Modifing the Hello Echo Board in Eagle / Eagle Resources

led and button added to hello echo

This week's assignment is to:

Contents:

 

Getting Started With Eagle

Step 1. Download and Install Eagle

eagle logo

What is Eagle?

EAGLE (Easily Applicable Graphical Layout Editor) is a flexible and expandable EDA schematic capture, PCB layout, autorouter and CAM program. EAGLE is popular among hobbyists because of its freeware license and rich availability of component libraries on the web. We will use Eagle to layout and modify a circuit board for this assignment.

Download and Install

Get Eagle Here: http://www.cadsoftusa.com/downloads/
There are installers for Mac, Linux and Windows. Download for your OS.

Step 2. Sample Echo Board Schematic / Board

Example Files to Start From

To help you along, you can download the Hello Echo schematic and board files. You can then add the necessary components to the schematic in these example files:
Board Hello Echo and Schematic

  1. Go to documents and copy the extracted folder into your Eagle folder.
    • Mac: In your "Documents" folder > eagle
    • Ubuntu: In your "home directory" > eagle
    • Windows: In C:/Program Files / eage6.1.0
  2. Open Eagle
  3. The helloEcho folder should be visible under "Projects" in the Control Panel.  
    • Make sure the little dot to the right of the libraries are green.  
    • If they are grey right click on it and check "use" to turn it green.

eagle control panel

Right click on the grey circle and select "use" from the menu. The circle should turn green.

control panel libaries enabled

Step 3: What is a Schematic?

A schematic in electronics is a drawing representing a circuit. It uses symbols to represent real-world electronic components. The most basic symbol is a simple conductor (traces), shown simply as a line. If wires connect in a diagram, they are shown with a dot at the intersection.

This is what the schematic for "Hello Echo" looks like:

hello echo schematic

Electrical Concepts

Schematic Symbols

resistor

A resistor is part of an electrical circuit that resists the flow of current.

resistor

capacitor

A capacitor is a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator. Capacitors are often used as filter devices to remove voltage or signal spikes in electronic circuits


capacitor
or

capicitor

LED

Light-emitting diode, a semiconductor diode that glows when a voltage is applied.

LED Symbol

ground

Ground is the reference point relative to which other voltages in the circuit are measured. Vcc+ is positive relative to ground. We usually call the ground "zero volts", to make the other measurements simpler.

Apply the black (-) end of your meter to ground on a powered circuit and the red (+) end of the meter on VCC to measure the voltage.

gnd

or

gnd

VCC (power)

Vcc+ is positive relative to ground.

VCC

Step 4: What is a Board Layout?

The board layout shows how the electrical componets and traces will be laid out on the board.

This is what the board layout looks like:

hello echo board

Step 5: Download and Install the Component Libaries

Eagle has a lot of built in libraries of components that you can use, but there are several specific libaries that you will need for this class.

Download

Download the Libaries:
You can download all of these libraries here: http://academy.cba.mit.edu/2012/labs/providence/tutorials/Downloads/eagle_libraries.zip

NOTE: I have renamed the libraries with a 01_ before the name of the library, so that they show up at the beginning of the "Add" list when adding new components.

Install the Libaries

Here is how to install the libaries.

After downloading them - unzip them and move them to the appropiate place for your operating system;

add libraries

Select all the libraries with 01 in front and click "open".

Now when you go to add a component - all of the libraries are available and at the top of the list.

libraries added

Step 6: How to Use Eagle

Eagle Basics

Eagle has two windows that you use simultaneously to design a board:

Working with the Eagle Interface

There are 2 ways to interact with Eagle.

Eagle has a command line (just start typing commands) - basic commands include:

Step 7: Edit the Schematic

What to Do (Overview)

First we edit the schematic.
More about how to add components and work with Eagle below in the next section.
  1. We will add components to the schematic view and create connections between them.
  2. Then we verify the design using the ERC (Electrical Rules Check)
  3. After we finish connecting the components and fixing any errors, we will go into the board view and place the components and route the traces.
Parts Already on the Hello Echo Board
You will need to add the following components to the schematic:

Led_calculator

Example Schematic with LED and button added with appropiate resistors and connections to power and ground.

example schematic with button and led

Step 8: How To Add / Connect Components in the Schematic

How to Add the Components

Add a component (either type "add" or select the "add icon from the toolbar". The add menu will open.

