An Arduino shield is an add-on circuit board designed to work with the connectors on a standard Arduino board like an Uno, Duemilanove, Leonardo, or Mega. A shield has pins that interface with the Arduino so that things like DC power, digital I/O, analog I/O, and so on are available to the shield. This chapter covers some of the Arduino-compatible shields that are available, and Chapter 10 describes the process of creating a custom shield.
Shields are available for a variety of applications, ranging from minimal boards for prototyping to motor controllers, Ethernet interfaces, SD flash memory, and displays. Many shields have the ability to be stacked, allowing a base Arduino board to interface with two or more shields at once.
This chapter references many different vendors and manufacturers, but it is not intended to be a specific endorsement of any of them. The shields shown here are representative of what is available, and for any given shield type you can likely find different vendors selling the same, or an equivalent, product. Shop around.
This chapter is by no means a complete list of all the various types of shields that are available. There is a quiet cottage industry that specializes in creating new variations on existing shields and new shields that have never been seen before. The selection of shields described here is broadly representative of what is available, and links are provided if you want to learn more, or perhaps buy a shield or two. ...