PROJECTS Squishy Tech
ingress ratings so you’ll know if you can use them
outside. A strip rated IP30 has no waterproofing;
IP65 has a rainproof silicone covering. Strips are
also often described by density — how many LEDs
there are per meter.
The individual LEDs within a panel or strip
also come in various package sizes. The most
common, and brightest, is the 5050 packaging,
which is 5mm×5mm square. Plain RGB, RGBW,
addressable, and many other kinds of LEDs come
in 5050 packaging. Other common sizes are 3528
and 5630, which are generally not as bright (or
big), and 3535, which Adafruit calls NeoPixel Mini.
Figure
F
shows a 5050 (left) and 3535 (right).
Phew, that's a mouthful but thankfully this
article is always here for reference!
CONTROLLING LEDS
You can control addressable LEDs in a variety
of ways depending on how customized you want
the pattern. Some LEDs come pre-programmed
with patterns or sequences that you can’t change;
this will usually be indicated as “auto flashing”
or similar. But it’s more fun to use controllers to
change up the patterns and sequences.
Generic controllers often come with LEDs
you can buy off the shelf. Usually these have an
IR remote that can set simple patterns or preset
colors, although some have buttons that cycle
through pre-set patterns, like your holiday lights!
To get a bit more advanced, you can program
your own patterns using an Arduino, no additional
can help you get the right LEDs for your project.
I’ll refer to these mostly as strips, but you can get
all kinds of panels, flexible matrixes, string lights,
rings, or other creative form factors.
Non-addressable LEDs come in a few types. Single
color LED strips are as they sound, a single color.
The whole strip can be on, off, or fading, but you
can’t control each individual light. These are
great for simple environmental lighting or just to
add light quickly to a project. They usually have 2
wires, red and black, as well as a voltage rating.
If a strip is described simply as RGB, it will
usually have 4 wires, one each for red, green,
blue, and ground, and you can make the entire
strip any color. RGBW strips have an additional
fourth channel for pure white LEDs and a fifth
wire to control it.
Speaking of white LEDs, you’ll find that there
is a range of warm and cool white. This color
temperature is measured in degrees Kelvin, and
goes from around 2700K (warm) to 6000K (cool)
with 4000K being considered roughly neutral.
Addressable LEDs are the type where you can
control each LED individually, as opposed to the
whole strip (or matrix) behaving the same way.
Using addressable LEDs, you can make patterns,
images, and all kinds of complex effects that
aren’t possible with plain RGB LEDs.
You may have heard these commonly
referred to as NeoPixels (Figure
E
), which is a
brand name in the Adafruit ecosystem. Not all
addressables are NeoPixels, and understanding
the part numbers can help you buy LEDs from
various suppliers. NeoPixels are WS2812 LEDs
(and their clone, SK6812) or the older version with
an external IC, WS2811. The benefit of WS2812
is that if there’s a broken LED, the sequence
continues after it instead of breaking the rest
of the line, unlike the WS2811. There is also
WS2813, which has Data In and Data Out pins
broken out, instead of a single data line.
APA102 or SK9822 are called DotStar by
Adafruit. They’re much faster, and require two
pins to control (data and clock). DotStars are
great for things that require speed, like POV
displays or fast animations.
LED strips also have dust/waterproofing
E
F
Adafruit, Dushan Milic, ElectroMage
72 makezine.com
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