Stuff Andy Makes – DIY, make, tinker, play

Charlieplexing LEDs with an AVR ATmega328

Apr 29

AndyEducational/Interesting, Electronics, Miscellaneous, Projects, Tips and Techniques atmel, avr, charlieplexing, led, microcontroller, pcb 3 Comments

This is the first in a two-part series. This first article made me realize there’s a lot of ground to cover and we’re already in the tl;dr territory.

How many times has this happened to you? You have a little LED project with an AVR ATmega328 microcontroller (or Arduino) at its core and you need to light up a boatload…. A dingyload of LEDs. Maybe it doesn’t happen a lot to you. It’s happened on three recent projects for me. My latest two LED projects are a timekeeping piece that illuminates 21 characters from behind and a simple LED chaser thing.

As usual I wanted to keep the component count down on these projects. I also tend to prefer not to use a ton of ICs with busses between them and whatnot, if I can help it. So much darn soldering and stuff. Meh. Luckily, back in 1995, so the Wikipedia story goes, a super-smart dood named Charlie Allen at Maxim Integrated devised a super-ingenius way to control a large number of LEDs using a not-so-large number of microcontroller pins. The method is called, “Charlieplexing” and it seems a but daunting, at first, but it’s not that bad once you figger it out.

The core of this concept is based on the fact that diodes only allow current to flow in one direction. The “D” in “LED” stands for “diode.” Ergo, LEDs are diodes. LEDs only light up when connected a particular direction. Put two diodes in parallel BUT in the opposite-facing direction and you can turn on one or the other simply by switching the polarity of the ends of the circuit. Fun! Diagram:

Two LEDs in Parallel

Let’s assume I have a 3V little coin cell running this thing and limiting resistors and CCRs are not our thing, today. Why not? Anyhoo… Looking at the diagram, you see I’m using GPIO pins from an Atmel ATmega168 AVR microcontroller (it was readily available in the library in Fritzing, the program I used to throw together the drawring diagram schematic thing above). If I configger A0 and A1 as outputs and then set A1 HIGH and A0 LOW, I can turn on LED1. If I flip the states of the two pins and make A1 LOW and A0 HIGH, LED2 will light. Here’s a animated GIF of how it works with direct connections from the LEDs to 3V lithium coin cell on a breadboard:

Parallel opposite polarity LEDs flipping state

Watch carefully and you’ll see that I switched the positive and negative to make one or the other LED light. Easy as pie. Imagine each wire from the battery is a GPIO pin from a microctonroller. All I’m doing up there is making one HIGH and one LOW and then flipping them back and forth.

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Standing Desk Improvisation Inspiration with Little Perspiration

Apr 09

AndyProjects, Tips and Techniques, Upgrades/Hacks desk hack, ikea, meltmedia, office upgrade, standing desk No Comments

Today at the office, I walked by a coworker’s desk and something was different: She’d put an Ikea table and shelf together and set them on top of her desk. Nutty, at first glance. Purposeful, after 0.25 seconds of thought. Here’s what I saw:

Stand-Up Desk at meltmedia

Kristian came across this article from Colin Nederkoorn’s Blog with instructions on how to make your regular desk a standing or stand-up desk for only $22 with a couple of items from Ikea! Whatabargain! More

meltmedia meltHack-A-Palooza V: The Lost Pushbutton

Apr 07

AndyEducational/Interesting arduino, coding, electronics, hack day, meltmedia, microcontroller, MSP430, pelican case, pizza, rotary encoder No Comments

Every few months I organize a hack day at the office, usually on a Saturday. This past Saturday we had our 5th installment of hack/make/tinker day at meltmedia and the turnout was great! Attendance was 8, up from 3 the last time around. YESSS!

meltmedia East Kitchen Table Hacking

Nick put together a little video of the goings on:

Or click here to see meltmedia Hack Day | April 6, 2013 from meltmedia on Vimeo.

We had all manner of making and designing, but most importantly, around 1:30-ish, we had PIZZA!!

Fueling the Making with Pizza

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Electronics Workbench LED Upgrade

Mar 17

AndyTips and Techniques, Upgrades/Hacks drawers, lamp, LED lighting, organization, workbench No Comments

I guess I forgot to post an update to the update of my workbench. Not only did I clean up the gigantic mess that had accumulated on it, I improved the lighting and workspace availability:

Electronic Workbench LED Lighting Upgrade

Prior to this upgrade, I had fluorescent lighting under the blue cabinets over the bench. They extended down about 3 to 4 inches and kinda got in the way. I also didn’t think through the placement, so they were back about half-way under the cabinets. This meant they didn’t put light out on the front edge of the tabletop like I would have hoped. Here’s the old lighting:

Old Fluorescent Lighting

The monitor on the left barely fit behind the light and the light extended down lower than the top of the monitor. Dumb. I might have been drinking bourbon that day. Like, more than a shot or two. No matter. That is history. Today, we have wonderLEDs!

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iPhone Lens Adapters from Photojojo

Mar 17

AndySwank-n-Funk, Tips and Techniques adapter, fisheye, iphone, lens, macro, photography, telephoto No Comments

I’ve seen a few different add-on lenses for iPhones out there and decided to nab a set for myself to make my detail photos and product shots a little more neato. I went with the Photojojo three-lens kit for $49 US.

