Geo Electronics "Geo Counter" / Mbed 2 deprecated GEO_SHOW2ME_F411RE_CDY

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Dependencies:   SDFileSystem_HelloWorld mbed FATFileSystem

QEI/QEI.h@0:aa13e1c335cd, 2018-11-04 (annotated)

Committer:
Charles David Young
Date:
Sun Nov 04 18:44:51 2018 -0700
Revision:
0:aa13e1c335cd
create new repo for show2me

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Charles David Young 0:aa13e1c335cd 1 /**
Charles David Young 0:aa13e1c335cd 2 * @author Aaron Berk
Charles David Young 0:aa13e1c335cd 3 *
Charles David Young 0:aa13e1c335cd 4 * @section LICENSE
Charles David Young 0:aa13e1c335cd 5 *
Charles David Young 0:aa13e1c335cd 6 * Copyright (c) 2010 ARM Limited
Charles David Young 0:aa13e1c335cd 7 *
Charles David Young 0:aa13e1c335cd 8 * Permission is hereby granted, free of charge, to any person obtaining a copy
Charles David Young 0:aa13e1c335cd 9 * of this software and associated documentation files (the "Software"), to deal
Charles David Young 0:aa13e1c335cd 10 * in the Software without restriction, including without limitation the rights
Charles David Young 0:aa13e1c335cd 11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Charles David Young 0:aa13e1c335cd 12 * copies of the Software, and to permit persons to whom the Software is
Charles David Young 0:aa13e1c335cd 13 * furnished to do so, subject to the following conditions:
Charles David Young 0:aa13e1c335cd 14 *
Charles David Young 0:aa13e1c335cd 15 * The above copyright notice and this permission notice shall be included in
Charles David Young 0:aa13e1c335cd 16 * all copies or substantial portions of the Software.
Charles David Young 0:aa13e1c335cd 17 *
Charles David Young 0:aa13e1c335cd 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Charles David Young 0:aa13e1c335cd 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Charles David Young 0:aa13e1c335cd 20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Charles David Young 0:aa13e1c335cd 21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Charles David Young 0:aa13e1c335cd 22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Charles David Young 0:aa13e1c335cd 23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Charles David Young 0:aa13e1c335cd 24 * THE SOFTWARE.
Charles David Young 0:aa13e1c335cd 25 *
Charles David Young 0:aa13e1c335cd 26 * @section DESCRIPTION
Charles David Young 0:aa13e1c335cd 27 *
Charles David Young 0:aa13e1c335cd 28 * Quadrature Encoder Interface.
Charles David Young 0:aa13e1c335cd 29 *
Charles David Young 0:aa13e1c335cd 30 * A quadrature encoder consists of two code tracks on a disc which are 90
Charles David Young 0:aa13e1c335cd 31 * degrees out of phase. It can be used to determine how far a wheel has
Charles David Young 0:aa13e1c335cd 32 * rotated, relative to a known starting position.
Charles David Young 0:aa13e1c335cd 33 *
Charles David Young 0:aa13e1c335cd 34 * Only one code track changes at a time leading to a more robust system than
Charles David Young 0:aa13e1c335cd 35 * a single track, because any jitter around any edge won't cause a state
Charles David Young 0:aa13e1c335cd 36 * change as the other track will remain constant.
Charles David Young 0:aa13e1c335cd 37 *
Charles David Young 0:aa13e1c335cd 38 * Encoders can be a homebrew affair, consisting of infrared emitters/receivers
Charles David Young 0:aa13e1c335cd 39 * and paper code tracks consisting of alternating black and white sections;
Charles David Young 0:aa13e1c335cd 40 * alternatively, complete disk and PCB emitter/receiver encoder systems can
Charles David Young 0:aa13e1c335cd 41 * be bought, but the interface, regardless of implementation is the same.
