Interfacing to the BeagleBone Input/Outputs
Derek Molloy · 2014
This chapter integrates the Linux, programming, and electronics groundwork to explain how to build circuits and write programs that interface to the BeagleBone's single-wire inputs and outputs. Examples presented here 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. The chapter also presents 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. An operational amplifier voltage-follower circuit describes how one can interface such a circuit to the BBB and use Linux sysfs to read values into software applications.