Sample code for working with the giant LED screen described at MakeUseOf.com, using Adafruit Neomatrix and GFX libraries

neomatrix_pixel_display.ino

#include <Adafruit_GFX.h>
#include <Adafruit_NeoMatrix.h>
#include <Adafruit_NeoPixel.h>

#define XSIZE 15
#define YSIZE 14
#define PIN  6

Adafruit_NeoMatrix matrix = Adafruit_NeoMatrix(XSIZE, YSIZE, PIN,
  NEO_MATRIX_BOTTOM     + NEO_MATRIX_LEFT +
  NEO_MATRIX_ROWS + NEO_MATRIX_ZIGZAG,
  NEO_GRB            + NEO_KHZ800);
  
// Some sprite definitions. Use "image to bitmap converter" included with Adafruit GFX library to create these
prog_uint8_t upArrow[] PROGMEM={
  0x0,0x0,
  0x1,0x0,
  0x3,0x80,
  0x7,0xc0,
  0xf,0xe0,
  0x1f,0xf0,
  0x3f,0xf8,
  0x7f,0xfc,
  0xf,0xe0,
  0xf,0xe0,
  0xf,0xe0,
  0xf,0xe0,
  0xf,0xe0,
  0x0,0x0
};

prog_uint8_t smile[] PROGMEM=
{
  0x0,0x0,
  0x3,0x80,
  0xc,0x60,
  0x10,0x10,
  0x24,0x48,
  0x44,0x44,
  0x40,0x4,
  0x48,0x24,
  0x48,0x24,
  0x27,0xc8,
  0x10,0x10,
  0xc,0x60,
  0x3,0x80,
  0x0,0x0
};


// Color definitions
#define BLACK    0x0000
#define BLUE     0x001F
#define RED      0xF800
#define GREEN    0x07E0
#define CYAN     0x07FF
#define MAGENTA  0xF81F
#define YELLOW   0xFFE0 
#define WHITE    0xFFFF

void setup(){
  matrix.begin();
  matrix.setTextWrap(false);
  matrix.setBrightness(255);
}





int x    = matrix.width();
int pass = 0;


void loop(){
  
  // randomize text and bitmap colours
  uint16_t bitmapColour = drawRGB24toRGB565(random(0,255),random(0,255),random(0,255));
  
  //display smiley bitmap before message 
  if(pass == 0) {
    pulseBitmap(smile,3,bitmapColour);
    uint16_t textColour = drawRGB24toRGB565(random(0,255),random(0,255),random(0,255));
    matrix.setTextColor(textColour);
    matrix.show();
  }
  
  pass++;
  
  
  matrix.fillScreen(0);
  matrix.setBrightness(255);
  matrix.setCursor(x, 3);
  String message = "MakeUseOf.com";
  int messageScrollLength = (message.length())*8;
  matrix.print(message);
  
  if(--x < -messageScrollLength) { // number of characters * 8
    x = matrix.width();
    pass = 0;
    
  }
  matrix.show();
  delay(100);
}

void pulseBitmap(uint8_t* bmp,int times, uint16_t colour){
  for(int x=1;x<=times;x++){
    for(int i=0;i<=10;i++){
       matrix.setBrightness(i*25);
       matrix.drawBitmap(0,0,bmp,15,14,colour);
       matrix.show();
       delay(20);
    }
    delay(200);
    for(int i=10;i>=0;i--){
       matrix.setBrightness(i*25);
       matrix.drawBitmap(0,0,bmp,15,14,colour);
       matrix.show();
       delay(20);
    }
  }
}

/**************************************************************************/
/*!
    @brief  Converts a 24-bit RGB color to an equivalent 16-bit RGB565 value

    @param[in]  r
                8-bit red
    @param[in]  g
                8-bit green
    @param[in]  b
                8-bit blue

    @section Example

    @code 

    // Get 16-bit equivalent of 24-bit color
    uint16_t gray = drawRGB24toRGB565(0x33, 0x33, 0x33);

    @endcode
*/
/**************************************************************************/
uint16_t drawRGB24toRGB565(uint8_t r, uint8_t g, uint8_t b)
{
  return ((r / 8) << 11) | ((g / 4) << 5) | (b / 8);
}