RotaryEncode.cpp

00001 /*
00002 RotaryEncode
00003 (c) 2009, cstyles
00004 */
00005 
00006 #include "RotaryEncode.h"
00007 #include "mbed.h"
00008 
00009 /*
00010  Constructor, pin names for I2C and the I2C addrss of the device
00011  */
00012 
00013 
00014 RotaryEncode::RotaryEncode(PinName A, PinName B) 
00015   : _rotary_in(A,B) {    
00016 
00017     _position = 0;
00018     
00019     // Attach ticker
00020     _ticker.attach(this, &RotaryEncode::_ticker_handler, 0.010);       
00021 }
00022 
00023 
00024 
00025 int RotaryEncode::read(void) {
00026    int rval = _position;
00027    _position = 0;
00028    return (rval);
00029 }
00030 
00031 
00032 
00033 
00034 void RotaryEncode::_ticker_handler(void) {
00035 
00036     _state = _rotary_in;
00037     _e = R_W;
00038 
00039     // we're in the no-change state
00040     if (_state == 0x03) {
00041         return;
00042     }
00043 
00044     while (_state != 0x03) {
00045     switch (_e) {
00046         case R_W:
00047             if (_state == 0x02)
00048                 _e = R_R1;
00049             else if (_state == 0x01)
00050                 _e = R_L1;
00051             break;
00052 
00053         case R_L1:
00054             if (_state == 0x00)
00055                 _e = R_R2;
00056             break;
00057         case R_L2:
00058             if (_state == 0x01) {
00059                 _e = R_R3;
00060                 _position++;
00061             }
00062             break;
00063         case R_R1:
00064             if (_state == 0x00)
00065                 _e = R_L2;
00066             break;
00067         case R_R2:
00068             if (_state == 0x02) {
00069                 _e = R_L3;
00070                 _position--;
00071             }
00072             break;
00073         }
00074     _state = _rotary_in;
00075     }
00076     
00077 }
00078 
00079 
00080 
00081