Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim

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Is there a way to convert a schematic file (.sch) into a functional
verilog module (.v/.vf) from the command line? I want to do this so I
can compile the resulting verilog file with modelsim for simulation. I
know how to do this from the ISE GUI, but it would be much easier if I
could do it from the command line.

Please bear in mind that I am using Xilinx ISE 9.1i or ModelSim XE III/
Starter 6.2c when posing your answers.

I appreciate any help you can provide.

Kind Regards,
Craig.

P.S. Out of curiosity, is there a way to simulate a project with mixed
verilog and schematic files in ModelSim from the command line?


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Craig,

Depending on what tools you used to capture the schematic, and what
models your flow supports, asking for a "verilog netlist" is a feature
of some tools.

The resulting verilog netlist will be at the transistor and wire level,
or gate level (which in the hierarchy is made up of gates and wires),
and will basically allow you to functionally simulate the schematic,
less any timing, or 'analog' behavior (after all, you only have 1's,
0's, 'don't cares', tri-states, and unknowns).

This is commonly done for ASIC/ASSP design:  one may synthesize higher
level RTL (like verilog and VHDL descriptions that have no specific
technology or functional modules like 'multiply this by that') into
lower level schematics of transistors (from standard cell library gates).

The resulting circuit netlist (like a spice netlist) will allow one to
perform many good (analog) simulations, but will either take too long,
or blow up, if there are close to a billion devices in the chip.  The
next choice is to simulate the verilog netlist of the wires and
transistors, which will run much much faster, but will be unable to tell
you anything about time, voltage, or current.

Since you posted on c.a.f. I am going to presume your HDL was
synthesized for a FPGA, and then it was placed, and routed in the FPGA.

You may also have a schematic of how the HDL blocks are connected
together.  The resultant netlist is in some format (for Xilinx: XDL)
which may then be simulated quickly for the functional behavior.

In an FPGA, the translation all the way down to transistors is not
provided, like it would be in the ASIC/ASSP flow....

Make sense?

Austin

Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Austin,

How accurate is the timing for post place and route simulations using the
Xilinx libraries?


---Matthew Hicks


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Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Matthew,

We stand by the speeds files.  In other words, if the actual part is
slower, on any path or feature, it may be returned (via the RMA
process), and we issue a new one that meets the specifications.

I have taken part in many such cases, and on only two occasions, we had
made a mistake in the speeds file, and we had to offer a faster speed
grade part to the customer, or work with them to improve their timing to
get around the failing path.

It is so extremely painful to have to issue a new (slower) speeds file
for our customers; we only do that when we have no other alternative
whatsoever (and you can believe we get hammered internally for having
the wrong number in the speeds file).

The same is true for IBIS models, packaging files, etc.

Austin

Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Sorry I'm trying to be very practical here. I just want to know what
command line tools I can use to create a verilog file from a schematic
file.

How do I do that from the command line using either ISE 9.1i or
ModelSim?

I'd appreciate it if you could give me an example?

Lets say my schematic is named: circuit.sch

I'd like to create a verilog file (netlist) that is equivilent to it,
say: circuit.v

I'm guessing at the command line it would be something like:

xst -sch circuit.sch > circuit.v

I have read through all the user manuals, developer manuals, etc... I
can't not figure out how to do this outside of the GUI interface.

Thanks again for any help you can provide.

Thanks,
Craig.


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Craig,

I must apologize, because I am an IC designer, not really a FPGA user (I
mostly use very simple and straightforward designs to verify the blocks,
and rely on others to write the systems level stuff).

I am also not a software expert.

There are Xilinx employees who read this newsgroup from our software
group, however.

If they do not respond, I am going to have to assume we can not do what
you ask with our tools.

Austin

Craig Moore wrote:
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Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Hi Craig,
it's so simple:

sch2verilog

is the name of the program. and this is how to use it :


