amin omar / QEI

Quadrature encoder interface by Aaron Berk

Dependents:   TEST_ENCODER

Fork of QEI by Aaron Berk

QEI.h@1:5f28ceec8280, 2016-05-04 (annotated)

Committer:
aminomar
Date:
Wed May 04 18:47:39 2016 +0000
Revision:
1:5f28ceec8280
Parent:
0:5c2ad81551aa 
test encoder;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
aberk 0:5c2ad81551aa 1
aberk 0:5c2ad81551aa 2 #ifndef QEI_H
aberk 0:5c2ad81551aa 3 #define QEI_H
aberk 0:5c2ad81551aa 4
aberk 0:5c2ad81551aa 5 #include "mbed.h"
aberk 0:5c2ad81551aa 6
aminomar 1:5f28ceec8280 7 #define PREV_MASK 0x1 //Mask for the previous state in determining direction of rotation.
aminomar 1:5f28ceec8280 8 #define CURR_MASK 0x2 //Mask for the current state in determining direction of rotation.
aberk 0:5c2ad81551aa 9 #define INVALID 0x3 //XORing two states where both bits have changed.
aberk 0:5c2ad81551aa 10
aminomar 1:5f28ceec8280 11
aberk 0:5c2ad81551aa 12 class QEI {
aberk 0:5c2ad81551aa 13
aberk 0:5c2ad81551aa 14 public:
aberk 0:5c2ad81551aa 15
aminomar 1:5f28ceec8280 16 typedef enum Encoding
aminomar 1:5f28ceec8280 17 {
aminomar 1:5f28ceec8280 18 X2_ENCODING,
aberk 0:5c2ad81551aa 19 X4_ENCODING
aminomar 1:5f28ceec8280 20 }
aminomar 1:5f28ceec8280 21 Encoding;
aberk 0:5c2ad81551aa 22
aberk 0:5c2ad81551aa 23 /**
aberk 0:5c2ad81551aa 24 * Constructor.
aberk 0:5c2ad81551aa 25 *
aberk 0:5c2ad81551aa 26 * Reads the current values on channel A and channel B to determine the
aberk 0:5c2ad81551aa 27 * initial state.
aberk 0:5c2ad81551aa 28 *
aberk 0:5c2ad81551aa 29 * Attaches the encode function to the rise/fall interrupt edges of
aberk 0:5c2ad81551aa 30 * channels A and B to perform X4 encoding.
aberk 0:5c2ad81551aa 31 *
aberk 0:5c2ad81551aa 32 * Attaches the index function to the rise interrupt edge of channel index
aberk 0:5c2ad81551aa 33 * (if it is used) to count revolutions.
aberk 0:5c2ad81551aa 34 *
aberk 0:5c2ad81551aa 35 * @param channelA mbed pin for channel A input.
aberk 0:5c2ad81551aa 36 * @param channelB mbed pin for channel B input.
aberk 0:5c2ad81551aa 37 * @param index mbed pin for optional index channel input,
aberk 0:5c2ad81551aa 38 * (pass NC if not needed).
aberk 0:5c2ad81551aa 39 * @param pulsesPerRev Number of pulses in one revolution.
aberk 0:5c2ad81551aa 40 * @param encoding The encoding to use. Uses X2 encoding by default. X2
aberk 0:5c2ad81551aa 41 * encoding uses interrupts on the rising and falling edges
aberk 0:5c2ad81551aa 42 * of only channel A where as X4 uses them on both
aberk 0:5c2ad81551aa 43 * channels.
aberk 0:5c2ad81551aa 44 */
aberk 0:5c2ad81551aa 45 QEI(PinName channelA, PinName channelB, PinName index, int pulsesPerRev, Encoding encoding = X2_ENCODING);
aberk 0:5c2ad81551aa 46
aberk 0:5c2ad81551aa 47 /**
