Datasheet

left lit by a prior program.

In the strandtest example, loop() doesn’t set any pixel colors on its own — it calls other functions that create animated

effects. So let’s ignore it for now and look ahead, inside the individual functions, to see how the strip is controlled.

There are two ways to set the color of a pixel. The first is:

or, if you're using RGBW strips:

The first argument — n in this example — is the pixel number along the strip, starting from 0 closest to the Arduino. If

you have a strip of 30 pixels, they’re numbered 0 through 29. It’s a computer thing. You’ll see various places in the

code using a for loop, passing the loop counter variable as the pixel number to this function, to set the values of

multiple pixels.

The next three arguments are the pixel color, expressed as red, green and blue brightness levels, where 0 is dimmest

(off) and 255 is maximum brightness. The last

optional

argument is for white, which will only be used if the strip was

defined during creation as an RGBW type and the strip actually is RGBW type.

To set the 12th pixel (#11, counting from 0) to magenta (red + blue), you could write:

to set the 8th pixel (#7 counting from 0) to half-brightness white, with no light from red/green/blue, use:

An alternate syntax has just two arguments:

Here, color is a 32-bit type that merges the red, green and blue values into a single number. This is sometimes easier

or faster for some (but not all) programs to work with; you’ll see the strandtest code uses both syntaxes in different

places.

You can also convert separate red, green and blue values into a single 32-bit type for later use:

Then later you can just pass “magenta” as an argument to setPixelColor rather than the separate red, green and blue

numbers every time.

strip.setPixelColor(n, red, green, blue);

strip.setPixelColor(n, red, green, blue, white);

strip.setPixelColor(11, 255, 0, 255);

strip.setPixelColor(7, 0, 0, 0, 127);

strip.setPixelColor(n, color);

uint32_t magenta = strip.Color(255, 0, 255);