#define ROW1 4
#define ROW2 5
#define ROW3 6
#define ROW4 7

#define COL1 0
#define COL2 1
#define COL3 2
#define COL4 3

void setup() {
  pinMode(ROW1, OUTPUT);
  pinMode(ROW2, OUTPUT);
  pinMode(ROW3, OUTPUT);
  pinMode(ROW4, OUTPUT);

  pinMode(COL1, OUTPUT);
  pinMode(COL2, OUTPUT);
  pinMode(COL3, OUTPUT);
  pinMode(COL4, OUTPUT);

  digitalWrite(ROW1, HIGH);
  digitalWrite(ROW2, HIGH);
  digitalWrite(ROW3, HIGH);
  digitalWrite(ROW4, HIGH);
}

void loop() {
  digitalWrite(ROW4, HIGH);
  digitalWrite(COL1, HIGH);
  digitalWrite(COL2, LOW);
  digitalWrite(COL3, LOW);
  digitalWrite(COL4, HIGH);
  digitalWrite(ROW1, LOW);
  delay(500);

  digitalWrite(ROW1, HIGH);
  digitalWrite(COL1, LOW);
  digitalWrite(COL2, HIGH);
  digitalWrite(COL3, HIGH);
  digitalWrite(COL4, LOW);
  digitalWrite(ROW2, LOW);
  delay(500);

  digitalWrite(ROW2, HIGH);
  digitalWrite(COL1, LOW);
  digitalWrite(COL2, HIGH);
  digitalWrite(COL3, HIGH);
  digitalWrite(COL4, LOW);
  digitalWrite(ROW3, LOW);
  delay(500);

  digitalWrite(ROW3, HIGH);
  digitalWrite(COL1, HIGH);
  digitalWrite(COL2, LOW);
  digitalWrite(COL3, LOW);
  digitalWrite(COL4, HIGH);
  digitalWrite(ROW4, LOW);
  delay(500);
}