David Duffy (AVD) wrote:
> Having only used PIC12 and PIC16 series before, the PIC18 looks quite
> foreign!

That's why there is a datasheet.  You need to read it carefully,
particularly the part about the memory organization and instruction set.
Once you do, you'll see a PIC 18 is actually a fairly logical extension of =
a
PIC 16.  Many things will be familiar.  Some things will be new, but mostly
they will make things easier for you.  For example, the memory model reduce=
s
the need for banking and makes it easier when you do need it, and the pagin=
g
issues are pretty much gone.

> I'm using assembler in absolute mode to start with.

Yucc, don't do that.  If you need instant gratification, then forget about
microcontrollers.  Learn to set up a relocatable project and don't look
back.  Too many people get stuck in the trap of learning with absolute mode=
,
then never wanting to make the perceived jump to relocatable mode.
Relocatable mode is nothing to be afraid of, and is important once you do a
real project.

>         BANKSEL TRISD
>         movlw   0x00
>         movwf   PORTA
>         movwf   PORTB
>         movwf   PORTC
>         movwf   PORTD
>
>         BANKSEL PORTD
>         movlw   b'10101010'
>         movwf   PORTA
>         movwf   PORTB
>         movwf   PORTC
>         movwf   PORTD

> That produces nothing from the LEDs,

Of course it won't.  As the manual clearly states (and as is customary with
all PICs), all pins wake up in high impedence state to the extent they can.
Writing values to the port registers isn't going to have any effect until
you set the pins to outputs.  At the very least this means clearing the TRI=
S
bits, but may also require disabling analog peripherals associated with the
pins of interest.  Just writing 0 then some value to the port registers has
no chance of producing a visible result without making pins outputs.


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