More LED testing...

gistfile1.c

// include the neo pixel library
#include <Adafruit_NeoPixel.h>

// how many leds in our string?
static const int NUM_LEDS =21*6;
static const int TOTAL_BYTES = NUM_LEDS*3;

// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_RGB     Pixels are wired for RGB bitstream
//   NEO_GRB     Pixels are wired for GRB bitstream
//   NEO_KHZ400  400 KHz bitstream (e.g. FLORA pixels)
//   NEO_KHZ800  800 KHz bitstream (e.g. High Density LED strip)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, 6, NEO_RGB + NEO_KHZ800);

// buffer to hold colors of our LEDs
char colorValues[TOTAL_BYTES];
char buffer[TOTAL_BYTES];
int index = 0;
boolean bufferReady = true;
boolean secondBuffer = false;

void setup() {
  strip.begin();
  strip.show();

  // initialize to black (off)
  for (int i=0; i < NUM_LEDS; i++) {
    int d = i*3;
    colorValues[d] = 255;
    colorValues[d+1] = 0;
    colorValues[d+2] = 255;
    buffer[d] = 0;
    buffer[d+1] = 0;
    buffer[d+2] = 0;
  }

  // initialize the strip to the current values
  for(int i=0; i<NUM_LEDS; i++) {
    int d = i*3;
    uint32_t c = strip.Color(colorValues[d], colorValues[d+1], colorValues[d+2]);
    strip.setPixelColor(i, c);
  }
  // update the strip
  strip.show();

   //Initialize serial and wait for port to open:
  Serial.begin(57600);
  while (!Serial) {
    ; // wait for port
  }
}

void loop() {
  // wait for bytes on serial port

  if (bufferReady) {
    for(int i=0; i<NUM_LEDS; i++) {
      int d = i*3;
      uint32_t c;
      if (secondBuffer) {
        c = strip.Color(buffer[d+1], buffer[d], buffer[d+2]);
      } else {
        c = strip.Color(colorValues[d+1], colorValues[d], colorValues[d+2]);
      }
      strip.setPixelColor(i, c);
    }
    // update the strip
    strip.show();
    bufferReady = false;
  }
}

int writeIndex = 0;
int remaining = TOTAL_BYTES;
char count = 0;
void serialEvent() {
 while (Serial.available() > 0) {
  // figure out how many bytes are remaining unwritten in the current buffer
  remaining = TOTAL_BYTES-writeIndex;
  // attempt to read that many bytes
  count = 0;
  if (secondBuffer) {
    count = Serial.readBytes(&colorValues[writeIndex],remaining);
  } else {
    count = Serial.readBytes(&buffer[writeIndex],remaining);
  }
  // advance writeIndex
  writeIndex += count;
  // check if we've hit the total bytes
  if (writeIndex >= TOTAL_BYTES) {
    // we have so switch buffers now and loop
    writeIndex = 0;
    // set data!
    bufferReady = true; 
    secondBuffer = !secondBuffer;
    break;
  }
 }
}