David Boone

Introducing CadSoft Eagle Layout Editor

There are many software packages out there that you can use to design circuit boards. They include Albium Designer (formerly Protel), OrCAD, FreePCB and CadSoft's Eagle Layout Editor...

We'll use the freeware version of Eagle Light Edition. downloadable from their website for Windows, Mac OS X or Linux. There's a couple limitations on this freeware version, such as the size of board you can create, but you can cram a lot in that 100 x 80 mm!

This program seems very intimidating at first, mostly because it acts nothing like you expect a windows program to. Things you think should work don't work as you think they should!

When designing a PCB, we don't just start with a blank sheet of copper and start drawing the parts and wires we need. First we're going to draw out the circuit using Eagle's Schematic Editor. On this virtual sheet we'll place all the parts we're using and draw lines between the pins as needed. This is where we'll be recording what we figured out last time. By laying the circuit out here, we'll be able to arrange everything in a logical fashion, making it easy to think about how the circuit is working and make sure we have everything hooked up the way we want it.

Once we're done doing that and are sure we have everything perfect, we can jump to the next step, creating the layout of the circuit board. Just because we laid out the design a certain way on the schematic doesn't mean we have to use the same type of layout on the PCB! We want to layout our circuit board in an organized and tidy way. We want to use the shortest wires possible and avoid wires having to cross. Certain parts such as connectors, plugs or buttons might have to be in a particular physical location. The great thing about using a software package such as Eagle is that the computer can keep track of all the details and makse sure that the circuit board matches our schematic.

Download and install Eagle so that you can join us next time as we jump into the Schematic Editor. We'll learn a bit of how to work with Eagle and get our design on paper, arguably the most important step in this whole process.

Posted by Boone at March 3, 2006 12:24 AM