#define delay_ 100000

void setup() {
  // put your setup code here, to run once:

  volatile char *dir; // declared the direction of the data to the port, whether input(0) or output(1).
  dir = 0x2a;         // this is the port address for the direction (Port D Data Direction Register).
  *dir = 0xff;        //setiing all 8 pins on this port to output (hex:ff >> bin:1111 1111).

}

void loop() {
  // put your main code here, to run repeatedly:

  volatile char *out; // declared the output port.
  out = 0x2b;         // this is the port address for the data.
  *out = 0x01;        // this is the data sent to the port. (hex:55 >> bin:0101 0101) pin 7 will be high and the rest low.

  for(int i = 0; i < 8; i++)
  {
    *out = (*out << 1);
    
    for(volatile long i = 0; i < delay_; i++); //delay

  }

  

}