> On Fri, 30 Nov 2001, Attila Lorincz wrote:
>
> > Hello
> >
> > I use PIC16f628, how can I set the PWM mode for 38 kHz?
> > The PWM mode work in SLEEP mode?
>
>   I don't know, never tried.
>
> > How I can simulate the PWM mode in MPLAB?
>

>   difficult, you can't simulate in real time, just to see the output pin
> is changing value
>
> > If you have an example with PWM settings please send me.
>
>   PWM module is the same like 877 has ( only just one module )
>
>   www.geocities.com/vsurducan/PIC/lib.html
>   hardpwm.jal or music.jal, the assemblerm algorithm is the same
>
>
>   regards, Vasile
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
>
>

> -----Original Message-----
> From: Simon-Thijs de Feber [SMTP:stdf23173KILLspamYAHOO.CO.UK]
> Sent: Tuesday, April 09, 2002 7:01 AM
> To:   .....PICLISTKILLspam.....MITVMA.MIT.EDU
> Subject:      [PIC]:PWM
>
> Hello All,
>
> Yesterday evening i have been struggling with a PWM
> function.
>
> A char should be loaded with e.g. 0xF0, afterwards
> rotated right, and every passing LSB should be put on
> a output pin.
>
> So i did this in CC5x
>
> led1 = pwm.0;
> pwm = pwm >> 1;
>
> this generates something like
>
> BTFSS pwm,0
> BCF   led1
> BTFSC pwm,0
> BSF   led1
> CLR   0x05, C  //clear carry
> RRF   pwm,1
>
> The clear carry is not required cause i want a
> continues rolling function.
>
> So i removed the "clear carry" in an inline assembly
> block and included that in my code, but that has not
> solved the problem.
>
> any one an idea ?
>

>
> What you have to do is preload the carry bit with the LSbit like thisL
>
>         rrf     pwm,w   ; move LSbit into carry, pwm unaffected
>         rrf     pwm,f   ; rotate pwm, carry bit now moved to MSbit
>
> Regards
>
> Mike
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>
>
>
>

> -----Original Message-----
> From: pic microcontroller discussion list
> [EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU] On Behalf Of Scott Dattalo
> Sent: Tuesday, April 09, 2002 12:25 PM
> To: PICLISTspam_OUTMITVMA.MIT.EDU
> Subject: Re: [PIC]:PWM
>
>
> On Tue, 9 Apr 2002, John Dammeyer wrote:
>
> > Hi Dag,
> >
> > Even more clever.  Learn something new every day.  Here's
> the Bytecraft
> > version:
> >
> > 08C5 1283    BCF    STATUS,RP0        WREG = RRF(ch);
> > 08C6 1303    BCF    STATUS,RP1
> > 08C7 0C4A    RRF    4A,W
> > 08C8 1803    BTFSC  STATUS,C          bHB_LED = STATUS.C;
> > 08C9 28CC    GOTO   08CCh
> > 08CA 1205    BCF    PORTA,4
> > 08CB 28CD    GOTO   08CDh
> > 08CC 1605    BSF    PORTA,4
> > 08CD 0CCA    RRF    4A                ch = RRF(ch);
> >
>
> It is clever, but like the routines posted before it, it has
> jitter and
> it's not isochronous. If you're just dimming an LED, then I suppose it
> really doesn't matter.
>
> But if you do care then consider:
>
>    rrf    ch,w
> loop
>    rrf    ch,f
>    skpc
>     goto  lo
>
> hi:
>    nop
>    bsf    IOPORT,IOBIT
>
>    goto   loop
>
> lo:
>    bcf    IOPORT,IOBIT
>
>    goto   loop
>
>
> Or for more more speed, you could unroll the loop:
>
>    btfss   ch,0
>     goto   lo_0
>
>    nop
>
>    bsf    IOPORT,IOBIT
>    goto   next_bit
>
> lo_0
>
>    bcf    IOPORT,IOBIT
>    goto   next_bit
>
> next_bit
>
> ...
>
> Of course, a better solution is to forget the bcf/bsf's and do this:
>
>
>    movlw   (1<<IOBIT)
>    btfsc   ch,0
>     clrw
>    xorwf   IOPORT,F
>
> Or if you're worried about rmw problems:
>
>    movf   IOPORT,w
>
>    andlw  ~(1<<IOBIT)
>    btfsc  ch,0
>     iorlw (1<<IOBIT)
>    movwf  IOPORT
>
>    andlw  ~(1<<IOBIT)
>    btfsc  ch,1
>     iorlw (1<<IOBIT)
>    movwf  IOPORT
>
> ... and so on for the next 6 bits
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>
>
>
>

