I have turn on 16 LEDs one by one using two 74HC595 shift register. I have some doubt regarding my code and need some help

Projects Programming
5

Yes, but not using shiftOut(), as already explained.

This code (untested) uses hardware SPI and can send all 16 bits in a single call.

With shiftOut(), you can use any pins you like, but with hardware SPI the pins are fixed and depend on the model of Arduino you are using. I have assumed you are using Uno R3 or similar Arduino based on ATMEGA328.

#include <SPI.h>

// ST_CP pin 12
const int latchPin = 10;
// SH_CP pin 11
const int clockPin = 13;
// DS pin 14
const int dataPin = 11;

void setup() {
  // Configure pins as outputs
  pinMode(latchPin, OUTPUT);
  SPI.begin();
  SPI.beginTransaction(SPISettings(10000000, LSBFIRST, SPI_MODE0));
}

void loop() {
  for (int i = 0; i < 16; i++) {
    uint16_t LED = 1 << i;

    digitalWrite(latchPin, LOW);
    SPI.transfer16(LED);
    digitalWrite(latchPin, HIGH);

    delay(1000);
  }
}

See this page for the pins to use for other models of Arduino:

https://docs.arduino.cc/language-reference/en/functions/communication/SPI/