Hi community, I have an interesting question for you. I have a schematic in xschem and the xschemrc file and I am able to simulate the schematic, now the question is, how can I run the simulation from a script in python? Theoretically what I done with the GUI, push "netlist" button and than "simulate", but how can I do this command? any example?

to generate a netlist use this command:

xschem -x -r -n -s -q /path/to/schematic.sch

the -x and -r are optional (do not open X windows and do not use tclreadline shell) -n: generate a netlist -s: spice netlist -q: quit when done. To run a simulation call ngspice directly on the netlist:

ngspice -i schematic.spice

but, how can I manager xschemrc file?

@Roberto Di Lorenzo: I think what you need is to use the

subprocess

package for python, not

os.system()

. The

subprocess.run()

subroutine has options for setting the environment and setting the directory from where the application is launched. So you can run the

xschem

application from a directory containing the

xschemrc

file that you want to apply.

I am close to the solution, but still something is wrong. I looked in the directory and the netlist is not generated.

Xschem is just a schematic editing tool. If you want to use Python to run the simulation, all you need is to just interface with

ngspice

:

import os
os.system('ngspice -b -o <some_name>.log <some_name>.spice')

I agree with you. How can I generate a netlist ? I would like to run a simulation with python because I can write a script to change the corner (SS, FF, SF...) in the schematic, and than, run all the simulation one by one. Any example of working code?

There is no such a very automated way to generate a netlist, to what I know. What I would do is create the schematic in xschem, export the netlist, and use Python to update the netlist.

You can generate the netlist by launching an xschem subprocess, it is very fast. The following example launches xschem with a specific xschemrc file and specifies a directory and a file name for the netlist.

xschem --rcfile /path/to/xschemrc -n -s -x -r -q -o /path/for/netlist -N netlist_filename /path/to/circuit.sch

example i just ran on my system:

xschem --rcfile /home/schippes/share/pdk/sky130A/libs.tech/xschem/xschemrc -n -s -x -r -q -o /tmp -N netlist.spice /home/schippes/share/pdk/sky130A/libs.tech/xschem/sky130_tests/test_ac.sch

it produces the file

netlist.spice

in

/tmp

of the schematic

test_ac.sch

For the meaning of the various options do a

xschem -h

. It is important to give the

-q

option so xschem quits after creating the netlist.

If I use this command i am able to generate the netlist.

os.system("xschem --rcfile /home/roberto/Documents/circuits/ids_vds_test/xschemrc -n -s -x -r -q -o /home/roberto/Documents/circuits/ids_vds_test/ -N netlist.spice /home/roberto/Documents/circuits/ids_vds_test/ids_vds_2.sch")

But with subprocess i am not able to run netlist

subprocess.run(["/usr/local/bin/xschem", "-c","xschem --rcfile /home/roberto/Documents/circuits/ids_vds_test/xschemrc -n -s -x -r -q -o /home/roberto/Documents/circuits/ids_vds_test/ -N netlist.spice /home/roberto/Documents/circuits/ids_vds_test/ids_vds_2.sch"])

I really don't understand this command "subprocess"...

@Roberto Di Lorenzo: All arguments to the program to run in "subprocess" go into a list as the first argument; the way you have it written above, you are effectively trying to call xschem twice. It should be something like:

subprocess.run(["/usr/local/bin/xschem", "--rcfile /home/roberto/Documents/circuits/ids_vds_test/xschemrc", "-n", "-s", "-x", "-r", "-q", "-o /home/roberto/Documents/circuits/ids_vds_test/", "-N netlist.spice", "/home/roberto/Documents/circuits/ids_vds_test/ids_vds_2.sch"])

Since the point of using "subprocess" was that you could launch xschem in a specific directory, you might want to add at the end a 2nd argument

cwd='/home/roberto/Documents/circuits/ids_vds_test'

But I think setting the cwd means that you don't need to specify the startup file which is in the same directory, so that should reduce the call to:

subprocess.run(["/usr/local/bin/xschem", "-n", "-s", "-x", "-r", "-q", "-o .", "-N netlist.spice", "ids_vds_2.sch"], cwd='/home/roberto/Documents/circuits/ids_vds_test')

Possibly

-o .

isn't needed, either.

