Wayne Chin
Edge-triggered quadrature decoder
main.cpp@0:646cd75bed54, 2010-10-29 (annotated)
- Committer:
- wac
- Date:
- Fri Oct 29 20:28:45 2010 +0000
- Revision:
- 0:646cd75bed54
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| wac | 0:646cd75bed54 | 1 | // 9430 Quadrature Decoder using mbed edge-triggered interrupts |
| wac | 0:646cd75bed54 | 2 | // |
| wac | 0:646cd75bed54 | 3 | // Read quadrature encoder and drive LEDs |
| wac | 0:646cd75bed54 | 4 | // Version 0.1 |
| wac | 0:646cd75bed54 | 5 | // Created by Wayne Chin |
| wac | 0:646cd75bed54 | 6 | // October 28, 2010 |
| wac | 0:646cd75bed54 | 7 | |
| wac | 0:646cd75bed54 | 8 | #include "mbed.h" |
| wac | 0:646cd75bed54 | 9 | |
| wac | 0:646cd75bed54 | 10 | #define ON 0 // LED drives are inverted |
| wac | 0:646cd75bed54 | 11 | #define OFF 1 // LED drives are inverted |
| wac | 0:646cd75bed54 | 12 | #define MAXAMPS200 200 |
| wac | 0:646cd75bed54 | 13 | #define MINAMPSET 25 |
| wac | 0:646cd75bed54 | 14 | #define DEBOUNCETIME 6000 // Debounce delay in us |
| wac | 0:646cd75bed54 | 15 | |
| wac | 0:646cd75bed54 | 16 | // mbed LEDs |
| wac | 0:646cd75bed54 | 17 | DigitalOut led1(LED1); |
| wac | 0:646cd75bed54 | 18 | DigitalOut led2(LED2); |
| wac | 0:646cd75bed54 | 19 | DigitalOut led3(LED3); |
| wac | 0:646cd75bed54 | 20 | DigitalOut led4(LED4); |
| wac | 0:646cd75bed54 | 21 | |
| wac | 0:646cd75bed54 | 22 | // Quadrature encoder inputs |
| wac | 0:646cd75bed54 | 23 | InterruptIn quada(p21); |
| wac | 0:646cd75bed54 | 24 | InterruptIn quadb(p22); |
| wac | 0:646cd75bed54 | 25 | InterruptIn quadsw(p30); |
| wac | 0:646cd75bed54 | 26 | |
| wac | 0:646cd75bed54 | 27 | // mbed API timers used for edge sensing and debouncing |
| wac | 0:646cd75bed54 | 28 | Timer debouncetimerrisea; |
| wac | 0:646cd75bed54 | 29 | Timer debouncetimerfalla; |
| wac | 0:646cd75bed54 | 30 | Timer debouncetimerriseb; |
| wac | 0:646cd75bed54 | 31 | Timer debouncetimerfallb; |
| wac | 0:646cd75bed54 | 32 | Timeout debouncerisea; |
| wac | 0:646cd75bed54 | 33 | Timeout debouncefalla; |
| wac | 0:646cd75bed54 | 34 | Timeout debounceriseb; |
| wac | 0:646cd75bed54 | 35 | Timeout debouncefallb; |
| wac | 0:646cd75bed54 | 36 | |
| wac | 0:646cd75bed54 | 37 | Ticker updateserial; |
| wac | 0:646cd75bed54 | 38 | Serial pc(USBTX, USBRX); // tx, rx |
| wac | 0:646cd75bed54 | 39 | |
| wac | 0:646cd75bed54 | 40 | int counter; // Global counter variable |
| wac | 0:646cd75bed54 | 41 | |
| wac | 0:646cd75bed54 | 42 | void serialout() |
| wac | 0:646cd75bed54 | 43 | { |
| wac | 0:646cd75bed54 | 44 | pc.printf("%d\n\r", counter); |
| wac | 0:646cd75bed54 | 45 | } |
| wac | 0:646cd75bed54 | 46 | |
| wac | 0:646cd75bed54 | 47 | void display() |
| wac | 0:646cd75bed54 | 48 | { |
| wac | 0:646cd75bed54 | 49 | if (counter > MAXAMPS200) |
| wac | 0:646cd75bed54 | 50 | counter = MAXAMPS200; // Clip counter at high end |
| wac | 0:646cd75bed54 | 51 | else if (counter < MINAMPSET) |
| wac | 0:646cd75bed54 | 52 | counter = MINAMPSET; // Clip at low end |
| wac | 0:646cd75bed54 | 53 | switch (counter % 4) // Get 2 LSBs and display sequence on mbed LEDs |
| wac | 0:646cd75bed54 | 54 | { |
| wac | 0:646cd75bed54 | 55 | case 0: |
| wac | 0:646cd75bed54 | 56 | led1 = 1; led2 = 0; led3 = 0; led4 = 0; |
| wac | 0:646cd75bed54 | 57 | break; |
| wac | 0:646cd75bed54 | 58 | case 1: |
| wac | 0:646cd75bed54 | 59 | led1 = 0; led2 = 1; led3 = 0; led4 = 0; |
