All three of the control
sensors are linked by way of the
Arduino to a Series 1 XBee
radio. The wiring diagram is
shown in Figure 5. The radio is
mounted on a 22-pin carrier
available from Parallax.
Remember that XBees are
designed for 3. 3 volt operation.
I’m using a carrier made for
either 3.3V or 5V operation. The
carrier has its own built-in 3.3V
regulator, so you can use the
Arduino’s 5V supply.
Why not just use the
Arduino’s 3.3V power supply?
It’s a matter of power
consumption. The 3.3V
regulator on the Arduino Uno
and similar boards is limited to
providing 50 mA of current.
That’s about what the XBee
uses when transmitting —
that’s too close for comfort.
Though the XBee works
on 3. 3 volts, the input and
output pins on the module are
5V tolerant. That means they
can be directly connected to a 5V device — like the Arduino
Uno — without the need for current-limiting resistors or level-shifting electronics.
The wiring diagram for the five-position switch is shown
in Figure 6. The switch comes on an eight-pin breakout
board that’s a bit oversized, but will still fit onto the
breadboard with the XBee module. Programming code is
provided in Listing 1. The sketch sends out a single byte
character, indicating the direction of the switch press: u for
up; d for down; and so forth. The completed remote control
is shown in Figure 7.
FIGURE 5. Connection diagram
for the XBee radio (mounted on
a 3.3V/5V carrier board from
Parallax) to the remote Arduino.
FIGURE 6. Wiring diagram
for the five-position
switch to the
remote Arduino.
FIGURE 4. This
five-position switch
provides an easy
method to control
several axes of your
remote controlled
robot.
FIGURE 7. The completed remote control with Arduino,
protoshield with mini breadboard, nine volt battery,
XBee radio, and five-position switch. I have a couple of
extra wires on my prototype, since it has the
tilt-compensated compass (not described here because
of space reasons).
SERVO 11.2012 53
