#define DATA_PIN  8  // Pin connected to DS of 74HC595
#define LATCH_PIN 9  // Pin connected to STCP of 74HC595
#define CLOCK_PIN 10 // Pin connected to SHCP of 74HC595


uint16_t leds = 0;
uint8_t numberOfLEDsOn = 16; //Increase or decrease for start number of LEDS
bool add = false;
uint32_t lastTime;
uint8_t bitNum  = numberOfLEDsOn - 1;
uint8_t count = 0;

void setup() {
  pinMode(DATA_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);
  Serial.begin(115200);
  leds = 0;        // Initially turns all the LEDs off, by giving the variable 'leds' the value 0
  updateShiftRegister();
  delay(500);
  for (int i = 0; i < numberOfLEDsOn; i++)        // Turn all the LEDs ON one by one.
  {
    bitSet(leds, i);                // Set the bit that controls that LED in the variable 'leds'
    updateShiftRegister();
    delay(100);
  }

}

uint16_t bits = 0; 

void loop() {

   

  if (millis() - lastTime > 100) {
    lastTime = millis();
    bits = random(0, 65536);
    updateShiftRegister();


    /*count ++;
    if (count < 8) {  //Increment at +=2/sec increase flash time
      if (add) bitSet(leds, bitNum);
      else bitClear(leds, bitNum);
      updateShiftRegister();
      add = !add;
    }
    else {
      count = 0;
      bitNum --;
      add = false;
    }*/
  }
  
}


void updateShiftRegister()
{
  digitalWrite(LATCH_PIN, LOW);
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, highByte(bits));
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, lowByte(bits));
  digitalWrite(LATCH_PIN, HIGH);
}