Release 9.1.01i - sch2verilog J.31
Copyright (c) 1995-2007 Xilinx, Inc.  All rights reserved.
Usage: sch2verilog [-intstyle <intstyle>] [-top] [-tf] [-tfonly] [-tfext
<ext>]
[-ti] [-tionly] [-tiext <ext>] [-nodrc] [-nets] [-NETS] [-inst] [-INST]
[-MODEL]
[-model] [-iterated] [-family <family>] [-synthesis <tool>] [-w]
<infile[.sch]>
[<outfile>]
        -intstyle <intstyle> Indicate contextual information when
invoking Xilinx applications within a flow or project environment.
<intstyle> can be ise, xflow or silent
        -top              Write out the top-level schematic only
        -tf               Generate test fixture file
        -tfonly           Generate test fixture file only
        -tfext <ext>      Set test fixture file extension (Default: vf)
        -ti               Generate instantiation template file
        -tionly           Generate instantiation template file only
        -tiext <ext>      Set instantiation template file extension
(Default: vi)
        -nodrc            Disable DRC check
        -NETS             Force net and pin names to uppercase
        -nets             Force net and pin names to lowercase
        -INST             Force instance names to uppercase
        -inst             Force instance names to lowercase
        -MODEL            Force VeriModel names to uppercase
        -model            Force VeriModel names to lowercase
        -iterated         Don't Use underscores when expanding iterated
names
        -family <family>  Specify device family (Default: virtex)
        -synthesis <tool> Specify synthesis tool: XST, EXEMPLAR,
                          PRECISION, SYNPLICITY (Default: XST)
        -w                Overwrite existing file without warning
        <infile>          Input file name (Default extension: .sch)
        <outfile>         Output file name (Default: <infile>.v)


So all you need for your everyday work is:

   sch2verilog -family virtex_or_whatever_U_use circuit.sch circuit.vf

For your modelsim question:
Yes: if you split your script in two parts:
a shell script that converts the schematics (and does the compilation of
your sources if you like) and the modelsim do script that controls your
simulation. Remember: vlib vmap and vlog (vcom for vhdl users) are
independent programs that can run without a modelsim gui. depending on
your scripting skills you can even prevent the simulator to start before
the sources are all compiled successfully.

e.g.:

#! /bin/sh
#       if you are a unix user
sch2verilog -family <your_family> circuit_1.sch circuit_1.vf
#...many more
sch2verilog -family <your_family> circuit_n.sch circuit_n.vf
vlib yourlib
vmap yourlib yourlib_path
vlog [options] circuit_1.vf
#...many more
vlog  [options] circuit_n.vf
vsim -do sim_script.do
# end of sh script

#sim_script
vlog [options] testbench.v

vsim [options] testbench
view wave -undock
do wave_circuit.do
# or
add wave *

run -all
# end of sim_script

 >>> divide et impera <<<

Have a nice simulation
   Eilert



snipped-for-privacy@googlemail.com schrieb:
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Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
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Usually most command issued by the ISE GUI are appended to a file
    <PATH_TO_THEPROJECT>/<PROJECT_NAME>.cmd_log

if You cleanup all project files and "rebuild all" You can have in
that file
all the command line to issue to rebuild your project (NOTE ofter the
rebuild You
souldn't re-cleanup the project files else you lose something...and
the command
line couldn't work...)

I don't know if that is the case for "sch2verilog" too... let try !

Sandro


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
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Yes, this works, and I can see the commands that Eilert referred to in
his post! This will be very handy in the future if I can't figure out
how the GUI is doing something!

Thanks,
Craig.


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
Eilert,

Thanks very much for your detailed response that is exactly what I
needed. I have written a bash script that automatically verifies the
functionality of a series of test circuits that use a specific module
I've developed. I was trying to come up with a way to quickly verify
that I haven't violated any rules with change I've made to that
module. However, I have a college that developed part of his work in
schematic, and I was having to open up ISE each time to convert the
files into Verilog. Now I can do it with my bash script! It will save
me quite a few steps.

Thanks,
Craig


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
On Jul 12, 3:12 pm, " snipped-for-privacy@googlemail.com"
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HI Craig,

As Eilert pointed out, you can use sch2verilog and sch2vhdl to convert
the schematic file that comes from ECS. This is the biggest confusion
I am hearing. ECS is the schematic capture tool you probably have
never heard this name used before. XST does not write out schematics.
XST is the Xilinx Synthesis tool. Basically what happens in the back
end is for us to convert it to HDL and then run XST on it.

Regarding your question on whether you can mix schematic and HDL in
modelsim, the answer is no. Modelsim is a HDL simulator only. It
cannot simulate gates. This is why you can psuedo implement this by
the method that Eilert provided that is to write a tcl script that
runs sch2verilog and then runs the simulation. You can combine the
shell script and do file into one Tcl file if you use the exec
command.

Thanks
Duth


Re: Convert Schematic Files (.sch) to Verilog Files (.v) for simulation in ModelSim
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Yes, I used xst as an example because I did not know the name of the
tool to use. I though it might be xst because the schematic files are
always converted inside the ISE GUI whenever I run the ISE simulator,
and this is where xst is run to compile the verilog files.

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Thanks for confirming this. You've saved a lot of time looking for a
way to do something that cannot be done!

Regards, Craig


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