4digit7segment.ino

int digit1 = 2;
int digit2 = 3;
int digit3 = 4;
int digit4 = 5;

// Serial
int clock = 10;
int latch = 11;
int data = 12;

// Delay time
int dTime = 5;

void setup() {
  pinMode(latch, OUTPUT);
  pinMode(clock, OUTPUT);
  pinMode(data, OUTPUT);

  pinMode(digit1, OUTPUT);
  pinMode(digit2, OUTPUT);
  pinMode(digit3, OUTPUT);
  pinMode(digit4, OUTPUT);
}

void pickDigit(int digit) {
  digitalWrite(digit1, LOW);
  digitalWrite(digit2, LOW);
  digitalWrite(digit3, LOW);
  digitalWrite(digit4, LOW);

  switch(digit) {
    case 1: digitalWrite(digit1, HIGH); break;
    case 2: digitalWrite(digit2, HIGH); break;
    case 3: digitalWrite(digit3, HIGH); break;
    case 4: digitalWrite(digit4, HIGH); break;
  }
}

void display(int num)
{
  // Draw shape
  digitalWrite(latch, HIGH);
  shiftOut(data, clock, MSBFIRST, num);
  digitalWrite(latch, LOW);

  // Clear segments
  digitalWrite(latch, HIGH);
  shiftOut(data, clock, MSBFIRST, 0);
  digitalWrite(latch, LOW); 
}

void loop() {
  pickDigit(1);
  display(B00111111);

  delay(dTime);
  
  pickDigit(2);
  display(B10000000);

  delay(dTime);

  pickDigit(3);
  display(B00000000);

  delay(dTime);

  pickDigit(4);
  display(B01011100);

  delay(dTime);
}