Using Opendbpy.md

Using Opendbpy

First of all, start by importing the module:

import odb

Creating a database

You need to start by creating a database. This database will be linked to all of your calls to opendbpy directly or indirectly from now on.

db = odb.dbDatabase.create()

Reading LEF files

lef = odb.read_lef(db, lef_file_path)
tlef = odb.read_lef(db, tech_lef_file_path)

Note that the lef object contains a reference to db.

You can just extract information from the lef files as follows:

cells = lef.getMasters()
sites = tlef.getSites()

Dealing with Cell Masters

cell = cells[0]

name = cell.getName()
width = cell.getWidth()

Reading DEF files

df = odb.read_def(db, def_file_path)

Getting data from block: Rows, Existing Instances and DEF units

chip = db.getChip() # Note how the db has been affected by the def_read imperatively.
block = chip.getBlock()

rows = block.getRows()
one_micron = block.getDefUnits()
existing_instances = block.getInsts()

Getting data from Rows

The OpenDB row object is not particularly interesting other than for extracting data. placeram creates its own Row object that offers placement functions.

for row in rows:
    [x, y] = row.getOrigin()
    [xMax, yMax] = [row.getBBox().xMax(), row.getBBox().yMax()]
    orientation = row.getOrient()

Interacting with Instances

MASTER_NAME = "sky130_fd_sc_hd__tapvpwrvgnd_1" # for example

row = rows[0] # You do not want to practically place everything on the first row, of course
x = row.getBBox().xMax()
y = row.getBBox().yMax()

# Create new instance
new_instance = odb.dbInst_create(block, MASTER_NAME, "tap_cell_x")

for i in existing_instances + [new_instance]:
    master = i.getMaster()
    width = master.getWidth()
    master_name = master.getName()

    i.setOrient(row.getOrient()) # Set Orientation
    i.setLocation(x, y) # Set X and Y locations of a cell
    i.setPlacementStatus("PLACED") # Set status as placed

    # Let's say we want to not place fill cells, for visual inspection, as an example
    if master_name == "sky130_fd_sc_hd__fill_1": 
        i.setPlacementStatus("UNPLACED") # Set status as unplaced

    x += width

Writing result

odb.write_def(block, output_def_path) # Returns 1 on success

These are all the basics you need to know when using opendbpy.