Exploring BeagleBone: Tools and Techniques for Building with Embedded Linux

CHAPTER 6 Interfacing to the BeagleBone Input/Outputs

This chapter integrates the Linux, programming, and electronics groundwork from earlier chapters to show you how to build circuits and write programs that interface to the BeagleBone's single-wire inputs and outputs. In this chapter, you will see practical examples that explain how to use a general-purpose input/output (GPIO) to output a binary signal to switch on an LED, or to read in a binary input from a push button. Also included are the steps required to read in an analog input and to send out a pulse-width modulated (PWM) output. Interfacing to GPIOs is a reasonably complex topic due to a recent change incorporated into the Linux kernel. However, the BBB has cape management features, and code is made available throughout this chapter that you can use to make interfacing reasonably straightforward.

Equipment Required for This Chapter:

• BeagleBone Black
• Component set from Chapter 4 and a generic light-dependent resistor

Further details on this chapter are available at www.exploringbeaglebone.com/chapter6/.

General-Purpose Input/Outputs

At this point in the book, you have seen how to administrate a Linux system, write high-level programming code, and build basic, but realistic, electronic interfacing circuits. It is now time to bring those different concepts together so that you can build software applications that run on Linux in order to control, or take input from, electronics circuits of your own design.

Introduction ...