Virtuoso Schematic Composer User Guide

Creating Schematics

If you want to renumber instances in the your entire library, change the Scope cyclic

field tolibrary.

Renumber Instances

3. Click OK.

Adding Blocks

You can use blocks when you design with a top-down methodology. Blocks let you create a symbol from the context of a higher-level schematic.

You create a block to represent a lower-level cell. As you develop the logic of your higher-level schematic, you can add wires to the block, which automatically creates block pins. After you name the wires, you can rename the block pins so they inherit the connected signal names.

You can automatically generate other views (for example, a schematic, VHDL, or Verilog® representation) for the lower-level block cell.

■Adding Blocks on page 143

■Adding Wires and Pins to Blocks on page 145

■Changing the Block Pin Direction Rule on page 145

■Changing the Direction or Name of a Single Block Pin on page 147

Virtuoso Schematic Composer User Guide

Creating Schematics

■Changing the Names and Directions of Multiple Block Pins on page 148

■Deleting Block Pins on page 150

■Disabling Automatic Block Pin Creation on page 150

Virtuoso Schematic Composer User Guide

Creating Schematics

Adding Blocks

Unlike adding multiple copies of a single instance in a schematic based on a single lib/cell/ view name, the Add – Block command lets you create multiple blocks, each with a different lib/cell/view name.

To add a block, do the following:

1.Choose Add – Block

The Add Block form appears.

2.In the Library, Cells, and View fields, specify the path to the block cellview.

The specified cellview cannot already exist in the library. Only one name (instance) can be entered for each cell. There is a one-to-one correspondence between the entries in the Cells and the Names fields. You can specify multiple cell names by using a space to separate each name. The Cells and Names fields must match in number. If there are more entries in Cells than in Names, the system assigns a name for each. If there are more entries in Names than in Cells, the system ignores the extra names.

3.In the Names field, type instance names using a space as a separator.

The editor generates unique names for you if you leave the field blank.

Virtuoso Schematic Composer User Guide

Creating Schematics

4.In the Pin Name Prefix field, type a new prefix name for the pin or leave the default as pin.

Later, when you add block pins, the system adds numbers sequentially to the prefix name; for example, pin1, pin2, pin3, and so forth.

5.Choose a block from the Block Shape cyclic field.

The freeform option lets you create a rectangular block of any size by entering opposite corners of the rectangle.

mux4 mux8

small

medium

large

alu

freeform

1 by 2

2 by 1

6.Move the pointer into your design.

The block symbol is attached to the pointer unless you chose freeform. You can toggle the block shape before you place it by pressing the right mouse button until you reach the shape you want.

7.Click to place the block in your design.

As you place a block, the system creates the specified block cellview and an instance of that block appears in your schematic.