stm32实现呼吸流水灯

以下是使用STM32实现呼吸流水灯的代码：

#include "stm32f10x.h"

#define LED_PIN GPIO_Pin_12
#define LED_PORT GPIOB

void delay(uint32_t ms)
{
    for (volatile uint32_t i = 0; i < ms * 1000; i++);
}

void init_led_gpio(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = LED_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(LED_PORT, &GPIO_InitStructure);
}

void pwm_set_duty_cycle(uint16_t duty_cycle)
{
    TIM_OCInitTypeDef TIM_OCInitStructure;
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = duty_cycle;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM3, &TIM_OCInitStructure);
    TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
}

void init_pwm_timer(void)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period = 9999;
    TIM_TimeBaseStructure.TIM_Prescaler = 719;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    pwm_set_duty_cycle(0);

    TIM_Cmd(TIM3, ENABLE);
}

void breath_led(void)
{
    uint16_t duty_cycle = 0;
    uint16_t direction = 1;

    while (1)
    {
        pwm_set_duty_cycle(duty_cycle);

        if (direction == 1)
        {
            duty_cycle++;
            if (duty_cycle >= 10000)
            {
                direction = 0;
            }
        }
        else
        {
            duty_cycle--;
            if (duty_cycle == 0)
            {
                direction = 1;
            }
        }

        delay(10);
    }
}

int main(void)
{
    init_led_gpio();
    init_pwm_timer();

    breath_led();

    return 0;
}

该代码使用了定时器TIM3和PWM输出来实现呼吸灯效果。在循环中不断调整PWM占空比，从而实现灯光亮度的逐渐变化。具体来说，当占空比从0逐渐增加到10000时，灯光会逐渐变亮；当占空比从10000逐渐减小到0时，灯光会逐渐变暗。通过不断循环这个过程，就可以实现呼吸流水灯的效果。