You look at the path of the timing violation.
Modelsim altera post synthesis example how to#
Sometimes after I finish completed compilation, there is critical warning that indicates the design does not meet timing requirements, but I don't know how to handle it.
Then place-and-route the design with the final. SDC file until you clear as many warnings as you see fit. You can place-and-route the design between iterations, or just use the TimeQuest GUI, and delete the netlist and re-read the. SDC constraints file is sometimes an iterative process, where you first identify the obvious (external) clocks, and then add PLL constraints, I/O setup and hold constraints, cut timing paths of the inputs and outputs you don't really care about (LEDs, push-buttons, asynchronous signals, etc), until all clocks and I/Os are constrained.
So how can I know whether design meets timing? Through timing analysis?
This gives you an overview as to why there are different netlists. This was before SignalTap II existed, but the post-synthesis netlist simulation showed the counter was not working, so pointed me in the direction I needed to look. I forget the exact details, but the synthesis tool either did not use the default, or it did not pass it via the EDIF netlist, and so the counter would not count up in the hardware. If you do not use the cin port, then the synthesis tool uses the default port value from the component definition. What type of error does this catch? One example I recall is that the LPM_COUNTER component should have a default value of '1' on its carry-in port, so that it will count up. I have not had to do this type of debugging with Quartus netlists. I have had to do this type of debugging in the past, but it was a long time ago (Mentor LeonardoSpectrum EDIF placed-and-routed using MAX+Plus II). If it appears to be specific to the hardware, then you can run a post-synthesis simulation, followed by a post-synthesis timing simulation to hopefully reproduce, and then resolve, the issue. You can add the SignalTap II sequence to your RTL simulation test case, and see if this is a testcase you missed, or is something specific to the hardware. If the design does not work, then you can use SignalTap II to see what is going wrong. Generally if your RTL simulation passes when run in a testbench that has good coverage, i.e., the test sequences test each operating mode of the device, and the TimeQuest indicates the design meets timing, then you can just test the design in hardware. In Modelsim, you use the -sdfxxx command to tell it what kind of timing simulation you want. The simulation can also be run in conjunction with a timing netlist or. You can use that to check that the top-level waveforms look identical. The post-synthesis simulation can be run without timing delays. Some of the 'secret sauce' of the FPGA will still be hidden from you using basic components, that Altera calls atoms (that's why you need a different set of libraries for netlist simulation in Modelsim-SE, Modelsim-ASE has them precompiled). If you look at that netlist, you'll see its been 'flattened' so its just one huge file.
Modelsim altera post synthesis example simulator#
In a post-synthesis simulation, the simulator compiles the netlist generated by the synthesis tool (the Quartus. In an RTL simulation, the simulator compiles the VHDL in your components and any simulation models, instantiates that in your testbench and runs. Could you explain to me what is difference between RTL functional simulation and post-synthesis simulation?
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