14 September 2017
kit (I found several in a drawer). Now you can put them to
use! Since John needs just one motor in his object, I kept
this very simple. If you’ve got spare cogs, you could run
multiple motors.
I’ve been thinking about an approach to running
multiple steppers in a single cog, but I think that’s best
done in PASM, and on another day. Unless you want to
jump in!
Help Me Help You
Most people remember the movie Jerry Maguire for
the line, “You had me at ‘Hello.’” For me, the most
memorable line is when Jerry (played by Tom Cruise) is on
his knees begging his client, Rod (played by Cuba
Gooding Jr.) with “Help me help you!” I like this line and
use it quite frequently — especially with people who are
new to the Propeller.
Writing for Nuts & Volts and being an active member
of the Parallax forums has provided many opportunities to
interact with other makers. With very few exceptions,
those interactions have been wonderful. I’ve even made
some great new friends — people like Dirk in Las Vegas
who builds amazing things for Burning Man and his
[perhaps eccentric] clients. It makes me happy that Dirk
has found some of my libraries helpful, and is putting
them to use for himself and his clients. Plus, he’s a really
smart, really nice guy whom I genuinely enjoy talking with.
Without going into the horrid details, I had a recent
email encounter with a new programmer who wasn’t able
to make one of my demos work. The solution was simple:
He was using a 1-Wire device and had neglected to add a
pull-up to the DQ pin. He thanked me for the solution,
and then went on a multi-part tirade about the
deficiencies of my code and style, even suggesting at one
point that I might not know what I’m doing.
Here’s the thing: I have this wacky idea that if you
want to use a 1-Wire device, you’ve taken at least a little
bit of time to look at a datasheet for it. The person in this
story was actually offended when I made that suggestion,
telling me that he didn’t want to be bothered with
datasheets.
It comes down to this: As embedded programmers,
we are responsible for code and for circuits — or, at the
very least, understanding the circuits we’re coding for. I
sincerely hope you find my code and libraries useful, and
it would make me very happy if you’re able to use what I
release under MIT license to provide for yourself and your
family.
That said, no matter how simple or sophisticated a
library (from anyone), as makers, we have the
responsibility to research and understand the component
associated with that library. To shirk this responsibility is
just inviting problems.
So ... help me (and other library creators) help you. If
you send an email, please make sure you have consulted
the datasheet for the part in question first as that process
may save you from writing. If you do still write, the
exchange should be quicker which will get you off and
running; me back to my clients; and I just might make a
great new friend to collaborate with.
Until next time, keep Spinning and winning with the
Propeller! NV
Jon “JonnyMac” McPhalen
jon@jonmcphalen.com
Parallax, Inc.
www.parallax.com
Propeller boards, chips, and programming tools
EFX-TEK
www.efx-tek.com
Propeller-based controllers and accessories
BOM
FliP module Parallax 32123
L293D SparkFun #14297, Mouser 511-L293D
10K resistor Mouser 299-10K-RC
Stepper motor SparkFun #10551 ( 7. 5 degrees)
Stepper motor SparkFun #9238 (1.8 degrees)
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