Development platforms like the BeagleBone provide an environment for a wonderful hybrid of both software and hardware hacking. In this chapter, you’re going to test drive the General Purpose Input/Output pins (GPIO) on the board to get a basic sense of how they work and how you can read from and write to them.
No doubt you’ve noticed the two sets of headers that run along the edges of the board. They’re labeled P8 (Figure 4-1) and P9. Each header has 46 pins and if you look closely you can see that pins 1, 2, 45, and 46 are labeled on each header (Figure 4-2). To identify pin numbers in the middle, you’ll have to count off from the pins on the end.