2020-08-08 15:47:34 +02:00
|
|
|
<!DOCTYPE html>
|
|
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<title>XSCHEM TUTORIAL: CREATE SYMBOL</title>
|
|
|
|
|
<link rel="stylesheet" type="text/css" href="xschem_man.css" />
|
|
|
|
|
<style type="text/css">
|
|
|
|
|
/* Local styling goes here */
|
|
|
|
|
p{padding: 15px 30px 10px;}
|
|
|
|
|
</style>
|
|
|
|
|
|
|
|
|
|
</head>
|
|
|
|
|
<body>
|
|
|
|
|
|
|
|
|
|
<!-- start of slide -->
|
|
|
|
|
<div class="content">
|
|
|
|
|
<!-- navigation buttons -->
|
|
|
|
|
<a href="xschem_man.html" class="home">UP</a>
|
|
|
|
|
|
|
|
|
|
<!-- slide title -->
|
|
|
|
|
<h1> TUTORIAL: Manage XSCHEM design / symbol libraries </h1>
|
|
|
|
|
<p>
|
|
|
|
|
There are 2 ways to describe symbols in xschem,<br>
|
|
|
|
|
</p>
|
|
|
|
|
<ul>
|
|
|
|
|
<li>
|
|
|
|
|
first approach: define a <kbd>XSCHEM_LIBRARY_PATH</kbd> that is a list of paths
|
|
|
|
|
to last level directories containing .sym /.sch files
|
|
|
|
|
</li>
|
|
|
|
|
<li>
|
|
|
|
|
second approach: define a <kbd>XSCHEM_LIBRARY_PATH</kbd> that is a list of paths
|
2020-08-13 02:19:08 +02:00
|
|
|
one or more levels above the directories containing .sym/.sch files
|
2020-08-08 15:47:34 +02:00
|
|
|
</li>
|
|
|
|
|
</ul>
|
|
|
|
|
<p>
|
|
|
|
|
In the first approach a '<kbd>npn.sym</kbd>' symbol placed in a schematic will be
|
|
|
|
|
saved as '<kbd>npn.sym</kbd>' in the .sch file, when loading back the parent
|
2020-08-13 02:19:08 +02:00
|
|
|
schematic xschem will go through the elements of <kbd>XSCHEM_LIBRARY_PATH</kbd> and look for
|
2020-08-08 15:47:34 +02:00
|
|
|
a directory containing <kbd>npn.sym</kbd>.
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
In the second approach the '<kbd>npn.sym</kbd>' will be saved as
|
|
|
|
|
'<kbd>devices/npn.sym</kbd>' (assuming <kbd>devices/</kbd> is the directory containing this
|
|
|
|
|
symbol) . This is because the <kbd>XSCHEM_LIBRARY_PATH</kbd> is pointing to
|
|
|
|
|
something like <kbd>/some/path/xschem_library/</kbd>
|
|
|
|
|
and <kbd>xschem_library/</kbd> contains <kbd>devices/</kbd> (names are just given as
|
|
|
|
|
examples, any dir name is allowed for <kbd>xschem_library/</kbd> and <kbd>devices/</kbd>)
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
The first approach is preferred by pcb hobbysts, people working on
|
|
|
|
|
small designs.
|
2020-08-13 02:19:08 +02:00
|
|
|
the second approach is preferred for big designs where a one or more directory level
|
2020-08-08 15:47:34 +02:00
|
|
|
indirection is desired for symbols, so any symbol in xschem is given
|
2020-08-13 02:19:08 +02:00
|
|
|
as '<kbd>libname/symname.sym</kbd>' (one level directory specification in symbol references)
|
|
|
|
|
or '<kbd>libgroup/libname/symname.sym</kbd>' (2 level directory specification in symbol references)
|
|
|
|
|
instead of just '<kbd>symname.sym</kbd>'<br>
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
In any case the real path of the symbol reference is obtained by prepending
|
|
|
|
|
the XSCHEM_LIBRARY_PATH paths to the symbol reference until the resulting file is found in
|
|
|
|
|
the machine filesystem.
|
|
|
|
|
</p>
|
2020-08-08 15:47:34 +02:00
|
|
|
|
2020-08-13 02:19:08 +02:00
|
|
|
<p>
|
2020-08-08 15:47:34 +02:00
|
|
|
For VLSI / big designs I <b>strongly</b> suggest using the second approach,
|
|
|
|
|
just as an example i have the following dirs:
|
|
|
|
|
</p>
|
|
|
|
|
<pre class="code">
|
|
|
|
|
~/share/xschem/xschem_library/
|
|
|
|
|
containing:
|
|
|
|
|
devices/
|
|
|
|
|
TECHLIB/
|
|
|
|
|
|
|
|
|
|
~/xschem_library/
|
|
|
|
|
containing:
|
|
|
|
|
stdcell_stef/
|
|
|
|
|
|
|
|
|
|
~/share/doc/xschem/
|
|
|
|
|
containing:
|
|
|
|
|
library_t9/
|
|
|
|
|
dram/
|
|
|
|
|
</pre>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
then in my xschemrc i have the following:
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
<kbd>set XSCHEM_LIBRARY_PATH \ <br>
|
|
|
|
|
$env(HOME)/share/xschem/xschem_library:$env(HOME)/share/doc/xschem/:$env(HOME)/xschem_library</kbd><br>
|
|
|
|
|
</p>
|
|
|
|
|
<h3>
|
|
|
|
|
You may choose either method, but please be consistent throughout your design.
