BYU Cadence Setup

Cadence Setup

Overview

This document explains how to set up your resource files and user environment to use the Cadence software.  It then helps you test your setup to ensure that everything works and you have access to the Cadence tools.

Finding a Machine

Currently Cadence is only installed correctly on a finite number of machines. These are the several linux machines grouped in the southwest corner of the CAEDM lab. Their names are:

Don't panic, you can ssh into these machines from any machine in the lab and most any machine in the building. Following are instructions on how to ssh in.
  1. From Unix or Linux - at a command prompt type ssh -X <machine-name>.ee.byu.edu
  2. From Windows - if you have an x-windows server, ssh in as above, if not, open citrix to a unix environment and ssh in as above.
If you are seeking additional information about the Spice machines, please visit this link. Now that you have a valid machine, go ahead and set everything up to run cadence.

Account Setup

You must have a spice account to log into the EE machines.  Your spice account lets you log into all the machines on the south side of the CAEDM lab.  If you don't have a spice account set up, take care of it before continuing.

It is a good idea to set up a group account where you can store your work and share it with your lab partners without worrying about permissions.  You can create a group folder from the CAEDM Account Manager.  It takes a couple minutes for the groups/<groupfolder> to appear in your home directory.  (You may have to log out and back in order for the new group folder to show up.)

Cadence creates a lot of configuration and data files.  In order to keep them all in one place, create a cadence subdirectory to hold all the files.  You can either put the subdirectory in your own home directory or in your group folder.  Groups have successfully run two instances of cadence from the same directory at the same time with no errors. Important Note: Whenever creating directories in Linux (including group names), do not use spaces - If you must, use the underscore character "_" - There are certain tools within Cadence that cannot recognize spaces.

cd ~/

mkdir cadence

Resource File Setup

Set up your global editor.  Cadence uses the global editor when opening files.  You may set your editor to emacs, vi, nedit or any other editor you wish.  If you are proficient with Windows text editors, then nedit will probably be the best choice because it has similar hot keys. Here are lines you need to add or modify in your .bashrc in order to use emacs:

export EDITOR=/usr/bin/emacs
 
 Here are the lines you need to add or modify in your .cshrc in order to use emacs:

set EDITOR=/usr/bin/emacs
 
Cadence uses a ton of global variables to configure its behavior.  We've supplied a resource file for you to reference in your .bashrc file.  You may want to open up the file and see what is in there.  Add these lines to the bottom of your .bashrc file:

Type the following at the command line: texteditorname filename

Example: emacs .bashrc

#----------------------------------------------

# Cadence Design Tools

#----------------------------------------------

source /opt/cadence/.bashrc_cadence

# Or for .cshrc, type: source /opt/cadence/.cshrc_cadence

Source your .bashrc file or open a new terminal window.

source .bashrc

Alternatively, source your .cshrc file or open a new terminal window.

source .cshrc

cds.lib File Setup

The cadence tools you will use most often require a file directing them to the available parts and technology libraries.  This file is called cds.lib.  You need to create one and tell it where to find the installed parts.

In the directory from where you will run Cadence, create a file called cds.lib and add the following lines to it:

INCLUDE /opt/cadence/cds.lib

Make sure to leave a blank newline at the end of the file!

Starting Cadence, Invoking the CIW

The CIW is your Command Interpreter Window. You will navigate through the cadence tools using this window. Any command you select in the pull down menus opens a different form or window in which you select more specific options for that command.

Open a terminal window, change to your cadence directory and start the CIW by typing:

icfb &      # the command to start cadence

Note: Icfb stands for integrated circuit front to back.  The & allows you to run the Cadence Tools and still use the terminal for other commands.

You will notice two windows open after a couple of seconds. If any type of warning message or window appears, check with a TA to see if it is important. You should now only have two windows open other than your terminal. The larger window is your library manager, and the smaller one is the CIW.  Note: The CIW is titled icfb - Log: <your cadence directory>.

AbiWord Image ciw.jpg

Stretch your CIW window to be taller (a few inches is fine). Notice that all of the commands executed in the setup are shown in the window. You will usually need to return to this window to check for error messages throughout the design process. Notice the three small sections at the bottom of the CIW. The first section, which has the cursor, is the command line. You can type in commands for Cadence if you know the syntax. The next section says mouse and has an L, M, and R which represent the three mouse buttons. These will change to show which command each mouse button is set to do. The third section is where Cadence will tell you what to do. For example, it will tell you to point at a location to draw a wire or to place a part.

The Library Manager

You will find the library manager more useful after you have made some designs as it lets you navigate through your designs and find the one you wish to open. The three large windows in the manager are used to navigate through your designs. A library is basically a folder with a set of rules which will be used to check your designs. Inside of the library there are sub folders called cells. These cells are the parts that you will be creating throughout the semester. Each cell can have several different views. (i.e. schematic, layout, extracted,...) Click on the NCSU_Digital_Parts library and then click on the inv cell. You will see five different cellviews in the views window.

AbiWord Image library_manager.jpg

Note: If the library manager does not contain any library information the cds.lib file is most likely incorrectly written or missing.  Check to make sure you saved your cds.lib file in the same directory from which you are running icfb.  Check to make sure your cds.lib file contains the text given above.

Creating a New Library

In the cadence tutorials you will create libraries to hold your designs.  This section of the cadence setup shows which buttons to press in order to create a new library and add cells to that libraary.

In the library manager choose File -> New -> Library... to open the Create Library form.

Name: Anything you want, for now choose MYLIB.

Path: Should be the current path.  Set the current path by typing in a period (.).  See the picture.

Technology Library: Choose Attach to existing tech library.  In the drop down that appears, choose the AMI 0.6u C5N (3M, 2P, high-res) process.

I/O Pad Type: Choose Perimeter.

AbiWord Image create_library.jpg

Press OK and your new library will appear in your library manager window.

Creating a new Cellview

Click on MYLIB, your new library.  Go to File -> New -> Cellview... to open up the Create New File form.

Library Name: Should default to MYLIB.  If it does not, choose MYLIB from the drop down.

Cell Name: Anything you want.  You probably want to name it something descriptive, for instance, inv if you are making an inverter.  For now just name it mycell.

View Name: Certain view names are linked to certain tools.  For instance, typing in schematic in this field causes the tool to default to Composer-Schematic.  Likewise, typing in layout causes tool to default to Virtuoso.  For now, simply choose schematic.

Tool: Leave the default.  (It should be Composer-Schematic)

Library Path File: Always leave this default.  It keeps your cds.lib file up to date.

AbiWord Image create_cellview.jpg

Press OK.  The Composer-Schematic window opens up.  Just choose Design -> Check and Save for now and close the window.  You should see an new cell in the library manager window called mycell with a new view called schematic.

Conclusion

You now have cadence set up and ready to run.  The rest of the tutorials show you how to use the tool.