用stm32设计一个呼吸灯的代码

在STM32微控制器上设计一个简单的呼吸灯，通常会涉及到GPIO配置、定时器控制以及状态循环更新。这里是一个基本的示例代码，假设我们使用的是STM32F103系列，LED连接到PA8引脚：

#include "stm32f10x.h"

// 定义LED引脚
#define LED_PIN GPIO_Pin_8
#define LED_GPIO_PORT GPIOA
#define LED_GPIO_RCC RCC_AHB1Periph_GPIOA

// 定义定时器
#define TIMER_ID TIM2
#define TIMER_CHANNEL CH1
#define TIMER_RCC RCC_APB1Periph_TIM2

void led_off(void);
void led_breathe(int duration, int pause);

int main(void) {
    // 初始化GPIO和定时器
    RCC_AHB1PeriphClockCmd(LED_GPIO_RCC, ENABLE);
    GPIO_Init(LED_GPIO_PORT, (GPIO_InitTypeDef){
        .Pin = LED_PIN,
        .Mode = GPIO_Mode_OUT,
        .Pull = GPIO_NOPULL,
        .Speed = GPIO_Speed_50MHz
    });
    
    RCC_APB1PeriphClockCmd(TIMER_RCC, ENABLE);
    TIM_TimeBaseInit(TIM2, (TIM_TimeBaseInitTypeDef){
        .Prescaler = 8399,   // 根据系统频率调整计数周期
        .CounterMode = TIM_CounterMode_Up,
        .AutoReload = 0xFFF  // 设置最大计数值（16位）
    });
    TIM_OCInit(TIM2, (TIM_OCInitTypeDef){
        .OCMode = TIM_OCMode_PWM1,
        ._OutputState = TIM_OutputState_Enable,
        .Pulse = 0x7FF,     // 50% PWM duty cycle for red state
        .Comparator = 0x7FF
    });

    TIM_OC2Cmd(ENABLE);  // Enable output channel 2 (LED)

    while (1) {
        led_breathe(500, 250); // 每次亮持续500毫秒，停顿250毫秒
    }
}

void led_off(void) {
    GPIO_SetBits(LED_GPIO_PORT, LED_PIN);
}

void led_breathe(int on_time, int off_time) {
    uint16_t cnt;
    TIM_Cmd(TIM2, ENABLE); // Start the timer
    
    for (cnt = 0; cnt < on_time + off_time; cnt++) {
        if (cnt >= on_time) {
            TIM_OC2Cmd(DISABLE); // Turn off LED when on_time elapsed
            cnt = on_time - 1;  // Reset counter for off period
        } else {
            TIM_OC2Cmd(ENABLE);  // Turn on LED
        }

        TIM_DelayUntilNextTrigger(TIM2); // Wait until next trigger
    }

    TIM_Cmd(TIM2, DISABLE); // Stop the timer after one full cycle
}