int main(void){
	RCC->IOPENR |= RCC_IOPENR_GPIOAEN; // Enable clock for GPIO Port A
	GPIOA->MODER &= ~(0b11 << (2*1)); //set pin2 as input
	GPIOA->PUPDR |= (0b10 << (2*1)); //select pull down for pin 2
	
	// ***** pin 1 config *******
	GPIOA->MODER &= ~(0b11 << (2*0));
	GPIOA->MODER |= (0b01 << (2*0));
	GPIOA->OTYPER &= ~0b1;
		
	while(1){
		// if(GPIOA->IDR & ~(0b10))
		if(GPIOA->IDR & 1 << 1){
      GPIOA->ODR ^= 1;
		}
	}
	
	return 0;
}