> misunderstand.  This is a
> correction.  A circular buffer would be something
> like this, and very
> much like another reply you got in asm.
>
> W=rr(pwm);
> led1=Carry;
> pwm=rr(pwm);
>
> This should generate something like:
>
>     RRF   pwm,W      ; Get bit
>     BTFSS Carry      ; Output it
>     BCF   led1
>     BTFSC Carry
>     BSF   led1
>     RRF   pwm,F      ; Re-insert
>
> It doesn't really matter.  You can just as well do
> something like
> this:
>
> W=rr(pwm);
> pwm=rr(pwm);
> led1=pwm.3;
>
>
> Dag S
>
>
> STdF> Hello,
>
> STdF> Thanks for the replies.
> STdF> Following Dag's hint, since i use CC5x, i
> found out it
> STdF> did not work.
> STdF> In MPASM i tried the piece of code which is
> shown
> STdF> below.
>
> STdF> start   clrw
> STdF>         CLRF    PORTA
> STdF>         BSF     STATUS, RP0
> STdF>         MOVLW   0x00
> STdF>         MOVWF   TRISA
> STdF>         BSF     STATUS, C
> STdF>         BCF     STATUS, RP0
> STdF>         MOVLW   0x55
> STdF>         MOVWF   pwm
>
>
> STdF> main    BTFSS   pwm,0
> STdF>         BCF     PORTA,0
> STdF>         BTFSC   pwm,0
> STdF>         BSF     PORTA,0
>
> STdF>         rrf     pwm,1
> STdF>         goto    main
> STdF> ;
> STdF> END
>
> STdF> So i filled pwm with 0xAA.
> STdF> I'd expected a bit pattern on the output which
> should
> STdF> look like 01010101.
> STdF> What i see happening in MPASM, when i trace
> pwm, is
> STdF> 0xAA, 0x55, 0x2A, 0x95, 0x4A, 0xA5, 0x52,
> 0xA9, 0x54,
> STdF> 0xAA. And this continues since pwm is not
> affected.
> STdF> So that is OK.
>
> STdF> However when i try it on my 16F84. I see the
> 01010101
> STdF> pattern and then it stops, and the led i
> connected at
> STdF> that pin stays low.
>
> STdF> What CC5x does with
>
> STdF> led1 = pwm.0;
> STdF> pwm = rr(pwm);
>
> STdF> is exactly what is in the main loop.
>
> STdF> As i said, when implemented on my PIC it does
> not
> STdF> work.
>
> STdF> grtz
>
> STdF> Simon
>
>
> STdF>
> __________________________________________________
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>
> --
> http://www.piclist.com hint: The PICList is archived
> three different
> ways.  See http://www.piclist.com/#archives for
> details.
>
>

> misunderstand.  This is a
> correction.  A circular buffer would be something
> like this, and very
> much like another reply you got in asm.
>
> W=rr(pwm);
> led1=Carry;
> pwm=rr(pwm);
>
> This should generate something like:
>
>     RRF   pwm,W      ; Get bit
>     BTFSS Carry      ; Output it
>     BCF   led1
>     BTFSC Carry
>     BSF   led1
>     RRF   pwm,F      ; Re-insert
>
> It doesn't really matter.  You can just as well do
> something like
> this:
>
> W=rr(pwm);
> pwm=rr(pwm);
> led1=pwm.3;
>
>
> Dag S
>
>

>The difference is in the last line of asm.
> >CC5x generates :
> >RRF pwm,1
> >
> >instead of
> >
> >RRF pwm,F
>
> After they are assembled they will be the same.  "F"
> is a symbolic
> reference to "file register" but the assembler
> translates it to
> a 1, which is what actually goes into the machine
> instruction.
>
> Barry
>
> --
> http://www.piclist.com hint: To leave the PICList
> piclist-unsubscribe-requestEraseME.....mitvma.mit.edu
>
>

> --- Barry Gershenfeld <RemoveMEbarryEraseMEEraseMEZMICRO.COM> wrote: >
>>The difference is in the last line of asm.
>> >CC5x generates :
>> >RRF pwm,1
>> >
>> >instead of
>> >
>> >RRF pwm,F
>>
>> After they are assembled they will be the same.  "F"
>> is a symbolic
>> reference to "file register" but the assembler
>> translates it to
>> a 1, which is what actually goes into the machine
>> instruction.
>