pwm ile sin oluşturma

[tuzluerik]

ürettiğim sinüs dalganın 1 periyodunun yarısı var yarısı yok sorun nerde olabilir
Ürettiğim sinüs dalganın 1 periyotunun yarısı var yarısı yok sorun nerede olabilir?

#include <16F877A.h>
#fuses HS,NOWDT,PROTECT,NOLVP    // if fuses WDT, program will reset every 2034ms
#use delay(clock=20000000)
#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7)  //
 
// the following sin data gotten according to the formula : Int((PR2+1)*sin(3.14159265*N/50)+0.5) in attahed excel file
// which named "sine data points.xls"
BYTE const SPWM_DATA[25]=
{16,31,47,62,77,92,106,120,134,147,159,171,182,193,202,211,219,226,232,238,242,246,248,250,250};
 
int8 period = 249;
int8 postscale = 4;
 
 
int16 duty;             // duty for CCPx. it will be changed in Interrupt function. no need to be inintialized
                        
 
int8 array_index = 0;   // Index for adjust wave - no beautiful but power
int8 sin_case = 0;      // sin_case=0 -- the first 1/4 period
                        // sin_case=1 -- the second 1/4 period
                        // sin_case=2 -- the third 1/4 period
                        // sin_case=3 -- the last 1/4 period
 
#INT_TIMER2    // This function is called every time the RTCC (timer2) overflows (255->0).
 
void clock2_isr() {
 
   // for 60hz ac signals
      switch (sin_case)
      {
         // double signal
 
         case 0:  // for the first period - 1/4 period
 
                 duty =SPWM_DATA[array_index];
                 set_pwm1_duty(duty<<2);        // (duty<<2) is the same as 4*duty, but it operates more fast.
                 set_pwm2_duty(0);
                 array_index++;
                 if(array_index==25)
                 {
                     array_index = 24;
                     sin_case = 1;
                 }
                 break;
 
         case 1:  // for the second period - 2/4 period
 
                 duty = SPWM_DATA[array_index];
                 set_pwm1_duty(duty<<2);
                 set_pwm2_duty(0);
                 if(array_index==0) sin_case = 2;
                 else array_index--;
                 break;
                 
         case 2:  // for the third period - 3/4 period
 
                 duty =  SPWM_DATA[array_index];
                 set_pwm2_duty(duty<<2);
                 set_pwm1_duty(0);
                 array_index++;
                 if(array_index==25)
                 {
                     array_index = 24;
                     sin_case = 3;
                 }
                 break;
 
            case 3:   // for the fourth period - 4/4 period
 
                 duty = SPWM_DATA[array_index];
                 set_pwm2_duty(duty<<2);
                 set_pwm1_duty(0);
                 if(array_index==0) sin_case = 0;
                 else array_index--;
                 break;
      }
}
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
void main()
{
 
   setup_ccp1(CCP_PWM);   // Configure CCP1 as a PWM
   setup_ccp2(CCP_PWM);   // Configure CCP2 as a PWM
 
   //***************************************************************************
 
   setup_timer_2(T2_DIV_BY_1, period, postscale);  //  Setup Timer2 interrupt
 
   enable_interrupts(INT_TIMER2);                  //  Enables the interrupt Timer2.
 
   enable_interrupts(global);                      // enabled all interruptions.
   //***************************************************************************
 
   while(TRUE)
   {
 
   }
 
}