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Simulators >> Circuit Simulators >> customizing user defined model in Cadence
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Message started by sheela on Mar 28^th, 2004, 9:58am

Title: customizing user defined model in Cadence
Post by sheela on Mar 28^th, 2004, 9:58am

Hi all,

I am presently working with spectre in the Command line interface. I am able to write my modules (ahdl.def codes) for various components, subcircuits and netlists and I am able to access them from the Command line interface in UNIX environment.

I would like to access my modules in the analog circuit design environment (schematic interface). I created a symbol view for my modules. But I am unable to create verilog views or other views by which I can access them as instances in my circuit.

Can anyone help me?

-Sheela

Title: Re: customizing user defined model in Cadence
Post by Andrew Beckett on Mar 28^th, 2004, 11:29am

You say you are unable to create these views - why?

You should be able to create a File->New->CellView
from the CIW and pick Verilog-A Editor as the tool name,
and then it will open up an editor, and you can copy the code
in there.

When you save and exit the editor, it will syntax check it,
and then prompt you if you want to create a symbol
automatically.

What are you trying to do - your question is very open
ended, and so it is hard to know what you've tried...

Regards,

Andrew.

Title: Re: customizing user defined model in Cadence
Post by sheela on Mar 29^th, 2004, 2:02am

Hi Andrew,

Thank you very much for your reply.

I am writing circuit models for ESD application. As the available models do not address this region.
Presently I have a module written for ggNMOSt.
As I had mentioned before, I am able to run them from the command line interface and look at my results.

But this model is to be used just as an instance in a larger circuit. If I need to write the netlist by myself everytime, I tend to make mistakes. So I wish to use the schematic interface. And I want to vary the parameters of this instance, just like how we can change the parameters for the built in models when we click on "property".

So the question is how to address (access) the user written module from the instance and property menu in the schematic view or rather how to include them in the list of libraries available (under instance) and use them in the circuit.

I wrote the ahdl code by using the examples in the (ahdl.def) ahdl.lib files. Do I have to write veriologa files also? When I see any instance in the ahdl.lib from the library manager, then they are almost always associated with three views, namely ahdl, veriloga and symbol.

Is my question clearer now?
eagerly awaiting your reply,
-Sheela

Title: Re: customizing user defined model in Cadence
Post by sheela on Mar 29^th, 2004, 3:52am

Hi Andrew,

I tried adding the Verilog A editor view for the module. But I don't get any editor window to copy my codes. So when I run it in the schematic, I get error message saying "unable to descent into view".

When I tried spectre HDL view (ahdl) then I get an error message saying " can't find license file (lic - error -24).

Am I doing something wrong here?

-Sheela

Title: Re: customizing user defined model in Cadence
Post by Andrew Beckett on Mar 29^th, 2004, 6:23am

Sheela,

Try typing:

editor

in the CIW - it should be the name of some editor. You can set it to the editor of your choice by doing (say):

editor="nedit".

Now, it sounds from the fact that you're referring to ahdl.def that your code may be spectreHDL, not Verilog-A?

When you create the view, using File->New->CellView,
you can choose one of two tools:

SpectreHDL-Editor
Verilog-A-Editor

The viewName can be whatever you want, but people commonly use "ahdl" for SpectreHDL and "veriloga" for Verilog-A (that's what you've seen in ahdlLib). You don't need to write both spectreHDL and verilog-a, one would be sufficient (if you're running spectre). However, I'd recommend that if you're going to choose one, choose verilog-a, since that's the standard, and if you're going to use AMS Designer, spectreHDL is not supported there...

The fact that you're getting a licensing error suggests that the licenses aren't set up properly for that session. Try typing:

lic_error -24

and this will give you lots of details as how to figure out why the licenses can't be found. It will be trying to check the licenses in various parts of the tools, hence the error.

Regards,

Andrew.

Title: Re: customizing user defined model in Cadence
Post by sheela on Mar 30^th, 2004, 6:05am

Hi Andrew,

I read your answer and tried again step by step.

I still get the error message "unable to descend into view".
So I tried this. I copied a cell from one of the existing models into mylibrary and changed the codes to mine, keeping the nodes unchanged. I deleted the veriloga view from that file and kept only the ahdl file (just to make sure, it takes my codes or none ;))

In this case, it works.
BUT
I do not have access to the module parameters (CDF parameters). I still get the list of parameters from the original module, which I had now modified.

How will I specify my parameters?

When I tried to attach veriloga or spectrehdl view, a window opens asking if I want the modelwriter to write a new view. This editor does not work for us. When I cancel, I get a window to write my ahdl or veriloga codes as you had said. So we use the text edirtor and not the modelwriter.

Can this be a reason why it gives me an error message as "unable to descend into view"? ???

Best Regards,
Sheela

Title: Re: customizing user defined model in Cadence
Post by sheela on Apr 1^st, 2004, 1:15am

Hi Andrew,

Finally I succeeded in adding my module in the chematic library. Now I see that the CDF parameters are getting added to it automatically.

Thank you very much for your help.

I have another question and this is regarding subscircuit. I have a subcircuit, which calls other user-defined modules. How can I call my subcircuit as an instance?
And where will I have to specify the path to the modules used in this subcircuit?

Eagerly awaiting your reply,
Sheela

Title: Re: customizing user defined model in Cadence
Post by Aigneryu on Apr 1^st, 2004, 7:38am

http://www.designers-guide.com/Forum/?board=circuit;action=display;num=1079882080

please refer to this message.