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Test points are placed on a PCB during the design process to ensure (some might say ‘test’) that the design performs as intended and provides the desired output. Test points also help ensure that the integrity of the component assembly process is not compromised.
A test point is a small area of exposed copper that is contacted by a probe. Test points provide the capability to program, test, calibrate, and set up the PCB Assembly during manufacturing. Allegro® PCB Editor supports simulating test points, which facilitates digital testing of your designs.
After routing the board, you can use the testpoint command to add test points to your design. Only certain elements in a design can be defined as test points, including vias, through pins, and cline segments. The elements that are not eligible for use with the command generate a warning and are ignored.
You can assign test points to the front, back, or both sides of the design. Multiple vias or a particular via can be defined as a test point. Additionally, a grid of vias can be used as test points as well, where you can specify a minimum spacing between the vias. If you do not specify a testpoint, Allegro PCB Editor chooses certain vias to be used as test points based on user-defined or default parameters when the command is run.
You can configure Allegro PCB Editor to place test points automatically in a design.
Use one of the following ways to facilitate automatic placement of testpoints:
Perform the following steps to generate test points automatically in a design:
You can also run the command directly from the command line by defining the constraints in the Allegro Command window. Use the following syntax:
testprep automatic (‘parameter name’ ‘value’)
For example, to create test points for all the nets by using the via, TSTVIA on the BOTTOM layer of a design with a minimum center-to-center spacing of 50 mils, run the following command:
testprep automatic (side back) (center_center 50) (use_via TSTVIA)
Note: Use the testprep automatic command only after routing is completed so that the vias do not contribute to routing channel congestion during the rip-up and reroute operations. Use the clean command after the testprep automatic command to minimize T-junctions and remove excess vias.
After this command is run, test points are generated in the design that you can use to track performance and efficiency during test simulations.
You can also add test points to your design manually. Follow these steps to add a test point to a design:
Test points are instrumental in validating design and routing integrity and help ensure that your design efforts produce the desired results. Test points in Allegro PCB Editor help you test the functionality of your designs digitally, ensuring that the PCB Assembly can be physically tested after manufacturing and optimizing the design process.
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The BoardSurfers series provides solutions to the various tasks related to the creation and management of PCB design using the Allegro platform products. The name and logo of this series are designed to resonate with the vision of making the design and manufacturing tasks enjoyable, just like surfing the waves. Regular, new blog posts by experts cover every aspect of the PCB design process, such as library management, schematic design, constraint management, stackup design, placement, routing, artwork, verification, and much more.