Using Electric 3-12: Automatic View Generation

Chapter III: HIERARCHY

| ## 12: Automatic View Generation |

Electric has facilities for automatically converting from one view to another. When converting the current facet, the newly generated facet is shown in a new window.

### Conversion between Layout and Schematic

To convert from IC layout to a schematic, use the Make Schematic command of the View menu. This builds a new facet using analog schematic parts that are equivalent to the IC components in the current facet. If there is already a schematic view of the current facet, a new version of that view is created.

To convert between different IC layout technologies or from schematics to layout, use the Make Layout command of the View menu. You will be prompted for the technology to use for the new facet. If both the current and the new facet are of the Layout view, the new facet becomes a newer version. Conversion between layout technologies is useful when the fabrication process or design rules have changed, but it can only be done within a similar family of technologies, i.e. between CMOS technologies. When converting from schematics to layout, all wires appear as Universal Arcs from the Generic technology. These must be converted to layout manually.

### Skeletonization

The Make Skeleton command of the View menu converts the current facet into a new, skeleton view. Skeleton facets contain only the important parts (the nodes with exports and a few others that define the boundary). When skeletonizing, the new facet has information stored on it that points to its original facet, so that it can be restored to its complete geometry later. (At this time, no automatic facilities exist for restoring skeleton facets. Use the Change... command of the Edit menu and select the nonskeleton facet.) Skeletonizing is useful when libraries get to be very large, for they allow entire levels of hierarchy to be abstracted, with their actual contents kept in another library.

### Icons

A particularly useful view type is icon. The icon facet is used for instances of an associated contents facet, which contains schematics. For example, you may have a facet called "adder{sch}" which contains a schematic. You may then create a facet called "adder{ic}" that contains a circle with a plus sign inside (these are nodes in the Artwork technology). This is then the icon for the layout facet "adder{sch}". Now, if you create an instance of the schematic facet, the icon facet will actually be placed, because it is the symbol that gets used for instances.

To automatically generate an icon facet, use the Make Icon command of the View menu. Be sure to create all relevant exports before issuing this command, so that the proper icon can be constructed. Note that any export that has its "Body only" attribute checked will not be placed in the icon.

To control the look of the icons, use the Icon Options... command of the View menu. This command lets you place each of the different export types on any of the four sides of the icon. You can choose the location of the exports (at the end of the leads, in the middle of the leads, or on the body). You can choose the style of the export text (whether it grows inward, outward). You can choose whether or not to draw the leads and the body of the icon. Finally, you can control whether or not the icon has a Facet-Center in it (see Section 3-3 for more on Facet centers). |

The icon facet is correctly tied to its contents in most respects. If you descend into it (with the Down Hierarchy command of the Facets menu), then you actually find yourself editing the associated contents facet. The Up Hierarchy command properly returns you to the location of the icon instance. Also, the network consistency checker and the simulators correctly substitute the contents whenever an icon appears. In order for this to work, however, all exports on the contents facet must exist with the same name in the icon facet.

### VHDL

The Make VHDL command of the View menu converts the current facet into a VHDL textual description. All subfacets used in the current one are also converted. By default, the VHDL is placed in facets with the "vhdl" view. However, by unchecking the "VHDL stored in facet" item of the VHDL Options... dialog (in the VHDL Compiler subcommand of the Tools menu), the VHDL will be placed in individual disk files. Recheck the entry to place VHDL in facets again. See Section 9-10 for more on Electric's VHDL facility.

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