led_matrix_sample_code.ino

/*
 * Example for 8x8 LED matrix
 * Original source http://hastebin.com/raw/wazuhujoga, linked from http://www.amazon.co.uk/forum/-/Tx3UWNLLPMFDQT6/ref=ask_dp_dpmw_al_hza?asin=B00GKEMQUM
 */

#define MAX7219_DIN 5
#define MAX7219_CS  3
#define MAX7219_CLK 2

const int wait = 100;

void initialise()
{
  digitalWrite(MAX7219_CS, HIGH);
  pinMode(MAX7219_DIN, OUTPUT);
  pinMode(MAX7219_CS, OUTPUT);
  pinMode(MAX7219_CLK, OUTPUT);
}

void output(byte address, byte data)
{
  digitalWrite(MAX7219_CS, LOW);
  shiftOut(MAX7219_DIN, MAX7219_CLK, MSBFIRST, address);
  shiftOut(MAX7219_DIN, MAX7219_CLK, MSBFIRST, data);
  digitalWrite(MAX7219_CS, HIGH);
}

void setTestMode(boolean on)
{
  output(0x0f, on ? 0x01 : 0x00);
}

void setShutdown(boolean off)
{
  output(0x0c, off ? 0x00 : 0x01); //shutdown register - normal operation
}

void showDigits(byte numDigits)
{
  output(0x0b, numDigits-1); //scan limit register
}

void setBrightness(byte brightness)
{
  output(0x0a, brightness); //intensity register - max brightness
}

void putByte(byte data) {
  byte i = 8;
  byte mask;
  while(i > 0) {
    mask = 0x01 << (i - 1);           // get bitmask
    digitalWrite(MAX7219_CLK, LOW);   // tick
    if (data & mask){                 // choose bit
      digitalWrite(MAX7219_DIN, HIGH);// send 1
    }else{
      digitalWrite(MAX7219_DIN, LOW); // send 0
    }
    digitalWrite(MAX7219_CLK, HIGH);  // tock
    --i;                              // move to lesser bit
  }
}

void maxSingle(byte reg, byte col) {
  digitalWrite(MAX7219_CS, LOW);       // CS has to transition from LOW to HIGH    
  putByte(reg);                        // specify register
  putByte(col);                        // put data  
  digitalWrite(MAX7219_CS, LOW);       // Load by switching CS HIGH
  digitalWrite(MAX7219_CS, HIGH);
}

void write8x8(byte a, byte b, byte c, byte d, byte e, byte f, byte g, byte h){
   maxSingle(1,a);
   maxSingle(2,b);
   maxSingle(3,c);
   maxSingle(4,d);
   maxSingle(5,e);
   maxSingle(6,f);
   maxSingle(7,g);
   maxSingle(8,h);
  delay(wait);
}

void setup() {
  initialise();
  setTestMode(false);
  setShutdown(false);
  setBrightness(1); // Brightness range 1..0x0f
  showDigits(8);    // Make sure all digits are visible
  output(0x09, 0);  // using an led matrix (not digits)
}

void loop() {
  // Generate bytes with something like the LED Byte Generator Chrome App: https://goo.gl/w4xhzm

write8x8(0x0,0x42,0x42,0x42,0x42,0x42,0x42,0x3c);
  /*
  write8x8(0x0,0x1,0x1,0x1,0x1,0x1,0x1,0x0);
  write8x8(0x0,0x2,0x3,0x2,0x2,0x2,0x2,0x0);
  write8x8(0x0,0x4,0x6,0x5,0x4,0x4,0x4,0x0);
  write8x8(0x0,0x8,0xc,0xa,0x9,0x8,0x8,0x0);
  write8x8(0x0,0x10,0x18,0x14,0x12,0x11,0x10,0x0);
  write8x8(0x0,0x21,0x31,0x29,0x25,0x23,0x21,0x0);
  write8x8(0x0,0x42,0x62,0x52,0x4a,0x46,0x42,0x0);
  write8x8(0x0,0x85,0xc5,0xa5,0x95,0x8d,0x85,0x0);
  write8x8(0x0,0xa,0x8a,0x4a,0x2a,0x1a,0xa,0x0);
  write8x8(0x0,0x14,0x15,0x95,0x55,0x35,0x14,0x0);
  write8x8(0x0,0x29,0x2a,0x2a,0xaa,0x6a,0x29,0x0);
  write8x8(0x0,0x53,0x54,0x54,0x54,0xd4,0x53,0x0);
  write8x8(0x0,0xa6,0xa9,0xa8,0xa8,0xa9,0xa6,0x0);
  write8x8(0x0,0x4c,0x52,0x50,0x50,0x52,0x4c,0x0);
  write8x8(0x0,0x99,0xa5,0xa1,0xa1,0xa5,0x99,0x0);
  write8x8(0x0,0x32,0x4a,0x43,0x43,0x4a,0x32,0x0);
  write8x8(0x0,0x64,0x95,0x86,0x86,0x95,0x64,0x0);
  write8x8(0x0,0xc9,0x2a,0xc,0xc,0x2a,0xc9,0x0);
  write8x8(0x0,0x92,0x54,0x18,0x18,0x54,0x92,0x0);
  write8x8(0x0,0x24,0xa8,0x30,0x30,0xa8,0x24,0x0);
  write8x8(0x0,0x48,0x50,0x60,0x60,0x50,0x48,0x0);
  write8x8(0x0,0x90,0xa0,0xc0,0xc0,0xa0,0x90,0x0);
  write8x8(0x0,0x20,0x40,0x80,0x80,0x40,0x20,0x0);
  write8x8(0x0,0x40,0x80,0x0,0x0,0x80,0x40,0x0);
  write8x8(0x0,0x80,0x0,0x0,0x0,0x0,0x80,0x0);
  write8x8(0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0);
  */
}