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.
EDITOR’S NOTE: I’ve attached PDF files of the pentagon PCB and the motherboard PCB. If I had time to label them and make them pretty, I would, but this was never designed for mass production or consumption. Use at your own risk and frustration. For those with a short attention span, I give you a photo […]
For those of you with short attention spans, like me, here is a quick and lame video I threw together in iMovie: I am building this for the new awesome bed I will be building this winter for our bedroom. There will be two of these lamps, one for me and one for my wife […]
UPDATE: Want a PCB and components for your own project? I’ve had a deluge of requests for the PCBs for this project. If you’re interested, please contact me through this blog. I’m trying to figure out whether it’s worth it to sell the boards alone or maybe as a kit with the LEDs and resistors (or […]
I’m building a bright LED reading light that will be powered by a “9V” wall wart power supply and will use a flexible stem to position the light to not disturb my wife while I read and she sleeps.