Maybe

--xschemrc

is missed? but i don't know where to take into account...

I'm guessing that it would work either to specify the filename as

./ids_vds_2.sch

or

/home/roberto/Documents/circuits/ids_vds_test/ids_vds_2.sch

. If you have to modify the

xschemrc

file to get it to add the current directory to xschem's search path, then I guess you do need the

--rcfile=

option, maybe

--rcfile=./xschemrc

. If all else fails, ask Stefan Schippers.

@Stefan Schippers I am trying to create a netlist with this command.

subprocess.run(["/usr/local/bin/xschem", "--rcfile=xschemrc", "-n", "-s", "-x", "-r", "-q", "-N netlist.spice", "ids_vds_2.sch"], cwd='/home/roberto/Documents/circuits/ids_vds_test/')

in the folder of schematic I have also

xschemrc

file, how can i do a netlist with this specific xschem rc file that is in the same folder of the schematic? I get this when I run this command.

runfile('/home/roberto/Documents/circuits/ids_vds_test/netlist_run.py', wdir='/home/roberto/Documents/circuits/ids_vds_test')
Unknown option:  netlist.spice
Unknown option: etlist.spice
Unknown option: .spice
Unknown option: e
xschem: cant do a netlist without a filename

`"-N netlist.spice`" is wrong, split into two arguments:

"-N", "netlist.spice"

I tried all the options.

process_1 =subprocess.run(["/usr/local/bin/xschem", "--rcfile=/home/roberto/Documents/circuits/ids_vds_test/xschemrc", "-n", "-s", "-q", "-N","netlist.spice","ids_vds_2.sch"], 
                          cwd='/home/roberto/Documents/circuits/ids_vds_test/')

Still the path is wrong and i don't know why....

I think you need to inspect the

xschemrc

file and see the list of paths assigned to

XSCHEM_LIBRARY_PATH

.If everything fails add

[pwd]

to the list of paths assigned to `XSCHEM_LIBRARY_PATH`:

append XSCHEM_LIBRARY_PATH :[pwd]

Now i have this setup:

#### xschemrc system configuration file

#### Flush any previous definition
set XSCHEM_LIBRARY_PATH {}
#### include devices/*.sym
append XSCHEM_LIBRARY_PATH ${XSCHEM_SHAREDIR}/xschem_library
#### include skywater libraries. Here i use [pwd]. This works if i start xschem from here.
append XSCHEM_LIBRARY_PATH :$env(PWD)
#### add ~/.xschem/xschem_library (USER_CONF_DIR is normally ~/.xschem)
append XSCHEM_LIBRARY_PATH :$USER_CONF_DIR/xschem_library 
################


append XSCHEM_LIBRARY_PATH :[pwd]


###########################################################################
#### list of tcl files to preload.
# lappend tcl_files ${XSCHEM_SHAREDIR}/change_index.tcl
lappend tcl_files ${XSCHEM_SHAREDIR}/ngspice_backannotate.tcl

Running this command with everything defined, still not produce the spice netlist.

subprocess.run(["/usr/local/bin/xschem", "--rcfile=/home/roberto/Documents/circuits/ids_vds_test/xschemrc", "-n", "-s", "-q", "-N", "netlist.spice","ids_vds_2.sch"], 
                          cwd='/home/roberto/Documents/circuits/ids_vds_test/')

You need to specify the path where you want the netlist, by default netlist goes to

~/.xschem/simulations

subprocess.run(["/usr/local/bin/xschem", "--rcfile=/home/roberto/Documents/circuits/ids_vds_test/xschemrc", "-n", "-s", "-q", "-N", "netlist.spice", "ids_vds_2.sch", *"-o", "/home/roberto/Documents/circuits/ids_vds_test"*], cwd='/home/roberto/Documents/circuits/ids_vds_test/')

thanks, it works... the only things that is not clear is, what is the order of the command. everything is clear until

"ids_vds_2.sch"

, but than how the command know that the spice netlist should be put in the next path? why the definition of the

cwd

is not took into account.

Arguments that begin with '-' or '--' are xschem command options. They are all read and parsed before doing anything, so the order does not matter. The directory where netlist is generated is by default ~/.xschem/simulations, it can be changed using the '-o' switch and does not depend on CWD.