Chapter 3: Hierarchy
3-9-2: Reading Libraries
The Open Library... command (in menu File) brings a new library into Electric from disk.
These libraries may have the extension ".elib", ".jelib", or ".delib" (the jelib format is the default,
see Section 10-1).
There is also a Open Recent Library entry that lists all recently opened libraries.
You can also use the open-library icon from the tool bar.
Electric users with very old ".elib" files may have difficulty reading them into Electric.
If you have been using versions of Electric prior to 7.00, it may help to upgrade to that version and read the libraries.
Saving ".elib" files from version 7.00 will work properly in the current system.
By default Electric searches for libraries in the working directory,
absolute file path references, and Electric's internal library directory.
Users can specify additional directories to search by using a file called
"LIBDIRS" placed in the working directory.
This file specifies additional paths to search for library files.
The file has the following syntax:
Paths may be absolute or relative.
Besides Electric libraries,
it is possible to read circuit descriptions that are in other formats with these commands in the File / Import menu:
- CIF (Caltech Intermediate Format) is used to describe integrated circuit layout.
It contains no connectivity, so after the library is read, it does not know about transistors and contacts:
You can use the node extractor to convert CIF to real Electric components
(see Section 9-10-2).
To affect how CIF is read, use the CIF Preferences (in menu File / Preferences..., "I/O" section, "CIF" tab).
See Section 7-3-2 for more on CIF.
- GDS II (Stream)... and GDS II (Stream) Skeleton are used to describe integrated circuit layout.
The Skeleton version of the command reads only a skeletonized version of the top-level cell
(bounding box and exports, no other content, see Section 3-11-2).
This skeletonized cell also has a pointer back to the original GDS file so that when it is written to disk,
the full GDS can be merged back in.
GDS contains no connectivity, so after the library is read, it does not know about transistors and contacts: just layers.
You can use the node extractor to convert GDS to real Electric components
(see Section 9-10-2).
To affect how GDS is read, use the GDS Preferences (in menu File / Preferences..., "I/O" section, "GDS" tab).
See Section 7-3-3 for more on GDS.
- EDIF (Electronic Design Interchange Format) is used to describe both schematics and layout.
Electric reads EDIF version 2 0 0.
Use the EDIF Preferences (in menu File / Preferences..., "I/O" section, "EDIF" tab) to affect how EDIF is read
(see Section 7-3-4).
- LEF (Library Exchange Format) is an interchange format that describes the cells in a library.
The cells that are read in contain ports, but very little contents.
- DEF (Design Exchange Format) is an interchange format that describes the contents of a library.
DEF input often makes use of associated LEF files which must already have been read.
Use the DEF Preferences (in menu File / Preferences..., "I/O" section, "DEF" tab) to affect how DEF is read
(see Section 7-3-5).
- DXF (AutoCAD) is a solid-modeling interchange format, and so it may contain 3D objects that cannot be read into Electric.
Nevertheless, Electric creates a library of artwork primitives as well as it can.
Use the DXF Preferences (in menu File / Preferences..., "I/O" section, "DXF" tab) to affect how DXF is read
(see Section 7-3-7).
- SUE (Schematic User Environment) is a schematic editor that captures a single cell in each file.
The circuitry in SUE files is added to the current library instead of being placed in its own library
(because many SUE files may have to be read to build up a single Electric library).
When reading a SUE file, any subdirectories that start with "suelib_" will also be examined for dependent
Use the SUE Preferences (in menu File / Preferences..., "I/O" section, "SUE" tab) to affect how SUE is read
(see Section 7-3-8).
- Gerber is a printed-circuit board artwork format.
Use the Gerber Preferences (in menu File / Preferences..., "I/O" section, "Gerber" tab) to affect how Gerber is read
(see Section 7-3-9).
- Spice Decks are input to the Spice simulator and define a netlist of circuitry.
See Section 9-4-3 for more on Spice.
Reading Spice Decks will create wired instances, but the placement of the instances will be automatically
generated because that information is not in the Spice deck.
- Applicon 860 is a layout format from old Applicon EDA systems.
- Bookshelf is an open format for specifying placement tasks.
- Verilog is a hardware description language used for simulation and fabrication.
Electric reads the Verilog file and constructs a schematic representation.
Because there is no placement in Verilog files, the schematic is topologically correct, but visually messy.
- ELIB is an older Electric library format that is in an undocumented binary format.
- Readable Dump is an older Electric library format that captures the entire database in a text-readable format.
These files were used when the ".elib" file was the main way of saving libraries, because a way was needed of reading
Now that the newer ".jelib" format is also text-readable, there is no need to use Readable Dumps anymore.
- Text Cell Contents is used to read a text file into a text cell.
The current window must be a textual view (such as VHDL, Verilog, documentation, etc.)
See Section 4-9 for more on text windows.
Some file formats (CIF, GDS, EDIF, LEF, DEF, SUE, and Applicon 860) are technology-specific.
Before reading them, you will be prompted for the layout technology to use.
The default is to use the current technology.
If you import a library that already exists in Electric,
the following warning appears:
You can save the previous library, overwrite the previous library, cancel the operation,
or merge the new library into the previous library.
The "Merge" option creates new versions of cells when the names conflict,
producing a library that has both the previous and new contents in it.