#include <SPI.h>

int latchPin = 10; 
int clockPin = 13; 
int dataPin = 11; 

int numOutputs = 8; 

byte sr1 = 0; 
byte sr2 = 0; 
byte sr3 = 0;
byte sr4 = 0;

void setup() {
  SPI.begin();
  SPI.setBitOrder(MSBFIRST); 
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
}

void loop() {
  
  sr1 = 0b00000011;
  update1();
  delay(700); 

  sr2 = 0b00001100;
  update2();
  delay(700); 

  sr3 = 0b00110000;
  update3();
  delay(700);
  
  sr4 = 0b11000000;
  update4();
  delay(700);

  
}

void update1(){
  digitalWrite(latchPin, LOW);
  SPI.transfer(sr1);
  digitalWrite(latchPin, HIGH);
}
void update2(){
  digitalWrite(latchPin, LOW);
  SPI.transfer(sr2);
  digitalWrite(latchPin, HIGH);
}
void update3(){
  digitalWrite(latchPin, LOW);
  SPI.transfer(sr3);
  digitalWrite(latchPin, HIGH);
}
void update4(){
  digitalWrite(latchPin, LOW);
  SPI.transfer(sr4);
  digitalWrite(latchPin, HIGH);
}