Hello Eric.

Try the following... (MPASM assembler)

        MOVFW   ADRES
        SUBWF   V,W
        DECF    D,W
        SKPNC
        INCF    D,W
        MOVWF   D
        MOVWF   CCPR1L

WBR Dmitry.


> I was wondering if some one could help me in figuring out how to compare two
> numbers and either add one or subtract one on the pic16c72.
>
> In the varable V there is a constant 100
> The ADC is read in to W and V needs to be compared with the value
> In the varable D is stored the result of the system, initilized to 100, this
> is either added to or subtracted to.
>
> I have tried this but it all it does is give me 50% duty cycle out.
>
>             MOVF    ADRES,W        ; Get A/D value
>            SUBWF V,W                     ; Test it
>             SKPNC                           ; Positive?
>             GOTO POS                     ; Yes goto add
>             MOVLW 0x01                 ; No setup for subtract
>             SUBWF     D,W                ; Subtract one
>             GOTO CONT                    ; go to continue
>
> POS     MOVF    D,W                    ;setup for add
>             ADDLW    0x01
>
> CONT     MOVWF     D                     ; stores new result back into D for
> next loop
>                 MOVWF     CCPR1L         ; to PWM register channel 1