I am working on motor control using LQG/LTR method. I am using a 3rd party dsp board. this board to be specific " http://www.gaotek.com/index.php?main_page=product_info&cPath=118_17&products_id=86" .
I want to read encoder using this board. I have figured out how to use the qep_theta_drv subroutine in DMC library from TI. my question is regarding defining the qep defaults
#ifndef __F281X_QEP_H__
#define __F281X_QEP_H__
#include "f281xbmsk.h"
/*------------------------------------------------------------------------------
Initialization states for T2CON and CAPCON
------------------------------------------------------------------------------*/
#define QEP_CAP_INIT_STATE 0x9004
#define QEP_TIMER_INIT_STATE (FREE_RUN_FLAG + \
TIMER_DIR_UPDN + \
TIMER_CLK_PRESCALE_X_1 + \
TIMER_ENABLE_BY_OWN + \
TIMER_ENABLE + \
TIMER_CLOCK_SRC_QEP + \
TIMER_COMPARE_LD_ON_ZERO)
/*-----------------------------------------------------------------------------
Define the structure of the QEP (Quadrature Encoder) Driver Object
-----------------------------------------------------------------------------*/
typedef struct {int16 ElecTheta; // Output: Motor Electrical angle (Q15)
int16 MechTheta; // Output: Motor Mechanical Angle (Q15)
Uint16 DirectionQep; // Output: Motor rotation direction (Q0)
Uint16 QepCountIndex; // Variable: Encoder counter index (Q0)
Uint16 RawTheta; // Variable: Raw angle from Timer 2 (Q0)
Uint32 MechScaler; // Parameter: 0.9999/total count (Q30)
Uint16 LineEncoder; // Parameter: Number of line encoder (Q0)
Uint16 PolePairs; // Parameter: Number of pole pairs (Q0)
int16 CalibratedAngle; // Parameter: Raw angular offset between encoder index and phase a (Q0)
Uint16 IndexSyncFlag; // Output: Index sync status (Q0)
void (*init)(); // Pointer to the init function
void (*calc)(); // Pointer to the calc function
void (*isr)(); // Pointer to the isr function
} QEP;
/*-----------------------------------------------------------------------------
Define a QEP_handle
-----------------------------------------------------------------------------*/
typedef QEP *QEP_handle;
/*-----------------------------------------------------------------------------
Default initializer for the QEP Object.
-----------------------------------------------------------------------------*/
// Applied-motion PMSM motor: 24-v, 8-pole, 2000 line encoder, CalibratedAngle = -1250
// MechScaler = 1/8000 = 0x00020C4A (Q30)
// PacSci 1-hp PMSM motor: 320-v, 4-pole, 1000 line encoder, CalibratedAngle = -2365
// MechScaler = 1/4000 = 0x00041893 (Q30)
#define QEP_DEFAULTS { 0x0, 0x0,0x0,0x0,0x0,_IQ30(1/240),0x0,1,-1250,0x0, \
(void (*)(Uint32))F281X_EV1_QEP_Init, \
(void (*)(Uint32))F281X_EV1_QEP_Calc, \
(void (*)(Uint32))F281X_EV1_QEP_Isr }
/*-----------------------------------------------------------------------------
Prototypes for the functions in F281XQEP.C
-----------------------------------------------------------------------------*/
void F281X_EV1_QEP_Init(QEP_handle);
void F281X_EV1_QEP_Calc(QEP_handle);
void F281X_EV1_QEP_Isr(QEP_handle);
#endif // __F281X_QEP_H__
i have a 240 pulses per revolution encoder with A,B and Z outputs. How should i find the calibrated angle value for my particular application? I thought of connecting the encoder output A and Z to the oscilloscope and rotate the rotor with hand (after providing 5 v power supply to the encoder) and measure the number of pulses of A before the pulse of Z is visible on the oscilloscope. Since i have one pole pair motor i can find out the corresponding angle which i need to subtract or add by just converting the number of pulses into angular position. Is it the right way to do it? If there is any simpler method i am open for suggestions
Girish