Basics - BeagleBone - page 40

Figure 1-20. Breadboard hole connections
The rails , or buses , are the pairs of columns of holes that run up and down on the left and
right side of the board. All the holes in one column are electrically wired together. There-
fore, attaching ground to the rightmost column makes ground available everywhere on
that column. Likewise with attaching 3.3 V to the next column over, it's easily wired from
anywhere up and down that column.
In the middle, groups of five holes are wired from left to right, as shown in Figure 1-20 .
For example, Figure 1-21 shows a pushbutton switch plugged into four holes.
Figure 1-21. Diagram for wiring a pushbutton
The lower-right pin of the pushbutton is connected to a hole of the breadboard that is elec-
trically connected to the four holes to the right of it. The rightmost hole of that group is
wired to the plus column; therefore, it attaches the pushbutton to the 3.3 V on the Bone.
The upper-right pin of the pushbutton is electrically connected to the four holes to the
right of it; the rightmost pin is wired to GPIO pin P9_42 on the Bone.
If you're careful when wiring to keep the wires flat on the board, it's easy to understand
and debug a moderately complex circuit.