main.c

#include "stm32f10x.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_tim.h"

#define SYSCLK 72000000
#define PRESCALER 72

GPIO_InitTypeDef port;
TIM_TimeBaseInitTypeDef timer;
TIM_OCInitTypeDef timerPWM;

void servo_init(void) {

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

	GPIO_StructInit(&port);
	port.GPIO_Mode = GPIO_Mode_AF_PP;
	port.GPIO_Pin = GPIO_Pin_6;
	port.GPIO_Speed = GPIO_Speed_2MHz;
	GPIO_Init(GPIOB, &port);

	TIM_TimeBaseStructInit(&timer);
	timer.TIM_Prescaler = PRESCALER;
	timer.TIM_Period = SYSCLK / PRESCALER / 50;
	timer.TIM_ClockDivision = 0;
	timer.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit(TIM4, &timer);

	TIM_OCStructInit(&timerPWM);
	timerPWM.TIM_Pulse = 1000;
	timerPWM.TIM_OCMode = TIM_OCMode_PWM1;
	timerPWM.TIM_OutputState = TIM_OutputState_Enable;
	timerPWM.TIM_OCPolarity = TIM_OCPolarity_High;
	TIM_OC1Init(TIM4, &timerPWM);

    TIM_Cmd(TIM4, ENABLE);
}

int main(void)
{
	int TIM_Pulse;
	int i;

	//Init buttons
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	GPIO_StructInit(&port);
	port.GPIO_Mode = GPIO_Mode_IPU;
	port.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
	port.GPIO_Speed = GPIO_Speed_2MHz;
	GPIO_Init(GPIOA, &port);

	servo_init();
	TIM_Pulse = timerPWM.TIM_Pulse;

    while(1)
    {
    	if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == 0) {
    		if (TIM_Pulse < 2000)
    			TIM_Pulse++;
    		TIM4->CCR1 = TIM_Pulse;

    	}
    	if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_1) == 0) {
    		if (TIM_Pulse > 1000)
    			TIM_Pulse--;
    		TIM4->CCR1 = TIM_Pulse;
    	}
   	    // delay
   	    for(i=0;i<0x1000;i++);
    }
}