Creating Your Own Shield - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 392

a component that you want, or maybe that fancy input and output shield has
a few components that you don't need. Also, the satisfaction of creating your
own shield is indescribable. You'll see.
The Idea
It all starts with an idea. The idea is normally the project you have on your desk—
a breadboard with dozens of wires linked to a few components. Large projects
can have 100 or more wires connected to dozens of components. Although this
works great for evaluation and development, it won't last long. Imagine that you
have just i nished a project for your house. You want to place a data-logging
Arduino in the ceiling, hidden away from sight behind some plaster, or in a
small hole in the wall. You have already thought of everything; a network cable
has been run through the wall to this location, providing a network connection
and power to the Arduino. All you have to do is to place the Arduino and the
breadboard that contains your project: temperature sensors, humidity sensors,
EEPROM data-logging, barometric sensors, and a few other components. You
place the Arduino, you place the breadboard, and you connect everything. A
job well done! You are about to take a break when you notice a wire on the l oor.
Where did it come from? It must be from a component when you installed the
breadboard; but where? From which component? There are more than a dozen
components, possibly 100 small wires, and even if the project works great, the
breadboard is a mess. Finding out where the wire came from could be a huge
task. Even worse, this device gives information about a single room; you still
have to install the ones for the kitchen, bedroom, garage, and attic. Imagine
snagging a wire on each. This could take hours, if not days.
Because each breadboard is identical, it is easy to create a shield. Because you
created a breadboard design, it is easy to create an electronic schematic, which
is explained in the section, “Your First Shield.” Having all the components on a
shield instead of a breadboard makes the design much more resilient; no more
wires to catch on clothes or nails. No more components ready to fall off. A nice,
clear design, smaller than a breadboard, which can probably last years (if not
decades). Even better, if you ever get that extension to your home i nished, you
already have the design for the shield, and you can add a sensor to the new
room as soon as the work is done.
The Required Hardware
If you have the Arduino IDE set up on a computer, you already have all the
hardware that you need. Back in the old days, you had to have transparent i lm,
a UV lamp, ferric chloride, and a steady hand. When not created on a computer,