Figure 6. Solarbotics wheels on Pololu gear motor in a mini Sumo robot.
Figure 8. RoboBuilder motor/wheel combination.
several modes including a web server to
simplify your interface to the outside world. I
found these modules at www.future
electronics.com for around US $45.
The last Wi-Fi module that I looked at was
the WiFly GSX 802.11b/g serial module from
Roving Networks (who provide Bluetooth
connectivity as well). The WiFly GSX does not
have a server mode; it does have FTP and a
Thin Client that will allow control in a similar
manner to other Wi-Fi embedded solutions. I
found these modules at www.mouser.com for
around US $40, but they are surface-mount
modules only. Over at www.sparkfun.com,
this module is available mounted on a breakout board for
easy hobby use for US $85.
All of these Wi-Fi modules require that you get an
antenna; they don't come with them. However, some will
be coming out soon with integrated antennas. Each one
of these modules will give you the connectivity you are
looking for to put a device or robot on the 'net. You will
still need to write some software for your on-board device
to talk to the modules over their UART or SPI interfaces,
unless you are doing simple sensor reporting projects.
(Most of these modules support this on power-up).
These modules are by far the easiest way to put your
device on the 'net, but there are things you’ll still need to
do. The modules simply remove the need for you to create
your own network stack.
Another task you will need to accomplish — and this is
beyond the scope of this column — is to deal with your
router's firewall. If you want your device to be controlled
from the outside world, you'll need to configure your
Figure 7. Bioloid Dynamixel motor/wheel combination.
firewall to allow access to your specific port and then
create some kind of security to keep the riffraff out. There
are plenty of sites on the Web that will tell you how to
accomplish this, so don't sweat it.
I have to say, this question has intrigued me. I will
need to pick one of these options and do this myself. With
the low cost of these Wi-Fi modules and their (typical)
range of 330' (100 m), they make a very reasonable
alternative to Bluetooth radios and open up the capability
for anyone with a Web browser to join in on the fun.
Well, that's it for this month. (Whew!) There may not
have been many questions, but they involved some serious
sleuthing skills. If you see anything that I may have missed
or simply want to comment on it (Thanks Paul Frenger!),
please feel free to drop me an email. And, as usual, if you
have a question send that to me at
firstname.lastname@example.org. I love to hear from you and
will do my best to answer your questions. Until then, keep
on working on those robots! SV
SERVO 08.2011 17