Extraced from a question by alwin
The complete DES pipeline uses the following resources.
> Number of Slices: 1415 out of 1920 73%
> Device utilization summary for this counter.
> Number of Slices: 28 out of 1920 1%
> All fine untill I place the counter in front of the pipline.
> The result of the synthesis process of the complete design is:
> Number of Slices: 1972 out of 1920 102% (*)
> WARNING:Xst:1336 - (*) More than 100% of Device resources are used
> Am I missing something here?
> This is a huge increase of used resources I can't explaine.
As a wild guess, perhaps part of the DES pipeline was being optomized away without the counter there to exercise its full designed functionality? If XST figures out that a bit of logic is never used, or the result never acted upon, then it gets eliminated.
What was taking the counter's place in the synthesis of the pipeline alone? Can you connect the 48 bit count value to IO's (so their value will be unkown to XST) and retry the DES part on it's own?