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Old 11-23-2005, 06:16 PM
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Default virtex II global buffer

I need to use more than 8 global buffer in a virtex II design
I know that VirtexII supports up to 16 Global Buffer divided in mor
clock regions, but ISE PAR doesn't automatically divide project i
two (or more) clock region and it uses only 8 global buffer. How ca
I use the other global buffer

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Old 11-23-2005, 06:40 PM
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Default Re: virtex II global buffer

You need to manually instantiate BUFG or BUFGMUX operators. The tools
are not going to infer more than 8 because there is only 8 global clock
connections. To use more than 8 you have to limit the connections on
some of them to one quadrant of the chip. Use the -timing parameter on
the mapper to place them or manually locate them yourself -- something
you will likely have to do anyway. When you manually instantiate them
make sure that some of them are only connected to objects in their
quadrant of the chip.

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