Virtuoso Schematic Composer User Guide

Automatically Creating Cellviews

6. Click Yes.

Modifying an Existing Symbol Cellview

You can replace or modify existing symbol cellviews. You can only replace (not modify) all other types of existing cellviews.

1.In the schematic editor, choose either Design – Create Cellview – From Cellview or

Design – Create Cellview – From Pin List.

2.Click OK.

If the symbol cellview to be created already exists, the Create Cellview dialog box appears.

Modifying a symbol cellview does the following:

Automatically edits the cellview with a minimal amount of changes to the current pin locations, graphics, and properties within the symbol cellview

Deletes pins that are no longer needed

Adds pins that do not yet exist in the new cellview

Pins are added near the bottom of the cellview. Use the symbol editor to reposition these new pins and to adjust any symbol graphics. The system determines attributes of the new pins by the currently active TSG template file.

Adds or updates cellview properties and terminal properties

Annotates the changes that were made in note format at the bottom of the cellview and in the Command Interpreter Window (CIW)

Virtuoso Schematic Composer User Guide

Automatically Creating Cellviews

Does not delete cellview or terminal properties

3.Click Modify.

The symbol cellview is automatically edited and saved.

The Overwrite Base Cell CDF dialog box appears.

4.Click Yes to update the base cell CDF with new simInfo port information. See Figure 6-3 on page 273.

Examples of Replacing and Modifying Pins on a Symbol

The following three figures show the difference between choosingReplace and Modify.

■Figure 6-1. The symbol

■Figure 6-2. The symbol after choosing Replace

■Figure 6-3. The symbol after choosing Modify

Figure 6-1 illustrates an original symbol that was created using Design – Create Cellview

– From Cellview from a schematic that had the pins { a bb ccc dddd eeeee f gg hhh iii k ll mmm }.

The following changes were then made to the schematic:

■Deleted input pin bb

■Deleted inputOutput pin iii

■Added input pins wwwwww and zz

Virtuoso Schematic Composer User Guide

Automatically Creating Cellviews

■Added inputOutput pin ii

All three figures show pina at the exact same location, (X,Y) = (0,0) which is the symbol’s origin point. By default, TSG puts the top-most left pin at the origin of the symbol.

Figure 6-1 The Symbol

Figure 6-2 The Symbol after Choosing Replace

After a Replace, only pin a is in the exact same position as the original pins. All other unaffected pins are in new locations for the following reasons:

■Pins ccc, dddd, and eeeee have moved up by one grid space, which was freed up by the deletion of pin bb.

Virtuoso Schematic Composer User Guide

Automatically Creating Cellviews

■Although the ordering and number of pins along the top is similar to the original (with new pin ii replacing pin iii), all four top pins have moved down by one-half a grid (due to the shorter label).

■Due to the length of new or deleted pin names, the graphic has been recalculated in size accordingly.

Figure 6-3 The Symbol after Choosing Modify

The modified cellview has all of the unaffected pins{a ccc dddd eeeee f gg hhh k ll mmm} at their original locations. The new pins {wwwwww, zz, ii} have been placed at the bottom of the cellview, outside of the bounding box of the original symbol. The pin and pin names {bb, iii} have been deleted, but the graphic pin line (pin stub) remains to show the position of the pins that were deleted. If necessary, you can delete these graphic pin lines using the symbol editor. Also shown is the note used to describe the changes that were made to the symbol.