Clock Domain Crossing!

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sakthikumaran87

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Hi All,

I have a design related question on CDC.

I have two black boxes working async. to each other and i am not aware of both the clk speed. Is it feasible to insert a sync. for the data / ctrl signal that is needed to pass data properly between the two black boxes. I need to design such sync. scheme. How to design it.

Regards,
SK
 

It depends on the kind of interface between the blocks. Could you detail the exact kind of interface you have?
 

It was an interview question to my friend, so couldnt provide more details.. the question itself is on how to design the interface to propagate signals between two black boxes of unknown freq. ...
 

a) One of the simple ways to do the CDC properly is to introduce synchronizers in the path. These are special cells which are available in a library. This is the simplest way of doing things.
b) There are complicated ways of doing CDC implementation with extra latency and feedback topologies.....you can go through this document
http://www.sunburst-design.com/papers/CummingsSNUG2008Boston_CDC.pdf
 

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