Nuts and Volts - September 2017

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)