dear all, I am in progress in finishing a design and nead to get it ready for Synthesis. In the Simulation it workrs fine and does what required. The problem with synthesis is timing cannot be met. I have also spended a lot of Flipflops allready and it still does not work. which possibilitys do exist to solve this problem general?
Manish Singh wrote: > which possibilitys do exist to solve this problem general? - Review where the worst paths are (STA results) and why they are so long. Think over what went bad and what you can do to reduce the length of those paths. - Reduce the number of logic Levels between registers (large "if-elsif-elsif-elsif-..." constructs are particularly bad) - If the timing is missed just a very small bit, try with other fitter settings/seed - Reduce your system clocking frequency - Take a faster FPGA
Manish Singh wrote: > which possibilitys do exist to solve this problem general? Use STA (static timing analysys) to find the critical path. Check out what components are involved and try to improve that path. Another possibility would be to say WHAT FPGA you usr and WHAT frequency you want. Maybe its simply not possible...
dear all, thanks for this informations I allready inspected all the crititcal patha, but most things are generated by coregen Generator automatically and can hardly be traced moreover the Signal names are weird taking a fast fpga is not easy, will customer will have to decide this and the fpga frequency is also fixed i will continue on monday with this issues. thanks very much
In case you are using multiple clock domains: Some tools assume all paths between clock domains valid, unless you declare them as false paths. This leads to some very tight timing requirements by default.
This issue is already under Investigation. It seems to be correctly done according to an FPGA expert's opinion. There are only 2 Domains with a high Speed Input data source. The whole thing seems more related the output of the coregen's cores. they seem not to be qualified for the required speeds.
Just out of interest, what core, FPGA, software and frequency is involved?