Assignment:

The task for week 5 was a follow on from the last project. This week we were introduced to a design software called Eagle, which is also made by Autodesk. Unlike something like Solidworks or Fusion 360 however, Eagle is only used to layout and produce the PCB’s. It features extensive tools to accomplish this and a vast, and frankly quite irritating library of parts to help layout the traces for different components.

Our job was to use Eagle to design the trace layout for a Echo Hello World Plus Board. We were free to make slight changes to the layout of the traces, but we needed to keep the components the same.

Component List:

Our first task was to recreate this example board with all the listed components.

The components for this board and what they do are as follows:

Library of Parts:

As mentioned above, Eagles Library of parts is vast, with manufactures producing their own products and letting people download their collections for use in the designs. For this assignment, I downloaded this Library from a site called Github.

Navigating this Library can be difficult, as you cannot just type in “Resistor” and get the exact component you need. If nothing else, you’ll get 12 different resistors that all look practically the same! that’s why it can help to pick one package of parts that all share a common identifier, as i did with this project.

Important: Eagles Library will only search for items within two asterix’s. for example, *ATtiny44*

The Design 

Once the Library has been figured out, the next step is to start planning out the schematic of the board. The Schematic is where you insert your components and connect them. This isn’t how your board will look when its done. this is just to connect the parts.

Once you’ve inserted all the parts from the Library and connected them, its time to switch to the Board view of Eagle. This window shows all the parts in their respective sizes and the various links between them. This is the view where you start to draw the traces for the PCB. In the settings, you can determine how close the traces are allowed to be laid together. Too close and the electricity could jump between them and too far, the board become over sized and empty. Note – The measurements for this are in Mil, which is a thousandth of an inch.

This is how my board turned out in the end! It looked a little different to the original Hello world example but is near enough.

The final step was to save the board as an Illustrator file and change the traces to Black, and add any extra details like the ones shown on the right.

In order for the CNC machine to understand the file. The art board must be reduced to the size of the Black outline around the PCB, and the outline itself needs to be saved separately as the CNC machine cuts the board in two operations.

This is what the Adobe illustrator file looks like when imported straight from Eagle. At this stage, it will be made of multiple layers and all non essential one’s, such as the lettering and the part outlines. the entire image should then be turned black for the machine to read.

And here is the board fully milled out, with some extra detail added in later as a logo.

This is the Adobe Illustrator file used to create the G-code for the Milling machine.