[Xcircuit-dev] Re: XCircuit - update

[R. Timothy Edwards]

Dear Oliver,

> My actual problem is: Is it possible to associate a symbol(Object) from one library with an symbol(Object) from another library?
> e.g. :  I want to use a logic-symbol like a AND (box with &, 2In,1Out) as a Symbol for a schematic out of cmos-transistors.
> When I understood it right, this association is only aktive in that session, so I have to save it as a XCIRCUIT-file.
>  In order to design some logic (Symbols for the actual schematic out of CMOS) I would have to load that certain file!?
> 
> ->It would be good to only have to load the two libs where the association is aktive and to just drag and drop the logic-symbols...

I think what you're looking for is covered by xcircuit version 3.6, which
was designed especially for dealing with hierarchies and libraries and
multiple files.  Unfortunately, I have not yet written a tutorial for it.

There are two ways to do this in xcircuit 3.6:

1) If the schematics are simple, you have a netlist (e.g., SPICE file)
    for each logic gate, and you don't really need to see or edit the
    transistor-level schematic, then the best way to handle it is to
    put an info-label in each symbol pointing to the netlist, e.g.,

    spice at 1:%Fstandard_cells.cir

    The "@1" ensures that the contents of standard_cells.cir are placed
    at the top of the output spice deck, and the "%F" ensures that the
    file is included only once in the output spice deck.  There should
    also be another info label in the cell declaring how to write the
    device to the SPICE deck, e.g.:

       spice:X? dvdd dgnd %pA %pB %pY NAND2

    where "dvdd" and "dgnd" are parameters of the cell (so they can
    be set to different strings, but are not pins on the symbol), and
    the "?" is the standard parameter "idx" that is the component
    number.

2) If you are drawing the schematic for each symbol, then the schematic
    should be in a separate file or files, and the symbol should have
    a parameter called "link" whose value is the name of the schematic
    file (normally without the ".ps" extension).  When you want to
    generate a SPICE file, choose "File->Load Dependencies" from the
    menu, which will load in all of the subcircuit schematics used by
    the top-level circuit.  I usually do this step with a shell script:

    #!/bin/tcsh
    xcircuit -nowindow -noconsole <<EOF
    page load $1 -replace
    while {[page links load -replace]} {}
    netlist write spice false
    quit
    EOF

I will send you an example symbol library.  However, I am CC'ing this
message to xcircuit-dev, since right now it is the only information
about how to use xcircuit-3.6, so I'll send the library in a separate
email.  Hopefully I will get around to writing the tutorial soon.

					Regards,
					Tim

+--------------------------------+-------------------------------------+
| Dr. R. Timothy Edwards (Tim)   | email: tim at opencircuitdesign.com    |
| Open Circuit Design, Inc.	 | web:   http://opencircuitdesign.com |
| 22815 Timber Creek Lane        | phone: (301) 528-9364               |
| Clarksburg, MD 20871-4001      | cell:  (240) 401-0616               |
+--------------------------------+-------------------------------------+


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