Charles David Young 0:aa13e1c335cd 42 *
Charles David Young 0:aa13e1c335cd 43 * +-----+ +-----+ +-----+
Charles David Young 0:aa13e1c335cd 44 * Channel A | ^ | | | | |
Charles David Young 0:aa13e1c335cd 45 * ---+ ^ +-----+ +-----+ +-----
Charles David Young 0:aa13e1c335cd 46 * ^ ^
Charles David Young 0:aa13e1c335cd 47 * ^ +-----+ +-----+ +-----+
Charles David Young 0:aa13e1c335cd 48 * Channel B ^ | | | | | |
Charles David Young 0:aa13e1c335cd 49 * ------+ +-----+ +-----+ +-----
Charles David Young 0:aa13e1c335cd 50 * ^ ^
Charles David Young 0:aa13e1c335cd 51 * ^ ^
Charles David Young 0:aa13e1c335cd 52 * 90deg
Charles David Young 0:aa13e1c335cd 53 *
Charles David Young 0:aa13e1c335cd 54 * The interface uses X2 encoding by default which calculates the pulse count
Charles David Young 0:aa13e1c335cd 55 * based on reading the current state after each rising and falling edge of
Charles David Young 0:aa13e1c335cd 56 * channel A.
Charles David Young 0:aa13e1c335cd 57 *
Charles David Young 0:aa13e1c335cd 58 * +-----+ +-----+ +-----+
Charles David Young 0:aa13e1c335cd 59 * Channel A | | | | | |
Charles David Young 0:aa13e1c335cd 60 * ---+ +-----+ +-----+ +-----
Charles David Young 0:aa13e1c335cd 61 * ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 62 * ^ +-----+ ^ +-----+ ^ +-----+
Charles David Young 0:aa13e1c335cd 63 * Channel B ^ | ^ | ^ | ^ | ^ | |
Charles David Young 0:aa13e1c335cd 64 * ------+ ^ +-----+ ^ +-----+ +--
Charles David Young 0:aa13e1c335cd 65 * ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 66 * ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 67 * Pulse count 0 1 2 3 4 5 ...
Charles David Young 0:aa13e1c335cd 68 *
Charles David Young 0:aa13e1c335cd 69 * This interface can also use X4 encoding which calculates the pulse count
Charles David Young 0:aa13e1c335cd 70 * based on reading the current state after each rising and falling edge of
Charles David Young 0:aa13e1c335cd 71 * either channel.
Charles David Young 0:aa13e1c335cd 72 *
Charles David Young 0:aa13e1c335cd 73 * +-----+ +-----+ +-----+
Charles David Young 0:aa13e1c335cd 74 * Channel A | | | | | |
Charles David Young 0:aa13e1c335cd 75 * ---+ +-----+ +-----+ +-----
Charles David Young 0:aa13e1c335cd 76 * ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 77 * ^ +-----+ ^ +-----+ ^ +-----+
Charles David Young 0:aa13e1c335cd 78 * Channel B ^ | ^ | ^ | ^ | ^ | |
Charles David Young 0:aa13e1c335cd 79 * ------+ ^ +-----+ ^ +-----+ +--
Charles David Young 0:aa13e1c335cd 80 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 81 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 82 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
Charles David Young 0:aa13e1c335cd 83 *
Charles David Young 0:aa13e1c335cd 84 * It defaults
Charles David Young 0:aa13e1c335cd 85 *
Charles David Young 0:aa13e1c335cd 86 * An optional index channel can be used which determines when a full
Charles David Young 0:aa13e1c335cd 87 * revolution has occured.
Charles David Young 0:aa13e1c335cd 88 *
Charles David Young 0:aa13e1c335cd 89 * If a 4 pules per revolution encoder was used, with X4 encoding,
Charles David Young 0:aa13e1c335cd 90 * the following would be observed.
