Thanks Andrew,
I have solved the problem in the same time when I have asked the question

You know what a good teacher said:
 "I have explained the problem to my students once, then twice and they
don't understood, third time almost I have understood the problem but they
still don't understood...What should I do with them ?"

I have do it almost in the same fashion like you say here... but I was
using 6 fixed time point comparations with the flowing seconds.
Thanks for the tip.
Vasile


On Tue, 2 Apr 2002, Andrew Warren wrote:

> Vasile Surducan <PICLIST@mitvma.mit.edu> wrote:
>
> > I need a finest resolution so every time the minimum period will be 10
> > seconds and no more, for 10 minutes and 10% I need to do 60 times 1
> > second on and 9 secons off.
>
>     Ah, ok... NOW I understand.  I, too, was puzzled when I saw that
>     question coming from you.
>
>     Something like this should work; it is -- as so many things are --
>  a
>     variation on the Bresenham line-drawing algorithm:
>
>     ; Enter with duty-cycle (0-100) in DUTY.  This routine uses a
>     ; register called SWITCH which must not change between calls
>     ; to the routine.  Note that I'm assuming RADIX=DEC.
>
>     TIMER_INTERRUPT:
>
>         TSTF    DUTY
>         BNZ     TESTSW
>
>         MOVLW   -1
>         MOVWF   SWITCH
>
>     TESTSW:
>
>         BTFSS   SWITCH,7
>         GOTO    TURNON
>
>         BCF     OUTPUT_PIN
>         GOTO    FINISH
>
>     TURNON:
>
>         BSF     OUTPUT_PIN
>
>         MOVLW   100
>         SUBWF   SWITCH
>
>     FINISH:
>
>         MOVF    DUTY,W
>         ADDWF   SWITCH
>
>     This will ALWAYS produce the minimum PWM period necessary for a
>     particular duty-cycle.  In other words, DUTY=50 will result in
>
>         ON-OFF
>         ON-OFF
>         etc.
>
>     and DUTY=10 will result in
>
>         ON-OFF-OFF-OFF-OFF-OFF-OFF-OFF-OFF-OFF
>         ON-OFF-OFF-OFF-OFF-OFF-OFF-OFF-OFF-OFF
>         etc.
>
>     -Andy
>
> === Andrew Warren - aiw@cypress.com
> ===
> === Principal Design Engineer
> === Cypress Semiconductor Corporation
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
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