Hi - thank you both (and veronica off-list) for taking a moment to=20
clarify.  I'm confident I can do the hardware design successfully at=20
least.  The USB firmware stack is a concern but a separate issue and the=20
time/risk to battle with it is part of the schedule and tradeoffs made=20
in selecting a chip/vendor for the project.  And fortunately the USB is=20
serial cable replacement type functionality with a small custom app on=20
the windows side so it need not be compatible with anything - just needs=20
to move small packets of data.

Thanks.
J



Olin Lathrop wrote:
> Jesse Lackey wrote:
>> According to the datasheet (page 32 table 2-3), for full-speed USB
>> 48Mhz is required.
>
> The USB peripheral requires a 48MHz clock, but that doesn't mean the
> processor has to run at that speed.  When using one of these chips, you
> really have to study the clock structure diagram on page 24 of the
> datasheet.  The USB PICs have a rather different clock structure with
> different options and restrictions from other PIC 18s.  For example, you =
can
> have the USB peripheral clocked at 48MHz as required while the CPU is
> clocked at 16MHz, all from a 8MHz crystal.  This is in fact exactly what =
I
> do in the LProg PIC programmer (http://www.embedinc.com/products/lprog).
>
>
> ********************************************************************
> Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
> (978) 742-9014.  Gold level PIC consultants since 2000.
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.