unsigned char conbyte = 0x55;
unsigned char reg;
unsigned int k;

void setup() {
  DDRC |= (1<<3);
}
void loop() {
  reg= conbyte;
  for(k=0; k<8; k++)
  {
    if(reg & 0x01)
    PORTC |= (1<<3);
    else
    PORTC &= ~(1<<3);
    reg = reg>>1;
    delay(500);
  }
  delay(1500);
}