int A = 11; // was 8
int C = 10; // was 9
int B = 9; // was 10
int D = 8; // was 11
void setup() {
Serial.begin(9600);
pinMode(A, OUTPUT);
pinMode(B, OUTPUT);
pinMode(C, OUTPUT);
pinMode(D, OUTPUT);
}
void loop() {
digitalWrite(D, HIGH);
digitalWrite(A, LOW);
digitalWrite(B, LOW);
digitalWrite(C, LOW);
delay(20);
digitalWrite(D, LOW);
digitalWrite(C, HIGH);
digitalWrite(B, LOW);
digitalWrite(A, LOW);
delay(20);
digitalWrite(D, LOW);
digitalWrite(C, LOW);
digitalWrite(B, HIGH);
digitalWrite(A, LOW);
delay(20);
digitalWrite(D, LOW);
digitalWrite(C, LOW);
digitalWrite(B, LOW);
digitalWrite(A, HIGH);
delay(20);
}