PCB Design Blogs

Design rule checks are essential to ensure the functionality, reliability, and manufacturing yield for a design.  You run DRCs several times during the design cycle to validate the design. If I say auditing design rules is an intense and time-consuming exercise, you will definitely agree with me. To deal with design DRCs, layout editors provide multiple commands and interfaces ─ indeed a tiresome way. If you are looking for a better solution, try the DRC browser, an advanced built-in utility available with all Allegro® layout editors.

DRC Browser lets you review and address DRCs in a design. You can review both internal and external design rule violations in DRC Browser. For each DRC type, the browser displays the description, image, DRC code, and other details. DRC Browser provides real-time feedback on the type and number of errors, and dynamically updates this data as issues are corrected or introduced while editing the design. The browser UI is intuitive and displays DRCs in a spreadsheet format that supports basic operations such as, column resizing, column reordering, sorting, filtering, zoom in, and out using mouse controls.          

Violations of each type are organized as a list and are represented in a pre-defined color scheme. When you select any row, the browser locates the DRC in the design and highlights its DRC marker keeping the rest of the design objects in dim mode. The status of the error changes from Unread to Read and so does its color.     

DRC Browser is convenient when you are interested in a specific area of design, let's say the flex part of your rigid-flex design. For speedy analysis, enable the Filter by Area checkbox to be able to grab the screen area using the window select method. DRCs are computed only for the selected area and the browser now only lists DRCs that are in that area. When DRCs are fixed in the selected region you can move on by clicking the Clear Area button.

Scanning DRCs Using Charts

You can also analyze the volume of DRCs through graphical representation in the form of bar and pie charts. The Show DRC Chart option opens DRC Charts where DRCs are displayed in assorted colors for different domains. Based on the severity of the DRC violation you can prioritize what errors are to be fixed first.

Click on the individual segment of the chart to drill down to the lowest level of the DRC category, for example, Line to Line. Charts at the DRC list level lets you filter the results further using an incremental slider. Drag the handle to select the numeric values for a more focused review.

Waiving DRCs in DRC Browser

If any violation is acceptable and meets design requirement, you can waive that DRC. The option is available on right-click, and you can attach an explanatory comment to ensure that those working on the design understand the rationale behind the waiver. DRCs when waived are labeled Waived DRC in the spreadsheet along with associated comments. You can also set the DRC status as Mark DRC as Review for further review, as a reminder. You can view these DRCs at any time using the Review filter.

Navigating in DRC Browser

Navigating through different DRC types can be done in multiple ways. The breadcrumb navigation path, available at the top of the UI, lets you move along the most recent DRC domain path. The DRC tree displayed in the left pane of the browser UI lists the total number of DRCs for all domains, down to the list of DRC locations. The navigation list available in the right pane of the browser lets you select rows and navigate down to the list of DRC locations. You can also traverse DRCs in the different DRC domains by selecting a segment of the DRC chart.

Filtering in DRC Browser

Filtering DRCs by the state can be done using radio buttons: All, Unread, or Review. In the spreadsheet, numeric filters are available with each column. You can also filter the DRC Chart using the sliding bars to filter the DRCs between maximum and minimum values for the DRC list display.

Customizing Display Options

The Options button provides controls to change the display and crossprobing modes and to restore the default settings in the browser window.

That is all about DRC Browser. Working with DRCs is no longer a tedious task! Any operation with DRC is possible in this singular environment that reflects the updated status in real-time. I am sure you will like this solution as much as I like it. I would love to hear about your experience. Do share your feedback to make DRC Browser more useful and intuitive in future versions!