pwm.c

#include "stm32f1xx.h"
#include "led.h"
int main() {

	RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;	
	RCC->APB2ENR |= RCC_APB2ENR_AFIOEN;

	MODIFY_REG(GPIOA->CRL,
	GPIO_CRL_CNF0 | GPIO_CRL_MODE0 | GPIO_CRL_CNF1 | GPIO_CRL_MODE1
	| GPIO_CRL_CNF2 | GPIO_CRL_MODE2,
	GPIO_CRL_CNF0_1 | GPIO_CRL_MODE0_1 | GPIO_CRL_CNF1_1 | GPIO_CRL_MODE1_1
	| GPIO_CRL_CNF2_1 | GPIO_CRL_MODE2_1);

	SET_BIT(RCC->APB1ENR, RCC_APB1ENR_TIM2EN);
	TIM2->PSC = 0;
	TIM2->ARR = 99;
	TIM2->CCR1 = 50; 
	CLEAR_BIT(TIM2->CCMR1, TIM_CCMR1_CC1S);
	SET_BIT(TIM2->CCMR1, 0x6 << TIM_CCMR1_OC1M_Pos);
	SET_BIT(TIM2->CCMR1, TIM_CCMR1_OC1PE);
	TIM2->CR1 |= TIM_CR1_ARPE;
	TIM2->EGR |= TIM_EGR_UG;
	TIM2->CR1 |= TIM_CR1_CEN;
	SET_BIT(TIM2->CCER, TIM_CCER_CC1E | TIM_CCER_CC2E | TIM_CCER_CC3E);
	led_init();
	while(1); 
}