbed pin for channel A input.
khaledelmadawi 0:b703833f6795 170 * @param channelB mbed pin for channel B input.
khaledelmadawi 0:b703833f6795 171 * @param index mbed pin for optional index channel input,
khaledelmadawi 0:b703833f6795 172 * (pass NC if not needed).
khaledelmadawi 0:b703833f6795 173 * @param pulsesPerRev Number of pulses in one revolution.
khaledelmadawi 0:b703833f6795 174 * @param encoding The encoding to use. Uses X2 encoding by default. X2
khaledelmadawi 0:b703833f6795 175 * encoding uses interrupts on the rising and falling edges
khaledelmadawi 0:b703833f6795 176 * of only channel A where as X4 uses them on both
khaledelmadawi 0:b703833f6795 177 * channels.
khaledelmadawi 0:b703833f6795 178 */
khaledelmadawi 0:b703833f6795 179 QEI(PinName channelA, PinName channelB, PinName index, int pulsesPerRev, Encoding encoding = X2_ENCODING);
khaledelmadawi 0:b703833f6795 180
khaledelmadawi 0:b703833f6795 181 /**
khaledelmadawi 0:b703833f6795 182 * Reset the encoder.
khaledelmadawi 0:b703833f6795 183 *
khaledelmadawi 0:b703833f6795 184 * Sets the pulses and revolutions count to zero.
khaledelmadawi 0:b703833f6795 185 */
khaledelmadawi 0:b703833f6795 186 void reset(void);
khaledelmadawi 0:b703833f6795 187
khaledelmadawi 0:b703833f6795 188 /**
khaledelmadawi 0:b703833f6795 189 * Read the state of the encoder.
khaledelmadawi 0:b703833f6795 190 *
khaledelmadawi 0:b703833f6795 191 * @return The current state of the encoder as a 2-bit number, where:
khaledelmadawi 0:b703833f6795 192 * bit 1 = The reading from channel B
khaledelmadawi 0:b703833f6795 193 * bit 2 = The reading from channel A
khaledelmadawi 0:b703833f6795 194 */
khaledelmadawi 0:b703833f6795 195 int getCurrentState(void);
khaledelmadawi 0:b703833f6795 196
khaledelmadawi 0:b703833f6795 197 /**
khaledelmadawi 0:b703833f6795 198 * Read the number of pulses recorded by the encoder.
khaledelmadawi 0:b703833f6795 199 *
khaledelmadawi 0:b703833f6795 200 * @return Number of pulses which have occured.
khaledelmadawi 0:b703833f6795 201 */
khaledelmadawi 0:b703833f6795 202 int getPulses(void);
khaledelmadawi 0:b703833f6795 203
khaledelmadawi 0:b703833f6795 204 /**
khaledelmadawi 0:b703833f6795 205 * Read the number of revolutions recorded by the encoder on the index channel.
khaledelmadawi 0:b703833f6795 206 *
khaledelmadawi 0:b703833f6795 207 * @return Number of revolutions which have occured on the index channel.
khaledelmadawi 0:b703833f6795 208 */
khaledelmadawi 0:b703833f6795 209 int getRevolutions(void);
khaledelmadawi 0:b703833f6795 210
khaledelmadawi 0:b703833f6795 211 private:
khaledelmadawi 0:b703833f6795 212
khaledelmadawi 0:b703833f6795 213 /**
khaledelmadawi 0:b703833f6795 214 * Update the pulse count.
khaledelmadawi 0:b703833f6795 215 *
khaledelmadawi 0:b703833f6795 216 * Called on every rising/falling edge of channels A/B.
khaledelmadawi 0:b703833f6795 217 *
khaledelmadawi 0:b703833f6795 218 * Reads the state of the channels and determines whether a pulse forward
khaledelmadawi 0:b703833f6795 219 * or backward has occured, updating the count appropriately.
khaledelmadawi 0:b703833f6795 220 */
khaledelmadawi 0:b703833f6795 221 void encode(void);
khaledelmadawi 0:b703833f6795 222
khaledelmadawi 0:b703833f6795 223 /**
khaledelmadawi 0:b703833f6795 224 * Called on every rising edge of channel index to update revolution
khaledelmadawi 0:b703833f6795 225 * count by one.
khaledelmadawi 0:b703833f6795 226 */
khaledelmadawi 0:b703833f6795 227 void index(void);
khaledelmadawi 0:b703833f6795 228
khaledelmadawi 0:b703833f6795 229 Encoding encoding_;
khaledelmadawi 0:b703833f6795 230
khaledelmadawi 0:b703833f6795 231 InterruptIn channelA_;
khaledelmadawi 0:b703833f6795 232 InterruptIn channelB_;
khaledelmadawi 0:b703833f6795 233 InterruptIn index_;
khaledelmadawi 0:b703833f6795 234
khaledelmadawi 0:b703833f6795 235 int pulsesPerRev_;
khaledelmadawi 0:b703833f6795 236 int prevState_;
khaledelmadawi 0:b703833f6795 237 int currState_;
khaledelmadawi 0:b703833f6795 238
khaledelmadawi 0:b703833f6795 239 volatile int pulses_;
khaledelmadawi 0:b703833f6795 240 volatile int revolutions_;
khaledelmadawi 0:b703833f6795 241
khaledelmadawi 0:b703833f6795 242 };
khaledelmadawi 0:b703833f6795 243
khaledelmadawi 0:b703833f6795 244 #endif /* QEI_H */