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I am trying to run a simulation on the modelsim INTEL FPGA STARTER EDITION 10.5b.
For the past few months it was running fine but recently I have not been able to run any testbench on model sim. Every time I try to run a test bench I get the "Invalid time string specified" error.
I don't know if it is related but this issue started after I tried using github as a version control to transfer files between devices.
This issue likely does not have to do with the actual code within the files, testbench, or .do files that run the testbench, because on my latop the simulation works perfectly fine. However I have attached the related files just in case.
I have tried uninstalling Quartus and Modelsim and reinstalling but that did not work. I tried removing the path variables and uninstalling quartus and modelsim then restarting and reinstalling and that did not work.
In other threads on related issues I have tried deleting the modelsim.ini config file found in C:\intelFPGA_lite\17.0\modelsim_ase but that caused more issues.
One user said that starting the simulation through the model sim GUI and doing Simulation -> Start Simulation -> *change resolution to something other than default, fixed the issue but it does not work for me.
If it matters, I usually simulate a testbench by entering the command "do runlab.do" into model sim. I have attached that file as well.
Has anyone solved this issue recently? Or is there a way to completely reset all quartus and model sim related settings and variables to default?
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I found another post from a third party that they have similar issue and resolved it by deleting the register key.
Could you try their method and see if it helps.
***Please make a backup by Export to .reg file, before deleting. As making incorrect changes to the Registry may cause issues to Windows and may cause programs crashing or no longer start***
This is their solution. (not tested and might be risky)
Press "Windows+R" to open the run window, enter 'regedit', find the path HKEY_CURRENT_USERS\Software\ModelTechnology Incorpporated\Modelsim, and delete all the folders.
I suspect something is wrong with your machine, do you see the same issue using a difference machine/PC?
At the same time, try below troubleshooting steps:
- If you are running antivirus software, try to temporarily disable the antivirus software during the Questa software download and installation process.
-Install the software with Administrator privileges.
- Try to download and auto install using the new Quartus installer.
- Check your OS history update, e.g. to check if the issue happen after some specific Window update.
Regards,
Richard Tan
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Could you try to install Questa Intel FPGA Starter Edition (requires no-cost license)? As Modelsim has been replaced by the Questa* - Intel® FPGA Edition (including Starter Edition) starting from the Intel® Quartus® Prime Pro Edition Software version 21.3 and Intel® Quartus® Prime Standard Edition Software version 21.1 onwards.
Please check the User guide below on how to setup the license.
https://www.intel.com/content/www/us/en/docs/programmable/683472/25-1/and-software-license.html
Btw, which Quartus version and Operating System are you using? Ensure that your Operating System is supported.
Then install the latest Quartus version (and Questa) and see if the issue still persists.
*Make sure there is no residue file left in the installation directory after you uninstall the software.
After Quartus installation, check your Environment Variables is correctly reflected in your Advance System Settings.
I have tried to simulate your design using the Questa Intel FPGA Edition ( Quartus Prime Pro 24.3) and everything works fine.
Regards,
Richard Tan
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Hi, I download the Quartus Prime 24 Lite edition along with the Questa pro 24 edition and tried running my simulation again but it did not work.
I am using Windows.
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Any update on this?
Do you able to resolve the issue?
Regards,
Richard Tan
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Have you tried adding a timescale directive to your testbench? It appears to be missing.
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I have added timescale to my testbench and it did not work, however I don't think code is an issue since it works without the timescale directive on my other device.
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I found another post from a third party that they have similar issue and resolved it by deleting the register key.
Could you try their method and see if it helps.
***Please make a backup by Export to .reg file, before deleting. As making incorrect changes to the Registry may cause issues to Windows and may cause programs crashing or no longer start***
This is their solution. (not tested and might be risky)
Press "Windows+R" to open the run window, enter 'regedit', find the path HKEY_CURRENT_USERS\Software\ModelTechnology Incorpporated\Modelsim, and delete all the folders.
I suspect something is wrong with your machine, do you see the same issue using a difference machine/PC?
At the same time, try below troubleshooting steps:
- If you are running antivirus software, try to temporarily disable the antivirus software during the Questa software download and installation process.
-Install the software with Administrator privileges.
- Try to download and auto install using the new Quartus installer.
- Check your OS history update, e.g. to check if the issue happen after some specific Window update.
Regards,
Richard Tan
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Hi Richard, thank you for providing this solution!
I did some extra steps top make sure everything was cleared out.
1) uninstall quartus and questa
2) remove registers using the provided method
3) restart pc
4) reinstall apps (Quartus 17 and modelsim 10.5b), I reinstalled the versions provided by my school and not the newest versions
After doing these steps I was able to run model sim again without the time string error.
The issue definitely had to do with my machine and not the code, as I mentioned in my original post I had no issues running the same files on my laptop.
Could you also provide the link of where you found this method?
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I'm pleased to know that your issue has been resolved.
Here the link that I found:
https://bbs.eetop.cn/thread-875445-1-1.html
Now, I will transitioning this thread to community support. If you have any further questions or concerns, please don't hesitate to reach out. Please login to https://supporttickets.intel.com/s/?language=en_US , view details of the desire request, and post a feed/response within the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support.
The community users will be able to help you on your follow-up questions.
Thank you and have a great day!
Best Regards,
Richard Tan

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