| wac | 0:646cd75bed54 | 60 | break; |
| wac | 0:646cd75bed54 | 61 | case 2: |
| wac | 0:646cd75bed54 | 62 | led1 = 0; led2 = 0; led3 = 1; led4 = 0; |
| wac | 0:646cd75bed54 | 63 | break; |
| wac | 0:646cd75bed54 | 64 | default: |
| wac | 0:646cd75bed54 | 65 | led1 = 0; led2 = 0; led3 = 0; led4 = 1; |
| wac | 0:646cd75bed54 | 66 | break; |
| wac | 0:646cd75bed54 | 67 | } // switch |
| wac | 0:646cd75bed54 | 68 | } |
| wac | 0:646cd75bed54 | 69 | |
| wac | 0:646cd75bed54 | 70 | // Read quadrature encoder, update counter variable, and update LEDs |
| wac | 0:646cd75bed54 | 71 | // Quadrature clockwise states: 00 -> 10 -> 11 -> 01 |
| wac | 0:646cd75bed54 | 72 | // Quadrature counter-clockwise states: 00 -> 01 -> 11 -> 10 |
| wac | 0:646cd75bed54 | 73 | void checkrisea() |
| wac | 0:646cd75bed54 | 74 | { |
| wac | 0:646cd75bed54 | 75 | debouncetimerrisea.stop(); |
| wac | 0:646cd75bed54 | 76 | debouncetimerrisea.reset(); |
| wac | 0:646cd75bed54 | 77 | debouncerisea.detach(); |
| wac | 0:646cd75bed54 | 78 | if (quada == 1 && quadb == 0) |
| wac | 0:646cd75bed54 | 79 | counter++; |
| wac | 0:646cd75bed54 | 80 | else if (quada == 1 && quadb == 1) |
| wac | 0:646cd75bed54 | 81 | counter--; |
| wac | 0:646cd75bed54 | 82 | display(); |
| wac | 0:646cd75bed54 | 83 | } |
| wac | 0:646cd75bed54 | 84 | |
| wac | 0:646cd75bed54 | 85 | void checkfalla() |
| wac | 0:646cd75bed54 | 86 | { |
| wac | 0:646cd75bed54 | 87 | debouncetimerfalla.stop(); |
| wac | 0:646cd75bed54 | 88 | debouncetimerfalla.reset(); |
| wac | 0:646cd75bed54 | 89 | debouncefalla.detach(); |
| wac | 0:646cd75bed54 | 90 | if (quada == 0 && quadb == 1) |
| wac | 0:646cd75bed54 | 91 | counter++; |
| wac | 0:646cd75bed54 | 92 | else if (quada == 0 && quadb == 0) |
| wac | 0:646cd75bed54 | 93 | counter--; |
| wac | 0:646cd75bed54 | 94 | display(); |
| wac | 0:646cd75bed54 | 95 | } |
| wac | 0:646cd75bed54 | 96 | |
| wac | 0:646cd75bed54 | 97 | void checkriseb() |
| wac | 0:646cd75bed54 | 98 | { |
| wac | 0:646cd75bed54 | 99 | debouncetimerriseb.stop(); |
| wac | 0:646cd75bed54 | 100 | debouncetimerriseb.reset(); |
| wac | 0:646cd75bed54 | 101 | if (quadb == 1 && quada == 1) |
| wac | 0:646cd75bed54 | 102 | counter++; |
| wac | 0:646cd75bed54 | 103 | else if (quadb == 1 && quada == 0) |
| wac | 0:646cd75bed54 | 104 | counter--; |
| wac | 0:646cd75bed54 | 105 | display(); |
| wac | 0:646cd75bed54 | 106 | } |
| wac | 0:646cd75bed54 | 107 | |
| wac | 0:646cd75bed54 | 108 | void checkfallb() |
| wac | 0:646cd75bed54 | 109 | { |
| wac | 0:646cd75bed54 | 110 | debouncetimerfallb.stop(); |
| wac | 0:646cd75bed54 | 111 | debouncetimerfallb.reset(); |
| wac | 0:646cd75bed54 | 112 | if (quadb == 0 && quada == 0) |
| wac | 0:646cd75bed54 | 113 | counter++; |
| wac | 0:646cd75bed54 | 114 | else if (quadb == 0 && quada == 1) |
| wac | 0:646cd75bed54 | 115 | counter--; |
| wac | 0:646cd75bed54 | 116 | display(); |
| wac | 0:646cd75bed54 | 117 | } |
| wac | 0:646cd75bed54 | 118 | |
| wac | 0:646cd75bed54 | 119 | // Start of edge-triggered interrupts |
| wac | 0:646cd75bed54 | 120 | void risea() |
| wac | 0:646cd75bed54 | 121 | { |
| wac | 0:646cd75bed54 | 122 | if (debouncetimerrisea.read_ms() == 0) |
| wac | 0:646cd75bed54 | 123 | { |
| wac | 0:646cd75bed54 | 124 | debouncetimerrisea.start(); |
| wac | 0:646cd75bed54 | 125 | debouncerisea.attach_us(&checkrisea, DEBOUNCETIME); // Check on switch later |