You can either look through the listed libaries for a component to add or you can type it into the box above the "drop" button.

Add LED (in the FAB_Hello library)

add LED

Add Resistors (You will need 2 - in the ng library)

add resistor

Click "0k" and then click on the schematic to place the component.

Add Button (in the fab library)

add button

Click "0k" and then click on the schematic to place the component.

Add Grounds
add gnd

Click "0k" and then click on the schematic to place the component.

Add VCC (connection to power)

add vcc

Click "0k" and then click on the schematic to place the component.

How to Connect the Components

There are two was to connect components in a schematic:
  1. You can connect the components with a wire (also called a "net" in Eagle). This may make conncetions obvious at first, but can get really messy quickly as nets cross over each other.

  2. You can also name the nets attached to components that need to be connected by naming them with the same name. See example schematic above. Eagle will ask you if you want them to be connected. (Say yes!). After you name the component - label it so the name appears in the diagram.

    For example:
    • All of the components in the schematic named GND are all connected to a common ground point.
    • the button is connected to a net on the button component and a pin on the microcontroller.

  3. Use pin 10 on the to connect to the button.
  4. Use pin 6 on the to connect to the LED.

diagram

Step 9: Route the Traces on the Board

routed traces

Eagle Tips and Tricks

 

Exporting a Board Design to be Used with Modela

To prep board for milling:
in layers menu in the top toolbar, select the only the top layer (traces only) traces only

Exported PNG

diagram

You can also edit your board .pngs in the Gimp. I find that the text added in the Gimp can be bolder (heavier and thicker) and is less likely to tear off when milling the board.

Editing Board Files / Creating Traces and Mill-out Files.

imags_canvassize

add 20 px

Add a White Border around the image

Create the Traces PNG
  1. Add 20px to the width (make sure the proportions are linked).
  2. After adding 20px, hit the "center" button to center the image on the resized canvas.
  3. Flatten the image - go to "Image" > flatten image
  4. You will now have a 20px white boarder around the board traces image.
  5. Save the file. This is the file you will use to mill the traces on the Modela.
  6. You can add white text or images if you like and they will be milled out along with the traces.

Example Traces Board File

This image is not to scale. This is on purpose! You need to create your own board files! If you mill these images below, the pad sizes will be incorrect.

finished traces

Create the Interior (mill out) PNG
  1. Start with the traces png that you have already created.
  2. Save the file with a different name.
  3. Use the bucket / fill tool to fill in the all the white spaces, EXCEPT the BORDER. Leave the white border around the image. This will be used to create the interior file for milling out the board. Using the traces image to start with ensures that your files are properly registered and you won't mill through your traces.
  4. Save the file. This is the file you will use to mill the traces on the Modela.

Example Interior Board File

This image is not to scale. This is on purpose! You need to create your own board files! If you mill these images below, the pad sizes will be incorrect.
finished interior

Additional Eagle Resources

Where to Get the FTDI Headers

To find the surface mount FTDI:
add_1X06-SMD
1X06-SMD Board View:
SMD board

Through Hole FTDI:

You can also use the through-hole component (you do not need to drill out the holes) and it will still work with the surface mount boards.

longpads

1X06-LONGPADS Board View:
SMD board

Eagle Tutorial Links

Useful Info
http://fab.cba.mit.edu/content/tools/circuits/pcb_design/pcb_design.html

CadSoft's Tutorial (Makers of Eagle)
http://academy.cba.mit.edu/tutorials/eagle/documents/cadsoft_tutorial.pdf

Beginner Tutorial
http://khammami.blogspot.com/2008/10/how-to-use-eagle-for-beginner.html

Create A Custom Library Part
http://www.instructables.com/id/How-to-make-a-custom-library-part-in-Eagle-CAD-too/


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tutorial by Anna Kaziunas France - Fab Academy AS220 Providence, RI - March 2012