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injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-08 by microbit

Hi All,
This might have come up before I think, but I can't seem to
readily find it in my LPC2000 folder.
Has anyone ever tried supplying LPC2000 with an external 4 MHz
clock signal, to be used with PLL at higher clock rates ?
Since it's a full swing Ext signal, I don't see any limitations, other
than the osc buffer ckty, which surely should handle that.
I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
And 8 X = 32 MHz is too low.
This is for LPC2119/29.
Space is critical and I need to save an SMT Xtal real estate wise.
-- Kris

Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-10 by embeddedjanitor

In some place in the datasheet, the external xtal is specified as 10 
to 25MHz. There might be problems trying to get the PLL running 
properly off a 4MHz clock.

If you need a 4MHz clock for some other part of your board then 
perhaps you can generate this out of the LPC2119.


--- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> Hi All,
> 
> This might have come up before I think, but I can't seem to
> readily find it in my LPC2000 folder.
> 
> Has anyone ever tried supplying LPC2000 with an external 4 MHz
> clock signal, to be used with PLL at higher clock rates ?
> 
> Since it's a full swing Ext signal, I don't see any limitations, 
other
Show quoted textHide quoted text
> than the osc buffer ckty, which surely should handle that.
> I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
> And 8 X = 32 MHz is too low.
> This is for LPC2119/29.
> Space is critical and I need to save an SMT Xtal real estate wise.
> 
> -- Kris

Re: [lpc2000] Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-10 by microbit

Hi Charles (and philips_apps ?) ,
> In some place in the datasheet, the external xtal is specified as 10
> to 25MHz. There might be problems trying to get the PLL running
> properly off a 4MHz clock.
The PLL divider can be set for eg. 16, and the prescaler still can be
set such that the CCO runs within its specified range ?

> If you need a 4MHz clock for some other part of your board then
> perhaps you can generate this out of the LPC2119.
I already have an accurate 4 MHz CLK output from an RF section on the
system (has its own crystal), and I was pondering over saving a crystal/caps
on the LPC2119/29 by injecting that 4 MHz into the CLKIN of LPC.
Board space needs to be minimal, an SMT crystal is quite big.
I might end up putting a low PPM crystal in after all, unless there is some clarification
to the actual freq range allowed with an Ext input Clock signal into LPC2000.
Robert at philips Apps team ?
Can you assist ?
Anywho,
Bit of a pain to bootstrap it, but it just comes down to a pull up resistor on
a control line - although the default clock on power up out of RF device is
500 kHz, until set to 4 MHz with an SPI instruction......
( I do this on MSP430, it clocks of its internal DCO, and the 4 MHz is used
as SMCLK for peripherals that need accuracy like timers and USARTs etc)
That could very well be the biggest problem : the LPC clock will only be
500 kHz at cold start for the first few mS.
I can't see why one couldn't inject a full rail-to-rail 50% duty signal like that
into the oscillator input of LPC2000, it *should* work.
Reliability is the issue of course.
I'm sure there's a reason for the restriction on EXT clock in, but I don't readily
see it. The 10-25 MHz as an oscillator with Xtal, that's understandable, it's quite
hard to provide an on-chip Pierce or similar that can cover a highly extended freq.
range.
The only other reason I could have seen for the equal freq. range restriction
on Ext Clock of 10-25 Mhz could have been some AC coupling time constant
that is too low for signals much lower than 10 MHz.
But that seems like it doesn't make sense either.
Thanks anyway !
;
B rgds
Kris

Re: [lpc2000] Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-10 by Bill Knight

Kris
  One quick point.  The LPC does not like a rail-to-rail
input clock.  I believe the max level is the same as the 
core voltage (1.8v) and the minimum is 200mV.  Also, the
signal should be capacitively coupled.
  It probably wouldn't hurt if you had the RTCLK signal
pinned out on your JTAG connector either and used it.
Otherwise debugging is going to be very slow.

-Bill
the ARM Patch

Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-10 by tphatrapornnant

Hi,

As I remember, I used to try 2.0 MHz crystal oscilator but it seemed 
PLL can't work at lower than 10MHz. I have just tested by changing 
OSC from now 10 MHz to 2 MHz with 6 time multiplier. The 1 ms 
interrupt timer changed to 1.8 ms, it should be 5 ms. So, I afraid it 
doesn't work at 4 MHz.    

Teera.

--- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> Hi All,
> 
> This might have come up before I think, but I can't seem to
> readily find it in my LPC2000 folder.
> 
> Has anyone ever tried supplying LPC2000 with an external 4 MHz
> clock signal, to be used with PLL at higher clock rates ?
> 
> Since it's a full swing Ext signal, I don't see any limitations, 
other
Show quoted textHide quoted text
> than the osc buffer ckty, which surely should handle that.
> I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
> And 8 X = 32 MHz is too low.
> This is for LPC2119/29.
> Space is critical and I need to save an SMT Xtal real estate wise.
> 
> -- Kris

Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-11 by philips_apps

"Crystal Oscillator" section in the "System Control Block" chapter of 
the LPC2114/2124/2212/2214 and LPC2119/2129/2194/2292/2294 User 
Manuals covers input frequency range topics.

If on-chip PLL system or boot-loader is used, input clock frequency 
is limited to exclusive range of 10 MHz to 25 Mhz. 

These restrictions are imposed by the design of the PLL circuitary. 
Since all Philips LPC2000 parts have the same PLL module, above 
requirements exist in the case of LPC2104/5/6 parts, too.

Regards,

Philips Apps Team



--- In lpc2000@yahoogroups.com, "tphatrapornnant" <tp35@l...> wrote:
> Hi,
> 
> As I remember, I used to try 2.0 MHz crystal oscilator but it 
seemed 
> PLL can't work at lower than 10MHz. I have just tested by changing 
> OSC from now 10 MHz to 2 MHz with 6 time multiplier. The 1 ms 
> interrupt timer changed to 1.8 ms, it should be 5 ms. So, I afraid 
it
Show quoted textHide quoted text
> doesn't work at 4 MHz.    
> 
> Teera.
> 
> --- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> > Hi All,
> > 
> > This might have come up before I think, but I can't seem to
> > readily find it in my LPC2000 folder.
> > 
> > Has anyone ever tried supplying LPC2000 with an external 4 MHz
> > clock signal, to be used with PLL at higher clock rates ?
> > 
> > Since it's a full swing Ext signal, I don't see any limitations, 
> other
> > than the osc buffer ckty, which surely should handle that.
> > I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
> > And 8 X = 32 MHz is too low.
> > This is for LPC2119/29.
> > Space is critical and I need to save an SMT Xtal real estate wise.
> > 
> > -- Kris

Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done si

2004-05-12 by slawcus

I haven't noticed this in datasheet:

Can I drive X1 with low speed external clock without PLL, then change
X1 frequency on the fly and after that use PLL?

Example: PDIUSBD12 CLKOUT - default is 4MHz (I'm aware of voltage
limitation at X1 of LPC device). 
LPC2106 X1 is driven by this 4MHz, during PDIUSBD12 setup change
CLKOUT to the higher value > 10MHz. Turn on the PLL, continoue with
normal operation. PDIUSBD12 CLKOUT change should be without glitches
and frequency is not changed with USB reset (according to datasheet). 

Is this possible?




--- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> wrote:
Show quoted textHide quoted text
> "Crystal Oscillator" section in the "System Control Block" chapter of 
> the LPC2114/2124/2212/2214 and LPC2119/2129/2194/2292/2294 User 
> Manuals covers input frequency range topics.
> 
> If on-chip PLL system or boot-loader is used, input clock frequency 
> is limited to exclusive range of 10 MHz to 25 Mhz. 
> 
> These restrictions are imposed by the design of the PLL circuitary. 
> Since all Philips LPC2000 parts have the same PLL module, above 
> requirements exist in the case of LPC2104/5/6 parts, too.
> 
> Regards,
> 
> Philips Apps Team
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "tphatrapornnant" <tp35@l...> wrote:
> > Hi,
> > 
> > As I remember, I used to try 2.0 MHz crystal oscilator but it 
> seemed 
> > PLL can't work at lower than 10MHz. I have just tested by changing 
> > OSC from now 10 MHz to 2 MHz with 6 time multiplier. The 1 ms 
> > interrupt timer changed to 1.8 ms, it should be 5 ms. So, I afraid 
> it 
> > doesn't work at 4 MHz.    
> > 
> > Teera.
> > 
> > --- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> > > Hi All,
> > > 
> > > This might have come up before I think, but I can't seem to
> > > readily find it in my LPC2000 folder.
> > > 
> > > Has anyone ever tried supplying LPC2000 with an external 4 MHz
> > > clock signal, to be used with PLL at higher clock rates ?
> > > 
> > > Since it's a full swing Ext signal, I don't see any limitations, 
> > other
> > > than the osc buffer ckty, which surely should handle that.
> > > I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
> > > And 8 X = 32 MHz is too low.
> > > This is for LPC2119/29.
> > > Space is critical and I need to save an SMT Xtal real estate wise.
> > > 
> > > -- Kris

Re: [lpc2000] Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-12 by microbit

Hi Bill,

Thanks for the tip !
I was still at concept stage and that hadn't occured to me yet :-)

