Bhakti Kulkarni / HOMEWORK_6

Homework 6

Fork of mbed-rtos by mbed official

DebouncedIn.cpp@31:4309b1a91247, 2014-06-09 (annotated)

Committer:
bhakti08
Date:
Mon Jun 09 21:10:35 2014 +0000
Revision:
31:4309b1a91247
Homework 6

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bhakti08 31:4309b1a91247 1 #include "DebouncedIn.h"
bhakti08 31:4309b1a91247 2 #include "mbed.h"
bhakti08 31:4309b1a91247 3
bhakti08 31:4309b1a91247 4 /*
bhakti08 31:4309b1a91247 5 * Constructor
bhakti08 31:4309b1a91247 6 */
bhakti08 31:4309b1a91247 7 DebouncedIn::DebouncedIn(PinName in)
bhakti08 31:4309b1a91247 8 : _in(in) {
bhakti08 31:4309b1a91247 9
bhakti08 31:4309b1a91247 10 // reset all the flags and counters
bhakti08 31:4309b1a91247 11 _samples = 0;
bhakti08 31:4309b1a91247 12 _output = 0;
bhakti08 31:4309b1a91247 13 _output_last = 0;
bhakti08 31:4309b1a91247 14 _rising_flag = 0;
bhakti08 31:4309b1a91247 15 _falling_flag = 0;
bhakti08 31:4309b1a91247 16 _state_counter = 0;
bhakti08 31:4309b1a91247 17
bhakti08 31:4309b1a91247 18 // Attach ticker
bhakti08 31:4309b1a91247 19 _ticker.attach(this, &DebouncedIn::_sample, 0.005);
bhakti08 31:4309b1a91247 20 }
bhakti08 31:4309b1a91247 21
bhakti08 31:4309b1a91247 22 void DebouncedIn::_sample() {
bhakti08 31:4309b1a91247 23
bhakti08 31:4309b1a91247 24 // take a sample
bhakti08 31:4309b1a91247 25 _samples = _samples >> 1; // shift left
bhakti08 31:4309b1a91247 26
bhakti08 31:4309b1a91247 27 if (_in) {
bhakti08 31:4309b1a91247 28 _samples |= 0x80;
bhakti08 31:4309b1a91247 29 }
bhakti08 31:4309b1a91247 30
bhakti08 31:4309b1a91247 31 // examine the sample window, look for steady state
bhakti08 31:4309b1a91247 32 if (_samples == 0x00) {
bhakti08 31:4309b1a91247 33 _output = 0;
bhakti08 31:4309b1a91247 34 }
bhakti08 31:4309b1a91247 35 else if (_samples == 0xFF) {
bhakti08 31:4309b1a91247 36 _output = 1;
bhakti08 31:4309b1a91247 37 }
bhakti08 31:4309b1a91247 38
bhakti08 31:4309b1a91247 39
bhakti08 31:4309b1a91247 40 // Rising edge detection
bhakti08 31:4309b1a91247 41 if ((_output == 1) && (_output_last == 0)) {
bhakti08 31:4309b1a91247 42 _rising_flag++;
bhakti08 31:4309b1a91247 43 _state_counter = 0;
bhakti08 31:4309b1a91247 44 }
bhakti08 31:4309b1a91247 45
bhakti08 31:4309b1a91247 46 // Falling edge detection
bhakti08 31:4309b1a91247 47 else if ((_output == 0) && (_output_last == 1)) {
bhakti08 31:4309b1a91247 48 _falling_flag++;
bhakti08 31:4309b1a91247 49 _state_counter = 0;
bhakti08 31:4309b1a91247 50 }
bhakti08 31:4309b1a91247 51
bhakti08 31:4309b1a91247 52 // steady state
bhakti08 31:4309b1a91247 53 else {
bhakti08 31:4309b1a91247 54 _state_counter++;
bhakti08 31:4309b1a91247 55 }
bhakti08 31:4309b1a91247 56
bhakti08 31:4309b1a91247 57 // update the output
bhakti08 31:4309b1a91247 58 _output_last = _output;
bhakti08 31:4309b1a91247 59
bhakti08 31:4309b1a91247 60 }
bhakti08 31:4309b1a91247 61
bhakti08 31:4309b1a91247 62
bhakti08 31:4309b1a91247 63
bhakti08 31:4309b1a91247 64 // return number of rising edges
bhakti08 31:4309b1a91247 65 int DebouncedIn::rising(void) {
bhakti08 31:4309b1a91247 66 int return_value = _rising_flag;
bhakti08 31:4309b1a91247 67 _rising_flag = 0;
bhakti08 31:4309b1a91247 68 return(return_value);
bhakti08 31:4309b1a91247 69 }
bhakti08 31:4309b1a91247 70
bhakti08 31:4309b1a91247 71 // return number of falling edges
bhakti08 31:4309b1a91247 72 int DebouncedIn::falling(void) {
bhakti08 31:4309b1a91247 73 int return_value = _falling_flag;
bhakti08 31:4309b1a91247 74 _falling_flag = 0;
bhakti08 31:4309b1a91247 75 return(return_value);
bhakti08 31:4309b1a91247 76 }
bhakti08 31:4309b1a91247 77
bhakti08 31:4309b1a91247 78 // return number of ticsk we've bene steady for
bhakti08 31:4309b1a91247 79 int DebouncedIn::steady(void) {
bhakti08 31:4309b1a91247 80 return(_state_counter);
bhakti08 31:4309b1a91247 81 }
bhakti08 31:4309b1a91247 82
bhakti08 31:4309b1a91247 83 // return the debounced status
bhakti08 31:4309b1a91247 84 int DebouncedIn::read(void) {
bhakti08 31:4309b1a91247 85 return(_output);
bhakti08 31:4309b1a91247 86 }
bhakti08 31:4309b1a91247 87
bhakti08 31:4309b1a91247 88 // shorthand for read()
bhakti08 31:4309b1a91247 89 DebouncedIn::operator int() {
bhakti08 31:4309b1a91247 90 return read();
bhakti08 31:4309b1a91247 91 }
bhakti08 31:4309b1a91247 92
bhakti08 31:4309b1a91247 93