There are drivers specifically designed for this, which do the magic by using a matrix where the "on" LEDs are on only part of the time - that's sufficient at high refresh rates for the human eye to convince you they are always on. You can do it yourself to drive 120 LEDs with 17 microcontroller I/O like this: http://www.nerdkits.com/videos/ledarray2/
<http://www.nerdkits.com/videos/ledarray2/>....or if you want a slightly fancier solution, you can use a few of these: http://www.ti.com/product/tlc59116 <http://www.ti.com/product/tlc59116>Up to 224 LEDs controlled over I2C, and that's easily muxed to get you more. * Drew Van Zandt Artisan's Asylum Craft Lead, Electronics & Robotics Cam # US2010035593 (M:Liam Hopkins R: Bastian Rotgeld) Domain Coordinator, MA-003-D. Masquerade aVST * On Fri, Jan 20, 2012 at 12:19 AM, David Kramer <[email protected]> wrote: > I would like to make a mask with a rotating message on it. I'm debating > two completely different designs; one mechanical and one electronic. > Full description of the project at > > http://wiki.thekramers.net/Main/GitsMask > > If I decide to go with the electronic solution, I would need a ring > roughly 9"-10" in diameter, with enough LEDs on it to scroll words, > meaning 120 or more LEDs, where about half of them may be on at any time. > > It's been a while since I've done serious embedded work, but I'm pretty > sure I'm up to the software and the hardware side. There must be > examples out there about scrolling words on a sign for pretty much every > appropriate platform, and this is just bending it into a circle. > > That's a lot of ports, though. Most microcontrollers only have 3 or 4 > 8-bit output, which wouldn't even do half the job. I am ideologically > attracted to Arduino, but if a more appropriate platform is available, I > would probably use it. > > Anyone have any suggestions? > > Thanks. > _______________________________________________ > Hardwarehacking mailing list > [email protected] > http://lists.blu.org/mailman/listinfo/hardwarehacking >
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