example_freqcal.h

TI公司TMS320F2883x浮点DSP的详细应用例程

// TI File $Revision: /main/6 $
// Checkin $Date: August 9, 2007   17:14:59 $
//###########################################################################
//
// FILE:	Example_freqcal.h
//
// TITLE:	Frequency measurement using EQEP peripheral
//
// DESCRIPTION:
//
// Header file containing data type and object definitions and
// initializers.
//
//###########################################################################
// Original Author: SD
//
// $TI Release: DSP2833x Header Files V1.01 $
// $Release Date: September 26, 2007 $
//###########################################################################

#ifndef __FREQCAL__
#define __FREQCAL__

#include "IQmathLib.h"         // Include header for IQmath library
/*-----------------------------------------------------------------------------
Define the structure of the FREQCAL Object
-----------------------------------------------------------------------------*/
typedef struct {
                Uint32 freqScaler_pr;   // Parameter : Scaler converting 1/N cycles to a GLOBAL_Q freq (Q0) - independently with global Q
                Uint32 freqScaler_fr;   // Parameter : Scaler converting 1/N cycles to a GLOBAL_Q freq (Q0) - independently with global Q
                Uint32 BaseFreq;        // Parameter : Maximum Freq
                _iq freq_pr;            // Output :  Freq in per-unit using capture unit
				int32 freqhz_pr;        // Output: Freq in Hz, measured using Capture unit
                Uint32 oldpos;
                _iq freq_fr;            // Output : Freq in per-unit using position counter
                int32 freqhz_fr; 	    // Output: Freq in Hz, measured using Capture unit
                void (*init)();     	// Pointer to the init funcion
                void (*calc)();    		// Pointer to the calc funtion
                }  FREQCAL;

/*-----------------------------------------------------------------------------
Define a QEP_handle
-----------------------------------------------------------------------------*/
typedef FREQCAL *FREQCAL_handle;

/*-----------------------------------------------------------------------------
Default initializer for the FREQCAL Object.
-----------------------------------------------------------------------------*/


#if (CPU_FRQ_150MHZ)
  #define FREQCAL_DEFAULTS {\
		234,200,10000,0,0,\
		0,0,0,\
		(void (*)(long))FREQCAL_Init,\
        (void (*)(long))FREQCAL_Calc }
#endif
#if (CPU_FRQ_100MHZ)
  #define FREQCAL_DEFAULTS {\
		313,200,10000,0,0,\
		0,0,0,\
		(void (*)(long))FREQCAL_Init,\
        (void (*)(long))FREQCAL_Calc }
#endif

/*-----------------------------------------------------------------------------
Prototypes for the functions in Example_freqcal.c
-----------------------------------------------------------------------------*/
void FREQCAL_Init(void);
void FREQCAL_Calc(FREQCAL_handle);

#endif /*  __FREQCAL__ */

/* Notes:

For 150 MHz Operation:
----------------------
1. freqScaler_fr
   v = (x2-x1)/T                                                                - Equation 1

 If max/base freq = 10kHz:   10kHz = (x2-x1)/(2/100Hz)                           - Equation 2
                      max (x2-x1) = 200 counts = freqScaler_fr
		Note: T = 2/100Hz. 2 is from (x2-x1)/2 - because QPOSCNT counts 2 edges per cycle
		                                         (rising and falling)
   freqhz_fr = 200 default

2. min freq = 1 count/(2/100Hz) = 50 Hz

3. freqScaler_pr
   v = X/(t2-t1)                                                                - Equation 4

 If max/base freq = 10kHz:  10kHz = 8/(2T)
        where 4 = QCAPCTL [UPPS] (Unit timeout - once every 4 edges)
		 T = time in seconds = t2-t1/(150MHz/128),  t2-t1= # of QCAPCLK cycles, and
		                                           1 QCAPCLK cycle = 1/(150MHz/128)
												 = QCPRDLAT
		        So: 10 kHz = 4(150MHz/128)/2(t2-t1)
		             t2-t1 = 4(150MHz/128)/(10kHz*2) = (150MHz/128)/(2*10kHz/4)   - Equation 5
		                   = 234 seconds = maximum (t2-t1) = freqScaler_pr
   freqhz_pr = 234 default


For 100 MHz Operation:
----------------------

The same calculations as above are performed, but with 100 MHz
instead of 150MHz when calculation freqhr_pr, and at UPPS of 8 instead of 4.
The value for freqScaler_pr becomes: (100MHz/128)/(2*10kHz/8) = 313
More detailed calculation results can be found in the Example_freqcal.xls
spreadsheet included in the example folder.

*/