| wac | 0:646cd75bed54 | 126 | } |
| wac | 0:646cd75bed54 | 127 | } // risea() |
| wac | 0:646cd75bed54 | 128 | |
| wac | 0:646cd75bed54 | 129 | void falla() |
| wac | 0:646cd75bed54 | 130 | { |
| wac | 0:646cd75bed54 | 131 | if (debouncetimerfalla.read_ms() == 0) |
| wac | 0:646cd75bed54 | 132 | { |
| wac | 0:646cd75bed54 | 133 | debouncetimerfalla.start(); |
| wac | 0:646cd75bed54 | 134 | debouncefalla.attach_us(&checkfalla, DEBOUNCETIME); // Check on switch later |
| wac | 0:646cd75bed54 | 135 | } |
| wac | 0:646cd75bed54 | 136 | } // falla() |
| wac | 0:646cd75bed54 | 137 | |
| wac | 0:646cd75bed54 | 138 | void riseb() |
| wac | 0:646cd75bed54 | 139 | { |
| wac | 0:646cd75bed54 | 140 | if (debouncetimerriseb.read_ms() == 0) |
| wac | 0:646cd75bed54 | 141 | { |
| wac | 0:646cd75bed54 | 142 | debouncetimerriseb.start(); |
| wac | 0:646cd75bed54 | 143 | debounceriseb.attach_us(&checkriseb, DEBOUNCETIME); // Check on switch later |
| wac | 0:646cd75bed54 | 144 | } |
| wac | 0:646cd75bed54 | 145 | } // riseb() |
| wac | 0:646cd75bed54 | 146 | |
| wac | 0:646cd75bed54 | 147 | void fallb() |
| wac | 0:646cd75bed54 | 148 | { |
| wac | 0:646cd75bed54 | 149 | if (debouncetimerfallb.read_ms() == 0) |
| wac | 0:646cd75bed54 | 150 | { |
| wac | 0:646cd75bed54 | 151 | debouncetimerfallb.start(); |
| wac | 0:646cd75bed54 | 152 | debouncefallb.attach_us(&checkfallb, DEBOUNCETIME); // Check on switch later |
| wac | 0:646cd75bed54 | 153 | } |
| wac | 0:646cd75bed54 | 154 | } // fallb() |
| wac | 0:646cd75bed54 | 155 | |
| wac | 0:646cd75bed54 | 156 | int main() { |
| wac | 0:646cd75bed54 | 157 | quada.mode(PullUp); // Enable pullup |
| wac | 0:646cd75bed54 | 158 | quadb.mode(PullUp); // Enable pullup |
| wac | 0:646cd75bed54 | 159 | quadsw.mode(PullUp); // Enable pullup |
| wac | 0:646cd75bed54 | 160 | quada.rise(&risea); // Call function risea() on rising edge |
| wac | 0:646cd75bed54 | 161 | quada.fall(&falla); // Call function falla() on falling edge |
| wac | 0:646cd75bed54 | 162 | quadb.rise(&riseb); // Call function riseb() on rising edge |
| wac | 0:646cd75bed54 | 163 | quadb.fall(&fallb); // Call function fallb() on falling edge |
| wac | 0:646cd75bed54 | 164 | counter = 0; // Reset counter |
| wac | 0:646cd75bed54 | 165 | |
| wac | 0:646cd75bed54 | 166 | pc.baud(19200); |
| wac | 0:646cd75bed54 | 167 | pc.printf("\n\rConnected to mBed...\r\n"); |
| wac | 0:646cd75bed54 | 168 | |
| wac | 0:646cd75bed54 | 169 | debouncetimerrisea.stop(); |
| wac | 0:646cd75bed54 | 170 | debouncetimerrisea.reset(); |
| wac | 0:646cd75bed54 | 171 | debouncetimerfalla.stop(); |
| wac | 0:646cd75bed54 | 172 | debouncetimerfalla.reset(); |
| wac | 0:646cd75bed54 | 173 | debouncetimerriseb.stop(); |
| wac | 0:646cd75bed54 | 174 | debouncetimerriseb.reset(); |
| wac | 0:646cd75bed54 | 175 | debouncetimerfallb.stop(); |
| wac | 0:646cd75bed54 | 176 | debouncetimerfallb.reset(); |
| wac | 0:646cd75bed54 | 177 | |
| wac | 0:646cd75bed54 | 178 | // Set up interrupt call for serial port update |
| wac | 0:646cd75bed54 | 179 | //updateserial.attach_us(&serialout, 500000); // setup updateserial to call serialout every 500 ms |
| wac | 0:646cd75bed54 | 180 | |
| wac | 0:646cd75bed54 | 181 | while (1) |
| wac | 0:646cd75bed54 | 182 | { |
| wac | 0:646cd75bed54 | 183 | }// while (1) |
| wac | 0:646cd75bed54 | 184 | } // main() |