Humboldt Microcontrollers Group: June 12 Meeting Notes

Getting started on this post much later than usual, so it will be just a few comments about what happened at tonight's meeting of the Humboldt Microcontrollers Group.

Due to people being out of town and having prior commitments, there were only four participants in tonight's meeting. We still had good discussions about microcontrollers and electronics, and I, at least, learned a few things about controlling motors with microcontrollers (MCUs).

TI Tiva C LaunchPad board

Ed started out the night by showing us the powerful $20 Texas Instruments (TI) Tiva C LaunchPad board he received recently from TI. He hasn't a chance to hook up any fancy demonstrations with it for the group yet, but he did seem pretty happy with it. We'll likely have a blog post about it from him in the next few weeks after he's had a chance to work with it.

Ed also brought his less expensive TI LaunchPad board which he is using for some capsense proximity sensing. He talked about that at the previous Humboldt Microcontrollers Group meeting, and brought the small LaunchPad to demonstrate some capsense work he'd done since that previous meeting.

The third item Ed brought were some nice oscilloscope screenshots of the PWM (pulse width modulation) control of the DC motor, since part of tonight's meeting was planned to be discussion of Jeremy Blum's 'Arduino Basics' #5 video tutorial about motors and transistors. You'll see those oscilloscope screenshots in an upcoming blog post. Ed explained what the screenshots showed and the difference between the various trace patterns.

Nick explains how the chicken coop door opener will work.

Nick brought the work-in-progress door opening mechanism for his new chicken coop. I'm trying to talk him into writing one or several blog posts about the project, but so far his time has been focused on finishing the design and getting it built. He powered the circuitry for opening and closing the door and showed us how it works. One of the door automation components is a part off an old Willys Jeep, which makes his chicken coop door more interesting and a bit unique. It's unlikely many other chicken coop doors in the USA have parts from a Willys Jeep. We just hope the chickens appreciate the history and character of their coop door!

After Nick demoed the chicken door opener, he talked briefly about the microcontroller educational kit he received from TI. We're looking forward to him bringing that to an upcoming meeting and maybe writing a blog post about the kit.

First circuit in #5 video tutorial

Next we spent some time talking about microcontrollers and motors, with the discussions being primarily to help me understand how circuits should be designed for controlling motors with an MCU and how the components for the circuits should be selected or sized. After we got most of my 'no load current,' 'voltage operating range,' 'stall current' and 'collector current' questions answered about motors and transistors, the group helped me finish breadboarding the first exercise in the #5 video, Nick typed up the sketch for the Arduino to operate the motor, we plugged it into power -- and the setup worked perfectly. Voila!

This weekend, I'll go through that exercise again by myself to make sure I understand it, polish up the code in the sketch a bit so it has comments in it and so I understand what each part of the code is doing. Then I'm hoping to work on the rest of the #5 video (although I still need to work on a couple previous videos in the series...).

One last thing discussed was the Humboldt Microcontrollers Group wiki. We started out with a Wikispaces wiki, but have decided to move away from that wiki service because they require everyone who wants to view their wikis to sign up for an account. That's just annoying for how we want to use the microcontroller wiki. So Ed is hosting a MediaWiki site, and we hope to have that operational in the next week or two. We'll put a link to the wiki on this blog once the site is up and running.

See you in two weeks (that's Thursday, June 26) for the next Humboldt Microcontrollers Group meeting.

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