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Lpc2000

Index last updated: 2026-04-28 23:31 UTC

Message

Re: PLL not locking

2004-08-25 by Leighton Rowe

All The IRQ/FIQ interrupts are disabled.

If I slowly step through with the debugger the PLLSTAT register 
doesn't even change after the feed sequence

PLLSTAT shows 0

And if I just let it run, it will still be stuck in the wait for 
lock loop...

PLLSTAT shows 0x0123 

...so the PLL's enabled but not locked

My only guess is the board wasn't connected up as it should be. 
Since the code is executing, the crystal seems to be ok but right 
now, it's made not to carry a Reset button.

Leighton

--- In lpc2000@yahoogroups.com, "Uwe Arends" <Uwe_Arends@o...> wrote:
> Leighton,
> 
> > Ok then...forgot about the divider value. Well, I tried out what 
u said too. I expect it to work but apparently the PLL's still
> not locking...Any ideas?
> >
> > > Your setting of PLLCFG would cause it to run at 4*14.7456MHz * 
2 * 1 == 117.96MHz,
> > > just outside the allowed range. Set P to 2 and you should be 
ok => PLLCFG = 0x23.
> > >
> <snip>
> > > PLLFEED = 0xAA;
> > > PLLFEED = 0x55;
> <snip>
> 
> the only thing left I can think of is, that the feed sequence 
doesn't do what it should.
> Do you have interrupts enabled during the above?
> 
> -wue

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