Charles David Young 0:aa13e1c335cd 91 *
Charles David Young 0:aa13e1c335cd 92 * +-----+ +-----+ +-----+
Charles David Young 0:aa13e1c335cd 93 * Channel A | | | | | |
Charles David Young 0:aa13e1c335cd 94 * ---+ +-----+ +-----+ +-----
Charles David Young 0:aa13e1c335cd 95 * ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 96 * ^ +-----+ ^ +-----+ ^ +-----+
Charles David Young 0:aa13e1c335cd 97 * Channel B ^ | ^ | ^ | ^ | ^ | |
Charles David Young 0:aa13e1c335cd 98 * ------+ ^ +-----+ ^ +-----+ +--
Charles David Young 0:aa13e1c335cd 99 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 100 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 101 * ^ ^ ^ +--+ ^ ^ +--+ ^
Charles David Young 0:aa13e1c335cd 102 * ^ ^ ^ | | ^ ^ | | ^
Charles David Young 0:aa13e1c335cd 103 * Index ------------+ +--------+ +-----------
Charles David Young 0:aa13e1c335cd 104 * ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Charles David Young 0:aa13e1c335cd 105 * Pulse count 0 1 2 3 4 5 6 7 8 9 ...
Charles David Young 0:aa13e1c335cd 106 * Rev. count 0 1 2
Charles David Young 0:aa13e1c335cd 107 *
Charles David Young 0:aa13e1c335cd 108 * Rotational position in degrees can be calculated by:
Charles David Young 0:aa13e1c335cd 109 *
Charles David Young 0:aa13e1c335cd 110 * (pulse count / X * N) * 360
Charles David Young 0:aa13e1c335cd 111 *
Charles David Young 0:aa13e1c335cd 112 * Where X is the encoding type [e.g. X4 encoding => X=4], and N is the number
Charles David Young 0:aa13e1c335cd 113 * of pulses per revolution.
Charles David Young 0:aa13e1c335cd 114 *
Charles David Young 0:aa13e1c335cd 115 * Linear position can be calculated by:
Charles David Young 0:aa13e1c335cd 116 *
Charles David Young 0:aa13e1c335cd 117 * (pulse count / X * N) * (1 / PPI)
Charles David Young 0:aa13e1c335cd 118 *
Charles David Young 0:aa13e1c335cd 119 * Where X is encoding type [e.g. X4 encoding => X=44], N is the number of
Charles David Young 0:aa13e1c335cd 120 * pulses per revolution, and PPI is pulses per inch, or the equivalent for
Charles David Young 0:aa13e1c335cd 121 * any other unit of displacement. PPI can be calculated by taking the
Charles David Young 0:aa13e1c335cd 122 * circumference of the wheel or encoder disk and dividing it by the number
Charles David Young 0:aa13e1c335cd 123 * of pulses per revolution.
Charles David Young 0:aa13e1c335cd 124 */
Charles David Young 0:aa13e1c335cd 125
Charles David Young 0:aa13e1c335cd 126 #ifndef QEI_H
Charles David Young 0:aa13e1c335cd 127 #define QEI_H
Charles David Young 0:aa13e1c335cd 128
Charles David Young 0:aa13e1c335cd 129 /**
Charles David Young 0:aa13e1c335cd 130 * Includes
Charles David Young 0:aa13e1c335cd 131 */
Charles David Young 0:aa13e1c335cd 132 #include "mbed.h"
Charles David Young 0:aa13e1c335cd 133
Charles David Young 0:aa13e1c335cd 134 /**
Charles David Young 0:aa13e1c335cd 135 * Defines
Charles David Young 0:aa13e1c335cd 136 */
Charles David Young 0:aa13e1c335cd 137 #define PREV_MASK 0x1 //Mask for the previous state in determining direction
Charles David Young 0:aa13e1c335cd 138 //of rotation.
Charles David Young 0:aa13e1c335cd 139 #define CURR_MASK 0x2 //Mask for the current state in determining direction
Charles David Young 0:aa13e1c335cd 140 //of rotation.
