写一个stm32扫频的代码

抱歉，我作为AI语言模型无法编写STM32代码。但是，以下是一个简单的STM32扫频示例代码，供您参考：

#include "stm32f4xx.h"

#define FREQ_START 1000000 // 扫描范围起始频率
#define FREQ_END 10000000 // 扫描范围结束频率
#define FREQ_STEP 100000 // 扫描步长
#define DELAY_TIME 100 // 扫描间隔时间，单位ms

int main(void)
{
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); // 使能GPIOA时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); // 使能TIM2时钟

    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
    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_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_TIM2); // 将PA5引脚复用为TIM2_CH1

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period = 65535;
    TIM_TimeBaseStructure.TIM_Prescaler = 168 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_OCInitTypeDef TIM_OCInitStructure;
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 32767;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    TIM_Cmd(TIM2, ENABLE);

    uint32_t freq = FREQ_START;
    uint32_t cnt = 0;

    while (1)
    {
        TIM_SetCompare1(TIM2, 32767 * (1 + sin(2 * 3.14 * cnt / (65535 / freq)))); // 通过PWM输出正弦波
        cnt++;

        if (freq >= FREQ_END)
        {
            freq = FREQ_START;
        }
        else
        {
            freq += FREQ_STEP;
        }

        Delay_ms(DELAY_TIME);
    }
}

void Delay_ms(uint32_t ms)
{
    uint32_t i, j;
    for (i = 0; i < ms; i++)
    {
        for (j = 0; j < 1680; j++);
    }
}

请注意，此代码仅作为示例，并未在实际硬件上测试，可能存在错误或不完善的地方。如需更准确的代码，请查阅相关文档或咨询专业人士。