Lpc2000

Hello Peter,
some time ago, I clocked a FPGA and a LPC2292 by a single source. I used 
a quarz oscillator with a 3.3V signal output (rather than a single 
quarz). In the LPC's datasheet you can find a specification on how to do 
this: Since the XTAL input of the LPC has a 1.8V logic input rating, you 
will need a 100pF decoupling capacitor between the output of your LVTTL 
oscillator and the LPC's XTAL input. In my application, this worked well...

Karsten

Peter Jakacki schrieb:

>Has anyone had experience with sharing the crystal over multiple LPC21xx 
>oscillators? I have a design where I am multidropping 2101s together 
>over the SPI bus (slave listen, master to talk). It seems a bit over the 
>top to have a separate crystal for each chip though and I am looking at 
>running the XTAL out from one chip to the XTAL in of another and so on 
>(to reduce loading). Of course, the line length will be short and shielded.
>
>Has anyone actually done this?
>Are there problems that you may have actually experienced?
>(Notice the "actually" :) )
>Have you perhaps had problems with similar arrangements?
>
>I have done this with other types of chips before and I can see no 
>problem with doing the same with the LPC21xx. Oscillator output levels 
>look fine and are in the 0.3 to 1.6V range which on the oscillator's 
>1.8V unbuffered gate indicates strong drive.
>
>
>*Peter*
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