DebounceIn.h

00001 #ifndef DEBOUNCEIN_H
00002 #define DEBOUNCEIN_H
00003 #include "mbed.h"
00004 
00005 class DebounceIn : public DigitalIn {
00006     public:
00007     
00008         /** set_debounce_us
00009          *
00010          * Sets the debounce sample period time in microseconds, default is 1000 (1ms)
00011          *
00012          * @param int i The debounce sample period time to set.
00013          */        
00014         void set_debounce_us(int i) { _ticker.attach_us(this, &DebounceIn::_callback, i); }
00015         
00016         /** set_samples
00017          *
00018          * Defines the number of samples before switching the shadow 
00019          * definition of the pin. 
00020          *
00021          * @param int i The number of samples.
00022          */        
00023         void set_samples(int i) { _samples = i; }
00024         
00025         /** read
00026          *
00027          * Read the value of the debounced pin.
00028          */
00029         int read(void) { return _shadow; }
00030         
00031 #ifdef MBED_OPERATORS
00032         /** operator int()
00033          *
00034          * Read the value of the debounced pin.
00035          */
00036         operator int() { return read(); }
00037 #endif  
00038  
00039         /** Constructor
00040          * 
00041          * @param PinName pin The pin to assign as an input.
00042          */
00043         DebounceIn(PinName pin) : DigitalIn(pin) { _counter = 0; _samples = 10; set_debounce_us(1000); };
00044         
00045     protected:
00046         void _callback(void) { 
00047             if (DigitalIn::read()) { 
00048                 if (_counter < _samples) _counter++; 
00049                 if (_counter == _samples) _shadow = 1; 
00050             }
00051             else { 
00052                 if (_counter > 0) _counter--; 
00053                 if (_counter == 0) _shadow = 0; 
00054             }
00055         }
00056         
00057         Ticker _ticker;
00058         int    _shadow;
00059         int    _counter;
00060         int    _samples;
00061 };
00062 #endif