Rick has training in mechanical engineering; I have training in electronics and programming; and when we combine our respective skills, magic frequently
happens. We have created some really fun things —
including a DEFCON Uber badge that was on display in
the Smithsonian Institution (my contribution to that project
was just a bit of code, but I was thrilled to do it). Through
our technical collaborations, Rick has become one of my
very best friends. I have a similar relationship with my
friend, Matt who — like Rick — creates amazing things and
sometimes asks for a code or circuit assist. I love
collaborating with these two friends/artists, and with many
others as well.
Another friend, John, whom I’ve known since our days
at Parallax, recently asked about upgrading a project from
a BASIC Stamp to the Propeller. I’m always happy to do
that! The meat of the project is controlling a stepper
motor. I looked in my Propeller library and to my surprise
... no stepper motor object!
Steppers are easy. So simple, it seems, that I have
taken them for granted and not bothered to write more
than a few lines of embedded code for them. It’s time to
fix that.
Stepper Basics
For review, a stepper motor is a special form of
brushless DC motor that uses a magnetized rotor (the
spinning part) and electromagnetic coils attached to the
stator (the stationary case). To turn the rotor, the coils are
engaged in a specific sequence which causes the motor to
“step.” Have a look at Figures 1, 2, and
3. These are simplified illustrations of
the basic methods used to turn the
rotor.
Stepping Up to Help Friends
My friend, Rick and his lovely wife, Geanie host wonderful parties. Rick is
a special effects engineer who got his big-screen start by building
dinosaurs for the first Jurassic Park movie. Over the years, he's built an
amazing shop filled with wonderful tools that really is a maker's heaven.
During parties, he gives tours of the shop and shares the things he's
working on. There was a point in the middle of one of these tours —
between the oohs and aahs of his guests — when he turned to me and
said with a smile, "The great thing about our lives is that if we want
something, we can just build it!"
■ BY JON MCPHALEN THE SPIN ZONE
ADVENTURES IN PROPELLER PROGRAMMING
10 September 2017
■ FIGURE 3.
Half-step drive.
■ FIGURE 2. Full-step drive.
■ FIGURE 1.
Wave drive.