const uint8_t CLR = 6;
const uint8_t CLK = 7;
const uint8_t A = 8;
const uint8_t B = 9;

void setup() {
  Serial.begin(115200);
  pinMode(CLR, OUTPUT);
  pinMode(CLK, OUTPUT);
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  digitalWrite(A, HIGH);
  digitalWrite(CLR, HIGH);
}

void loop() {
  for (int i = 0; i < 255; ++i) {
    shiftOut(B, CLK, MSBFIRST, i);
    Serial.println(i);
    delay(1000);
    digitalWrite(CLR, LOW);
    digitalWrite(CLR, HIGH);
  }
}