Lpc2000

ok, got home and have tried on my dev board...
Using a 12Mhz crystal, I configured the VPBDiv=0

As a result modified the Fac and Int settings to:
PREINT 		= 0x000001c8;//Set RTC prescaler for 12.000Mhz Xtal,
	VBP=15Mhz
PREFRAC 	= 0x000061c0;

using the calculations from databook.

I also then had to change my UART settings to match, sicne the PCLK 
was now 1/4.....
Anyway: ALL WORKS OK. RTC functions normally.

Can you check what values you used for the Prefac/int when you 
adjusted the VPBDiv?

Or, since you have it working maybe issue is closed?

anyway, thought i would report my findings!

rgds
pete


So I am confused that you say you had problem with the 

--- In lpc2000@yahoogroups.com, "bty639886" <peter.brown@b...> wrote:
> 
> when i get home i will check this out on my systsem.
> 
> I do however have a 12Mhz clock rather than the 14.xx that u are 
> using. So my preints and facs will be different.
> Im suspecting the problem could well be with your prefac being 0 
> given the divider settings...
> 
> anyway, i will check it out and re-post for future reference.
> 
> glad you got it working !
> rgds
> pete
> 
> 
> --- In lpc2000@yahoogroups.com, "Leighton Rowe" 
<leightonsrowe@y...> 
> wrote:
> > 
> > > 3. have you tried running with vpbdiv set to 1 (ie resulting 
in 
> > > 60mhz opertion (ish).. i am using that for my system without 
any 
> > > problem...
> > 
> > Good news!
> > 
> > After setting VPBDIV = 1 (pclk =cclk) and setting PREINT and 
> PREFRAC 
> > (based on the user manual), the RTC counted correctly. Thanks 
> Pete. 
> > The RTC also worked for VPBDIV = 2 (pclk = cclk/2).
> > 
> > But interestingly, the RTC still counted twice as fast after 
using 
> > VPBDIV = 0. I repeated everything on 2 different lpcs (lpc2114 
> > @14.7456MHz & lpc2129 @12MHz). You can even try it out on your 
> own; 
> > I wouldn't be surprised you'll get the same results. and got the 
> > same results. 
> > 
> > So RTC's OK only when vpbdiv = 1 (pclk=cclk) or 2 (pclk = 
cclk/2). 
> > Otherwise RTC's doubles in speed when vpbdiv = 0 (cclk/4). I 
hope 
> > Philips has an explanation for this one...I have no clue why. 
> > 
> > For now, I can live with using a different vpbdiv setting to 
make 
> > everything work. 
> > 
> > Thanks again