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by fpgaminer 3226 days ago
That's good in theory, but ... it's not realistic. The compilers are too unstable. I lost a couple days of my life last year because Quartus forgot how to route its multipliers.

But usually you only have to floor plan if you're near the limits of your target FPGA, or if you're using some of its special IP (like say pinning some of DRAMs or PLLs).

1 comments

Yup or your design is just large. Due to the non-deterministic nature of the compiler guiding it at a high level makes it less likely to choose resources in weird locations. e.g. I roughly map out block ram assignments for some of the top level modules but still give it plenty of wiggle space.
Not only that but you don’t want to have to redo analysis and verification on blocks that have been already mapped, placed and routed. Especially as one does minor bug fixes towards the end of a design. It’s like refusing to use libraries.