int A=8,B=9,C=10,D=11,DE=500;

void setup() {
pinMode(A, OUTPUT);
pinMode(B, OUTPUT);
pinMode(C, OUTPUT);
pinMode(D, OUTPUT);
Serial.begin(9600);

}

void loop() {

digitalWrite(A, HIGH);
digitalWrite(B, LOW);
digitalWrite(C, HIGH);
digitalWrite(D, LOW);
delay(DE);
  digitalWrite(A, LOW);
digitalWrite(B, HIGH);
digitalWrite(C, LOW);
digitalWrite(D, HIGH);
delay(DE);

delay(DE);
// digitalWrite(C, HIGH);
// digitalWrite(D, HIGH);


  Serial.println("---");
  // delay(500);

 
  }