ProblemwithPWMfrequency

[sangaboy]

Hi every one
(1) Previous I thought that the problem of flat spot on my SPWM signal was due to the simulator(ISIS) but I was wrong because I implement it on the actual hardware using PIC16F877V1-V2 DEVELOPMENT BOARD board and DLIS40L oscilloscope but the problem still remain now I'm totally confused what cause that problem of flat spot to my wave form. I try to scale my look up table so that my dutycycle lie on the range of (0 to 4*199) but nothing was change to my signal
when viewed.
(2)ARE the ten bit look table is not working on 8bit chip like 16F877 0R 16F777 ? I think those values greater than 255 is one cause that problems

define OSC 4
Wsave var byte   $70system
Wsave1 var byte  $A0system
Wsave2 var byte  $120system
Wsave3 var byte  $1A0system
 
STEPCOUNT var byte
STEPCOUNT1 var byte
 
LED1   VAR  PORTB.1
 
STEPCOUNT = 0   'pointer for phase one in sinearray
STEPCOUNT1 = 12 'pointer for phase two  in sine array
ADCON0 = %00000000
ADCON1 = %00000000
 
TRISB = %11111101
TRISC = %11111001  'PMW output for CCP1 AND CCP2
TRISA = %11111111
TMR2 = 0
PR2 = 199 'generate 5khz  '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 word[36]
sineval[0] = 512   
sineval[1] = 556  
sineval[2] = 599
sineval[3] = 640
sineval[4] = 676
sineval[5] = 707
sineval[6] = 733
sineval[7] = 752
sineval[8] = 763
sineval[9] = 767 
sineval[10] =763
sineval[11] =752
sineval[12] =733  
sineval[13] =707
sineval[14] =676
sineval[15] =640
sineval[16] =599
sineval[17] =556
sineval[18] =512  
sineval[19] =468
sineval[20] =425
sineval[21] =385
sineval[22] =348
sineval[23] =317
sineval[24] =291
sineval[25] =272
sineval[26] =261
sineval[27] =257
sineval[28] =261
sineval[29] =272
sineval[30] = 291
sineval[31] = 317
sineval[32] = 348
sineval[33] = 385
sineval[34] = 425
sineval[35] = 468
 
timerone var word
Temp var byte
Temp1 var byte
INCLUDE "DT_INTS-14.bas"     ; Base Interrupt System          emp
INCLUDE "ReEnterPBP.bas"
 
ASM
 
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,   _sine,   PBP,  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 =  65080' gives1818hz nterruptfrequency or about 50 htz sine
Main:
       PAUSE 5
 
GOTO Main
 
'---[TMR1_INT - interrupt handler]------------------------------------------
 
sine:
     T1CON = 000000
 
    TMR1L = timerone.byte0 
    TMR1H = timerone.byte1
    T1CON = 000001         
   
   
    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 = Temp1.0 ' bit 0
    CCP2CON.5 = Temp1.1 ' bit 1      
    CCPR2L = Temp1 >>2  'Bit 2-7
    TOGGLE LED1
    stepcount =  stepcount +1
    stepcount1 =  stepcount1 +1
   
    if stepcount =36 then stepcount =0
    if stepcount1 =36 then stepcount1 =0
    
 
@    INT_RETURN

(3) I'm not clear on the WINPIC800V358 software parameter on the attachment.



Any one can help me to solve these problems
Thankx