In diesem Wiki-Eintrag soll es im Gegensatz zum anderen LED-Matrix-Eintag, nicht um die selbstgebauten Matrizen, sondern um LED-Matrizen vom Typ max7219 gehen. Hier sind im Folgenden einige Code-Beispiele, um solche Matrizen mit dem Arduino zu bedienen, sowie das Anschließen an eben diesen zu finden.

// *****************   Beginn Initialisierung Matrix   ************************
 
int dataIn = 2;
int load = 3;
int clock = 4;
 
int maxInUse = 4;    //change this variable to set how many MAX7219's you'll use
 
int e = 0;           // just a varialble
 
// define max7219 registers
byte max7219_reg_noop        = 0x00;
byte max7219_reg_digit0      = 0x01;
byte max7219_reg_digit1      = 0x02;
byte max7219_reg_digit2      = 0x03;
byte max7219_reg_digit3      = 0x04;
byte max7219_reg_digit4      = 0x05;
byte max7219_reg_digit5      = 0x06;
byte max7219_reg_digit6      = 0x07;
byte max7219_reg_digit7      = 0x08;
byte max7219_reg_decodeMode  = 0x09;
byte max7219_reg_intensity   = 0x0a;
byte max7219_reg_scanLimit   = 0x0b;
byte max7219_reg_shutdown    = 0x0c;
byte max7219_reg_displayTest = 0x0f;
 
void putByte(byte data) {
  byte i = 8;
  byte mask;
  while (i > 0) {
    mask = 0x01 << (i - 1);      // get bitmask
    digitalWrite( clock, LOW);   // tick
    if (data & mask) {           // choose bit
      digitalWrite(dataIn, HIGH);// send 1
    } else {
      digitalWrite(dataIn, LOW); // send 0
    }
    digitalWrite(clock, HIGH);   // tock
    --i;                         // move to lesser bit
  }
}
 
void maxAll (byte reg, byte col) {    // initialize  all  MAX7219's in the system
  int c = 0;
  digitalWrite(load, LOW);  // begin
  for ( c = 1; c <= maxInUse; c++) {
    putByte(reg);  // specify register
    putByte(col);//((data & 0x01) * 256) + data >> 1); // put data
  }
  digitalWrite(load, LOW);
  digitalWrite(load, HIGH);
}
void maxOne(byte maxNr, byte reg, byte col) {    
//maxOne is for adressing different MAX7219's, 
//whilele having a couple of them cascaded
 
  int c = 0;
  digitalWrite(load, LOW);  // begin     
 
  for ( c = maxInUse; c > maxNr; c--) {
    putByte(0);    // means no operation
    putByte(0);    // means no operation
  }
 
  putByte(reg);  // specify register
  putByte(col);//((data & 0x01) * 256) + data >> 1); // put data 
 
  for ( c =maxNr-1; c >= 1; c--) {
    putByte(0);    // means no operation
    putByte(0);    // means no operation
  }
 
  digitalWrite(load, LOW);
  digitalWrite(load,HIGH); 
}
 
void setup() {
 
  Serial.begin(9600);
 
  pinMode(dataIn, OUTPUT);
  pinMode(clock,  OUTPUT);
  pinMode(load,   OUTPUT);
 
  //initiation of the max 7219
  maxAll(max7219_reg_scanLimit, 0x07);
  maxAll(max7219_reg_decodeMode, 0x00);  // using an led matrix (not digits)
  maxAll(max7219_reg_shutdown, 0x01);    // not in shutdown mode
  maxAll(max7219_reg_displayTest, 0x00); // no display test
  for (e = 1; e <= 8; e++) { // empty registers, turn all LEDs off
    maxAll(e, 0);
  }
  maxAll(max7219_reg_intensity, 0x0f & 0x0f);    // the first 0x0f is the value you can set
  // range: 0x00 to 0x0f
 
}
 
// *********************************   Ende Initialisierung Matrix   **********************************