GPIO speed

#include "stm32f10x.h"

void gpio_init(void);

void gpio_init() {
	// enable PORTC GPIO13 to output push-pull with max_speed 50MHz
	RCC->APB2ENR |= RCC_APB2ENR_IOPCEN;
	GPIOC->CRH &= ~(GPIO_CRH_CNF13|GPIO_CRH_MODE13);
	GPIOC->CRH |= GPIO_CRH_MODE13;
}

int main() {
	gpio_init();

	for (;;) {
		GPIOC->ODR =  0x2000;
		GPIOC->ODR =  0x0000;
		GPIOC->ODR =  0x2000;
		GPIOC->ODR =  0x0000;
		GPIOC->ODR =  0x2000;
		GPIOC->ODR =  0x0000;
		GPIOC->ODR =  0x2000;
		GPIOC->ODR =  0x0000;
		GPIOC->ODR =  0x2000;
		GPIOC->ODR =  0x0000;
	}
}