sinusoidal PWM

[ScaleRobotics]

I don't see any kind of wave form on the scope???

[bwaxing]

sure,it is just a line and not a sine wave form as expected....the simulation log say there are attempts to read unimplemented memory locations being ignored..i dont know what does that mean and if it may be one of the cause...i need help.

[walter]

Maybe it is complaining that you have set your array to:
sineval var byte[72]

and then you go from 1 to 72.

You either need to change it to 0 to 71, or change your array size to 73

[bwaxing]

i have changed the number of array size together with other modifications but there is no change in the simulation result,it is still a line....

define OSC 20
 
;*****************VARIABLE DECLARATION******************************************
wsave   VAR BYTE    $70     SYSTEM      ' alternate save location for W 
wsave1  VAR BYTE    $A0     SYSTEM      ' location for W if in bank1
wsave2  VAR BYTE    $120    SYSTEM      ' location for W if in bank2
wsave3  VAR BYTE    $1A0    SYSTEM      ' location for W if in bank3
STEPCOUNT var byte                      'Define stepcount as byte type variable
stepcount = 256
 
;**************SETTING THE REGISTERS WITH APPROPIATE BIT DEFINITION************* 
ADCON0 = %00000000
ADCON1 = %00000000  ;all anolog output
trisb = %11111111   ;define porta as input
trisc = %11111011   ;make ccp1/portc.2 an output pin
trisa = %11111111   ;define porta as input
TMR2 = 16
PR2 = 34           ;set for 36Khz HPWM(=72 steps*10 times*50hz)        
CCP1CON = %000001100       ;set to pwm mode
T2CON=%00000110           ;enable timer2 and set timer2 prescaler value of 1:4
 
;****************A sine lookup table in an array********************************
sineval var byte[73]
sineval[1] = 128      ;0 degree
sineval[2] = 137      ;5 degree
sineval[3] = 146
sineval[4] = 154
sineval[5] = 163
sineval[6] = 171
sineval[7] = 179
sineval[8] = 187
sineval[9] = 194
sineval[10] = 200
sineval[11] = 206
sineval[12] = 212
sineval[13] = 216
sineval[14] = 220
sineval[15] = 224
sineval[16] = 227
sineval[17] = 228
sineval[18] = 229
sineval[19] = 230     ;90 degree
sineval[20] = 229
sineval[21] = 228
sineval[22] = 227
sineval[23] = 224
sineval[24] = 220
sineval[25] = 216
sineval[26] = 212
sineval[27] = 206
sineval[28] = 200
sineval[29] = 194
sineval[30] = 187
sineval[31] = 179
sineval[32] = 171
sineval[33] = 163
sineval[34] = 154
sineval[35] = 146
sineval[36] = 137
sineval[37] = 128  ;180 degree
sineval[38] = 119
sineval[39] = 110
sineval[40] = 102
sineval[41] = 93
sineval[42] = 85
sineval[43] = 77
sineval[44] = 69
sineval[45] = 62
sineval[46] = 56
sineval[47] = 50
sineval[48] = 44
sineval[49] = 40
sineval[50] = 36
sineval[51] = 32
sineval[52] = 29
sineval[53] = 28
sineval[54] = 26
sineval[55] = 26
sineval[56] = 26
sineval[57] = 28
sineval[58] = 29
sineval[59] = 32
sineval[60] = 36
sineval[61] = 40
sineval[62] = 44
sineval[63] = 50
sineval[64] = 56
sineval[65] = 62
sineval[66] = 69
sineval[67] = 77
sineval[68] = 85
sineval[69] = 93
sineval[70] = 102
sineval[71] = 110
sineval[72] =119
 
timerone var word 
 
INCLUDE "DT_INTS-14.bas"     ; Base Interrupt System
 
;********Define INT_Handler as ISR********************************************** 
ASM
 
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,   _sine,   ASM,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
 
T1CON = $31    ; Prescaler = 8, TMR1ON          
TMR1L = 255    
TMR1H = 254
@   INT_ENABLE  TMR1_INT     ; Enable Timer 1 Interrupts  
timerone = $EE16           ;gives about 50 hz sine 
Main:
        pause 5
        'if timerone = $F9FF then timerone = $FF00
 
GOTO Main
 
'---[TMR1_INT - interrupt handler]------------------------------------------
 
sine:
    TMR1L = timerone.byte0
    TMR1H = timerone.byte1     
    CCPR1L = sineval[STEPCOUNT]>>1 
    stepcount = stepcount -1
    if stepcount = 1 then stepcount = 73
@    INT_RETURN

[cncmachineguy]

First thing I would do is make sure the ISR is working. Make an unused pin an output, then toggle it in the ISR. hook a scope to that and make sure it toggles. Also you can do the same in your main with another pin.

