使用stm32最小系统板实现呼吸灯

呼吸灯是一种常见的LED灯效，其亮度会逐渐增强或减弱，仿佛在呼吸一样，给人一种柔和的感觉。使用STM32最小系统板可以很方便地实现呼吸灯效果。

首先，我们需要连接一个LED到STM32的GPIO引脚上。假设我们连接的是PA5引脚，代码如下：

/* 定义GPIO引脚 */
#define LED_PIN GPIO_PIN_5
#define LED_PORT GPIOA

/* 使能GPIO时钟 */
__HAL_RCC_GPIOA_CLK_ENABLE();

/* 配置GPIO引脚为推挽输出模式 */
GPIO_InitTypeDef GPIO_InitStruct = {0};
GPIO_InitStruct.Pin = LED_PIN;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LED_PORT, &GPIO_InitStruct);

接下来，我们使用定时器来控制LED的亮度。以TIM2为例，代码如下：

/* 定义TIM2的预分频器和周期值 */
#define PWM_PRESCALER 999
#define PWM_PERIOD 999

/* 使能TIM2时钟 */
__HAL_RCC_TIM2_CLK_ENABLE();

/* 配置TIM2为PWM模式 */
TIM_HandleTypeDef htim2 = {0};
htim2.Instance = TIM2;
htim2.Init.Prescaler = PWM_PRESCALER;
htim2.Init.Period = PWM_PERIOD;
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
HAL_TIM_PWM_Init(&htim2);

/* 配置TIM2通道1为PWM输出 */
TIM_OC_InitTypeDef sConfigOC = {0};
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_1);

/* 启动TIM2 */
HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);

现在，我们可以在主循环中不断调整TIM2的占空比来实现呼吸灯效果。代码如下：

while (1)
{
    for (int i = 0; i <= PWM_PERIOD; i++)
    {
        __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);
        HAL_Delay(10);
    }
    for (int i = PWM_PERIOD; i >= 0; i--)
    {
        __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);
        HAL_Delay(10);
    }
}

在上述代码中，我们使用HAL_Delay函数来停顿一段时间，以控制呼吸灯的速度。可以根据需要调整停顿时间来改变呼吸灯的速度。

完整代码如下：

#include "main.h"

/* 定义GPIO引脚 */
#define LED_PIN GPIO_PIN_5
#define LED_PORT GPIOA

/* 定义TIM2的预分频器和周期值 */
#define PWM_PRESCALER 999
#define PWM_PERIOD 999

/* 使能GPIO和TIM2时钟 */
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM2_Init(void);

int main(void)
{
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_TIM2_Init();

    while (1)
    {
        for (int i = 0; i <= PWM_PERIOD; i++)
        {
            __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);
            HAL_Delay(10);
        }
        for (int i = PWM_PERIOD; i >= 0; i--)
        {
            __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);
            HAL_Delay(10);
        }
    }
}

void SystemClock_Config(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

    /* Initializes the RCC Oscillators according to the specified parameters
     * in the RCC_OscInitTypeDef structure.
     */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
        Error_Handler();
    }

    /* Initializes the CPU, AHB and APB buses clocks */
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
                                  | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
    {
        Error_Handler();
    }
}

static void MX_GPIO_Init(void)
{
    /* 使能GPIO时钟 */
    __HAL_RCC_GPIOA_CLK_ENABLE();

    /* 配置GPIO引脚为推挽输出模式 */
    GPIO_InitTypeDef GPIO_InitStruct = {0};
    GPIO_InitStruct.Pin = LED_PIN;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(LED_PORT, &GPIO_InitStruct);
}

static void MX_TIM2_Init(void)
{
    /* 使能TIM2时钟 */
    __HAL_RCC_TIM2_CLK_ENABLE();

    /* 配置TIM2为PWM模式 */
    TIM_HandleTypeDef htim2 = {0};
    htim2.Instance = TIM2;
    htim2.Init.Prescaler = PWM_PRESCALER;
    htim2.Init.Period = PWM_PERIOD;
    htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
    htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
    HAL_TIM_PWM_Init(&htim2);

    /* 配置TIM2通道1为PWM输出 */
    TIM_OC_InitTypeDef sConfigOC = {0};
    sConfigOC.OCMode = TIM_OCMODE_PWM1;
    sConfigOC.Pulse = 0;
    sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
    sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
    HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_1);

    /* 启动TIM2 */
    HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);
}