T
C OLOR CODE
We have at least 10 colors of wire in the lab, so do not limit yourself to two or three colors.
Use black for ground and a different color for every power supply (+5V, +15V, and -15V).
Use a different color for each input and output to the Arduino, if possible.
U SE SHORT RUNS OF WIRE
Keeping your wires relatively short will help you trace your circuits while debugging.
D
C
B REAK THE PROBLEM DOWN
Try to isolate potential hardware problems from software bugs as much as possible.
C HECK GROUNDS
Many circuits fail because they are not grounded correctly. This can lead to some very strange behavior, so double check that everything is connected correctly.
V ERIFY CONNECTIONS WITH A MULTIMETER
Use a multimeter to confirm continuity and voltages. For example, if you expect two wires to be connected, test for continuity with the circuit off. If you expect the voltage in one part of your circuit to be +5V DC, use your multimeter to confirm the voltage.
Never connect the +5V supply from the breadboard to the +5V supply on the Arduino while you are connected to your PC.
Also, never connect the +15V or -15V supply directly to any of the Arduino pins.