Photojojo Three Lens Kit

These lenses are just little guys. They come with front covers and magnetic back covers that double as little string handles.

Lenses with Covers next to Kinekt Ring

Kinekt Design Gear Ring not included.

The lenses are tough little buggers. Appear to be made from aloominum (or Al U. Minium, if you’re from Canadia, eh), or something like it. The black front caps are flexible plastic and the backs with the little handles are magnetic metal something something. Quality is nice and the glass appears to be very clean and clear. My telephoto lens did not ship with a fingerprint. I had to accidentally add that myself. It was easy to clean off with a standard microfiber cloth.

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Home-Aged Bourbon YUM!

Mar 04

AndyBourbon, Tips and Techniques aging, bourbon, charred oak, home age, moonshine, oak barrel, white dog No Comments

While wandering around at the 2012 Kentucky Bourbon Festival, I stumbled upon the Bluegrass Barrels tent. The guys there showed me how easily white dog (moonshine, or corn whiskey before it goes into the barrel to eventually become bourbon) can be aged at home in your own little charred oak barrel. Is that awesome or what??

BOOM! Brand New Charred Oak Mini Barrel

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Lipstick Camera Turned Video Microscope

Mar 03

AndyProjects, Tips and Techniques, Upgrades/Hacks gooseneck, hacked lamp, lipstick camera, microscope, ntsc, tft lcd, video No Comments

Backstory: In a previous life, I was a freefall photographer. I took photos and shot video while skydiving. Before GoPro and others started popping up on the scene, I had devised a little rig for shooting freefall video without the need for the bulky miniDV camera on my helmet. The setup used a “bullet” or “lipstick” camera which provided a video input signal for a miniDV camera (used as a tape deck at this point) located OFF my helmet and in a pouch under my jumpsuit. I don’t remember where I got the camera. They can be found on the InterWebs for $100-ish, maybe less. Anyhoo, if you’ve ever stuck your hand out of the window of a car moving at highway speed, I’m pretty sure you’ll be able to figure out how non-aerodynamic a miniDV camera is. Needless to say, a lipstick camera cuts through the wind WAY easier than a full-on Sony TRV-20 miniDV camera. A lipstick camera also weighs considerably less than a miniDV camera.

Lipstick Camera

OK, now that I’ve barfed out a giant intro paragraph, let’s get to the nutty-tasting inside of this story: I have this lipstick camera sitting around in a box. I know that when I twist the lens away from the sensor, the camera acts more and more like a video microscope. I have many tiny things I’d like to look at with minimal camera shake. More

2012 Kentucky Bourbon Festival

Feb 25

AndyMiscellaneous No Comments

2012 was the second year I visited Kentucky for the Bourbon Festival. Just like 2011, it was a hoot. This time around (see my previous post) I was able to hit the entire Kentucky Bourbon Trail in one trip. The combination of the two made it that much more enjoyable. Because I was sloppy about taking photos this second trip, I am going to borrow some photos from 2011 for scenery, but not events.

We wandered into town and as usual started in the Bardstown center of downtown to get our tickets and passes and whatnot. The building is beautiful and the people are friendly as can be.

Bardstown Center of Downtown (at night, of course)

Also, this is a famous place, in case you were wondering and I’m sure you were:

Site of First Amputation from Hip Joint

In 2011, I rode a turkey barrel.

Turkey Barrel Ride

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2012 Kentucky Bourbon Trail

Feb 25

AndyMiscellaneous bourbon, four roses, heaven hill, jim beam, kentucky bourbon festival, kentucky bourbon trail, maker's mark, rick house, rick warehouse, whiskey, white oak barrel, wild turkey, woodford reserve No Comments

Kentucky Bourbon Trail Passport Stamp – Cover

I now make the yearly pilgrimage to the Kentucky Bourbon Festival. I start out by flying into Nashville, Tennessee to make the road trip with my best friend, Dan. I’ve known him for 30 years (insert old jokes here). He works at Country Music Television (insert country music jokes here). I can’t stand country music (insert… Oh, carry on). To prime my liver, however, we went to honky tonks in downtown Nashville. You can tell by the photo that I am not a country music fan. But, we had a great time, nonetheless.

A fish out of water in the honky tonks of Nashville

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Making Mad Props for meltmedia’s Interactive Superhero Marketing Launch: The Rest of the Props

Nov 01

AndyProjects, Propmaking 2 Comments

This is the 3rd in a series of articles about the props I built for my company’s internal marketing launch, which was themed around superheroes. I had to wait to write these three articles because we hadn’t launched yet when I had finished the props. This article focusses on the last partner prop and the simplest of the three, plus the capes, boots, masks and toolbelts used as props near the front doors of our office spaces (making it look like the meltmedia Interactive Superheroes had come in and hung up their stuff on coatracks after a long day of saving organizations from mediocre designs).

Here is one of the coatracks with the Interactive Superhero uniform:

meltmedia Interactive Superhero Uniform on Coatrack

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