“In Transylvania, cloves of garlic, sharp
wooden stakes, hawthorn branches, and
a cross are just a few of the necessary
tools one needs to combat vampires ...”
Running water, daylight and holy silver bullets are
also potent vampire killers. If your vampire pest was once a
mortal human being (most all of them were), every vampire
killing tool I’ve just called out will do the job. However, if
your vampire smells of silicon and steel, forget about
getting any killer results from the garlic and wood as only
a steady stream of running water and a carefully placed
bullet will kill a G203V Gecko Vampire stepper motor drive.
My soldering iron is still hot from our last project. So,
put some water on your soldering iron tip cleaning sponge
and get your Moto-Tool ready to grind and spin some drill
bits. Fire up your soldering iron as this month we’re going
to scratch build a PIC-based step and direction controller
that will act as an intelligent front end to a Gecko G203V
stepper motor drive.
Enter the Vampire
The “V” in G203V does indeed stand for “Vampire.”
The idea is that the Gecko G203V is virtually indestructible.
To understand why, we must examine the G203V’s
ancestral roots. The Gecko G203V is really an armored
Gecko G201. The G201 is the most basic and eldest of
the line of GeckoDrives. Unlike its vampire cousin, you can
kill the G201 if you are not careful.
I’ve removed the cover from my G201 in Photo 1 to
give you an idea of where the Gecko G203V came from.
Note the heavy use of discrete CMOS logic within the
innards of the G201. Despite CMOS circuitry being able
to eat just about anything thrown at it, the STEP and
DIRECTION inputs of the G201 are optically isolated. The
idea is to sacrifice the Gecko and save the controller if
something goes awry at the stepper motor end. You
can easily see the G201’s socketed eight-pin optoisolator
PHOTO 1. Discrete CMOS circuitry rules the G201. All of the
Geckos are equipped with an integral heatsink, which has been
machined for easy mounting to a larger heat-conducting surface.
42 SERVO 04.2008