Charles David Young 0:aa13e1c335cd 141 #define INVALID 0x3 //XORing two states where both bits have changed.
Charles David Young 0:aa13e1c335cd 142
Charles David Young 0:aa13e1c335cd 143 /**
Charles David Young 0:aa13e1c335cd 144 * Quadrature Encoder Interface.
Charles David Young 0:aa13e1c335cd 145 */
Charles David Young 0:aa13e1c335cd 146 class QEI {
Charles David Young 0:aa13e1c335cd 147
Charles David Young 0:aa13e1c335cd 148 public:
Charles David Young 0:aa13e1c335cd 149
Charles David Young 0:aa13e1c335cd 150 typedef enum Encoding {
Charles David Young 0:aa13e1c335cd 151
Charles David Young 0:aa13e1c335cd 152 X2_ENCODING,
Charles David Young 0:aa13e1c335cd 153 X4_ENCODING
Charles David Young 0:aa13e1c335cd 154
Charles David Young 0:aa13e1c335cd 155 } Encoding;
Charles David Young 0:aa13e1c335cd 156
Charles David Young 0:aa13e1c335cd 157 /**
Charles David Young 0:aa13e1c335cd 158 * Constructor.
Charles David Young 0:aa13e1c335cd 159 *
Charles David Young 0:aa13e1c335cd 160 * Reads the current values on channel A and channel B to determine the
Charles David Young 0:aa13e1c335cd 161 * initial state.
Charles David Young 0:aa13e1c335cd 162 *
Charles David Young 0:aa13e1c335cd 163 * Attaches the encode function to the rise/fall interrupt edges of
Charles David Young 0:aa13e1c335cd 164 * channels A and B to perform X4 encoding.
Charles David Young 0:aa13e1c335cd 165 *
Charles David Young 0:aa13e1c335cd 166 * Attaches the index function to the rise interrupt edge of channel index
Charles David Young 0:aa13e1c335cd 167 * (if it is used) to count revolutions.
Charles David Young 0:aa13e1c335cd 168 *
Charles David Young 0:aa13e1c335cd 169 * @param channelA mbed pin for channel A input.
Charles David Young 0:aa13e1c335cd 170 * @param channelB mbed pin for channel B input.
Charles David Young 0:aa13e1c335cd 171 * @param index mbed pin for optional index channel input,
Charles David Young 0:aa13e1c335cd 172 * (pass NC if not needed).
Charles David Young 0:aa13e1c335cd 173 * @param pulsesPerRev Number of pulses in one revolution.
Charles David Young 0:aa13e1c335cd 174 * @param encoding The encoding to use. Uses X2 encoding by default. X2
Charles David Young 0:aa13e1c335cd 175 * encoding uses interrupts on the rising and falling edges
Charles David Young 0:aa13e1c335cd 176 * of only channel A where as X4 uses them on both
Charles David Young 0:aa13e1c335cd 177 * channels.
Charles David Young 0:aa13e1c335cd 178 */
Charles David Young 0:aa13e1c335cd 179 QEI(PinName channelA, PinName channelB, PinName index, int pulsesPerRev, Encoding encoding = X2_ENCODING);
Charles David Young 0:aa13e1c335cd 180
Charles David Young 0:aa13e1c335cd 181 /**
Charles David Young 0:aa13e1c335cd 182 * Reset the encoder.
Charles David Young 0:aa13e1c335cd 183 *
Charles David Young 0:aa13e1c335cd 184 * Sets the pulses and revolutions count to zero.
Charles David Young 0:aa13e1c335cd 185 */
Charles David Young 0:aa13e1c335cd 186 void reset(void);
Charles David Young 0:aa13e1c335cd 187
Charles David Young 0:aa13e1c335cd 188 /**
Charles David Young 0:aa13e1c335cd 189 * Read the state of the encoder.
