int column_pins[6] = {
  12,11,10,9,8,7
};

int plate_pins[4] = {
  6,4,3,5,
};

void init_pins(void)
{
  for(int i=0;i<6;i++){
    pinMode(column_pins[i], OUTPUT);
    digitalWrite(column_pins[i], LOW);
  }
  for(int i=0;i<4;i++){
    pinMode(plate_pins[i], OUTPUT);
    digitalWrite(plate_pins[i], LOW);
  }
}

void set_column(int old,int new_column)
{
  digitalWrite(column_pins[old], LOW);
  delayMicroseconds(100);
  digitalWrite(column_pins[new_column], HIGH);
}

void set_plate(int value)
{
  digitalWrite(plate_pins[3], (value & 0x8));
  digitalWrite(plate_pins[2], (value & 0x4));
  digitalWrite(plate_pins[1], (value & 0x2));
  digitalWrite(plate_pins[0], (value & 0x1));
}

long last_time;
int plate;
int column;

void setup()
{
  init_pins();
  last_time = millis();
  column = plate = 0;
  set_plate(plate);
}

void loop()
{
  int new_column = column + 1;
  if(new_column > 5)
    new_column = 0;
  set_column(column,new_column);
  column = new_column;
  delayMicroseconds(900);

  if((millis() - last_time) > 1000){
    plate++;
    if(plate > 9)
      plate = 0;
    set_plate(plate);
    last_time = millis();
  }
}