PADRING - a padring generator for ASICs

This tool makes padrings for ASICs using a LEF file and a placement/configuration file. The padrings can be output in GDS2, DEF and/or SVG format. Check out the example in the example directory.

Commandline options

• -h : show help.
• -L, --lef <filename> : mandatory, filename of LEF file that describes the ASIC cells.
• --svg <filename> : optional, filename of SVG to generate.
• --def <filename> : optional, filename of DEF to generate.
• --ver <filename> : optional, filename of Verilog to generate. Useful to instance in verilog-driven netlist.
• --csv <filename> : optional, filename of CSV to generate. Useful to import in Excel sheets.
• --filler <prefix> : optional, filler cell prefix string to use when searching for filler cells.
• -o, --output <filename> : optional, filename of GDS2 to generate.

The filler cells are auto-detected by the padring program. Should this process fail, the user can add an explicit prefix which will be used to find the filler cells.

Multiple LEF files can be specified. During loading, existing cells with the same name will be overwritten.

Configuration file

The following commands are available:

DESIGN <name> ;

• Sets the name of the design in the GDS2/DEF output file.
• Optional
• Default = PADRING

GRID <grid size> ;

• Sets the placement grid size in microns.
• Optional
• Default = 1 micron

AREA <width> <height> ;

• Defines the chip size in microns.
• Mandatory

CORNER <instance_name> <location> <cell_name> ;

• instance_name: name of the corner instance, i.e. corner_1.
• location: location of the corner, one of NE,SE,NW,SW.
• cell_name: name of corner cell from the cell library.

LOC <location> ;

• Hints the location of the next batch of PADs.
• Optional. Calling PAD with specific location have the same effect.
• Useful to assign the fillers for a single domain before filling from CORNER.
• Useful to give zero-space or given-space after the designed CORNER.
• location: location of the next pads, one of N,S,E,W.
• NOTE: N (for north) goes left -> right
• NOTE: S (for south) goes left -> right
• NOTE: W (for west) goes down -> up
• NOTE: E (for east) goes down -> up

FILLER <instance_names> ;

• At given moment, the filler list will be replaced with these instance names.
• This command overrides the --filler option.
• Useful to use different filler groups. You can use FILLER command to change the fillers at any given time.
• Recommend to call before LOC to have a default filler list.
• instance_names (Separated by space): Use these instances as fillers.

PAD <instance_name> <location> [FLIP] <cell_name> ;

• Instances a PAD. Can be used also for CUT cells.
• instance_name: name of the pad instance, i.e. gpio_1.
• location: location of the pad, one of N,S,E,W.
• optional 'FLIP': flips cell in Y axis.
• cell_name: name of pad cell from the cell library.
• NOTE: If needed to do CUT, use this PAD command instead.

BOND <instance_name> [FLIP] <cell_name> [AFTER] ;

• Instances a BOND. This instance will be put on/outside the previous called PAD.
• instance_name: name of the pad instance, i.e. bd_gpio_1.
• optional 'FLIP': flips cell in Y axis. Call this if the bond needs to be put outside the PAD instead of above.
• cell_name: name of pad cell from the cell library.
• optional 'AFTER' (in microns): The BOND will be located 'AFTER' microns from the location of previous called PAD.

SPACE <space> ;

• space: the space between the preceeding and succeeding cell, in microns.

Space between the I/O pads is distributed evenly unless a specific space between two pads is specified directly using the SPACE command.

Building

Dependencies:

• CMAKE 3.10 or better.
• Ninja build.
• C++17 capable compiler.
• Optionally: Doxygen.

Building:

• Run bootstrap.sh to initialize the CMAKE/Ninja build system.
• Run ninja from the build directory.