#define A        10                    
#define A_bar    12                    
#define B        11                   
#define B_bar    13                    
#define x        101

void setup() {
  pinMode(A, OUTPUT);
  pinMode(A_bar, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(B_bar, OUTPUT);
}

void loop() {    
    digitalWrite(A, LOW);
    digitalWrite(A_bar, HIGH);
    digitalWrite(B, HIGH);
    digitalWrite(B_bar, LOW);
    delay (x);
    digitalWrite(A, LOW);
    digitalWrite(A_bar, HIGH);
    digitalWrite(B, LOW);
    digitalWrite(B_bar, LOW);
    delay (x);
    digitalWrite(A, HIGH);
    digitalWrite(A_bar, LOW);
    digitalWrite(B, LOW);
    digitalWrite(B_bar, HIGH);
    delay (x);
    digitalWrite(A, HIGH);
    digitalWrite(A_bar, LOW);
    digitalWrite(B, HIGH);
    digitalWrite(B_bar, LOW);
    delay (x);
}