Difference between revisions of "Simulating Verilog"
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== Running Verilog == | == Running Verilog == | ||
− | You can use | + | You can use three different Verilog simulators: ncverilog ("ncverilog"), VCS ("vcs") or verilog-XL ("verilog"). There is also a 4th GNU simulator called [http://www.icarus.com/eda/verilog/ Icarus Verilog] that you can install on your own computer. |
− | + | ||
=== ncverilog === | === ncverilog === | ||
Line 29: | Line 28: | ||
ncverilog -f project.f +gui | ncverilog -f project.f +gui | ||
+ | |||
+ | or | ||
+ | ncverilog -f project.f +gui +access+rwc //This will solve problems if there is an error about read access | ||
This will compile the verilog and run SimVision. There is more on SimVision in the [[Advanced Testbenches]] tutorial. | This will compile the verilog and run SimVision. There is more on SimVision in the [[Advanced Testbenches]] tutorial. | ||
You can also put these extra arguments in the project.f file. | You can also put these extra arguments in the project.f file. | ||
+ | |||
+ | === VCS === | ||
+ | |||
+ | To run VCS: | ||
+ | |||
+ | vcs +v2k -f project.f | ||
+ | ./simv | ||
+ | |||
+ | Specifying -R on the command line will run it immediately and not produce the simv binary. Specifying -gui on the command line will load the SimVision GUI. On 64-bit machines, you may get an error message like this: | ||
+ | |||
+ | Error: DVE in 64Bit mode requires a special license. | ||
+ | For more details, please contact Synopsys VCS Support. | ||
+ | |||
+ | To avoid this, you must load the simulation in dve (the GUI) manually like this: | ||
+ | |||
+ | export VCS_ARCH_OVERRIDE="redhat72" | ||
+ | vcs +v2k -gui -f project.f | ||
+ | export VCS_ARCH_OVERRIDE="" | ||
+ | dve | ||
+ | |||
+ | Then, go to Simulator->Setup and select the simulator executable. | ||
=== Verilog-XL === | === Verilog-XL === | ||
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=== Icarus Verilog === | === Icarus Verilog === | ||
+ | |||
+ | Icarus can be run like this: | ||
+ | |||
+ | iverilog -c project.f | ||
+ | |||
+ | Note that this will *compile* the verilog into a binary called "a.out". To actually run the Verilog, you must now run it: | ||
+ | |||
+ | ./a.out | ||
+ | |||
+ | Icarus Verilog seems to be more lenient on errors in Verilog code. You should make sure it compiles in NCVerilog too. Icarus does not come with a GUI, so you will either need to use the $display command or install [http://home.nc.rr.com/gtkwave/ GTKWave]. | ||
== Simulating Verilog in Ultrasim == | == Simulating Verilog in Ultrasim == | ||
Line 50: | Line 83: | ||
For non-digital simulations, you can simulate a structural Verilog netlist in Ultrasim as well. However, you need to supply the spice subcircuits of the library: | For non-digital simulations, you can simulate a structural Verilog netlist in Ultrasim as well. However, you need to supply the spice subcircuits of the library: | ||
− | /mada/software/techfiles/osu_soc_v2.7/cadence/lib/tsmc025/signalstorm/osu025_stdcells.sp | + | /mada/software/techfiles/osu_soc_v2.7/cadence/lib/tsmc025/signalstorm/osu025_stdcells.sp |
+ | |||
+ | See more in the [http://bacon.cse.ucsc.edu/wiki/index.php/Analog/Mixed_Signal Analog/Mixed Signal] section. | ||
+ | |||
+ | == Saving a VCD == | ||
+ | |||
+ | Some waveform viewers and other tools accept VCD as an input. A VCD file is a vector change dump. It simply has some or all of the signal changes over the entire simulation time. You can dump a VCD file from your simulation using: | ||
+ | |||
+ | initial begin | ||
+ | $dumpvars(0,topmodule); | ||
+ | $dumpfile("mydump.vcd"); | ||
+ | end | ||
+ | |||
+ | The 0 specifies the number of levels to dump. 0 is a shortcut for all levels whereas 4 would just mean 4 hierarchical levels down from topmodule. The arguments to dumpvars are optional. By default it dumps the current module only, I believe. | ||
+ | == Assertions == | ||
+ | ncverilog supports PSL assertions with the +assert option. All of the simulators can be used with the [http://www.accellera.org/activities/ovl/ OVL] assertion library. Tutorials on both PSL and OVL are available on [http://www.asic-world.com/verilog/assertions1.html ASIC World]. | ||
== Back-Annotation == | == Back-Annotation == |
Latest revision as of 00:18, 15 May 2008
Contents
Introduction
This section will briefly talk about how to simulate Verilog. You can simulate Verilog that is either behavioral, gate-level, or back-annotated (with delays). Behavioral and gate-level are done in the same way, but back annotate requires an extra system call in your Verilog.