Charles David Young 0:aa13e1c335cd 190 *
Charles David Young 0:aa13e1c335cd 191 * @return The current state of the encoder as a 2-bit number, where:
Charles David Young 0:aa13e1c335cd 192 * bit 1 = The reading from channel B
Charles David Young 0:aa13e1c335cd 193 * bit 2 = The reading from channel A
Charles David Young 0:aa13e1c335cd 194 */
Charles David Young 0:aa13e1c335cd 195 int getCurrentState(void);
Charles David Young 0:aa13e1c335cd 196
Charles David Young 0:aa13e1c335cd 197 /**
Charles David Young 0:aa13e1c335cd 198 * Read the number of pulses recorded by the encoder.
Charles David Young 0:aa13e1c335cd 199 *
Charles David Young 0:aa13e1c335cd 200 * @return Number of pulses which have occured.
Charles David Young 0:aa13e1c335cd 201 */
Charles David Young 0:aa13e1c335cd 202 int getPulses(void);
Charles David Young 0:aa13e1c335cd 203
Charles David Young 0:aa13e1c335cd 204 /**
Charles David Young 0:aa13e1c335cd 205 * Read the number of revolutions recorded by the encoder on the index channel.
Charles David Young 0:aa13e1c335cd 206 *
Charles David Young 0:aa13e1c335cd 207 * @return Number of revolutions which have occured on the index channel.
Charles David Young 0:aa13e1c335cd 208 */
Charles David Young 0:aa13e1c335cd 209 int getRevolutions(void);
Charles David Young 0:aa13e1c335cd 210
Charles David Young 0:aa13e1c335cd 211 private:
Charles David Young 0:aa13e1c335cd 212
Charles David Young 0:aa13e1c335cd 213 /**
Charles David Young 0:aa13e1c335cd 214 * Update the pulse count.
Charles David Young 0:aa13e1c335cd 215 *
Charles David Young 0:aa13e1c335cd 216 * Called on every rising/falling edge of channels A/B.
Charles David Young 0:aa13e1c335cd 217 *
Charles David Young 0:aa13e1c335cd 218 * Reads the state of the channels and determines whether a pulse forward
Charles David Young 0:aa13e1c335cd 219 * or backward has occured, updating the count appropriately.
Charles David Young 0:aa13e1c335cd 220 */
Charles David Young 0:aa13e1c335cd 221 void encode(void);
Charles David Young 0:aa13e1c335cd 222
Charles David Young 0:aa13e1c335cd 223 /**
Charles David Young 0:aa13e1c335cd 224 * Called on every rising edge of channel index to update revolution
Charles David Young 0:aa13e1c335cd 225 * count by one.
Charles David Young 0:aa13e1c335cd 226 */
Charles David Young 0:aa13e1c335cd 227 void index(void);
Charles David Young 0:aa13e1c335cd 228
Charles David Young 0:aa13e1c335cd 229 Encoding encoding_;
Charles David Young 0:aa13e1c335cd 230
Charles David Young 0:aa13e1c335cd 231 InterruptIn channelA_;
Charles David Young 0:aa13e1c335cd 232 InterruptIn channelB_;
Charles David Young 0:aa13e1c335cd 233 InterruptIn index_;
Charles David Young 0:aa13e1c335cd 234
Charles David Young 0:aa13e1c335cd 235 int pulsesPerRev_;
Charles David Young 0:aa13e1c335cd 236 int prevState_;
Charles David Young 0:aa13e1c335cd 237 int currState_;
Charles David Young 0:aa13e1c335cd 238
Charles David Young 0:aa13e1c335cd 239 volatile int pulses_;
Charles David Young 0:aa13e1c335cd 240 volatile int revolutions_;
Charles David Young 0:aa13e1c335cd 241
Charles David Young 0:aa13e1c335cd 242 };
Charles David Young 0:aa13e1c335cd 243
Charles David Young 0:aa13e1c335cd 244 #endif /* QEI_H */