Setting-up and using DeCiDa (Cadence Users)

First-time setup for Cadence Users

The applications are found in the python bin directory, after installation (which or whence python to find the bin directory). These should be in the path so that simply typing an appication name, (calc, for example) should run the application.

The pre-installed tool wrappers are in the distribution ./etc/wrappers directory. These are installed to ~/.DeCiDa/bin

./etc/skill files

These skill scripts are used by Cadence Virtuoso users for generating starter DeCiDa scripts and verilog test-benches from a test-bench schematic. They are installed to ~/.DeCiDa/skill. They will be loaded by the user’s .cdsinit Cadence startup script. The provided example .cdsinit file is in ./etc/dot

skill script:	description:
RVBmenu.il	sets up application (schematic) menu
RVBdcdlines.il	(from menu) generates python decida Tckt script
RVBvtblines.il	(from menu) generates verilog test-bench directory
RVBcomp.il	(from menu) generates list of schematic components
RVButil.il	utilities used in other scripts
RVBdcd_help.txt	help file for generating python script
RVBvtb_help.txt	help file for generating verilog testbench

These skill scripts also expect that the following files are available in the following locations. Two example projects are included (bird and trane). Revise the scripts as appropriate, prior to or after installation to modify the directory locations, include different or additional projects/technologies.

file:	description:
~/.DeCiDa/models/ptm_130nm.scs	case-corner library for Spectre simulations
~/.DeCiDa/models/ptm_130nm_mos.scs	MOSFET models for Spectre simulations
~/.DeCiDa/models/ptm_45nm.scs	case-corner library for Spectre simulations
~/.DeCiDa/models/ptm_45nm_mos.scs	MOSFET models for Spectre simulations
~/.DeCiDa/stdcell/ptm_130nm/*.v	standard cell library for NCsim simulations
~/.DeCiDa/stdcell/ptm_45nm/*.v	standard cell library for NCsim simulations
~/.DeCiDa/verilog/make_body	make include file for verilog simulations
~/.DeCiDa/verilog/make.bird	make include file for the bird project
~/.DeCiDa/verilog/make.trane	make include file for the trane project

These are the two example projects. The project drive is where Cadence tools are launched. The scratch drive is where Cadence tools write netlists and where DeCiDa writes simulation data.

project:	technology:	simulator:	project_drive:	scratch_drive:
bird	ptm_130nm	Spectre	~/.DeCiDa/projects/bird	~/.DeCiDa/projects/bird/scratch
trane	ptm_45nm	Spectre	~/.DeCiDa/projects/trane	~/.DeCiDa/projects/trane/scratch

./etc/verilog files

These files are used to run simulations using NCsim/SimVision. The verilog testbench is generated using the skill scripts.

file :
Makefile	example Makefile for verilog simulations
simvision_core.tcl	include file for SimVision plot setup
make_body	make include file for verilog simulations
make.bird	make include file for the bird project
make.trane	make include file for the trane project

First-time tool resource file setup

1. add or modify your home (~/.cdsinit) file

   if you don’t have a ~/.cdsinit:

   cp dot/.cdsinit ~/.
   

   (which is also installed in ~/.DeCiDa/dot/.cdsinit)

   otherwise add the following lines at the bottom of the file:

   setSkillPath( append( getSkillPath() list( "~/.DeCiDa/skill" )))
   load("RVButil.il")
   load("RVBmenu.il")
   load("RVBdcdlines.il")
   load("RVBvtblines.il")
   

2. you might also want to copy over the ocean resource file if you are using ocean:

   cp dot/.oceanrc ~/.
   

   (which is also installed in ~/.DeCiDa/dot/.oceanrc)

3. modify your project .cdsinit file

   add the following lines at the bottom of the file (modify to project specifics, accordingly):

   RVBproject="trane"
   RVBtechnology="ptm_45nm"
   RVBsimulator="Spectre"
   RVBscratch="~/.DeCiDa/projects/trane/scratch"
   

4. Start a cadence session. The .cdsinit files will be sourced. If you’re already in a cadence session, type this in the CIW:

   load "~/.cdsinit"
   

Generate a starter python script for doing spectre simulations

1. generate a starter python script:

   • open a testbench schematic
   • type y: –RVB– menu button will appear at the top of the window
   • select “Generate DeCiDa testpack” from the menu
   • project, technology, and simulator are filled in based on the values from First-time setup for cadence users
   • click “OK”: starter script is written to ~/. (HOME directory)

2. netlist the testbench schematic:

   • Schematic -> Launch -> ADE L
   • ADE -> Simulation -> Netlist -> Create

3. make a project subdirectory for running the simulations:

   mkdir -p ~/.DeCiDa/projects/trane/work/<circuit>
   

4. move the python script to the subdirectory:

   cd ~/.DeCiDa/projects/trane/work/<circuit>
   mv ~/<circuit>.py .
   

5. modify the test appropriately. Changeing the value of tstop is usually the only change you need to make initially

6. run the python script by typing its name

   if you type only the script name alone, a test selector dialog is displayed with test selection boxes

   if you type the script name followed by a list of tests, the tests are run in the same sequence that they were defined in the script.

Generate a starter verilog testbench for doing verilog simulations

1. generate a starter verilog testbench:

   the testbench must be named tb_<DUT> where “tb” is lower-case and <DUT> is the circuit under test.

   • open a testbench schematic
   • type y: –RVB– menu button will appear at the top of the window
   • select “Generate verilog testbench” from the menu
   • project, technology, and simulator are filled in based on the values from First-time setup for cadence users
   • if there are any wreals in the top-level testbench, then type them into the “wreals” entry box
   • click “OK”: starter testbench directory is written to ~/. (HOME directory)

2. netlist the testbench schematic:

   • Schematic -> Launch -> Simulation/ncVerilog
   • generate run-directory (press 1st icon)
   • netlist (press 2nd icon)

3. make a project subdirectory for running the simulations:

   mkdir -p ~/.DeCiDa/projects/trane/work/<circuit>
   

4. move the testbench files to the subdirectory:

   cd ~/.DeCiDa/projects/trane/work/<circuit>
   mv ~/tb_<circuit> .
   

5. change to the tb_<circuit> directory and run the generate_ncsim.py script:

   generate_ncsim.py
   

   this produces the module library: ncsim_tb_<circuit>/lib_tb_<circuit>

6. modify the automatically-generated testbench tb_<circuit>.v appropriately

7. run ncsim (ncs-pre means ncsim, pre-synthesis, type “make” to find out other options):

   make ncs-pre