Electronics - Eagle - Basics to set up and create schematics

It may be possible that one day you said to yourself: "I would like to design my own schematics for my electronic integrated circuits".

But you didn't know how to start.

Let's see this by learning basics in this Eagle design tutorial.

First of all

Let’s start by downloading the Eagle software on the official CAD website at the following URL:

• http://www.cadsoftusa.com/download-eagle/?language=en

Then install it, for our tutorial we’ll use the directory:

• C:/soft/design/eagle

When the Eagle license is asking you which one you would like to have, select Run as Freeware.

In this tutorial we’ll see how to create a basic schematic and its board.

But before that we’ve to create a library in order to add our own components.

With eagle we call that a “part”.

So let’s create our first part.

Creating a part

Once the eagle software opened, you can see the main window with a tiny red eagle as an icon.

This is the Control Panel.

We’re going to add our first library, but not in the same directory as the default one.

The reason is that if one day you had to remove the eagle software and its directory, you wouldn’t lose your libraries.

Furthermore it’s a good way to learn how to do that and manipulate paths.

OK, let’s first create the path until our own library.

We’re going to create it in the following directory:

• C:\dev\design\eagle\my-lib

And eagle needs to know where is this directory.

For that, in the Control Panel, let’s click > Options > Directories...

In the Libraries input, there is already something written, in our case:

• $EAGLEDIR\lbr

Let’s replace this value by:

• $EAGLEDIR\lbr;C:\dev\design\eagle\my-lib

Now eagle knows where are our libraries.

We can see that the library folder is shrunk by lbr.

It’s the same for your future projects, it’s a good practise to create them in a different folder.

In any case, if you had some problems with paths, you could remove the following directory:

• C:\Documents and Settings\YOUR_NAME\Application Data\CadSoft

Indeed, they are all inside.

Well, let’s continue.

The software pops up the following message:

The directory C:\Documents and Settings\YOUR_NAME\My documents\eagle doesn’t exist!

…

Create it?

To avoid to have this every time you launch Eagle, just replace the following path:

• $HOME\eagle;$EAGLEDIR\projects\examples

by

• $EAGLEDIR\projects\examples;C:\dev\design\eagle\my-project

Now our projects will be created in:

• C:\dev\design\eagle\my-project

Let's recapitulate

We've now the software created in:

• C:\soft\design\eagle

And we’ve also the two following folders, the one for our libraries and the second for our projects:

• C:\dev\design\eagle\my-lib

• C:\dev\design\eagle\my-project

Adding a new part

Now that everything is ready, we can create a new library called badprog.

Still in the Control Panel, click > File > New > Library.

The Library windows appears.

Save it in the following directory:

• C:\dev\design\eagle\my-lib\tuto1

It will create a new folder named tuto1.

So we’ve:

• C:\dev\design\eagle\my-lib\tuto1\badprog.lbr

Go back to the Control Panel, and left-click on the my-lib folder and press F5 (for a refresh).

The tuto1/badprog.lbr file is now visible.

Let’s go back to our Library window.

Creating a symbol

Click Library > Symbol

The Edit window appears.

Let’s write SYMBOL_1 as a new name in the New input and click OK.

A warning windows tells you do you want to create it? Of course, click Yes.

The new symbol is now onto the library window.

Let’s create a square (our device) with the Wire tool.

Click it and draw a square.

It’s red because you’ve selected the Symbols layer (with the 94 prefix).

And this is what we wanted to have.

So let’s go ahead.

Click the Pin tool and create 2 pins on the left and 2 pins on the right of the square.

Right-click to rotate the pins.

We have now to give them a name.

Click the Name tool and click on the green circle, the Name window appears.

Write the first name as VDD.

For the second: AUX.

For the third: GND.

And the fourth: PA1.

Save it.

Our symbol is ready.

Let’s create a package.

Creating a package

Click Library > Package.

Name it PACKAGE_1.

Same as before, click the Wire tool and draw a square.

This time it’s grey.

Then click the Pin tool in order to add 4 pins just as before.

You can let the ALT key down during the move of your pin to have a more precise placement of your pin.

Click the Name tool and name them: 1, 2, 3 and 4.

Save it.

Let’s now create our device.

Creating a device

Click Library > Device > DEVICE_1.

Click then at the bottom of the window, on the New button.

Select PACKAGE_1.

The package is now on the upper left of the window.

Click the Add tool to add a symbol, in our case the SYMBOL_1 and put this symbol on the right of the window.

Click now Connect (at the bottom) and connect each pin with its corresponding pad.

Once finished, click OK and click save.

To finish our “part”, we could add some description.

Just click on the blue description link.

OK, let’s now see how to create a schematic with our new brand device.

Creating a schematic

Let’s first create a new project.

Let’s go back to the Control Panel and expand the Projects folder in the window by clicking the plus icon until you see the my-project directory.

Once done, right click my-project > New project.

Give it a name like project1.

Now right click project1 > New > Schematic.

The Schematic window appears.

Save it as badprog.sch.

Let’s now create a frame.

Creating a Frame

What’s this?

A frame is something useful to know when the schematic has been updated the last time for example.

And our schematics will have to be created inside this frame.

Click the Add tool and search for frame.

Select the first one, A3L-LOC and draw it.

Save it.

Let’s go back now to the Control Panel in order to activate our device.

Right-click on the tuto1 folder > Use all.

A green ball will appear, meaning that our device is now reachable from the libraries.

Reopen the Schematic window and click the Add tool again, and search for device_1 in the badprog library.

Once found, put 2 devices onto the Schematic.

We’re now ready to link these two devices.

For that, we’ll use the Net tool in order to connect pins together.

Conclusion

A bit difficult to handle at beginning, Eagle comes up as a great free design tool for your electronic schematics.

Once again, well done, you've made it.