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Voyager
Voyager
2,969 Views
Registered: ‎07-28-2008

DSP48 synchronous or asynchronous?

What's the difference between having math operation (which synthesize into DSP48) to be clock sensitive or not?

 

I've tested XST synthesizes A/B/MREG into DSP48 if the pipeline registers are clock sensitive regardless the math operation to be clock sensitive or not.

 

Just being curious about if there is a difference or not? I imagine since DSP48 core runs faster than any clock, so it doesn't matter for the core to respond to clock edge or not.

 

Please comment, thanks,

 

 

 

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2 Replies
Advisor eilert
Advisor
2,941 Views
Registered: ‎08-14-2007

Re: DSP48 synchronous or asynchronous?

Hi,

this seems to be more of an ISE (XST) synthesis topic rather than DSP-Tools (like sysgen).

 

Anyway...

 

If you have some math operation it is not neccessarily implemented with a DSP48.

It might be,  if the synthesis tool detects some advantage for this solution.

 

Now, if you have a combinatorical math function sourrounded by registers it is quite similar to having a synchronous math function.

The synthesis tool grabs some bigger chunk of the design and tries to put it into the DSP48 fabric if possible.

So the DSP48 will never be asynchronous even if the math operation has been coded without a clock.

See this page for DSP48 structure details:

http://www.xilinx.com/technology/dsp/xtremedsp.htm

 

With out any registers the multiplier won't use a DSP48.

 

Have a nice synthesis

  Eilert

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Voyager
Voyager
2,936 Views
Registered: ‎07-28-2008

Re: DSP48 synchronous or asynchronous?

Thanks for your kindly comment.

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