Hi Scott!

On Wed, 24 Apr 2002, Scott Dattalo wrote:

>   ; delay table - or you could check the low four bits
>   ; as shown below
>
>    movf   temp,W
>    sublw  0x0f
>    addwf  pcl,f
>
>    nop
>    nop

Yes, I thought about that, but since I'm putting the assembler inline with
C it would take someone smarter than me to figure out how to do it safely.
Likely it'd cross a page boundary and I'd be falling in midair.

> delay13
>    call   delay4
> delay9:
>    call   delay4
> delay5
>    nop
> delay4
>    return

Yes, this is the kind of thing I was hoping for, keep it coming...


> Another variation similar to your solution can be found in:
>
> http://www.dattalo.com/technical/software/pic/pwm256.txt
>
> Look specifically at the "end_pulse" routine. (Actually, there several
> phase delay tricks in this code.)

several is an understatement - where's that can of Pepsi I was guzzling?

> For example, here's a portion of it that will give you 5-bit
> single-cycle resolution pulse with 11 cycles of overhead.
>
>         BTFSC   pw,4            ;01;01;
>          CALL   delay17         ;02;02
> ep1     BTFSC   pw,3            ;03;19
>          CALL   delay9          ;04;20
>         BTFSC   pw,2            ;05;29
>          CALL   delay5          ;06;30
> ep2     BTFSS   pw,1            ;07;35
>          goto   $+3             ;08;36
>         NOP                     ;  ;37
>         GOTO    $+1             ;  ;38
> ep3     BTFSS   pw,0            ;10;40
>          BCF    PWM             ;11;sk
>         BCF     PWM             ;12;42
>

Nice.




> Turning this into a 4-bit delay is straight forward.
>
> There are also tricks like this:
>
>      movf   countLO,w
>      sublw  0x8
>      andlw  7
>      addwf
>
>      bsf    porta,0
>      bsf    porta,0
>      bsf    porta,0
>      bsf    porta,0
>
>      bsf    porta,0
>      bsf    porta,0
>      bsf    porta,0
>      bsf    porta,0
>

This I am not following. How do jump into this nest of bsf's?

Thanks!

Best regards,

Bob

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.