On Sun, Jan 4, 2009 at 7:16 PM, Joseph Bento <joseph@kirtland.com> wrote:
> OK, I'm reviewing some documentation for the 18F2620.  I'm going to
> try and avoid printing 412 pages of documentation, so for the time
> being I'll refer to the pdf datasheet as needed.
>
> I created a new project in MPLAB, and am going to begin using the
> MPASM tool suite.  I've copied the template file for the 18F2620 and
> renamed it simply, "blinky" as a basis to begin my project.
>
> One thing I immediately see that appears different from the 16F series
> is how the configuration bits are defined
>
> ;Configuration bits
> ;Microchip has changed the format for defining the configuration bits,
> please
> ;see the .inc file for futher details on notation.  Below are a few
> examples.
>
> (I don't know where to find this 'inc' file mentioned)
>
> ;   Oscillator Selection:
>     CONFIG     OSC = LP             ;LP
>
> (OK, I can see this means 'low-powered crystal'. )
>
> So far, so good.   On the pull down menu, however, under 'configure,
> configuration bits' there is a check box to either set the bits in
> code (default, it seems) or to select from the individual fields.  I'm
> new enough at this to not know what needs to be set (ie _MCLRE_ON &
> _CP_OFF &  _WDT_OFF) as I might have done with a 16F84.  If I am
> understanding these functions, it appears I would set them the same
> way as I did previously, and if the default condition is correct, no
> further action needs to be done.  I might assume that setting the bits
> in code is preferred over the pull down configuration to allow you as
> well as anyone else to see what is configured.
>
> Bear with me here...  I'm trying this out on paper before ever
> plugging anything into the breadboard.
>
> I want to light a single LED on RB0 of the 18F2620.
>
> list                    p=18F2620
> #include                <p18F2620.inc>
>
> CONFIG  OSC=LP                                  ;I'll use a 20MHz crystal at OSC1 & OSC2
>
>
> start
>                CLRF            PORTB                           ;initialize port B
>                MOVLW           b'11111110'                     ;configure RB0 as output
>                MOVWF           TRISB
>                MOVLW           b'00000001'                     ;set RB0 high
>                MOVWF           TRISB
>
>                goto            $
>
>
> As Olin suggests, I came up with this by quickly looking at sections
> of the datasheet.  Much extensive study is obviously required.  My
> next step should be to see if this compiles - IT DOESN'T.   I receive
> errors such as:   Executable code and data must be defined in an
> appropriate section.  I'll need to learn what that means.
>
> At any rate, if someone can let me know if I'm on the right track to
> start.
>
> Thanks.
>
> Joe
>

I also have a bunch of 18F2620 that I haven't even touched yet. Also
have two C compilers for them. I am as interested as you are in these
things. Try this:

list                    p=18F2620
#include                <p18F2620.inc>

CONFIG  OSC=LP                                  ;I'll use a 20MHz
crystal at OSC1 & OSC2


start  code
               CLRF            PORTB
;initialize port B
               MOVLW           b'11111110'
;configure RB0 as output
               MOVWF           TRISB
               MOVLW           b'00000001'                     ;set RB0 high
               MOVWF           TRISB

               goto            $


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solarwind
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