Lpc2000

Hi,

To generate a baudrate of 9600 does LPC210x need specific xtal 
frequency or just any xtal would do?

Regards,

Chetan Bhargava

Depends on what you mean by special.  To get any particular baudrate the 
VPB frequency and the baudrate divider have to have a relationship that 
allows the divided rate to be 'close' to 9600*16.  In practice 10MHz works 
just fine.  There will be other frequencies that work well too.  Take a 
look at the user manual.  There is a table of baud rates that can be used 
for ISP with a selection of crystal frequencies that you can use as an 
overview.  If you want to use a particular crystal frequency you have lying 
around you will have to work out whether it's possible or not.

Robert

At 03:19 AM 2/6/04 +0000, you wrote:
>Hi,
>
>To generate a baudrate of 9600 does LPC210x need specific xtal
>frequency or just any xtal would do?
>
>Regards,
>
>Chetan Bhargava
>
>

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

Hi Robert,

That's my answer :-) I use quite a lot of 8051 based micros and in 
there 11.0592MHz is used to generate various rates. I had sme 25MHz 
xtals so I wanted to use them.  :-)

Haven't gone through the UM fully.

Thanks,

Chetan

--- In lpc2100@yahoogroups.com, Robert Adsett <subscriptions@a...> 
wrote:
> Depends on what you mean by special.  To get any particular 
baudrate the 
> VPB frequency and the baudrate divider have to have a relationship 
that 
> allows the divided rate to be 'close' to 9600*16.  In practice 
10MHz works 
> just fine.  There will be other frequencies that work well too.  
Take a 
> look at the user manual.  There is a table of baud rates that can 
be used 
> for ISP with a selection of crystal frequencies that you can use as 
an 
> overview.  If you want to use a particular crystal frequency you 
have lying 

> around you will have to work out whether it's possible or not.
> 
> Robert
>

----- Original Message ----- 

From: "Chetan Bhargava" <cbhargava@...>
To: <lpc2100@yahoogroups.com>
Sent: Friday, February 06, 2004 3:19 AM
Subject: [lpc2100] ISP baudrate


> Hi,
>
> To generate a baudrate of 9600 does LPC210x need specific xtal
> frequency or just any xtal would do?

The crystal has to be between 10 MHz and 25 MHz. I use 10 MHz. 14.7456 MHz
will support higher bit rates and is quite easy to find.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

At 05:45 AM 2/6/04 +0000, you wrote:
>That's my answer :-) I use quite a lot of 8051 based micros and in
>there 11.0592MHz is used to generate various rates. I had sme 25MHz
>xtals so I wanted to use them.  :-)

The table (pg 185 of the UM) shows both as capable of 9600 baud.  Curiously 
enough the table shows rates for crystal frequencies to slightly over 44MHz.

Robert


" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

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