aberk 0:5c2ad81551aa 48 * Reset the encoder.
aberk 0:5c2ad81551aa 49 *
aberk 0:5c2ad81551aa 50 * Sets the pulses and revolutions count to zero.
aberk 0:5c2ad81551aa 51 */
aberk 0:5c2ad81551aa 52 void reset(void);
aberk 0:5c2ad81551aa 53
aberk 0:5c2ad81551aa 54 /**
aberk 0:5c2ad81551aa 55 * Read the state of the encoder.
aberk 0:5c2ad81551aa 56 *
aberk 0:5c2ad81551aa 57 * @return The current state of the encoder as a 2-bit number, where:
aberk 0:5c2ad81551aa 58 * bit 1 = The reading from channel B
aberk 0:5c2ad81551aa 59 * bit 2 = The reading from channel A
aberk 0:5c2ad81551aa 60 */
aberk 0:5c2ad81551aa 61 int getCurrentState(void);
aberk 0:5c2ad81551aa 62
aberk 0:5c2ad81551aa 63 /**
aberk 0:5c2ad81551aa 64 * Read the number of pulses recorded by the encoder.
aberk 0:5c2ad81551aa 65 *
aberk 0:5c2ad81551aa 66 * @return Number of pulses which have occured.
aberk 0:5c2ad81551aa 67 */
aberk 0:5c2ad81551aa 68 int getPulses(void);
aberk 0:5c2ad81551aa 69
aberk 0:5c2ad81551aa 70 /**
aberk 0:5c2ad81551aa 71 * Read the number of revolutions recorded by the encoder on the index channel.
aberk 0:5c2ad81551aa 72 *
aberk 0:5c2ad81551aa 73 * @return Number of revolutions which have occured on the index channel.
aberk 0:5c2ad81551aa 74 */
aberk 0:5c2ad81551aa 75 int getRevolutions(void);
aberk 0:5c2ad81551aa 76
aberk 0:5c2ad81551aa 77 private:
aberk 0:5c2ad81551aa 78
aberk 0:5c2ad81551aa 79 /**
aberk 0:5c2ad81551aa 80 * Update the pulse count.
aberk 0:5c2ad81551aa 81 *
aberk 0:5c2ad81551aa 82 * Called on every rising/falling edge of channels A/B.
aberk 0:5c2ad81551aa 83 *
aberk 0:5c2ad81551aa 84 * Reads the state of the channels and determines whether a pulse forward
aberk 0:5c2ad81551aa 85 * or backward has occured, updating the count appropriately.
aberk 0:5c2ad81551aa 86 */
aberk 0:5c2ad81551aa 87 void encode(void);
aberk 0:5c2ad81551aa 88
aberk 0:5c2ad81551aa 89 /**
aberk 0:5c2ad81551aa 90 * Called on every rising edge of channel index to update revolution
aberk 0:5c2ad81551aa 91 * count by one.
aberk 0:5c2ad81551aa 92 */
aberk 0:5c2ad81551aa 93 void index(void);
aberk 0:5c2ad81551aa 94
aberk 0:5c2ad81551aa 95 Encoding encoding_;
aberk 0:5c2ad81551aa 96
aberk 0:5c2ad81551aa 97 InterruptIn channelA_;
aberk 0:5c2ad81551aa 98 InterruptIn channelB_;
aberk 0:5c2ad81551aa 99 InterruptIn index_;
aberk 0:5c2ad81551aa 100
aberk 0:5c2ad81551aa 101 int pulsesPerRev_;
aberk 0:5c2ad81551aa 102 int prevState_;
aberk 0:5c2ad81551aa 103 int currState_;
aberk 0:5c2ad81551aa 104
aberk 0:5c2ad81551aa 105 volatile int pulses_;
aberk 0:5c2ad81551aa 106 volatile int revolutions_;
aberk 0:5c2ad81551aa 107
aberk 0:5c2ad81551aa 108 };
aberk 0:5c2ad81551aa 109
aberk 0:5c2ad81551aa 110 #endif /* QEI_H */