Of course, there are SBCs that are
larger or smaller, and some available
in kit form. For example, the BotBoard
series of single board computers
(designed by robot enthusiast Marvin
Green) combine a Motorola 68HC11
microcontroller with outboard interfacing electronics (the HC11 has its own
interfacing capability as well, though
many robot engineers like to add
more). Both the Miniboard and
HandyBoard — designed by instructors
at MIT — are other single-board computers based on the HC11; both are
provided in kit and ready-made form
from various sources.
PC Motherboards
and Laptops
You probably already have a
computer on your desk or in a
briefcase. Naturally, you may want to
extend it to control your robot. There
are pros and cons of using full-size
computers for robotics.
For a desktop PC, you need a
power cord to plug it in or — at best
— a big battery and an AC inverter.
While it’s been done, this method is
far from efficient.
Rather than the whole PC, you
can use just the motherboard. Forget
full-size motherboards because of the
power requirements. The mini ITX
form factor is practical for many
mid-size bots (measuring at least 10
inches square). There’s also the nano,
pico, and mobile ITX form factors,
though availability of these is far less
common and at much higher prices.
The nano ITX form factor, for
example, is 120 mm square — small
enough for most desktop bots.
Whatever the form factor, you need a
power supply to complement the
motherboard. Power supplies are
available that provide the proper
voltages from a single 12 volt source.
Laptops provide an all-in-one
solution, but can be expensive unless
you adapt your spare computer to
your robot or find one second-hand.
In all cases, you can interface to
the computer/motherboard/laptop via
a serial, parallel, or USB connection.
USB is probably the most convenient
overall, as many laptops don’t have
serial or parallel ports. With USB,
you’re also less likely to damage the
computer if you have some misbehaving electronics elsewhere on your bot
(though even this is not a given).
In the case of a desktop PC or
mini ITX motherboard, you can use a
spare PCI slot for interfacing,
assuming the board is so equipped
(not all have PCI slots). Prototyping
boards for PCI interfacing are available
with and without the decoding logic,
at prices from $15 to well over
$1,500, depending on features.
Retro Computers
In years gone by, I might have
recommended re-purposing an old
Commodore 64, Timex Sinclair 1000,
or RadioShack Model 100 portable
as a robot brain. No longer.
The peculiarities of each of these
platforms — and the fact that if in
working condition they’re probably
worth more to a collector than as a
robot controller — these days make
them of little practical use. A low-cost
microcontroller, SBC, or mini ITX
board tends to be less expensive in
the long run, and much more capable
than press ganging any spare
computers you may have in the
back of your closet. For example, a
$30 Arduino microcontroller board
programmed in C has all the power of
most any 1980’s era hobby computer
(and then some), is easier to interface,
is considerably more compact, and
uses modern programming languages.
Sources
Atmel Corp.
www.atmel.com
Makers of several lines of
microcontrollers, including AVR, a
very popular eight-bit controller used
extensively in amateur robotics.
Axiom Manufacturing, Inc.
www.axman.com
Products include single-board
computers based on the Motorola
68HC1x microcontrollers, as well
as others.
Basic Micro, Inc.
www.basicmicro.com
Basic Micro produces the
BasicAtom microcontroller and
prototyping boards.
BasicX
www.basicx.com
The BasicX is a general-purpose
microcontroller with a built-in
programming language. Variations of
the product include the BasicX 24, an
all-in-one module that is pin-compatible
with the Parallax BASIC Stamp.
BD Micro
www.bdmicro.com
Developers and sellers of the
MAVRIC line of Atmel AVR-based
microcontrollers, designed principally
for use in robots.
BittyBot
www.bittybot.com
Makers and sellers of the
MEGAbitty miniature microcontroller
board which uses the Atmel MEGA
AVR microcontroller. Though small —
literally postage stamp sized — these
boards are full function.
Chuck Hellebuyck Electronics
www.elproducts.com
Chuck, a regular contributor to
the Nuts & Volts/SERVO family of
magazines, resells the Basic Atom
from Basic Micro, as well as his own
custom boards. His BasicBoard is a
general-purpose microcontroller board
with LCD panel, speaker, LEDs, and
other components built in.
Dontronics, Inc.
www.dontronics.com
Dontronics specializes in
microcontrollers, as well as the
SimmStick prototyping development
board system. Based in Australia,
he ships worldwide.
EMAC, Inc.
www.emacinc.com
Single-board computers and
microcontrollers in a range of sizes
and types. A line of their single-board
computers are PC compatible, and can
run DOS, Windows, or Linux.
SERVO 11.2009 73
