IncrementalEncoder.h

00001 #ifndef __INCREMENTALENCODER_H
00002 #define __INCREMENTALENCODER_H
00003 
00004 #include "mbed.h"
00005 
00006 /** An interface for a simple, 1-track, incremental encoder. If using a simple reflectance sensor, then a voltage comparator
00007  *  circuit will be required to generate the pulsetrain.  See: http://www.bot-thoughts.com/2011/03/avc-bot-wheel-encoders.html
00008  *
00009  */
00010 class IncrementalEncoder
00011 {
00012     public:
00013         /** Create an incremental encoder interface.  Increments counter at every rise and fall signal 
00014          *
00015          * @param pin -- the pin to which a digital pulsetrain is sent
00016          */
00017         IncrementalEncoder(PinName pin);
00018 
00019         /** Get ticks since last call
00020          *
00021          * @returns the number of ticks since the last call to this method
00022          */        
00023         unsigned int read();
00024 
00025         /** Get total tick count since last reset
00026          *
00027          * @returns total ticks since the last reset or instantiation
00028          */
00029         unsigned int readTotal();
00030        
00031         /** Get total rise tick count
00032          *
00033          * @returns total rise ticks
00034          */
00035         unsigned int readRise();
00036 
00037         /** Get total fall tick count
00038          *
00039          * @returns total fall ticks
00040          */
00041         unsigned int readFall();
00042 
00043         /** Read time interval between ticks
00044          *
00045          * @returns filtered time between encoder pulses
00046          */
00047         unsigned int readTime();
00048        
00049         /** Reset the tick counter
00050          *
00051          */
00052         void reset();
00053 
00054     private:
00055         Timer _t;
00056         unsigned int _lastTime;
00057         unsigned int _time;
00058         unsigned int _lastTicks;
00059         unsigned int _ticks, _rise, _fall;
00060         bool _new;
00061         InterruptIn _interrupt;
00062         void _increment();
00063         void _incRise();
00064         void _incFall();
00065 };
00066 
00067 #endif