#define clk   4    // SHCP =>  SRCLK = Shif Register Clock
#define dat     2    // DS   =>  SER   = Serial Input
#define latch    3    // STCP =>  RCLK  = Storage Register Clock

void setup() {
  ShiftRegisterInit();
}


void loop() {
  wr(0x5689);
}

void ShiftRegisterInit() {
  pinMode(latch, OUTPUT);      // Output Pin Mode
  pinMode(dat, OUTPUT);       // Output Pin Mode
  pinMode(clk, OUTPUT);     // Output Pin Mode
}

void wr(uint16_t data) {
  digitalWrite(latch, LOW);
  shiftOut(dat, clk, LSBFIRST, data>>8&0xff);
  shiftOut(dat, clk, LSBFIRST, data&0xff);
  digitalWrite(latch, HIGH);
}