-- Kris

----- Original Message -----
From: "Bill Knight" <BillK@...>
To: <lpc2000@yahoogroups.com>
Sent: Monday, May 10, 2004 9:02 PM
Subject: Re: [lpc2000] Re: injecting an external 4 MHz clk into LPC2000, and
using PLL - anyone done similar ?
Show quoted textHide quoted text
> Kris
>   One quick point.  The LPC does not like a rail-to-rail
> input clock.  I believe the max level is the same as the
> core voltage (1.8v) and the minimum is 200mV.  Also, the
> signal should be capacitively coupled.
>   It probably wouldn't hurt if you had the RTCLK signal
> pinned out on your JTAG connector either and used it.
> Otherwise debugging is going to be very slow.
>
> -Bill
> the ARM Patch

Re: [lpc2000] Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-13 by microbit

> If on-chip PLL system or boot-loader is used, input clock frequency
> is limited to exclusive range of 10 MHz to 25 Mhz.
>
> These restrictions are imposed by the design of the PLL circuitary.
> Since all Philips LPC2000 parts have the same PLL module, above
> requirements exist in the case of LPC2104/5/6 parts, too.
>
> Regards,
>
> Philips Apps Team


Ok, so it's the ref. input on the phase comparator that's the limiting
factor,
or similar.
That makes sense now.

Thanks !

-- Kris

Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done si

2004-05-13 by philips_apps

Hello Slawcus,

Philips has not conducted test(s) that would exactly match what you 
have described in the post, however if proper PLL setup & connect 
scheme are applied, we expect no problems. As long as the transition 
from one clock to another is kept glitch-free on the X1, and all side 
effects are taken in consideration prior to the design (i.e. impact 
on all of the on-chip peripherals), you are safe.

Regards,

Philips Apps Team



--- In lpc2000@yahoogroups.com, "slawcus" <slawcus@y...> wrote:
> I haven't noticed this in datasheet:
> 
> Can I drive X1 with low speed external clock without PLL, then 
change
> X1 frequency on the fly and after that use PLL?
> 
> Example: PDIUSBD12 CLKOUT - default is 4MHz (I'm aware of voltage
> limitation at X1 of LPC device). 
> LPC2106 X1 is driven by this 4MHz, during PDIUSBD12 setup change
> CLKOUT to the higher value > 10MHz. Turn on the PLL, continoue with
> normal operation. PDIUSBD12 CLKOUT change should be without glitches
> and frequency is not changed with USB reset (according to 
datasheet). 
> 
> Is this possible?
> 
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
wrote:
> > "Crystal Oscillator" section in the "System Control Block" 
chapter of 
> > the LPC2114/2124/2212/2214 and LPC2119/2129/2194/2292/2294 User 
> > Manuals covers input frequency range topics.
> > 
> > If on-chip PLL system or boot-loader is used, input clock 
frequency 
> > is limited to exclusive range of 10 MHz to 25 Mhz. 
> > 
> > These restrictions are imposed by the design of the PLL 
circuitary. 
> > Since all Philips LPC2000 parts have the same PLL module, above 
> > requirements exist in the case of LPC2104/5/6 parts, too.
> > 
> > Regards,
> > 
> > Philips Apps Team
> > 
> > 
> > 
> > --- In lpc2000@yahoogroups.com, "tphatrapornnant" <tp35@l...> 
wrote:
> > > Hi,
> > > 
> > > As I remember, I used to try 2.0 MHz crystal oscilator but it 
> > seemed 
> > > PLL can't work at lower than 10MHz. I have just tested by 
changing 
> > > OSC from now 10 MHz to 2 MHz with 6 time multiplier. The 1 ms 
> > > interrupt timer changed to 1.8 ms, it should be 5 ms. So, I 
afraid 
> > it 
> > > doesn't work at 4 MHz.    
> > > 
> > > Teera.
> > > 
> > > --- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> 
wrote:
> > > > Hi All,
> > > > 
> > > > This might have come up before I think, but I can't seem to
> > > > readily find it in my LPC2000 folder.
> > > > 
> > > > Has anyone ever tried supplying LPC2000 with an external 4 MHz
> > > > clock signal, to be used with PLL at higher clock rates ?
> > > > 
> > > > Since it's a full swing Ext signal, I don't see any 
limitations, 
> > > other
> > > > than the osc buffer ckty, which surely should handle that.
> > > > I'm thinking of multiplying up to 64 MHz cclk.. a tad too 
high.
> > > > And 8 X = 32 MHz is too low.
> > > > This is for LPC2119/29.
> > > > Space is critical and I need to save an SMT Xtal real estate 
wise.
> > > > 
> > > > -- Kris

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