sinusoidal PWM

[sangaboy]

Hi HenrikOlsson
thankx for your coments and Idea you gave me on the code I posted last time which make my output to be some how clear. But is not quiet clear. here are some challenges I faced again

(1) The ouput does not apper smoth. I tttach the output as seen from ISIS and code.

STEPCOUNT var byte
STEPCOUNT1 var byte

STEPCOUNT = 0   'pointer for phase one in sinearray
STEPCOUNT1 = 12 'pointer for phase two  in sine array
ADCON0 = %00000000
ADCON1 = %00000000

TRISB = %11111001
TRISC = %11111001  'PMW output for CCP1 AND CCP2
TRISA = %11111111
TMR2 = 117
PR2 = 55   'set for 18Khz HPWM
CCP1CON = %00001100 'set CCP1 for PWM OPERATION
CCP2CON = %00001100 'set CCP2 for PWM OPERATION
T2CON = %00000100  'TIMER2ON and prescale of 1:1 

sineval var byte[36]
sineval[0] = 128   
sineval[1] = 150   
sineval[2] = 171
sineval[3] = 191
sineval[4] = 209
sineval[5] = 225
sineval[6] = 238
sineval[7] = 247
sineval[8] = 253
sineval[9] = 255  
sineval[10] = 253
sineval[11] = 247
sineval[12] = 238   
sineval[13] = 225
sineval[14] = 209
sineval[15] = 191
sineval[16] = 171
sineval[17] = 150
sineval[18] = 128   
sineval[19] = 105
sineval[20] = 84
sineval[21] = 64
sineval[22] = 46
sineval[23] = 30
sineval[24] = 17
sineval[25] = 8
sineval[26] = 2
sineval[27] = 0
sineval[28] = 2
sineval[29] = 8
sineval[30] = 17
sineval[31] = 30
sineval[32] = 46
sineval[33] = 64
sineval[34] = 84
sineval[35] = 105
 
 timerone var word 
Temp var byte
Temp1 var byte
INCLUDE "DT_INTS-14.bas"     ; Base Interrupt System          emp
 
 
ASM
 
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,   _sine,   ASM,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
 
T1CON = 000001                 ; Prescaler = 1;1, TMR1 ON
@   INT_ENABLE  TMR1_INT     ; Enable Timer 1 Interrupts 

 
timerone = 64980   ;gives about 50 htz sine 
Main:  

PAUSE 5
 GOTO Main
 
'---[TMR1_INT - interrupt handler]------------------------------------------

sine:
     T1CON = 000000 'stop the timer

    TMR1L = timerone.byte0 'reload the timer
    TMR1H = timerone.byte1
    
    
    T1CON = 000001         'start the timer
     
    TeMP = sineval[STEPCOUNT]
    CCP1CON.4 = Temp.0 ' bit 0
    CCP1CON.5 = Temp.1 ' bit 1       
    CCPR1L = Temp >>2  'Bit 2-7 
    
    TeMP1 = sineval[STEPCOUNT1]
    CCP2CON.4 = Temp.0 ' bit 0
    CCP2CON.5 = Temp.1 ' bit 1       
    CCPR2L = Temp >>2  'Bit 2-7 
    stepcount =  stepcount +1
    stepcount1 =  stepcount1 +1    
    if stepcount = 36 then stepcount =0
    if stepcount1 = 36 then stepcount1 =12   
 
@    INT_RETURN

(2) I try to write a code so that I can measure if the interrupt frequence is 1800hz.
When I start learning timer in the previous days I passed I cross the link http://www.microcontrollerboard.com/...-tutorial.html there is formural for calcalating a numeric value(count) to be placed to obtain the desired output frequency.
count=fclk/(4*prescale*(65536-TMR1)*fout

where for me
fout=1800hz, prescale 1, TMRI=64980 and fclk=4MHz

gives count = 1 ohh! here I'm confusing how should I proceed since is very small count I cant use it.

can you help which count should I use so I can measure my interrupt frequecy
thankx