Hardware Reference
In-Depth Information
Wall Power Adapters
A third option for powering your remote Arduino is to use a wall adapter. These
plug into an ordinary outlet and have a barrel jack connector on the other end for
connecting to your Arduino. There are three important specifications you need
to check for when choosing a wall power adapter: the physical characteristics
of the jack, the supplied voltage, and the maximum current output capabilities.
The Arduino requires a 2.1mm center-positive DC barrel jack plug. In other
words, the inside of the jack should be at a positive voltage, and the outside con-
tact should be connected to ground. This is generally indicated on the charger
by a symbol that looks like the one in Figure 11-15.
Figure 11-15:
Center-positive symbol
Because the Arduino has a built-in voltage regulator, you can use any DC
voltage between 7V and 12V. This voltage will also be available on the Vin pin,
which can prove useful for powering higher-power devices such as motors.
All DC wall adapters are also rated for the maximum current that they sup-
ply. The higher the current, the more things you will be able to power with it.
A 1-amp supply is fairly common and provides more than enough power for
your Arduino's 5V regulated logic and some additional components.
RevisitingtheSerialExamples:ControllingProcessingwith
aPotentiometer
At this point, you're finally ready to start doing some wireless communication.
Because XBee is nothing more than a serial pass-through, you can start by test-
ing your setup with the examples you already created in Chapter 6. You need
to complete the following steps:
1. Upload the sketch that allows you to change the color of a Processing
window using a potentiometer connected to your Arduino.
Do this before you install the XBee shield on to your Arduino, because of
the shared UART complexities that were discussed earlier in the chapter.
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