This returns a 32-bit merged RGB color value. This is always RGB, even if the “ColorHSV()” function (described below)
was used.
The number of pixels in a previously-declared strip can be queried using numPixels():
The overall brightness of all the LEDs can be adjusted using setBrightness(). This takes a single argument, a number in
the range 0 (off) to 255 (max brightness). For example, to set a strip to 1/4 brightness:
Just like setPixel(), this does not have an immediate effect. You need to follow this with a call to show().
setBrightness() was intended to be called
once,
in setup(), to limit the current/brightness of the LEDs throughout the
life of the sketch. It is
not
intended as an animation effect itself! The operation of this function is “lossy” — it modifies
the current pixel data in RAM, not in the show() call — in order to meet NeoPixels’ strict timing requirements. Certain
animation effects are better served by leaving the brightness setting at the default maximum, modulating pixel
brightness in your own sketch logic and redrawing the full strip with setPixel().
HSV (Hue-Saturation-Value) Colors…
The NeoPixel library has some support for colors in the “HSV” (hue-saturation-value) color space. This is a different
way of specifying colors than the usual RGB (red-green-blue). Some folks find it easier or more “natural” to think
about…or quite often it’s just easier for certain color effects (the popular rainbow cycle and such).
In the NeoPixel library,
hue
is expressed as a 16-bit
number. Starting from 0 for red, this increments first
toward yellow (around 65536/6, or 10922 give or take a
bit), and on through green, cyan (at the halfway point of
32768), blue, magenta and back to red. In your own
code, you can allow any hue-related variables to
overflow
or
underflow
and they’ll “wrap around” and do
the correct and expected thing, it’s really nice.
Saturation
determines the intensity or purity of the
color…this is an 8-bit number ranging from 0 (no
saturation, just grayscale) to 255 (maximum saturation,
pure hue). In the middle, you’ll start to get sort of pastel
tones.
Value
determines the brightness of a color…it’s also an
8-bit number ranging from 0 (black, regardless of hue or
saturation) to 255 (maximum brightness).
setPixelColor() and fill() both still want RGB values though, so we convert to these from HSV by using the ColorHSV()
function: