写一段stm32f103c8t6驱动步进电机的代码

以下是一段使用STM32F103C8T6微控制器驱动ULN2003步进电机驱动器的代码，其中使用了GPIO库和TIM库[^1]。

#include "stm32f10x_gpio.h"
#include "stm32f10x_tim.h"

#define STEP_NUM 4
#define STEPS_PER_REV 2048

GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
TIM_OCInitTypeDef TIM_OCInitStructure;

unsigned char step_map[STEP_NUM] = {{1, 0, 0, 1}, {1, 0, 0, 0}, {1, 1, 0, 0}, {0, 1, 0, 0}};
int current_step = 0;
int steps_remaining = 0;

void delay_us(int num) {
    TIM_Cmd(TIM4, ENABLE);
    TIM_SetCounter(TIM4, 0);
    while (TIM_GetCounter(TIM4) < num);
    TIM_Cmd(TIM4, DISABLE);
}

void step(void) {
    for (int pin = 0; pin < 4; pin++) {
        GPIO_WriteBit(GPIOB, GPIO_Pin_0 + pin, step_map[current_step][pin]);
    }
    current_step++;
    if (current_step == STEP_NUM) {
        current_step = 0;
    }
    steps_remaining--;
}

void rotate(int degrees) {
    int steps = degrees * STEPS_PER_REV / 360;
    steps_remaining = steps;
    for (int i = 0; i < steps; i++) {
        step();
        delay_us(1000);
    }
}

int main(void) {
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    TIM_TimeBaseInitStruct.TIM_Period = 1680 - 1;
    TIM_TimeBaseInitStruct.TIM_Prescaler = (SystemCoreClock / 1000000) - 1;
    TIM_TimeBaseInitStruct.TIM_ClockDivision = 0;
    TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseInitStruct);

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 840 - 1;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM4, &TIM_OCInitStructure);

    while (1) {
        rotate(90);
    }
}