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Have you checked out the new VSR Preset feature and the related forms in the IC6.1.7 and ICADV12.3 releases? We all have heard how automatic routing has significantly reduced the turnaround time for layout designers. VSR Preset is a bonus from Cadence to further reduce the time required. It is a "Jewel in the Crown" of Automatic Routing.
A VSR preset is a simple and user-friendly mechanism that lets you save all routing options and user override constraints in a text file and reload them with a single click. That's right, there is no need to define the same routing options again. You can directly load the predefined routing options from the text file just by a single click. This ultimately saves time and ensures consistent results.
The VSR Preset feature can be accessed from the VSR Preset toolbar, which is a part of the Virtuoso Space-based Router toolbar, and is available in Virtuoso Layout XL. Alternatively, you can access the VSR Preset options from the Wire Assistant toolbar.
A preset file lets you change the Virtuoso environment variables quickly and easily. It is similar in format to the .cdsenv file and can be manually edited using a generic ASCII text editor. The VSR Preset file lets you save and restore the router-related environment variables not only for Pin to Trunk routing, but also for other automatic routing commands. The beginning section of a sample VSR Preset is shown below.
Note: Each preset is stored as an individual text file. These text files are easy to understand, edit, and can be shared with a specific user, for a specific project, or at an organization level.
The VSR Save Preset form is displayed when you click the VSR Save Preset icon. The form lets you save the modified override constraint values and the automatic routing and interactive routing environment variables to a preset file. The steps to save a preset file are as follows:
Open a layout design in Layout XL.
Open the Wire Assistant.
Specify the desired automatic and interactive routing options in the Wire Assistant.
Note: To add the saved preset as an icon on the VSR Preset toolbar, select the Create Toolbar Icon check box in the VSR Save Preset form. For more information, see Saving a Preset File.
After saving the file, load the preset file to set the specified routing options.
On clicking the VSR Load Preset icon, the preset files found in the preset search paths are searched and loaded. Also, the list of available VSR presets is refreshed and the last preset file, if any, is reloaded. Preset files are searched and loaded in the following order.
To load a particular preset file on startup, specify the following command:
ia presetDefaultFile string "file.preset"
The first file that is found with the specified name in the search path gets loaded.
Note that, by default, when a preset file with errors is encountered, it will fail to load. When this happens:
A window with the detail of errors is displayed.
Any settings or overrides loaded from the preset file are not considered and the previously specified settings remain as is.
Any SKILL procedures in the preset file do not get executed.
To avoid this and allow preset files to be shared between different users and projects, you can specify that the errors and inconsistencies in the file are ignored on loading. To do this, set the following environment variable:
ia presetLoadMode cyclic "setting"
Setting the environment variable lets you partially load the preset file and skip the lines with errors.
Clicking the VSR Delete Preset icon lets you delete a preset file. When you click Delete, the preset file is actually not deleted but is only renamed and saved as <file-name>.presetDeleted. As a result, it is possible to restore a deleted preset file and use it later. In case you do not have permissions to delete the preset file, the Delete button is disabled.
On clicking the Reset VSR Options button, based on the selected option, the routing settings are set to the respective .cdsenv default value.
The function of the Reset button can be customized.
"A" mode clears both constraint overrides and all VSR options.
"C" mode clears only constraint overrides.
"O" mode clears only VSR options.
Expert users can edit the preset file to execute SKILL after the settings in the preset file are loaded. Locate the [postcmd] keyword in the .preset file, and insert the SKILL function name between the quotes as shown below:
;; [postCmd]: "mySkillFunction()"
A preset, which executes SKILL is displayed in the drop-down list with an asterisk (*), and the icon text is displayed in blue, as highlighted in the figure below.
Introduction to Presets
Virtuoso Space-based Router User Guide
Virtuoso Space-based Router Preset Toolbar
Saving a Preset File
Loading a Preset File
Deleting a Preset File
VSR Save Preset Form
VSR Delete Preset Form
Virtuoso Layout Suite SKILL Reference Manual
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