File content as of revision 2:261228f701a1:

/**
 * DebouncedIn class version 1.0
 * Created by Andres Moya Bedoya, updated by Ben Faucher
 */

#include "DebouncedIn.h"
#include "mbed.h"
 
/**
 * Constructor
 */
DebouncedIn::DebouncedIn(PinName in) 
    : _in(in) {    
        
    // Reset all the flags and counters    
    _samples = 0;
    _output = 0;
    _output_last = 0;
    _rising_flag = 0;
    _falling_flag = 0;
    _state_counter = 0;
    
    // Attach ticker
    _ticker.attach(this, &DebouncedIn::_sample, 0.005);     
}

DebouncedIn::DebouncedIn(PinName in, PinMode mode) 
    : _in(in, mode) {    
        
    // Reset all the flags and counters    
    _samples = 0;
    _output = 0;
    _output_last = 0;
    _rising_flag = 0;
    _falling_flag = 0;
    _state_counter = 0;
    
    // Attach ticker
    _ticker.attach(this, &DebouncedIn::_sample, 0.005);     
}

// Public member functions

/** Read the input state, represented as 0 or 1 (int)
 *
 *  @returns
 *    An integer representing the state of the input pin,
 *    0 for logical 0, 1 for logical 1. State changes when input 
 *    has been steady for at least 40ms (8 ticker cycles of 5ms).
 */
int DebouncedIn::read(void) {
    return(_output);
}
 
/** An operator shorthand for read()
 */
DebouncedIn::operator int() {
    return read();
}
 
// return number of rising edges
/** Rising edge count (int)
 *
 *  @returns
 *    An integer representing the number of times the switch has
 *    changed from low to high. Count resets to zero when this
 *    function is called.
 */
int DebouncedIn::rising(void) {
    int return_value = _rising_flag; 
    _rising_flag = 0;
    return(return_value);
}
 
// return number of falling edges
/** Falling edge count (int)
 *
 *  @returns
 *    An integer representing the number of times the switch has
 *    changed from high to low. Count resets to zero when this
 *    function is called.
 */
int DebouncedIn::falling(void) {
    int return_value = _falling_flag; 
    _falling_flag = 0;
    return(return_value);
}
 
// return number of ticks we've bene steady for
/** Steady state tick count (int)
 *
 *  @returns
 *    An integer representing how many ticker cycles the input has been
 *    steady for. Ticker cycles every 5ms.
 */
int DebouncedIn::steady(void) {
return(_state_counter);
}

// Private member functions
void DebouncedIn::_sample() {
 
    // take a sample
    _samples = _samples >> 1; // shift right 1 bit
      
    if (_in) {
        _samples |= 0x80;
    }  
      
    // examine the sample window, look for steady state
    if (_samples == 0x00) {
        _output = 0;
    } 
    else if (_samples == 0xFF) {
        _output = 1;
    }
 
 
    // Rising edge detection
    if ((_output == 1) && (_output_last == 0)) {
        _rising_flag++;
        _state_counter = 0;
    }
 
    // Falling edge detection
    else if ((_output == 0) && (_output_last == 1)) {
        _falling_flag++;
        _state_counter = 0;
    }
    
    // steady state
    else {
        _state_counter++;
    }
    
   // update the output
    _output_last = _output;
    
}