Diff: QEIx4.h

Revision:

0:46b8d5680f66

Child:

1:ac6b7b1bf6c5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/QEIx4.h	Tue Sep 02 18:23:36 2014 +0000
@@ -0,0 +1,170 @@
+/* 
+* @author Jochen Krapf
+*
+* @section LICENSE
+*
+* Copyright (c) 2012 Jochen Krapf, MIT License
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+* and associated documentation files (the "Software"), to deal in the Software without restriction,
+* including without limitation the rights to use, copy, modify, merge, publish, distribute,
+* sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all copies or
+* substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*
+* @section DESCRIPTION
+* mbed QEI (quadrature encoder interface) library, for decoding AB signals from a rotary encoder 
+*
+* Use cases:
+* - Rotary encoder in closed loop motor regulation
+* - Hand wheel
+* - Input device for motion control (MoCo)
+*/
+
+#include "mbed.h"
+
+
+/** Quadrature encoder interface. A class to decode pulses on a AB rotary encoder. It uses all 4 edges on AB signals to increase resolution 4 times.
+*
+* In opposite to commen QEI implementation this is resistent to jitter on AB signals and motor vibration. When using interrupts only the needed edge and pin is activated to prevent jamming CPU time with interrups. 
+*
+* It can also be used in polling mode i.g. in idle routines.
+*
+* Example:
+*
+* @code
+#include "mbed.h"
+#include "QEIx4.h"
+
+DigitalOut myled(LED1);
+Timer t;
+
+// ports for nxp LPC 1768
+QEIx4 qei1(p30, p29, p28);          // QEI with index signal for zeroing
+QEIx4 qei2(p27, p26, NC);           // QEI only with AB signals
+QEIx4 qei3(p25, p24, NC, false);    // QEI without interrups for polling mode
+
+int main() {
+    t.start();
+
+    qei1.SetZeroOnIndex(true);      // Set the flag to zero counter on next index signal rises
+
+    while(1) 
+    {
+        qei3.poll();   // poll manually without interrupt - sampling in this loop with about 2kHz
+        
+        if ( t.read_ms() > 500 )   // every half second
+        {
+            t.reset();
+            t.start();
+            myled = !myled;
+            
+            printf ( "\r\n%6d %6d %6d", (int)qei1, (int)qei2, (int)qei3 );   // print counter values
+        }
+
+    wait_us(500);   // for about 2kHz
+    }
+}
+* @endcode
+*/
+class QEIx4 {
+public:
+
+    /** constructor of QEIx4 object
+    *
+    * @param pinA     Pin number of input/interrupt pin for encoder line A. All port pins are possible except p19 and p20
+    * @param pinB     Pin number of input/interrupt pin for encoder line B. All port pins are possible except p19 and p20
+    * @param pinI     Pin number of input pin for optional encoder index or reference switch.
+    * @param bUseIRQ  Flag to use interrups to detect changes on line A and B. If FALSE the function poll() has to be called frequently
+    */
+    QEIx4 ( PinName pinA, PinName pinB, PinName pinI=NC, bool bUseIRQ=true );
+    
+    /** destructor of QEIx4 object
+    */
+    ~QEIx4();
+
+    /** Gets the actual counter value.
+    *
+    * @return        Actual counter value
+    */
+    int read()
+        { return _counter; }
+
+    /** Gets the actual counter value as int operator.
+    *
+    * @return        Actual counter value as int operator
+    */
+    operator int ()     // int-Operator
+        { return _counter; }
+        
+    /** Sets the counter value at actual encoder position to given value.
+    *
+    * @param        Counter value
+    */
+    void write ( int counter )
+        { _counter = counter; }
+        
+    /** Sets the counter value at actual encoder position to given value as assign operator.
+    *
+    * @param        Counter value
+    */
+    int operator= ( int counter )     // Assign-Operator
+        { write(counter); return counter; }
+    
+    /** Polls the state machine manually and updates the counter value.
+    */
+    void poll ()
+        { ProcessISR(); }
+    
+    /** Gets the actual counter value as float value. A value of 1.0 is one rotation
+    *
+    * @return        Actual encoder position as float
+    */
+    float GetPosition ()
+        { return (float)_counter / (_cpr*4.0); }
+        
+    /** Sets the number of cycles per rotation (CPR) for function GetPosition().
+    *
+    * @param        Cycles per rotation for a full rotation
+    */
+    void SetCPR ( int cpr )
+        { _cpr = cpr; }
+        
+    /** Sets the flag for zeroing on next high on index pin while AB lines triggers next counting. The trigger forces the counter set to zero
+    *
+    * @param        Flag for triggering. Is reset on next zeroing
+    */
+     void SetZeroOnIndex ( bool bZeroOnIndex )
+        { _bZeroOnIndex = bZeroOnIndex; }
+
+        
+    /** Callback in derived classes to act on counter change
+    */
+    virtual void CounterChange ( void ) {};
+
+    /** Callback in derived classes to act on zeroing trigger
+    */
+    virtual void CounterZero ( void ) {};
+    
+protected:
+    InterruptIn _pinA, _pinB;
+    DigitalIn _pinI;
+    int _counter;
+    short _mode;
+    int _cpr;
+    bool _bUseIRQ;
+    bool _bZeroOnIndex;
+    
+    void ProcessISR ( void );
+
+private:    
+    static short _modeLUT[16];
+};
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