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What's Good About DEHDL’s Constraints Comparison? The Secret's in the 16.6 Release!

Comments(0)Filed under: PCB design, Constraint Manager, Allegro, PCB Editor, Schematic, property, PCB, Allegro Design Entry, layout, design, Constraint-driven PCB Design flow, Grzenia, Allegro 16.6, 16.6, constraint databases, constraint difference

The Allegro 16.6 Design Entry HDL release provides designers a mechanism to compare two databases for constraint differences. The databases that can be compared are of the following types:
• Schematics (.cpm)
• Layout design (.brd, .sip, .mcm)
• Constraints Manager Database (.dcf, .tcf)

The Constraint Comparison Utility can be used for comparing two different revisions/versions of the schematic or board databases. This utility can also be used for comparing the schematic database with the board database. A report is generated as a result of the comparison and lets you see all the changes which have been made to the design database since it was last synced up. This report helps you ensure that none of the constraints are conflicting and thus might overwrite on sync up.

The utility can be integrated in any of your design flows where you feel that you need to see the constraints differences in two databases before proceeding further in the design.
The utility can be invoked from the command line using command cmDiffUtility. This command launches the Cadence Constraints Differencing Utility dialog box, as shown below, where you can specify the two databases which need to be compared for constraints differences:



The   button (browse) can be used to select the database. Once you click this button, the file selection dialog box appears. This dialog box displays the files based on the file type filter. By default the filter is set to “Constraints Files (*.dcf, *.tcf)”.

You can select any of the following options to change the filter setting and select appropriate databases:


Once both the databases are selected, the “Compare Files” button is enabled. Click this button to start the database comparison. The results of comparison between the two databases are reported in a Firefox window:


The report is displayed as a single screen, with two frames – left frame containing the object tree and the right frame containing the details of the selected tree item.

The complete report contains hyperlinks and helps in navigating through any of the objects within the various tools – Design Entry HDL, Allegro PCB Editor, Constraint Manger. When you click a category in the tree in the left frame, the details containing lists of all the objects of that category are opened in the right frame. These details contain the object name and brief description of the changes observed.

All the object names are also hyperlinked. You can click any of the objects to view more details. The object names are also visible in the tree view in the left frame, and the detailed view can also be opened by selecting the object name there. Since the different object categories are listed in the tree view, you will notice that you can navigate to the same difference from multiple places. 

Please share your experiences using this new feature.

Jerry “GenPart” Grzenia


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