This code has the disadvantage that it is not isochronous -- ie: it doesn't 
take the same amount of time for each execution. That may or may not be 
important in the OP's application.

Bob Ammerman
RAm Systems

----- Original Message ----- 
From: "Mark Rages" <markrages@gmail.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Thursday, May 26, 2005 4:39 PM
Subject: Re: [PIC] Indirect file registers, 8 pin software pwm


> D'oh!
>
> scewed it up.
>
> still untested code follows...
>
> ; Be careful where this goes in the program space -- 
> ; the addwf must clear the carry bit...
> ; Uses one scratch file, named scratch
>
> set_bit macro ; bit is in 'w' 0..7
> clrf scratch
> bsf scratch,7
> addwf PCL,f
> rrf scratch,f ; 0100 0000
> rrf scratch,f ; 0010 0000
> rrf scratch,f           ; 0001 0000
> rrf scratch,f           ; 0000 1000
> rrf scratch,f           ; 0000 0100
> rrf scratch,f           ; 0000 0010
> rrf scratch,f           ; 0000 0001
>
> movfw scratch
> iorwf PORTA,f
> endm
>
> clear_bit macro ; bit is in 'w' 0..7
> clrf scratch
> bsf scratch,7
> addwf PCL,f
> rrf scratch,f ; 0100 0000
> rrf scratch,f ; 0010 0000
> rrf scratch,f           ; 0001 0000
> rrf scratch,f           ; 0000 1000
> rrf scratch,f           ; 0000 0100
> rrf scratch,f           ; 0000 0010
> rrf scratch,f           ; 0000 0001
> comf scratch,w
> andwf PORTA,f
> endm
>
> -- 
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>  - fortune cookie
>
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