|
|
|
|
|
</h3>
|
|
|
|
|
|
2022-10-14 11:23:46 +02:00
|
|
|
<h1> Change project setup runtime</h1>
|
|
|
|
|
<p>
|
|
|
|
|
Since Xschem now handles multiple windows or tabs, it is desirasble to load schematics from different projects
|
|
|
|
|
into a single running instance of xschem.
|
|
|
|
|
This is not difficult to do and you might want to write your own procedure into your xschemrc to automate this.
|
|
|
|
|
Lets suppose you open a new schematic tab. After opening the new tab go to the xschem prompt in the terminal
|
|
|
|
|
you launched Xschem from, and redefine your XSCHEM_LIBRARY_PATH:</p>
|
|
|
|
|
<pre class="code">
|
|
|
|
|
set XSCHEM_LIBRARY_PATH {} ;# clear previous definitions
|
|
|
|
|
append XSCHEM_LIBRARY_PATH :${XSCHEM_SHAREDIR}/xschem_library ;# for devices/
|
|
|
|
|
append XSCHEM_LIBRARY_PATH :/home/schippes/share/pdk/sky130A/libs.tech/xschem ;# for sky130 libs
|
|
|
|
|
# project specific variables (either tcl variables or shell variables via the TCL env() array)
|
|
|
|
|
set PDK_ROOT /home/schippes/share/pdk
|
|
|
|
|
set PDK sky130A
|
|
|
|
|
set SKYWATER_MODELS ${PDK_ROOT}/${PDK}/libs.tech/ngspice
|
|
|
|
|
set SKYWATER_STDCELLS ${PDK_ROOT}/${PDK}/libs.ref/sky130_fd_sc_hd/spice
|
|
|
|
|
</pre>
|
|
|
|
|
<p>
|
|
|
|
|
At this point your new tab will work with the new defnitions while the previous tab
|
|
|
|
|
will continue with its previous settings.
|
|
|
|
|
</p>
|
|
|
|
|
<p class="important">
|
|
|
|
|
you should create a small procedure and put int into your xschemrc so you will just need to type the
|
|
|
|
|
procedure name:
|
|
|
|
|
</p><br>
|
|
|
|
|
<pre class="code">
|
|
|
|
|
proc set_sky130 {} {
|
|
|
|
|
## XSCHEM_SHAREDIR points to XSCHEM install path, example: /usr/local/share/xschem
|
|
|
|
|
## USER_CONF_DIR is usually ~/.xschem
|
|
|
|
|
## env may be used to set environment variables, like:
|
|
|
|
|
## set env(PDK_ROOT) .....
|
|
|
|
|
global XSCHEM_LIBRARY_PATH XSCHEM_SHAREDIR USER_CONF_DIR env
|
|
|
|
|
## Other global TCL variables listed here depend on the project setup.
|
|
|
|
|
global PDK_ROOT PDK SKYWATER_MODELS SKYWATER_STDCELLS
|
|
|
|
|
|
|
|
|
|
# project specific variables (either tcl variables or shell variables via the TCL env() array)
|
|
|
|
|
set PDK_ROOT /home/schippes/share/pdk
|
|
|
|
|
set PDK sky130A
|
|
|
|
|
set SKYWATER_MODELS ${PDK_ROOT}/${PDK}/libs.tech/ngspice
|
|
|
|
|
set SKYWATER_STDCELLS ${PDK_ROOT}/${PDK}/libs.ref/sky130_fd_sc_hd/spice
|
|
|
|
|
|
|
|
|
|
set XSCHEM_LIBRARY_PATH {} ;# clear previous definitions
|
|
|
|
|
append XSCHEM_LIBRARY_PATH :${XSCHEM_SHAREDIR}/xschem_library ;# for devices/
|
|
|
|
|
append XSCHEM_LIBRARY_PATH :${PDK_ROOT}/${PDK}/libs.tech/xschem
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
|
2020-08-08 15:47:34 +02:00
|
|
|
<!-- end of slide -->
|
|
|
|
|
<div class="filler"></div>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- frame footer -->
|
|
|
|
|
<iframe seamless src="xschem_footer.html" class="footer_iframe" >
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
|
|
|
|
|
