ordering info regarding 4MHz crystal or 20MHz crystal??

thanks for the reply.
1. can we specify in the ordering info which crystal
we want on the board?? because i did not find any such
detail in ordering info on phytec's site.

2. how do we find out the resultant clock frequecy
after programming it that whether its 56MHz or not??

3. does anyone have any demo programs for mpc565 board
besides the hello world demo pgm that comes with it.

thanks in advance,
HZ
 


--- Dees Randy-rsaf30 <[email protected]>
wrote:

> yes. you can get the same frequencies with either
> crystal, however, each
> requires different settings of the multiplication
> factor (MF) and the
> pre-divider of the PLL (DIVF). These are set in the
> PLPRCR (register).
> To get to 56 MHz, the input to the PLL must be set
> to 2 MHz to obtain 56
> MHz system frequency.
>  
> Choice of crystal depends on two main trade offs:
> - 4 MHz crystal has lower crystal operating current
> (on KAPWR power
> supply)
> - 20 MHz crystal has slightly better jitter
> performance if the MF is
> kept low.
> 
> ________________________________
> 
> From: [email protected]
> [mailto:[email protected]] On Behalf
> Of huzaec
> Sent: Monday, April 23, 2007 6:50 AM
> To: [email protected]
> Subject: [MPC500] 4MHz crystal or 20MHz crystal??
> 
> 
> 
> what is the difference in system clock speed if we
> choose 20MHz 
> crystal instead of 4MHz crystal in MPC565???
> or its the same thing and that we can achieve the
> same frequency of 
> 56MHz by using both the crystals??
> 
> .
> 
> 
> [Non-text portions of this message have been
> removed]
> 
> 


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