Lpc2000

Thanks for the response, yes, I realize the fractional divider can 
give me any baud rate (well, within tolerance).  More specifically 
what I am trying to get at is for the choice of the external 
crystal.  If I want to use USB then I have to use either 12MHz, 
16MHz or 24MHz external crystals, right?  I.e. it's not possible to 
use USB with a 10MHz or 15MHz or 20MHz external crystal?

If that is the case then I think that the LPC2148 datasheet should 
be updated to mention that.  The only place that it is mentioned 
(directly) at all (that I found) is in the user guide, and even 
that's just under an example, not as a direction.

--- In lpc2000@yahoogroups.com, "Joel Winarske" <joelw@i...> wrote:
>
> seangra wrote:
> 
> > Anyone have a response to this?
> > 
> > If I use the LPC2148 am I essentially stuck with a 12MHz external
> > crystal if I want to use USB and have the uC running at full 
speed?
> 
> There are two PLLs in the LPC2148.  If you run an external crystal 
of 12MHz,
> the two PLL's allow you to run the CPU at 60MHz, and USB at 48MHz.
> 
> Utilizing the Fractional divider in the UART peripheral, you can 
achieve
> nearly any required baud rate.
> 
> Does that limit your app?
> 
> 
> Joel
>