NeoPixels done with SPI

Intended for Adafruit NeoPixels (800 kHz version).

Run from an Arduino Uno / Mega or similar running at 16 MHz clock speed.

Connection

Since this library uses SPI for the precise timing needed, the data pin for the NeoPixels is MOSI.

On the Uno that is pin D11 (digital pin 11)
On the Mega that is D51
On other boards like the Leonardo you will need to pick up MOSI from the ICSP header

How to use

ledsetup ();

Get ready to send.
Call once at the beginning of the program.

sendPixel (r, g, b);

Send a single pixel to the string.

Call this once for each pixel in a frame.
Each colour is in the range 0 to 255.

show ();

Latch the recently sent pixels onto the LEDs .
Call once per frame.

showColor (count, r, g, b);

Set the entire string of count Neopixels to this one colour.
This automatically turns interrupts off, so you don't need to do it yourself.

Note that if you are sending individual pixels (with sendPixel) you should first call noInterrupts(), send all the pixels you need, and then call interrupts(). Otherwise a timer or other interrupt may pause the sending long enough for the string to reset.

For example:

    noInterrupts ();          // prevent interrupts while we are sending colours
    for (byte i = 0; i < 10; i++)
      {
      sendPixel (100, 0, 0);    // red
      sendPixel (0, 100, 0);    // green
      sendPixel (0, 0, 100);    // blue
      } // end of for loop
    interrupts ();            // interrupts are OK now
    show ();                  // latch the colours

More information

The forum post Simple method for using NeoPixels has a lot of details and explanations.

nickgammon / NeoPixels_SPI