The Four Basic Parts of Every EDA Tool
In the next several weeks, you will have the chance to gain to work with each portion of your Electronic Design Automation (EDA) software. This book is meant to provide a brief overview while you work through the sample projects provided on the EDA tool websites.
1. Introduction
Background
Every Electronic Design Automation (EDA) tool is a bit different. Some have more features than others, some have different features, some offer simulation, some don't. But they all have a few features in common: they allow designers to capture a schematic and layout a PCB.
In a schematic diagram, components are represented as abstract symbols.
Schematic symbols by Filip Dominec from Wikipedia.org.
On a printed circuit board, components are attached to copper pads arranged in carefully designed land patterns.
Image of land patterns from practicalcomponents.com
To create a design, you need a part library that has all of your components' land patterns associated with the components' schematic representation.
Basic EDA Structure
There are four basic parts of every EDA tool. The pattern editor, component editor, schematic layout, and PCB layout program. The names of the modules might vary from program to program, and they might be used differently, but they all exist in one form or another.
- Component editors alter the appearance of schematic symbols.
- Pattern editors alter the appearance of land patterns.
- Libraries hold collections of linked components and patterns for reuse from design to design.
- Schematic Layout arranges the connections between components.
- PCB Layout arranges the patterns and the traces that connect them.
Libraries hold groups of footprints and components. When a component is selected for use in a schematic, it's associated land pattern is prepared for use in the PCB layout portion of the software.
"I have never worked in any version of any EDA program that had a complete, up-to-date, and accurate parts library. I've always had to add several components of my own. Sometimes the libraries are so bad, I've added all of my own parts. Creating custom libraries and ensuring their accuracy is probably the most time-consuming and tedious aspect of any design. If you don't enjoy managing your own parts libraries, services such as PCBLayout.com and Octopart's eConcierge service will manage your libraries for you."