写一个stm32通过按键外部中断控制呼吸灯的代码

好的，以下是基于STM32F103C8T6芯片的按键外部中断控制呼吸灯的代码。

首先，需要定义一些宏定义和全局变量：

#include "stm32f10x.h"

#define LED_PIN GPIO_Pin_13
#define LED_PORT GPIOC

#define BUTTON_PIN GPIO_Pin_0
#define BUTTON_PORT GPIOA

volatile uint32_t ticks = 0;

然后，在主函数中初始化时钟、GPIO和外部中断：

void init()
{
    // 初始化时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);

    // 初始化GPIO
    GPIO_InitTypeDef gpio;
    gpio.GPIO_Pin = LED_PIN;
    gpio.GPIO_Mode = GPIO_Mode_Out_PP;
    gpio.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(LED_PORT, &gpio);

    gpio.GPIO_Pin = BUTTON_PIN;
    gpio.GPIO_Mode = GPIO_Mode_IPU;
    gpio.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(BUTTON_PORT, &gpio);

    // 初始化外部中断
    EXTI_InitTypeDef exti;
    exti.EXTI_Line = EXTI_Line0;
    exti.EXTI_Mode = EXTI_Mode_Interrupt;
    exti.EXTI_Trigger = EXTI_Trigger_Falling;
    exti.EXTI_LineCmd = ENABLE;
    EXTI_Init(&exti);

    // 配置NVIC
    NVIC_InitTypeDef nvic;
    nvic.NVIC_IRQChannel = EXTI0_IRQn;
    nvic.NVIC_IRQChannelPreemptionPriority = 0;
    nvic.NVIC_IRQChannelSubPriority = 0;
    nvic.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic);

    // 初始化定时器
    TIM_TimeBaseInitTypeDef tim;
    tim.TIM_Prescaler = 7199; // 72MHz / (7199 + 1) = 10kHz
    tim.TIM_CounterMode = TIM_CounterMode_Up;
    tim.TIM_Period = 1000; // 10kHz / 1000 = 10Hz
    tim.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM2, &tim);
    TIM_Cmd(TIM2, ENABLE);
    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
}

int main()
{
    init();

    // 呼吸灯
    uint16_t brightness = 0;
    int8_t direction = 1;

    while (1) {
        for (uint16_t i = 0; i < 1000; i++) {
            if (direction == 1) {
                brightness++;
            } else {
                brightness--;
            }

            if (brightness == 1000) {
                direction = -1;
            } else if (brightness == 0) {
                direction = 1;
            }

            if (i < brightness) {
                GPIO_SetBits(LED_PORT, LED_PIN);
            } else {
                GPIO_ResetBits(LED_PORT, LED_PIN);
            }

            while (ticks == 0);
            ticks--;
        }
    }

    return 0;
}

在外部中断的中断处理函数中控制呼吸灯的暂停和重启：

void EXTI0_IRQHandler()
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET) {
        EXTI_ClearITPendingBit(EXTI_Line0);

        if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET) {
            TIM_ClearITPendingBit(TIM2, TIM_IT_Update);

            if (GPIO_ReadInputDataBit(BUTTON_PORT, BUTTON_PIN) == RESET) {
                TIM_Cmd(TIM2, DISABLE);

                while (GPIO_ReadInputDataBit(BUTTON_PORT, BUTTON_PIN) == RESET);

                TIM_Cmd(TIM2, ENABLE);
            }
        }
    }
}

这个代码中使用了定时器来控制呼吸灯的亮度，每隔10ms更新一次亮度。按下按键时，通过外部中断检测到并暂停定时器，等待再次按下按键后再重启定时器，控制呼吸灯的暂停和重启。

在以上代码的基础上，你可以根据实际需要进行修改和优化。