Eduardo de Mier / UIEncoder

Library for manual Encoders as used in user interfaces. Very simple, reduced and rock solid encoder library. Counts full pulses only. Inherent debouncing through state machine. Running on a regular timer IRQ. No IRQ jamming through bouncing. Immune to false edges giving unwanted counts when moving partial steps. Not depending on PinDetect or anything else. May be enhanced by adding acceleration and push button debouncing in the future.

Library for manual Encoders as used in user interfaces. Very simple, reduced and rock solid. Counts full pulses/steps only. Inherent debouncing through state machine. No time dependency for debouncing. Very tight code running in a regular timer IRQ. No IRQ jamming through bouncing edges. Immune to false edges giving unwanted counts when moving partial steps back and forth. Not depending on PinDetect or any other debouncing library. May be enhanced in the near future by adding acceleration and push button debouncing.

Encoder.cpp@5:70534b19d8bf, 2015-01-16 (annotated)

Committer:
eduardoG26
Date:
Fri Jan 16 15:33:21 2015 +0000
Revision:
5:70534b19d8bf
Parent:
4:ee384561bfa4
Child:
6:c2af98aa7d2b
Pushbutton Debouncing added.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
eduardoG26 2:603b47d3755e 1 // Encoder lib for user interfaces
eduardoG26 1:158a3886aced 2 // Extremely simple time driven state machin with inherent debouncing.
eduardoG26 1:158a3886aced 3 // No irq-jamming because of switch bouncing
eduardoG26 1:158a3886aced 4 // No counting on first edges when encoder leaves idle state (both switches open).
eduardoG26 1:158a3886aced 5 // Rock solid
eduardoG26 2:603b47d3755e 6 /*
eduardoG26 2:603b47d3755e 7 The MIT License (MIT)
eduardoG26 2:603b47d3755e 8
eduardoG26 2:603b47d3755e 9 Copyright (c) 2014 calima engineering
eduardoG26 2:603b47d3755e 10
eduardoG26 2:603b47d3755e 11 Permission is hereby granted, free of charge, to any person obtaining a copy
eduardoG26 2:603b47d3755e 12 of this software and associated documentation files (the "Software"), to deal
eduardoG26 2:603b47d3755e 13 in the Software without restriction, including without limitation the rights
eduardoG26 2:603b47d3755e 14 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
eduardoG26 2:603b47d3755e 15 copies of the Software, and to permit persons to whom the Software is
eduardoG26 2:603b47d3755e 16 furnished to do so, subject to the following conditions:
eduardoG26 2:603b47d3755e 17
eduardoG26 2:603b47d3755e 18 The above copyright notice and this permission notice shall be included in
eduardoG26 2:603b47d3755e 19 all copies or substantial portions of the Software.
eduardoG26 2:603b47d3755e 20
eduardoG26 2:603b47d3755e 21 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
eduardoG26 2:603b47d3755e 22 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
eduardoG26 2:603b47d3755e 23 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
eduardoG26 2:603b47d3755e 24 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
eduardoG26 2:603b47d3755e 25 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
eduardoG26 2:603b47d3755e 26 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
eduardoG26 2:603b47d3755e 27 THE SOFTWARE.
eduardoG26 2:603b47d3755e 28 */
eduardoG26 1:158a3886aced 29
eduardoG26 0:fc87dcec05fd 30 #include "mbed.h"
eduardoG26 1:158a3886aced 31 #include "Encoder.h"
eduardoG26 2:603b47d3755e 32 #include "EncoderConfig.h"
eduardoG26 1:158a3886aced 33
eduardoG26 1:158a3886aced 34 // Chose encoder pins, default, nucleo-XXX
eduardoG26 1:158a3886aced 35 #ifndef ENCODER_PIN_A
eduardoG26 1:158a3886aced 36 #define ENCODER_PIN_A D6
eduardoG26 1:158a3886aced 37 #endif
eduardoG26 5:70534b19d8bf 38
eduardoG26 1:158a3886aced 39 #ifndef ENCODER_PIN_B
eduardoG26 1:158a3886aced 40 #define ENCODER_PIN_B D7
eduardoG26 1:158a3886aced 41 #endif
eduardoG26 1:158a3886aced 42
eduardoG26 5:70534b19d8bf 43 #ifndef ENCODER_PIN_PB
eduardoG26 5:70534b19d8bf 44 #define ENCODER_PIN_PB D5
eduardoG26 5:70534b19d8bf 45 #endif
eduardoG26 5:70534b19d8bf 46
eduardoG26 1:158a3886aced 47 // Sample every ... microseconds, default
eduardoG26 1:158a3886aced 48 // 250µs is a good value for cheap 24 ppr encoders (ALPS EC12E24...) with strong bouncing.
