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AR# 23207

8.2i ISE Simulator (ISim) - Known Issues with ISE Simulator

Description

Keywords: simulation, problems

This Answer Record contains all the Known Issues for ISE Simulator 8.2i.

Solution

Q1. When running a design for 60 seconds or more of simulation time, ISE seems to freeze up and hang. Why does this occur?
A1. This has been improved. Now ISE no longer hangs, and instead it issues an out of memory error. This problem will be addressed in the future releases of ISE Simulator.

Q2. I cannot view parameters or generics in the hierarchy view. Is there any way to access this information from the simulator?
A2. ISE Simulator does not currently have the ability to display parameter and generics. The simulator reads the information, but cannot display it in the GUI. This issue is fixed in ISE 9.2i.

Q3. After installing an ISE Service Pack, I find that the design does not simulate correctly.
A3. After every Service Pack install, it is a requirement to clean up project files before running through the design. To clean up project files, select Project -> Cleanup Project Files from the Project Navigator toolbar.

Q4. When I type "help" and "HELP," I receive different results in the ISE Simulator console window.
A4. This is a known issue with TCL in the Windows Operating System environment. The TCL interface in the simulation console supports simulation commands as well as all valid System Environment commands, such as HELP. Therefore, "HELP" will access the Windows System help command, and "help" will access the ISE Simulator help. There is no fix scheduled for this issue.

Q5. ISE Simulator is not optimized to be a structural simulator, and this is why some structural netlists (Post-translate/post-MAP/post-PAR) can cause the simulator to hit its maximum limits during compilation.
A5. One way to fix this is to maintain hierarchy in the netlist. Refer to the Synthesis and Simulation Guide for more information, which can be found at:http://toolbox.xilinx.com/docsan/xilinx8/books/docs/sim/sim.pdf.

Q6. When stepping through the code in the console window, the focus changes from the console window to the HDL Editor window as a new file is opened.
A6. This is currently a limitation of the ISE Simulator. To work around this issue, either use the step button (see ISE Simulator help for details), or click back to the main console window as needed. This issue will be addressed in the future releases of ISE Simulator.

Q7. When using Generate Expected Results in a design that contains only bidirectional ports, this does not do anything.
A7. The Generate Expected Simulation does not work when using bidirectional signals. This will be fixed in ISE 9.1i.

Q8. ISE Simulator errors out when the ISE design tools are installed in a directory containing spaces.
A8. ISE Simulator will not work if the Xilinx installation is in a directory with spaces. This issue will be fixed in ISE 9.1i.

Q9. ISE Simulator runs out of memory on large designs.
A9. This issue will be addressed in ISE 9.1i.

Q10. ISE Simulator dialog boxes are getting truncated when using Linux.
A10. There are multiple reasons why this is happening, and the issue is currently being investigated. This issue will be addressed in ISE 9.1i.

Q11. When running ISE Simulator on Linux, the number in the prompt does not increment when typing "run."
A11. This is a known issue with ISE Simulator 8.1i. This issue will be fixed in ISE 9.1i. There will not be any numbers as prompt in ISE 9.1i; instead, this will be %.

Q12. Can ISE Simulator read third-party binary files?
A12. See (Xilinx Answer 21796).

Q13. Test Bench Waveform pattern wizard adds random numbers to the end of a pattern.
A13. When a specific non-random pattern is used with the waveform creation tool and then the pattern is changed to a random pattern, it seems as if the numbers are now random for some of them. This issue will be fixed in ISE 9.1i.

Q14. When running in batch mode, ISIM crashes with a seg fault if there is a "quit" in the customer TCL file.
A14. ISIM engine cannot break at any line, and you cannot set any break points. If your custom command file contains quit, or $finish/$stop in a Verilog design with custom command file, ISIM engine is not able to correctly handle these situations. These operations are only allowed in interactive mode. This issue will be fixed in ISE 9.1i.

Q15. "ERROR:Simulator:222 - Generated C++ compilation was unsuccessful"
A15. See (Xilinx Answer 23037).

Q16. Cannot simulate bi-directional signals correctly when the signal is driven in the beginning of the testbench waveform - VHDL only
A16. See (Xilinx Answer 23142).

Q17. XAD file is empty when using ISIM for Xpower

A17.The XAD file gets populated only when "quit" is explicitly typed in the console window.
AR# 23207
Date Created 09/04/2007
Last Updated 10/16/2008
Status Archive
Type General Article