const int dataPin = 2;   /* DS */
const int clockPin = 3;  /* SHCP */
const int latchPin = 4;  /* STCP */

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

  TCCR1A = 0;           // Init Timer1A
  TCCR1B = 0;           // Init Timer1B
  TCCR1B |= B00000001;  // Prescaler = 1
  OCR1A = 16000;        // Timer Compare1A Register
  TIMSK1 |= B00000010;  // Enable Timer COMPA Interrupt
}

int cnt=0;
// 0b 1  0  0  0  0  0  0  0  0  0  0  0  0  1  1  1
//    C1 C2 C3 C4 NC NC NC NC R5 R4 R3 R2 R1 NR NR NR

int16_t pattern [2][5] =  { { 0b0010000011110111,
                              0b0110000011101111,
                              0b0010000011011111,
                              0b0010000010111111,
                              0b0111000001111111 },
                            { 0b0110000011110111,
                              0b1001000011101111,
                              0b0010000011011111,
                              0b0100000010111111,
                              0b1111000001111111 } };

void loop() {
  
  for(uint8_t i=0;i<5;i++)
  { digitalWrite(latchPin, LOW);
    shiftOutManual(dataPin, clockPin, pattern[1][i]);
    digitalWrite(latchPin, HIGH);
    delay(5);
  }
  delay(500);
}

void shiftOutManual(int dataPin, int clockPin, uint16_t val) {
    for (int i = 0; i < 16; i++) {
        int bit = val & (1 << i); // Get the bit at position 'i'
        digitalWrite(dataPin, bit != 0 ? HIGH : LOW); // Set dataPin HIGH if bit is 1, else LOW

        // Pulse the clock pin
        digitalWrite(clockPin, HIGH);
        delayMicroseconds(1); // short delay to ensure the clock pulse is registered
        digitalWrite(clockPin, LOW);
    }
}

ISR(TIMER1_COMPA_vect)
{ OCR1A += 16000; // Advance The COMPA Register
   
}