eduardoG26 1:158a3886aced 49 // 1000µs is a good value for quality 24 ppr encoders (ALPS EC12E24...) with low bouncing.
eduardoG26 1:158a3886aced 50 // 250µs is a good value for fast 24+ ppr encoders (Sparkfun, Qubig Panel1 type...).
eduardoG26 1:158a3886aced 51 #ifndef ENCODER_SAMPLE_PERIOD_US
eduardoG26 1:158a3886aced 52 #define ENCODER_SAMPLE_PERIOD_US (250)
eduardoG26 1:158a3886aced 53 #endif
eduardoG26 0:fc87dcec05fd 54
eduardoG26 5:70534b19d8bf 55 // Calc debounce cpounter reload
eduardoG26 5:70534b19d8bf 56 #define PB_DEBOUNCE_RELOAD (((uint32_t)ENCODER_PB_DEBOUNCE_MS * 1000uL) / ENCODER_SAMPLE_PERIOD_US)
eduardoG26 5:70534b19d8bf 57
eduardoG26 4:ee384561bfa4 58 // Counts steps := pulses
eduardoG26 0:fc87dcec05fd 59 static volatile uint16_t Pulses;
eduardoG26 4:ee384561bfa4 60
eduardoG26 4:ee384561bfa4 61 // State variables
eduardoG26 5:70534b19d8bf 62 static volatile bool UpDown, Ready, PB_RawState_b, PB_State_b;
eduardoG26 0:fc87dcec05fd 63
eduardoG26 5:70534b19d8bf 64 // Counter for bebouncing
eduardoG26 5:70534b19d8bf 65 static volatile uint16_t PB_DebounceCounter_u16;
eduardoG26 5:70534b19d8bf 66
eduardoG26 5:70534b19d8bf 67 DigitalIn PinA(ENCODER_PIN_A), PinB(ENCODER_PIN_B), PinPB(ENCODER_PIN_PB);
eduardoG26 0:fc87dcec05fd 68
eduardoG26 0:fc87dcec05fd 69 static Ticker EncoderTick;
eduardoG26 1:158a3886aced 70 static void EncoderTickIRQ();
eduardoG26 0:fc87dcec05fd 71
eduardoG26 1:158a3886aced 72 // Call once in main.
eduardoG26 1:158a3886aced 73 void EncoderStart ()
eduardoG26 1:158a3886aced 74 {
eduardoG26 5:70534b19d8bf 75 PinA.mode(PullUp); // Encoder pin A
eduardoG26 5:70534b19d8bf 76 PinB.mode(PullUp); // Encoder pin B
eduardoG26 1:158a3886aced 77 EncoderTick.attach_us (&EncoderTickIRQ, ENCODER_SAMPLE_PERIOD_US);
eduardoG26 5:70534b19d8bf 78 PinPB.mode(PullUp); // Pushbutton pin
eduardoG26 5:70534b19d8bf 79 PB_DebounceCounter_u16 = PB_DEBOUNCE_RELOAD; // Start
eduardoG26 1:158a3886aced 80 }
eduardoG26 1:158a3886aced 81
eduardoG26 4:ee384561bfa4 82 // Switch off IRQ and change Pullups to PullDowns to save power
eduardoG26 1:158a3886aced 83 void EncoderStop ()
eduardoG26 1:158a3886aced 84 {
eduardoG26 3:e8e1481ac042 85 PinA.mode(PullDown);
eduardoG26 3:e8e1481ac042 86 PinB.mode(PullDown);
eduardoG26 5:70534b19d8bf 87 PinPB.mode(PullDown);
eduardoG26 1:158a3886aced 88 EncoderTick.detach();
eduardoG26 1:158a3886aced 89 }
eduardoG26 5:70534b19d8bf 90
eduardoG26 1:158a3886aced 91 // Get counting variable.
