You’ve heard it said: “there’s no school like the old school.” Is that always true though? When I was a kid my “old school” taught me to type on a typewriter, not a word processor. If I was using that old school typewriter today, it would take me significantly longer to write this article. I wouldn’t have access to spell checking or any of the other helpful utilities that I’ve become accustomed to. I wouldn’t be able to easily backspace and re-write sections, and I would go through reams of paper in a week. “Old school” wisdom is certainly more precious than gold, but old school techniques are not always as such.
Take for instance the connectivity data that you work within your PCB design application. Your schematic capture tools will contain all the nets of your design, and then your layout tools will use that data for you to design the board with. The key is getting that net data from the schematic to the layout tools, and then back into the schematic again. You may not realize the amount of difficulty that the old school method took to transfer this data from one tool to the other. Even now in some design tools, this can still be a difficult operation.
Memory lane is always fun to walk down; however, even more, fun when it is showing exactly how much more painful a process was before it got to the point it is at now. The best modern schematic to board synchronization software will streamline the process for you now, but that wasn’t always the case. These old school techniques were painful, but you can do and benefit more with the modern approach of schematic to layout synchronizations.
Working with a Netlist
Back in the old school days, there were a lot of different schematic capture applications in use as well as different layout tools. Although some of these tools were packaged together, it was much more common to use a combination of tools from different vendors. This would force you into extracting a netlist from the schematic application in order to get connectivity data into a different set of layout tools.
As a PCB designer at that time working in a service bureau, I had to use netlist data that came from all kinds of different schematic sources used by our customers. Sometimes the netlist would be in a usable format for our layout software, but most of the time it required some kind of alteration in order to work. These alterations included adding component information to the netlist, or assigning correct reference designators. As you can guess, manually editing the netlist in order to change it into a usable format was prone to data entry errors. I remember once, a coworker of mine placed an order for 100 parts instead of 10 and nearly broke our bank.
Once we were done with the layout, we would then extract the netlist from the layout tools to return to the customer. Since we were swapping pins and gates during the layout, the netlist was different than what we originally started with. We would also have to supply the customer with a was/is list of all of our swaps. This required more manual edits on our end, and then the customer would have to make the manual changes on their end. It’s a wonder anything ever got built correctly back then.
Netlist data used to be sent to PCB layout on a floppy disk
Working with an Interface to Annotate Between Two Different Systems
Fortunately most CAD systems today have a much easier time of synchronizing back and forth between the schematic and the layout. However, there are a great many installations still in use today where the schematic tools and the layout tools are different from each other. In order to communicate with each other, these installations will often use an interface for the synchronization process.
A schematic to layout interface gives the appearance of the two systems functioning together as one integrated tool. You can run into problems when the interface breaks due to changes in either of the tools. In some cases, only a portion of the interface breaks leaving the users with partial functionality. In other cases, the entire interface fails leaves the user stranded. Software vendors might also decide that they no longer want to allow other tools access, thus removing the ability to interface. This leaves the customer stranded and unable to continue in their regular design process.
The Best Schematic Software Synchronization
When the schematic capture and layout tools are created by the same software company, the unified design environment makes the synchronization process more reliable as well as enabling best design results. While enabling tool synchronization, often there are more options and functionality available then would be found with an interface. Additionally, as each tool is updated and enhanced the synchronization process is enhanced along with it as part of the complete schematic to layout design process, guaranteeing higher degrees of accuracy and efficiency.
If you’ve been relying on interfaces or manually edited netlists to transfer your connectivity data, you should look at PCB design tools that automatically handle this task for you in a unified design environment. Manual edits open the door for human error, while interfaces may not give you all of the functionality that could be helpful to you. On the other hand, a PCB design system where both the schematic capture and the board layout tools are designed to work together will give you the best results.
The best schematic software synchronization is when both tools are in a unified design environment
Just like I don’t want to be writing this on a typewriter anymore, although I will admit it does still have a good feeling to it, I am sure you don’t want to be hand-drawing all of your PCB designs, and sending your data through postal mail. Consider this my old wisdom to you: keep up-to-date with your PCB design software and make your life easier.
If you’re looking for both schematic capture and board layout tools in one unified design environment, Altium Designer is PCB Design Software that has both. This will allow you to easily work between the schematic and the board instead of coordinating multiple systems and interfaces.
Would you like to find out more about how Altium can help you to synchronize your schematic and layout together in one unified design environment? Talk to an expert at Altium.
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