// Don't forget to use current limiting resistors for LEDs (220 ohm are ok)


// 74HC595 signal pins (MR tied HIGH and OE tied LOW)
#define DATA 28     // DS
#define LATCH 27    // STCP
#define CLOCK 26    // SHCP

#define DELAY_MS 200

// DATA and LATCH set on rising edge
void pulse(int pin){ 
  digitalWrite(pin, HIGH);
  delay(10);
  digitalWrite(pin, LOW);
}

void setup() {
  pinMode(DATA, OUTPUT);
  pinMode(LATCH, OUTPUT);
  pinMode(CLOCK, OUTPUT);
}

void loop() {
  // Write a 1 to DS
  digitalWrite(DATA, HIGH);
  pulse(CLOCK);
  pulse(LATCH);
  delay(DELAY_MS);

  // Write four 0s to DS
  digitalWrite(DATA, LOW);
  for(int i = 0; i < 4; i++){
    pulse(CLOCK);
    pulse(LATCH);
    delay(DELAY_MS);
  }
}