Bhakti Kulkarni / mbed-rtos

Working input data stream

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DebouncedIn.cpp@31:fc3f56da6b77, 2014-06-03 (annotated)

Committer:
bhakti08
Date:
Tue Jun 03 04:26:15 2014 +0000
Revision:
31:fc3f56da6b77
Input datastream

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bhakti08 31:fc3f56da6b77 1 #include "DebouncedIn.h"
bhakti08 31:fc3f56da6b77 2 #include "mbed.h"
bhakti08 31:fc3f56da6b77 3
bhakti08 31:fc3f56da6b77 4 /*
bhakti08 31:fc3f56da6b77 5 * Constructor
bhakti08 31:fc3f56da6b77 6 */
bhakti08 31:fc3f56da6b77 7 DebouncedIn::DebouncedIn(PinName in)
bhakti08 31:fc3f56da6b77 8 : _in(in) {
bhakti08 31:fc3f56da6b77 9
bhakti08 31:fc3f56da6b77 10 // reset all the flags and counters
bhakti08 31:fc3f56da6b77 11 _samples = 0;
bhakti08 31:fc3f56da6b77 12 _output = 0;
bhakti08 31:fc3f56da6b77 13 _output_last = 0;
bhakti08 31:fc3f56da6b77 14 _rising_flag = 0;
bhakti08 31:fc3f56da6b77 15 _falling_flag = 0;
bhakti08 31:fc3f56da6b77 16 _state_counter = 0;
bhakti08 31:fc3f56da6b77 17
bhakti08 31:fc3f56da6b77 18 // Attach ticker
bhakti08 31:fc3f56da6b77 19 _ticker.attach(this, &DebouncedIn::_sample, 0.005);
bhakti08 31:fc3f56da6b77 20 }
bhakti08 31:fc3f56da6b77 21
bhakti08 31:fc3f56da6b77 22 void DebouncedIn::_sample() {
bhakti08 31:fc3f56da6b77 23
bhakti08 31:fc3f56da6b77 24 // take a sample
bhakti08 31:fc3f56da6b77 25 _samples = _samples >> 1; // shift left
bhakti08 31:fc3f56da6b77 26
bhakti08 31:fc3f56da6b77 27 if (_in) {
bhakti08 31:fc3f56da6b77 28 _samples |= 0x80;
bhakti08 31:fc3f56da6b77 29 }
bhakti08 31:fc3f56da6b77 30
bhakti08 31:fc3f56da6b77 31 // examine the sample window, look for steady state
bhakti08 31:fc3f56da6b77 32 if (_samples == 0x00) {
bhakti08 31:fc3f56da6b77 33 _output = 0;
bhakti08 31:fc3f56da6b77 34 }
bhakti08 31:fc3f56da6b77 35 else if (_samples == 0xFF) {
bhakti08 31:fc3f56da6b77 36 _output = 1;
bhakti08 31:fc3f56da6b77 37 }
bhakti08 31:fc3f56da6b77 38
bhakti08 31:fc3f56da6b77 39
bhakti08 31:fc3f56da6b77 40 // Rising edge detection
bhakti08 31:fc3f56da6b77 41 if ((_output == 1) && (_output_last == 0)) {
bhakti08 31:fc3f56da6b77 42 _rising_flag++;
bhakti08 31:fc3f56da6b77 43 _state_counter = 0;
bhakti08 31:fc3f56da6b77 44 }
bhakti08 31:fc3f56da6b77 45
bhakti08 31:fc3f56da6b77 46 // Falling edge detection
bhakti08 31:fc3f56da6b77 47 else if ((_output == 0) && (_output_last == 1)) {
bhakti08 31:fc3f56da6b77 48 _falling_flag++;
bhakti08 31:fc3f56da6b77 49 _state_counter = 0;
bhakti08 31:fc3f56da6b77 50 }
bhakti08 31:fc3f56da6b77 51
bhakti08 31:fc3f56da6b77 52 // steady state
bhakti08 31:fc3f56da6b77 53 else {
bhakti08 31:fc3f56da6b77 54 _state_counter++;
bhakti08 31:fc3f56da6b77 55 }
bhakti08 31:fc3f56da6b77 56
bhakti08 31:fc3f56da6b77 57 // update the output
bhakti08 31:fc3f56da6b77 58 _output_last = _output;
bhakti08 31:fc3f56da6b77 59
bhakti08 31:fc3f56da6b77 60 }
bhakti08 31:fc3f56da6b77 61
bhakti08 31:fc3f56da6b77 62
bhakti08 31:fc3f56da6b77 63
bhakti08 31:fc3f56da6b77 64 // return number of rising edges
bhakti08 31:fc3f56da6b77 65 int DebouncedIn::rising(void) {
bhakti08 31:fc3f56da6b77 66 int return_value = _rising_flag;
bhakti08 31:fc3f56da6b77 67 _rising_flag = 0;
bhakti08 31:fc3f56da6b77 68 return(return_value);
bhakti08 31:fc3f56da6b77 69 }
bhakti08 31:fc3f56da6b77 70
bhakti08 31:fc3f56da6b77 71 // return number of falling edges
bhakti08 31:fc3f56da6b77 72 int DebouncedIn::falling(void) {
bhakti08 31:fc3f56da6b77 73 int return_value = _falling_flag;
bhakti08 31:fc3f56da6b77 74 _falling_flag = 0;
bhakti08 31:fc3f56da6b77 75 return(return_value);
bhakti08 31:fc3f56da6b77 76 }
bhakti08 31:fc3f56da6b77 77
bhakti08 31:fc3f56da6b77 78 // return number of ticsk we've bene steady for
bhakti08 31:fc3f56da6b77 79 int DebouncedIn::steady(void) {
bhakti08 31:fc3f56da6b77 80 return(_state_counter);
bhakti08 31:fc3f56da6b77 81 }
bhakti08 31:fc3f56da6b77 82
bhakti08 31:fc3f56da6b77 83 // return the debounced status
bhakti08 31:fc3f56da6b77 84 int DebouncedIn::read(void) {
bhakti08 31:fc3f56da6b77 85 return(_output);
bhakti08 31:fc3f56da6b77 86 }
bhakti08 31:fc3f56da6b77 87
bhakti08 31:fc3f56da6b77 88 // shorthand for read()
bhakti08 31:fc3f56da6b77 89 DebouncedIn::operator int() {
bhakti08 31:fc3f56da6b77 90 return read();
bhakti08 31:fc3f56da6b77 91 }
bhakti08 31:fc3f56da6b77 92
bhakti08 31:fc3f56da6b77 93