The first thing I recommend that you do is to create a "project.f" file that is just a list of all of your Verilog files. Like this:
sram.v sram_tb.v
Running Verilog
You can use three different Verilog simulators: ncverilog ("ncverilog"), VCS ("vcs") or verilog-XL ("verilog"). There is also a 4th GNU simulator called Icarus Verilog that you can install on your own computer.
ncverilog
Simply run:
ncverilog -f project.f
Look for any warnings or errors. At the end of the output, you should see:
Simulation complete via $finish(1) at time 10 US + 0 ./sram_tb.v:64 $finish(); ncsim> exit
If you want to view the outputs in a GUI, you can run:
ncverilog -f project.f +gui
or
ncverilog -f project.f +gui +access+rwc //This will solve problems if there is an error about read access
This will compile the verilog and run SimVision. There is more on SimVision in the Advanced Testbenches tutorial.
You can also put these extra arguments in the project.f file.
VCS
To run VCS:
vcs +v2k -f project.f ./simv
Specifying -R on the command line will run it immediately and not produce the simv binary. Specifying -gui on the command line will load the SimVision GUI. On 64-bit machines, you may get an error message like this:
Error: DVE in 64Bit mode requires a special license. For more details, please contact Synopsys VCS Support.
To avoid this, you must load the simulation in dve (the GUI) manually like this:
export VCS_ARCH_OVERRIDE="redhat72" vcs +v2k -gui -f project.f export VCS_ARCH_OVERRIDE="" dve
Then, go to Simulator->Setup and select the simulator executable.
Verilog-XL
Verilog-XL does not support much of Verilog 2001. However, given that, it can be run in the same way:
verilog -f project.f
or:
verilog -f project.f +gui
Icarus Verilog
Icarus can be run like this:
iverilog -c project.f
Note that this will *compile* the verilog into a binary called "a.out". To actually run the Verilog, you must now run it:
./a.out
Icarus Verilog seems to be more lenient on errors in Verilog code. You should make sure it compiles in NCVerilog too. Icarus does not come with a GUI, so you will either need to use the $display command or install GTKWave.
Simulating Verilog in Ultrasim
For non-digital simulations, you can simulate a structural Verilog netlist in Ultrasim as well. However, you need to supply the spice subcircuits of the library:
/mada/software/techfiles/osu_soc_v2.7/cadence/lib/tsmc025/signalstorm/osu025_stdcells.sp
See more in the Analog/Mixed Signal section.
Saving a VCD
Some waveform viewers and other tools accept VCD as an input. A VCD file is a vector change dump. It simply has some or all of the signal changes over the entire simulation time. You can dump a VCD file from your simulation using:
initial begin $dumpvars(0,topmodule); $dumpfile("mydump.vcd"); end
The 0 specifies the number of levels to dump. 0 is a shortcut for all levels whereas 4 would just mean 4 hierarchical levels down from topmodule. The arguments to dumpvars are optional. By default it dumps the current module only, I believe.
Assertions
ncverilog supports PSL assertions with the +assert option. All of the simulators can be used with the OVL assertion library. Tutorials on both PSL and OVL are available on ASIC World.
Back-Annotation
In order to back-annotate, you should output an SDF file from either Synopsys Design Compiler (before physical design) or from SoC encounter. Each SDF format is sometimes different, so you may have to hack it to get it to work. Common incompatibilities are the dilimiting characters in hierarchical names, for example. Carefully watch the warnings!
The system call to back-annotate is like this:
initial begin $sdf_annotate("gate/lfsr-final.sdf", l0); end
where lfsr.sdf is the SDF file and l0 is the instance name of the top module that you synthesized. Note that you should not be using your unsynthesized verilog now. Use the output from synthesis in the file, gate/lfsr-final.v, along with your original testbench.