Hello Alan & PIC.ers,

----- Original Message ----- 
From: "alan smith" <micro_eng2@yahoo.com>


> Using a PIC18F and writing in assembly, I have a group of outputs
> sprinkled among
>  several ports to turn on LEDs and the like.
>
>  The idea is I have a group of registers, where I keep track of what
> device is being enabled.  Only one output on at a time, per each register.
>
>  For example:
>
>  LeftSide is a register, bits [4:0] where only one bit is active at any
> given time.
>  RightSide is similar.
>
>  But, the 5 bits that are to be driven are perhaps in PortA, PortB and
> PortD...
>  basically to make the board layout easier because afterall...each bit in
> each port
>  is controlled via LAT opcode...
>  bsf  LATA,0
>

I had a similar situation where I wanted to layout a drive to a 44780 lcd
module.

If I'd tried to use the port pins available, sticking to the original
schematic all neat and regular then the pcb would have ended
up like a rats-nest. Better to wire it up as directly as possible,
then make the adjustment in  s/w.

I just wrote a macro for it, ugly as all hell but works like a charm.


convert_o_patt_for_LCD_PCB     MACRO
        ;this macro `fixes up' the abnormal pin configuration on
        ;the i2c 8574 > 44780 pcb
 clrf        scratch6          ;bit logical 44780 job  >converts to>
                                    ;physical bit no
 btfsC    o_patt,0          ;0 DB4 >> bit 3
 bsf        scratch6,5       ;
 btfsC     o_patt,1          ;1 DB5 >> 1
 bsf        scratch6,1       ;
 btfsC     o_patt,2          ;2 DB6  4
 bsf        scratch6,6       ;
 btfsC     o_patt,3          ;3 DB7  6
 bsf        scratch6,0       ;
 btfsC     o_patt,4          ;4 EN  5
 bsf         scratch6,2      ;
 btfsC     o_patt,5          ;5 R/W  0
 bsf         scratch6,4      ;
 btfsC     o_patt,6          ;6 RS  2
 bsf         scratch6,3      ;
 movff     scratch6,o_patt
    endm

...should give you the general idea...  I'm sure someone here has
a much more elegant way.


        best regards,  John


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JS Controls, Manufacturer & Purveyor of laboratory force testing
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PO Box 1887, Boksburg 1460, Rep. of S. Africa
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