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Some basic questions about ISim

Explorer
Posts: 253
Registered: ‎06-09-2011

Some basic questions about ISim

Hi all,

 

I have some questions about ISim which I tried to find answers for them in ISim user guide but I couldn't so I am writing this post to ask you the answers, below are my questions:

 

  1. How can we change time resolution of ISim? Sometimes post-route simulation is very time consuming while there is no need to such highest default value of 1ps, I want to change it to - say 100 ps - to speed up post-route simulation time, once I changed resolution in SDF file but I think it didn't take it into account.
  2. Is there a way for changing signal format to analog instead of digital literals? As you may know MODELSIM has already this feature in it and you can select a signal and change its format to analog.

I am using ISE12.4.

 

Thanks in advance,

Hossein,

Teacher
Posts: 8,720
Registered: ‎08-14-2007

Re: Some basic questions about ISim

1.  The time resolution is specified in the source files.  For post-P&R this would be the library

modules that are not easy to change.  However, I don't think that the simulation resolution is

really the factor slowing you down.  Modern simulators including ISIM use event scheduling,

so the execution time does not necessarily have a linear relationship to simulation resolution.

Also it's worth noting that many of the models need the 1 ps resolution to work properly.  Are

you using the "full" version or the "light" version of ISIM?  The full version should run a bit faster,

but probably not as fast as ModelSim.

 

2.  I'm not aware of this feature in ISIM.  Perhaps some Xilinx guru could chip in...

 

-- Gabor

-- Gabor
Voyager
Posts: 287
Registered: ‎04-02-2011

Re: Some basic questions about ISim

Yes you can change your time resolution from your source file only.

Still you want to change the timing pattern on ISIM you have to change it to 100 ms or like that according to your need.

 

By default it is set to 1.00 micro seconds. change it according to your requirement & then relauch it.

 

Request you to use latest 13.1 or 13.2 version of ISIM.

 

 

Most welcome for further queries.

Thanks,

Sushant.M

Explorer
Posts: 253
Registered: ‎06-09-2011

Re: Some basic questions about ISim

[ Edited ]

Hi Gabor,

 

Thanks for your answer,

I am using full version of ISim and I see that it is not as fast as MODELSIM, I thought I may be able to change that resolution to speed up simulation time in the case of post-PAR, if this can't help, what is the reason of slow simulation by ISim then? 

I should tell that my design is simple not very complex nor having many IP cores and the like.

In MODELSIM I can change the simulation resolution from process properties - inside ISE - and I see this speeds up post-PAR simulation, is MODELSIM a time based simulator?

What is that 1ps defined in the .SDF file then?

 

Regards,

Hossein

Explorer
Posts: 253
Registered: ‎06-09-2011

Re: Some basic questions about ISim

Hi Sushantm,

 

Thanks for your answer,

I say again that I want to change time resolution not final resolution time!..  According to your statements I think you misunderstood my question and tried to explain how to change final simulation time or step. This is not my case.

If you correctly get what I mean , would you please specify which file I need to change?

If your last recommendation is about my second question, I should tell not know but maybe in the near future I may use that.

 

 

Regards,

Hossein

Voyager
Posts: 287
Registered: ‎04-02-2011

Re: Some basic questions about ISim

Hi Hossein,

 

Refer to the following thread and the Answer record.

 

 

http://208.74.204.60/t5/Simulation-and-Verification/Need-help-with-ISim-Time-resolution-setting/td-p/49972

 

http://www.xilinx.com/support/answers/22498.htm

 

let me know if this helps.

 

Thanks,

Sushant.M