pwm

#include "stm32f10x.h"

void TIM2_IRQHandler(void);

static void gpio_init() {
	// enable PORTA GPIO0 to alt. function push-pull with max_speed 50MHz
	RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
	RCC->APB2ENR |= RCC_APB2ENR_AFIOEN;
	GPIOA->CRL &= ~(GPIO_CRL_CNF0|GPIO_CRL_MODE0);
	GPIOA->CRL |= GPIO_CRL_CNF0_1|GPIO_CRL_MODE0;
}

static void pwm_init(uint16_t psc, uint16_t arr, uint16_t ccr) {
	// timer init
	RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
	TIM2->SR = 0;
	TIM2->PSC = psc;
	TIM2->ARR = arr;
	TIM2->CCR1= ccr;
	// set up interrupt
	TIM2->DIER = TIM_DIER_UIE|TIM_DIER_CC1IE;
	NVIC->ISER[0] = NVIC_ISER_SETENA_28;
	// set output to PWM1 mode
	TIM2->CCMR1 = TIM_CCMR1_OC1M_2|TIM_CCMR1_OC1M_1;
	TIM2->CCER = TIM_CCER_CC1E;
}

void TIM2_IRQHandler() {
	TIM2->SR ^= TIM_SR_CC1IF|TIM_SR_UIF;
}

int main() {
	gpio_init();
	pwm_init(1, 1, 1);
	// enable timer2
	TIM2->CR1 |= TIM_CR1_CEN;
	for (;;);
}