Re: [usb] Can anyone give me advices of the clock design in USB.

[Rudolf Usselmann <rudi@asics.ws>]

On Thu, 2003-07-10 at 11:08, xiongdh@hed.com.cn wrote:
>    Can anyone give me advices of the clock design in USB.
> My USB device support full speed and low speed and has no external 
> crystals oscillator but a internal crystals oscillator.
> Can you give me some informations ,url link and advices about clock 
> recovery,DPLL,and oversampling.
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Well, if you support only FS & LS you will need at least
48 Mhz clock (4x oversampling of the FS data stream).

I would use one clock only for both FS & LS and generate
anprobierte Clock Enables. This makes the design simple,
and the interface to the outside world consistent.

The only paper I am aware of is the robust sei design
guide on usb.org.

Regards, 
rudi               
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