Is it expected the

sim_pinnumber

stuff has no effect if you just have a schematic ? Unless I create a

.sym

, when generating the LVS netlist, the pins won't have the right order, it ignores the attribute in the

.sch

.

@tnt yes this is current behavior, I will add the feature for top schematic without a symbol. Thank you for pointing this out.

Thanks, it's not a huge deal, but it took me a minute to understand what was going on 😅

@tnt Keep in mind how xschem finds components. If a component reference like

xxx/dev.sym

is found in a schematic xschem tries to append this reference to all search paths defined in

XSCHEM_LIBRARY_PATH

, in the order they are listed. The first existing file is used, so if I have:

set XSCHEM_LIBRARY_PATH /a/b/c:/a/b:/c

and

/a/b/xxx/dev.sym

is an existing file this symbol will be loaded. If no matching file is found the component reference is assumed to be in the same directory of the parent schematic. This is a last resort and not recommended way. Always provide the list of component libraries to search for in XSCHEM_LIBRARY_PATH. If you want to include the current dir into XSCHEM_LIBRARY_PATH use

[pwd]

(and not

.

) :

set XSCHEM_LIBRARY_PATH ...:...:[pwd]:...:...

That said I don't understand well your case, what is the directory layout what are the symlinks there? Can you please elaborate? https://xschem.sourceforge.io/stefan/xschem_man/tutorial_xschem_libraries.html

I know about

XSCHEM_LIBRARY_PATH

but the use case is for project specific symbols, I don't really want to put them in my global

xschemrc

and have them everywhere. So instead I just assumed it would look into current dir which it did as a fallback. But then for a bigger project I wanted some "local" symbols that happened to be maintained in another git repo so I just tried symlinking. So say in a directory I have

main.sch

and next to it, a symlink

sub

to a directory somewhere completely different. And that directory has a

xxx.sym

in it. And in

main.sch

I try to use

sub/xxx.sym

that doesn't work properly. When loading it the first time it works fine and everything is there. But then when I click "netlist" button, it will print

l_s_d(): Symbol not found: sub/xxx.sym

and then it won't work anymore.

@tnt please do this in the xschem terminal and send me the result:

puts $XSCHEM_LIBRARY_PATH

in the session that has problems.

abs_sym_path usb/digital.sym

returns the right path when typed in the console, I tried it when I was looking at how thing worked. But at somepoint it's almost like

$curr_dirname

ends up pointing to

/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/usb/

instead of

/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/

tnt@rei ~/projects/asic/tinytapeout/tt07-diff-rx/xschem $ xschem tt_um_tnt_diff_rx.sch 
open_pdks installation: using /home/tnt/projects/asic/pdk/
SKYWATER_MODELS: /home/tnt/projects/asic/pdk//sky130A/libs.tech/combined
SKYWATER_STDCELLS: /home/tnt/projects/asic/pdk//sky130A/libs.ref/sky130_fd_sc_hd/spice
setup_tcp_bespice: success : listening to TCP port: 2022
% puts $XSCHEM_LIBRARY_PATH
/opt/asic/share/xschem/xschem_library:~/.local/share/xschem/library
% abs_sym_path usb/digital.sym
/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/usb/digital.sym
% l_s_d(): Symbol not found: usb/digital.sym
l_s_d(): Symbol not found: usb/bias_gen.sym
l_s_d(): Symbol not found: usb/diff_rx.sym

%  abs_sym_path usb/digital.sym
/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/usb/digital.sym
% 
tnt@rei ~/projects/asic/tinytapeout/tt07-diff-rx/xschem $ ls /home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/usb/digital.sym -l
-rw-r--r-- 1 tnt tnt 1032 May 28 15:48 /home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem/usb/digital.sym

@tnt what is the content of $XSCHEM_LIBRARY_PATH in your runnng xschem session that has this problem?

See above :

% puts $XSCHEM_LIBRARY_PATH
/opt/asic/share/xschem/xschem_library:~/.local/share/xschem/library

@tnt Thank you. Apologies, I did not see the path at first look :-) add this directory to XSCHEM_LIBRARY_PATH:

/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem

% puts $XSCHEM_LIBRARY_PATH
/opt/asic/share/xschem/xschem_library:~/.local/share/xschem/library:/home/tnt/projects/asic/tinytapeout/tt07-diff-rx/xschem

you can easily do this in the xschemrc file:

append XSCHEM_LIBRARY_PATH :[pwd]

Well yes and no ... that only works if I start xschem from that directory ...

yes, if you want this to work from any directory add the full qualified path.

That's not ideal either, I don't want to put project specific path in my xschemrc. symbol name relative to the schematic they are in is really what I want and it mostly works... expect when I press the "SPICE netlist" button because looking at it it messes with

curr_dirname

and doesn't properly put it back or something ...

@tnt ok, I have pushed a commit to xschem. This new xschemrc variable:

use_pwd_instead_of_current_dirname

will use (if set to 1)

[pwd]

as the base path of referenced symbols (if not found in any of the

XSCHEM_LIBRARY_PATH

paths) instead of the directory of currently loaded schematic (which changes depending on the hierarchy level you are in and will mess up if using a hierarchic netlist command). Update xschem and add this:

set use_pwd_instead_of_current_dirname 1

to your xschemrc file. The default value for this variable is

0

, after some time may be I will flip to

1

as default (if no design breaks as a consequence of this).

It's only used in the top level.

@tnt if you add this to your xschemrc:

append XSCHEM_LIBRARY_PATH :[file dirname [info script]]

it will add the path of the directory where the xschemrc file is read from. This works also if you call xschem from a different directory. PS: no more need to set the

use_pwd_instead_of_current_dirname

variable in xschemrc. I have made the switch and a . in search path is a synonim of [pwd] so this setting is no more needed.