This way you will know some basic info like is my pic running, is my interrupt firing. do that and report back

[bwaxing]

hi,
i've managed to get the sinusoidal output sine wave although i'm getting frequency of 202Hz instead of 50Hz and peak voltage of 4.58v instead of 4.5v.Also the waveform is not smooth.Simulation results.docWhat should i do to acheave this parameters?
code:

define OSC 4
;*****************VARIABLE DECLARATION******************************************
wsave   VAR BYTE    $70     SYSTEM      ' alternate save location for W 
wsave1  VAR BYTE    $A0     SYSTEM      ' location for W if in bank1
wsave2  VAR BYTE    $120    SYSTEM      ' location for W if in bank2
wsave3  VAR BYTE    $1A0    SYSTEM      ' location for W if in bank3 
ADCON0 = %00000000
ADCON1 = %00000000
trisb = %11111111
trisc = %11111011
trisa = %11111111
TMR2 = 16
PR2 = 15      ;set for 16Khz HPWM        
CCP1CON.3 = 1        ' set to pwm mode
CCP1CON.2 = 1
T2CON.2=1
T2CON.0=1
STEPCOUNT var byte
stepcount = 32
; Set sine "table" in an array
sineval var byte[32]
sineval[1] = 128
sineval[2] = 148
sineval[3] = 167
sineval[4] = 185
sineval[5] = 200
sineval[6] = 213
sineval[7] = 222
sineval[8] = 228
sineval[9] = 230
sineval[10] = 228
sineval[11] = 222
sineval[12] = 213
sineval[13] = 200
sineval[14] = 185
sineval[15] = 167
sineval[16] = 148
sineval[17] = 128
sineval[18] = 108
sineval[19] = 89
sineval[20] = 71
sineval[21] = 56
sineval[22] = 43
sineval[23] = 34
sineval[24] = 28
sineval[25] = 26
sineval[26] = 28
sineval[27] = 34
sineval[28] = 43
sineval[29] = 56
sineval[30] = 71
sineval[31] = 89
sineval[32] = 108
 
 
timerone var word 
 
INCLUDE "DT_INTS-14.bas"     ; Base Interrupt System
;include "ReEnterPBP-18.bas"  ;not needed for ASM type interrupt service routines
 
ASM
 
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,   _sine,   ASM,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM
 
T1CON = $31                 ; Prescaler = 8, TMR1ON
TMR1L = 255
TMR1H = 254
@   INT_ENABLE  TMR1_INT     ; Enable Timer 1 Interrupts  
timerone = 65504               ;gives about 50 htz sine 
Main:
        pause 5
        'timerone = timerone - 1      'uncomment to vary 60hz sine
        if timerone = $F9FF then timerone = $FF00
 
GOTO Main
 
'---[TMR1_INT - interrupt handler]------------------------------------------
 
sine:
    TMR1L = timerone.byte0
    TMR1H = timerone.byte1     
    CCPR1L = sineval[STEPCOUNT]>>1 
    stepcount = stepcount -1
    if stepcount = 0 then stepcount = 32
 
@    INT_RETURN

[HenrikOlsson]

Hi,
You're still off on the array.

Sinval VAR BYTE[32]

This creates an array of 32 elements numbered 0-31 but you assign values to it starting at 1 and ending at 32 - not very good. There is no SineVal[32], when you read/write to that variable you're actually accessing the "next" RAM location, something I'm sure you don't want to do here.

You can adjust the peak value by "scaling" the value in your sine-table but really, you're not even 2% off target.

Are you using a 4MHz x-tal like the code says or are you using something else?

If I'm not mistaken a reload value of 65505 with a prescaler of 1:8 running at 4Mhz gives an interrupt frequency of 4032Hz, you have 32 "steps" to your cycle so you "should" get around 126Hz....

For accuracy it's usually better to stop the timer and then ADD the preload value to the timers current value since this will take into account the interrupt latency etc. Stop it, copy it to a WORD, add the reload value, copy it back and restart the timer.

Any specific reason you're using a TMR1 prescaler of 8? Using a lower prescaler ratio will give you better "resolution" on the interrupt frequency.

/Henrik.