用stm32f4写一个控制直流减速电机的代码

首，需要明确直流减速电机的驱动方式和控制策略。一般来说，可以采用PWM控制电机转速，同时根据电机转速与目标转速之间的误差来调整PWM的占空比，实现闭环控制。

下面是一个简单的示例代码，仅供参考：

#include "stm32f4xx.h"

#define PWM_MAX_VALUE 10000     // PWM最大值
#define TARGET_SPEED   1000     // 目标转速

volatile uint32_t encoder_count = 0;   // 编码器计数器，用于计算电机转速
volatile uint32_t pwm_duty_cycle = 0;  // PWM占空比，用于控制电机转速

void TIM2_IRQHandler(void) {
    if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET) {
        TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
        encoder_count++;   // 每次定时器计数器溢出，编码器计数器加1
    }
}

int main(void) {
    /* 初始化GPIO、定时器等 */
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_TIM2);

    TIM_TimeBaseStructure.TIM_Period = 9999;   // 定时器周期为10000
    TIM_TimeBaseStructure.TIM_Prescaler = 83;  // 定时器预分频，时钟频率为84MHz
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    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 = 0;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    TIM_Cmd(TIM2, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    /* 进行电机控制 */
    while (1) {
        // 计算当前电机转速
        uint32_t current_speed = (encoder_count * 60 * 1000) / (TIM2->ARR + 1);

        // 根据当前转速与目标转速之间的误差调整PWM占空比
        int32_t error = TARGET_SPEED - current_speed;
        if (error > 0) {
            pwm_duty_cycle += error;
            if (pwm_duty_cycle > PWM_MAX_VALUE) {
                pwm_duty_cycle = PWM_MAX_VALUE;
            }
        } else if (error < 0) {
            pwm_duty_cycle += error;
            if (pwm_duty_cycle < 0) {
                pwm_duty_cycle = 0;
            }
        }

        // 更新PWM占空比
        TIM_OCInitStructure.TIM_Pulse = pwm_duty_cycle;
        TIM_OC1Init(TIM2, &TIM_OCInitStructure);

        // 等待一段时间
        for (volatile int i = 0; i < 100000; i++);
    }
}

需要注意的是，该示例代码仅供参考，具体实现需要根据具体的硬件平台和电机参数进行调整。同时，为了提高电机控制精度，可以采用PID等更为复杂的控制策略。