Now that you had a whirlwind lesson on electrical engineering fundamentals, let's look at the BeagleBone side. On the BeagleBone, there are two connectors that can be used to interface to the BeagleBone. These are the same two connectors used by the expansion boards, which we will discuss in Chapter 8, Advanced Software Topics. This chapter will focus on some of the lower-level details for interfacing. The connector is electrically compatible between the BeagleBone Black and the BeagleBone White. However, some signals on the BeagleBone Black are shared with onboard features such as the onboard flash and the video interface. Most of these features can be disabled by following the procedures described in the BeagleBone Black SRM.

The two connectors are labeled P8 and P9. See the SRM document at http://www.beagleboard.org/ for the signals and pin assignment. These connectors are 0.1 inch spaced 2 x 23 female headers. They mate with common 0.1 inch male connectors. You can see...