帮我写一个使用stm32控制步进电机正反转的代码

好的，以下是使用stm32控制步进电机正反转的代码：

#include "stm32f10x.h"

#define DIR_PIN GPIO_Pin_
#define STEP_PIN GPIO_Pin_1

void delay_us(uint32_t us)
{
uint32_t i;
for(i=;i<us*8;i++);
}

int main(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

GPIO_InitStructure.GPIO_Pin = DIR_PIN | STEP_PIN;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

TIM_TimeBaseStructure.TIM_Period = 100 - 1;
TIM_TimeBaseStructure.TIM_Prescaler = 72 - 1;
TIM_TimeBaseStructure.TIM_ClockDivision = ;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 500 - 1;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM2, &TIM_OCInitStructure);

TIM_Cmd(TIM2, ENABLE);

while(1)
{
GPIO_SetBits(GPIOA, DIR_PIN);
delay_us(100);
GPIO_ResetBits(GPIOA, STEP_PIN);
delay_us(100);
GPIO_SetBits(GPIOA, STEP_PIN);
delay_us(100);

GPIO_ResetBits(GPIOA, DIR_PIN);
delay_us(100);
GPIO_ResetBits(GPIOA, STEP_PIN);
delay_us(100);
GPIO_SetBits(GPIOA, STEP_PIN);
delay_us(100);
}
}