Page 200 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

• Rotary encoder with push switch

• Two-pin header output for connection to a relay module

Arduino R3 Shield Template

Adafruit has created an EAGLE part for making a shield for the latest version of the Arduino Uno (the
R3 at the time of writing). To use this, you will need to download and install the Adafruit EAGLE
library. This is well worth doing anyway because there are lots of other useful things in the library.

If you did not install this library back in Chapter 1, then download the file adafruit.lbr from
https://github.com/adafruit/Adafruit-Eagle-Library/blob/master/adafruit.lbr. Right click on the “Raw”
button, and save the file to the .lbr folder in your EAGLE installation folder. You will then need to
restart EAGLE.

A Four-Digit LED Example

Now that we have clarified what the board will do, create a new project (called TimerShield) and

then a new schematic within the project also called TimerShield (see Chapter 2).

Schematic

First, let’s add a letter-sized frame into which we can add our components. This step is obviously

optional, but it does lend a certain air of professionalism to the design and is expected if you are
going to be releasing the design to others, say, as an open-source hardware (OSH) design, as is the
case for this shield.

You can find the frame part in the Sparkfun Aesthetics library, where it is called
FRAME_LETTER. Use the Text tool to add some text over the “Design by” and “REV” fields. Before
you drop the text over the field, change the layer in the Action toolbar to be layer “94 – Symbols.”
You probably also want to set the font size using the “Size” dropdown in the Action toolbar.
My prefered way of designing a schematic is to first add all the key large components that I am

going to need and then move and rotate them into well-spaced positions. I then add in all the smaller
components such as resistors and capacitors.
In this case, this means adding the components listed in Table 8-1 to the schematic.

TABLE 8-1 Key Components