eduardoG26 5:70534b19d8bf 92 uint16_t EncoderGetPulses ()
eduardoG26 1:158a3886aced 93 {
eduardoG26 1:158a3886aced 94 return Pulses;
eduardoG26 1:158a3886aced 95 }
eduardoG26 1:158a3886aced 96
eduardoG26 5:70534b19d8bf 97 // Get pushbutton state.
eduardoG26 5:70534b19d8bf 98 bool EncoderGetPB ()
eduardoG26 5:70534b19d8bf 99 {
eduardoG26 5:70534b19d8bf 100 return not PB_State_b; // invert, pressed == true
eduardoG26 5:70534b19d8bf 101 }
eduardoG26 5:70534b19d8bf 102
eduardoG26 1:158a3886aced 103 // State machine. Runs in IRQ. Static.
eduardoG26 0:fc87dcec05fd 104 static void EncoderTickIRQ()
eduardoG26 0:fc87dcec05fd 105 {
eduardoG26 1:158a3886aced 106 // If-then-else structure is good because every pin is read max. once.
eduardoG26 0:fc87dcec05fd 107 if(PinB) {
eduardoG26 0:fc87dcec05fd 108 if(PinA) { // clockwise?
eduardoG26 0:fc87dcec05fd 109 Ready = true;
eduardoG26 0:fc87dcec05fd 110 } else {
eduardoG26 0:fc87dcec05fd 111 UpDown = true;
eduardoG26 0:fc87dcec05fd 112 }
eduardoG26 0:fc87dcec05fd 113 } else {
eduardoG26 0:fc87dcec05fd 114 if(PinA) { // counterclockwise?
eduardoG26 0:fc87dcec05fd 115 UpDown = false;
eduardoG26 0:fc87dcec05fd 116 } else {
eduardoG26 0:fc87dcec05fd 117 if(Ready) {
eduardoG26 0:fc87dcec05fd 118 if (UpDown) {
eduardoG26 0:fc87dcec05fd 119 Pulses++; //moving forward
eduardoG26 0:fc87dcec05fd 120 } else {
eduardoG26 0:fc87dcec05fd 121 Pulses--; //moving reverse
eduardoG26 0:fc87dcec05fd 122 }
eduardoG26 0:fc87dcec05fd 123 Ready = false;
eduardoG26 0:fc87dcec05fd 124 }
eduardoG26 0:fc87dcec05fd 125 }
eduardoG26 0:fc87dcec05fd 126 }
eduardoG26 5:70534b19d8bf 127 if(PinPB == PB_RawState_b) {
eduardoG26 5:70534b19d8bf 128 if(--PB_DebounceCounter_u16 == 0) {
eduardoG26 5:70534b19d8bf 129 PB_State_b = PB_RawState_b;
eduardoG26 5:70534b19d8bf 130 PB_DebounceCounter_u16 = PB_DEBOUNCE_RELOAD; // Restart
eduardoG26 5:70534b19d8bf 131 }
eduardoG26 5:70534b19d8bf 132 } else {
eduardoG26 5:70534b19d8bf 133 PB_RawState_b = PinPB;
eduardoG26 5:70534b19d8bf 134 PB_DebounceCounter_u16 = PB_DEBOUNCE_RELOAD; // Restart
eduardoG26 5:70534b19d8bf 135 }
eduardoG26 0:fc87dcec05fd 136 }
eduardoG26 0:fc87dcec05fd 137
eduardoG26 0:fc87dcec05fd 138 // End of file