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My friend and I are planning on covering a non-square object(we were thinking of covering something with a wire mesh, such as a chair) with RGB LEDs and being able to control each LED individually. We looked into the different strips, but it seems like those LEDs are a bit too far spaced out, and we could easily save money per foot if we bought them in bulk.

My idea for this is to use an expander such as this one: http://goo.gl/PXJV1
to drive every 16 LEDs(or 16x16 LEDs for some areas if we multiplex). We are planning on using surface mounted LEDs such as: http://goo.gl/2w8I6
Would using this IC be the best way for management, or is there a better way to individuality control a large number of LEDs? I was also wondering if there were any ideas that could be cheaper than the one I proposed, or if my idea would even work.

Thanks for the assistance!
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Colorado
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You can buy cheaper RGB LEDs from mainland China.  For example: http://www.aliexpress.com/item/free-shipping-1000pcs-lot-SMD-LED-5050-RGB/824046864.html

The question I have is, based on how close people are going to be to this object, do you really want the LEDs so tightly packed?  You may find that those strips are more than adequate.  Some are packed 1.5cm apart while others are 3.1cm.
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Valencia, Spain
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You can RGB leds with individually addressable LED controllers built-in:

eg. http://www.aliexpress.com/item/5050-SMD-LED-WS2811-built-in-the-5050-smd-rgb-led-chip-DC5V/655201062.html

The WS2811 uses a 1-wire protocol to set the LED color and you can chain them together into strings, no limit on length.


Are you sure that 60 LEDs/meter isn't enough?

http://www.aliexpress.com/item/4m-WS2811-LED-digital-strip-60leds-m-with-60pcs-WS2811-built-in-tthe-5050-smd-rgb/633124138.html
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I guess that I had not researched those strips enough. 60 LED/m seems like it could fit our design goals, if I were to get these strips, what would be the easiest interface to allow for communication between the strips and an arduino?

Another thing that deterred us from using the strips is that since we might be making some sort of LED-covered animal, there would be many edges where having strips could be problematic. For these areas, what would be the best way of controlling many LEDs? Would using an I/O expander work with these?
http://www.aliexpress.com/item/5050-SMD-LED-WS2811-built-in-the-5050-smd-rgb-led-chip-DC5V/655201062.html
« Last Edit: April 30, 2013, 02:51:34 am by cyberjip » Logged

Valencia, Spain
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I guess that I had not researched those strips enough. 60 LED/m seems like it could fit our design goals, if I were to get these strips, what would be the easiest interface to allow for communication between the strips and an arduino?

One Arduino pin can drive millions of them. Just connect a wire to the first LED in the string.

Another thing that deterred us from using the strips is that since we might be making some sort of LED-covered animal, there would be many edges where having strips could be problematic. For these areas, what would be the best way of controlling many LEDs?

You can cut those strips into pieces with scissors between the brown dots.

(the "brown dots" are solder pads for attaching wires to the freshly-cut ends...)

Would using an I/O expander work with these?

One piece of wire is all you need, that's the whole point of the WS2811.
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One wire from Arduino running code such as FastSPI_LED(2).  Two wires to an external power source (because the Arduino will not be able to source that many.)
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