README.md

ioPlacer

Place pins on the boundary of the die on the track grid to minimize net wirelengths. Pin placement also creates a metal shape for each pin using min-area rules.

For designs with unplaced cells, the net wirelength is computed considering the center of the die area as the unplaced cells' position.

Commands

Place All Pins

Use the following command to perform pin placement:

place_pins [-hor_layers <h_layers>]
           [-ver_layers <v_layers>]
           [-random_seed <seed>]
           [-exclude <interval>]
           [-random]
           [-group_pins <pins>]
           [-corner_avoidance <length>]
           [-min_distance <distance>]
           [-min_distance_in_tracks]

• -hor_layers (mandatory). Specify the layers to create the metal shapes of pins placed in horizontal tracks. Can be a single layer or a list of layer names.
• -ver_layers (mandatory). Specify the layers to create the metal shapes of pins placed in vertical tracks. Can be a single layer or a list of layer names.
• -random_seed. Specify the seed for random operations.
• -exclude. Specify an interval in one of the four edges of the die boundary where pins cannot be placed. Can be used multiple times. The interval is defined in microns.
• -random. When this flag is enabled, the pin placement is random.
• -group_pins. Specify a list of pins to be placed together on the die boundary.
• -corner_avoidance distance. Specify the distance (in microns) from each corner within which pin placement should be avoided.
• -min_distance distance. Specify the minimum distance between pins on the die boundary. This distance can be in microns (default) or in number of tracks between each pin.
• -min_distance_in_tracks. Flag that allows setting the min distance in number of tracks instead of microns.

The exclude option syntax is -exclude edge:interval. The edge values are (top|bottom|left|right). The interval can be the whole edge, with the * value, or a range of values. For example, in place_pins -hor_layers metal2 -ver_layers metal3 -exclude top:* -exclude right:15-60.5 -exclude left:*-50 three intervals are excluded: the whole top edge, the right edge from 15 microns to 60.5 microns, and the left edge from its beginning to 50 microns.

Place Individual Pin

place_pin [-pin_name <pin_name>]
          [-layer <layer>]
          [-location <{x y}>]
          [-pin_size <{width height}>]

The place_pin command places a specific pin in the specified location, with the specified size.

• -pin_name option is the name of a pin of the design.
• -layer defines the routing layer where the pin is placed.
• -location defines the center of the pin (in microns).
• -pin_size option defines the width and height of the pin (in microns).
• -force_to_die_boundary. When this flag is enabled, the pin will be snapped to the nearest routing track, next to the die boundary.

It is recommended that the placement of individual pins be done before the place_pins command, as the routing tracks occupied by these individual pins will be blocked, preventing overlaps.

Pin Constraints

Set IO Pin Constraint

The set_io_pin_constraint command sets region constraints for pins according to the pin direction or the pin name. This command can be called multiple times with different constraints. Only one condition should be used for each command call.

The -direction argument is the pin direction (input, output, inout, or feedthrough). The -pin_names argument is a list of names. The -region syntax is the same as that of the -exclude syntax.

The -mirrored_pins argument is a list of pins that sets pairs of pins that will be symmetrically placed in the vertical or the horizontal edges. The number of pins in this list must be even. For example, in set_io_pin_constraint -mirrored_pins {pin1 pin2 pin3 pin4 pin5 pin6}, the pins pin1 and pin2 will be placed symmetrically to each other. Same for pin3 and pin4, and for pin5 and pin6.

The -group flag places together on the die boundary the pin list defined in -pin_names, similar to the -group_pins option on place_pins command. The -order flag places the pins ordered in ascending x/y position.

Note that if you call define_pin_shape_pattern before set_io_pin_constraint, the edge values are (up, top, bottom, left, right). Where up relates to the layer created by define_pin_shape_pattern. To restrict pins to the pin placement grid defined with define_pin_shape_pattern use:

• -region up:{llx lly urx ury} to restrict the pins into a specific region in the grid. The region is defined in microns.
• -region up:* to restrict the pins into the entire region of the grid.

set_io_pin_constraint -direction <direction>
                      -pin_names <names>
                      -region <edge:interval>
                      -mirrored_pins <names>
                      -group
                      -order

Define Pin Shape Pattern

The define_pin_shape_pattern command defines a pin placement grid on the specified layer. This grid has positions inside the die area, not only at the edges of the die boundary.

define_pin_shape_pattern [-layer <layer>]
                         [-x_step <x_step>]
                         [-y_step <y_step>]
                         [-region <{llx lly urx ury}>]
                         [-size <{width height}>]
                         [-pin_keepout <dist>]

• The -layer option defines a single top-most routing layer of the placement grid.
• The -region option defines the {llx, lly, urx, ury} region of the placement grid in microns.
• The -x_step and -y_step options define the distance (in microns) between each valid position on the grid, in the x- and y-directions, respectively.
• The -size option defines the width and height (in microns) of the pins assigned to this grid. The centers of the pins are placed on the grid positions. Pins may have half of their shapes outside the defined region.
• The -pin_keepout option defines the boundary (in microns) around existing routing obstructions that the pins should avoid; this defaults to the layer minimum spacing.

Face-to-Face direct-bonding IOs

The define_pin_shape_pattern command can be used to place pins in any metal layer with the minimum allowed spacing to facilitate 3DIC integration of chips using face-to-face packaging technologies. These technologies include micro bumps and hybrid bonding for high density face-to-face interconnect.

Clear IO Pin Constraints

The clear_io_pin_constraints command clears all the previously-defined constraints and pin shape patterns created with set_io_pin_constraint or define_pin_shape_pattern.

clear_io_pin_constraints

Pin dimension

Set Pin Length

The set_pin_length command defines the length of all vertical and horizontal pins.

set_pin_length [-hor_length h_length]
               [-ver_length v_length]

• The -hor_length option defines the length (in microns) of the horizontal pins.
• The -ver_length option defines the length (in microns) of the vertical pins.

Set Pin Extension

The set_pin_length_extension command defines the an extension of the length of all vertical and horizontal pins. Note that this command may generate pins partially outside the die area.

set_pin_length_extension [-hor_extension h_extension]
                         [-ver_extension v_extension]

• The -hor_extension option defines the extension length (in microns) for the horizontal pins.
• The -ver_extension option defines the extension length (in microns) for the vertical pins.

Set Pin Thick Multiplier

The set_pin_thick_multiplier command defines a multiplier for the thickness of all vertical and horizontal pins.

set_pin_thick_multiplier [-hor_multiplier h_mult]
                         [-ver_multiplier v_mult]

• The -hor_multiplier option defines the thickness multiplier for the horizontal pins.
• The -ver_multiplier option defines the thickness multiplier for the vertical pins.

Example scripts

Regression tests

Limitations

External references

• This code depends on Munkres.

FAQs

Check out GitHub discussion about this tool.

License

BSD 3-Clause License. See LICENSE file.