Page 74 - Programming the Photon Getting Started With the Internet of Things

Figure 4.2 Setting the output to HIGH.

With the following in mind, you can easily see how we can use the Photon board to
control electronic devices and components using some simple commands and basic
circuitry.

Flashing an LED

Moving on from the previous experiment, we will use the same principle but this time will
be creating a circuit with an LED and a resistor so we can flash the LED on and off.

LEDs will definitely be one of the most commonly used parts in your projects

throughout this book. They are inexpensive and easy to obtain from your local electronics
store (see Appendix A for a list of suppliers). LEDs are polarized, which means that it
matters which way you connect it to your circuit. The positive leg on the LED is called the
anode, and the negative leg on the LED is called the cathode. If you look at your LED, on
the top of the plastic shell you can usually see a flat side to the casing. This side is the

cathode. Another simple way to determine which side is anode and which is cathode is by
taking a look at the length of the legs of the LED. The longest leg is always the anode and
the shortest is the cathode.