Datasheet

Shield, Lights, Servo Motors • Chapter 2
Robotics with the BOE Shield-Bot • 49
When you build an LED circuit, you will have to make sure the anode
and cathode leads are connected to the circuit properly. You can tell
them apart by the shape of the LED’s plastic case. Look closely at the
case—it’s mostly round, but there is a small flat spot right near one of
the leads, and that tells you it’s the cathode. Also note that the LED’s
leads are different lengths. Usually, the shorter lead is connected to
the cathode.
Always check the LED’s plastic case. Usually, the longer lead is connected to
the LED’s anode, and the shorter lead is connected to its cathode. But
sometimes the leads have been clipped to the same length, or a
manufacturer does not follow this convention. So, it’s best to always look
for the flat spot on the case. If you plug an LED in backwards, it will not hurt
it, but it won’t emit light until you plug it in the right way.
Introducing the Prototyping Area
On your Board of Education Shield (and also in the next illustration), the white board with
lots of square sockets in it is called a solderless breadboard. This breadboard has 17 rows of
sockets. In each row, there are two five-socket groups separated by a trench in the middle.
All the sockets in a 5-socket group are connected together underneath with a conductive
metal clip. So, two wires plugged into the same 5-socket group make electrical contact. This
is how you will connect components, such as an LED and resistor, to build circuits. Two
wires in the same row on opposite sides of the center trench will not be connected.
+
_
LED
Need to connect
two or more
leads or wires
together? Just
plug them into
the same row of
five sockets.