const byte dataPin = 4, latchPin = 5, clockPin = 6;
byte pattern = 1;
unsigned long changedAt = 0;

void showPattern(byte value) {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, value);
  digitalWrite(latchPin, HIGH);
}

void setup() {
  pinMode(dataPin, OUTPUT); pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  showPattern(pattern);
}

void loop() {
  if (millis() - changedAt >= 300) {
    changedAt = millis();
    pattern = pattern == 128 ? 1 : pattern << 1;
    showPattern(pattern);
  }
}