five volts to 10 volts, so I fed it the voltage of the LiPol
without change. (Just a quick caveat about LiPols: they are
totally destroyed if discharged below about 2.6 volts per
cell (three to be sure).) To ensure the Lipols were not
discharged, I used a small device called a “Batt Signal,”
which issues a tonal warning as the voltage nears three volts
per cell. Photo 4 shows a layout of some of the parts prior
Since I had laser-cut the holes in the circular platform in
all the right spots, bolting everything together and wiring up
the electronics was the work of 30 minutes. When finished
— for a quick hack and a quick build — it looked kinda cool
(see Photos 5 and 6).
talk to multiple robots at the same time.
I hope this project has given you some ideas and
encourages you to try playing with Zigbee yourself. Let me
know if you get the “synchronized dancing” working. NV
DID IT RUN?
You bet it did. It buzzed all over the place. Moving the
velocity slider caused it to accelerate and decelerate, as
well as move backwards when the slider was moved down
I must say, the way I chose to control the robot — that
is “sliders” — proved to be very difficult and sensitive
(needed tuning), though I suppose you would get used to
it. In any case, the premise of this project was not to build
a remote-controlled robot, but rather to have an
autonomous robot with either the intelligence on the PC or
the intelligence on the robot, with information being passed
back to the PC.
THINGS TO PLAY WITH
There are more available ports surfaced on the 26 pin
header which can be used as either input or output, so for
example, you might want to attach sensors, switches, or
indeed control other devices other than the motors.
The simple protocol could have
additional commands added to it, e.g.,
a “B” for beeping a buzzer or an “S”
for requesting sensor data.
In this project, we did not build a
second robot to show the “Star” network actually working, however, we
did connect up additional Sard cards
and had the commands they received
passed out the serial port, which we
then monitored. In this way, we were
able to show ourselves that we could
ABOUT THE AUTHOR
■ Phil Davis has a computer
science degree from British
University and was a member of
the Royal British Computer Society.
Comfortable both with software
and mechanics, he is passionate
about doing things that have not
been done (much) before. He can
be reached at firstname.lastname@example.org
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