Having a system to find many similar items in a short amount of time can be helpful in staying organized. Everybody has a silverware drawer and most are organized with caddys that divide the flatware into forks, knives, and spoons. It becomes easy to grab a spoon when you’ve put some soup in the micro to assuage hunger.
Reference designators are the unique identifiers on a PCB for each and every component or free pad on the design. Best design practice is to number the reference designators consecutively on the PCB to allow easy discovery of components. If the arrangement of reference designators is maintained from the schematic, the numbering would be erratic.
Tools to rearrange location of the reference designators on the PCB have been lacking in EDA tools. This has necessitated PCB designers to manually re-annotate layouts during the design process. Manually re-annotating can take days, so many legacy designs have disorderly annotation.
Annotation Cannot Be Done Without a Third-Party Script
PCB designers are left with searching the web to find if colleagues have discovered workarounds. EDA user websites point to third-party apps that will re-annotate your design components. But the re-annotating script contains limitations that require manual manipulation as well. Learning a third-party script without support information becomes difficult as guesswork by trial and error is the only way to limp through the tool.
Third-party apps with their limitations work differently in every layout situation. Working through the limitations is time-consuming with no guarantee that the board will be correctly re-annotated. Painful hours are spent manually manipulating the script and manually relabeling reference designators. Although the PCB is re-annotated the Schematic contains the original designations. This will be a problem during the lifetime of the board when defects are found and reference designators do not match the schematic.
Altium Designer presents mismatches for resolution before annotating
Manual Annotation Required With Limited Features in Script
Although user websites offer third-party apps that will re-annotate your design, all come with restrictions. Taking time to read through the messages results in three possible apps to use. Realizing time needed to try each script leads to project delays. Delays are caused by need to try each script to understand how it can help.
After spending time in third-party scripts with their deficiences, designers may turn to writing Visual Basic scripts. Help pages indicate that manually writing an ECO file could re-annotate but this, too, requires many hours of manual attention to reference designators, their components, and their new locations on the PCB layout. The learning curve eats time and leaves the designer with more takes to fully complete the re-annotation. If errors are encountered on the final ECO they remain the same with no error message to the user.
Annotation Menus Within EDA Tools Eases Job
It would be so much better if the re-annotation tools were available within the EDA design tools. Any change to reference designators would automatically populate the schematic, the layout, and the Bill of Material. Menus would scope the annotation to target components and free pads. Pulldown menus would be familiar with elegant commands allowing choice of starting point, direction of the sequential count, and include additional options.
Information about the annotation would be tabulated showing old vs new designator values. Generation of files using the re-annotation information would be shared with the Schematic editor. By sharing information in a recognizable file format within the tool, other design documents within the container would propage all re-annotations to their respective locations. The Schematic would match the PCB layout and debugging of the boards further along the lifecycle would occur with ease.
Choose and visually display re-annotation scheme in the menu
Altium’s PCB Editor Includes Comprehensive Annotation Tools
Altium’s PCB Editor has a command for re-annotate within the menu and command structure. The menu and the commands are easily accessed with intuitive design built into the environment. Accessing the Positional re-annotate dialog allows the designer to scope the annotation. Scoping allows origination configuration of components to establish a starting point for the re-annotation. Know the tool will operate in a consecutive fashion a direction can be selected. There are additional options as well such as starting index for re-annotations on double-side boards where the standard is to number the back side starting with 101 for each designator. Should the circuit designer have locked specific components these annotations may be protected from resequencing.
The Re-annotation tool generates an ASCII text file showing initial annotations alongside new re-annotated designator values. The text file can be used by Altium’s Schematic editor to match the re-annotation to the layout using the Back Annotate feature. This allows the Schematc and the PCB Layout to be synced, relieving stress downstream when defect efforts occur.
Altium Designer 18 has elegant and thorough tools for annotating reference designators. With generation of an ASCII file the tool provides customization of global properties while maintaining consistency across Schematic, PCB layout, and Bill of Materials. Having consistent annotating across documents enables lifecycle management efficiencies. Annotating consistency allows differing users to be looking at the same component across documents, to ensure communication regards the same part within the design.
Put your components in sequential order with re-annotation tools at your fingertips. If you’d like to know more talk to an Altium expert.
“We switched from PADS to Altium because we needed a EDA solution that would allow real time collaboration with other R&D teams within our organization, something that PADS does not offer. In addition to the collaboration, we found that Altium integrates with SolidWorks much better than PADS integration, therefore improving the accuracy of our models and decreasing our time to market.”
Senior Manager, Engineering at Gibson Brands
About the Author
PCB Design Tools for Electronics Design and DFM. Information for EDA Leaders.More Content by Altium Designer