From Bits to Bytes... to Bots
The goal of this course is for you to gain the skills you will need
to connect your PC to the world. Not the "world wide web," but the
actual world of real things. There are many ways to do this, but
the strategy I take is to use the cheapest and easiest route possible.
In that way, the joy of experimenting with motion control (elementary robotics)
is available to the greatest number of interested people.
Why use IBM-compatibles?
Using the rule of "cheapest and easiest" I rely on IBM-compatible computers--
not because they are the best, but because old ones are cheap (and often
free). Also, information about how they work (down to the most minute
detail) is widely published. Another advantage is that old "throw
away" PC's are still compatible with new Pentium-based, Windows machines.
They both can write and read the same floppy disks. During the process
of experimentation mistakes are easy to make. Although
not a common occurrence, it is possible to damage the control computer.
It is important to realize this, and do all experimental work with a computer
which you consider expendable!
Why the parallel (not the serial) port?
While both types of ports can be used to connect to the outside world,
I chose the parallel ("printer") port because the translation of programmed
information into electrical signals on 8 wires of this port is direct,
and extremely easy to understand. Serial port communication has some
advantages (fewer wires, works with longer cables) but is more complicated
in how information is converted to electrical signals. Apple / MacIntosh
systems do not use the parallel port which all PC's have.
Why stepper motors?
Any type of motor can be controlled by a computer-- but if you want to
precisely move a certain amount, stepper motors are the easiest (and cheapest)
solution. The disadvantage of learning to use steppers (which have 4-8
wires) is that they are more complicated to hook up than the motors most
people are used to (only two wires). But once you learn how to run
them, you will be amazed how easy it is to (almost) exactly control the
movement of a real object. New stepper motors can be surprisingly
expensive, but fortunately, they are easy to find as surplus and junk,
at very affordable prices.
next-- bits and bytes
Copyright © 2000 Bruce Shapiro