#define PBA_DIR (*((volatile uint8_t*)0x24))
#define PB_DATA (*((volatile uint8_t*)0x25))
int main(){
  PBA_DIR |= (1<<0);
  PB_DATA |= (1<<0);
  while(1){
    PB_DATA ^= 0X01;// XORing ie if 0 it changes to 1 and viseversa:
    for(volatile long i = 0; i<100000; i++);
  }

}