RT-Thread-RT-Thread Studio使用记录（二）pwm呼吸灯RT-Thread问答社区

RT-Thread Studio使用记录（二）pwm呼吸灯

发布于 2021-01-28 22:43:06 浏览：3880 订阅该版

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[RT-Thread Studio使用记录（二）pwm呼吸灯](https://club.rt-thread.org/ask/article/2520.html)
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[RT-Thread Studio使用记录（五）USB 虚拟串口](https://club.rt-thread.org/ask/article/2524.html)
[RT-Thread Studio使用记录（六）ESP8266网络设备](https://club.rt-thread.org/ask/article/2527.html)
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本章使用 RT-Thread 的 pwm 驱动，做呼吸灯的效果，熟悉 RT-Thread 的驱动使用方法。

1、 打开 CubeMX 配置文件，配置 pwm 选项。此处 led 接口在 A3 引脚，为 TIM2 的 CH4，配置如下：

![cube-config.png](https://oss-club.rt-thread.org/uploads/20210128/e3a599ec9c3e127b6a760a288d1abac0.png)

此处只需将 TIM2 的 Channel4 设置为 PWM Generation CH4 模式即可，下边的详细配置已经在  drv_pwm.c 中做过了。如果有不同的需求，可以选择更改 drv_pwm.c 中的相关代码。
生成代码。删除生成的 main.c 及 stm32f4xx_it.c ，注释掉 stm32f4xx_fal_msp.c 中的 ' #include "main.h" '，并添加 ' #include "drv_common.c" '。

```
/* Includes ------------------------------------------------------------------*/
//#include "main.h"
/* USER CODE BEGIN Includes */
#include "drv_common.h"
/* USER CODE END Includes */
```

2、打开定时器使能。此处用的 stm32f4xx_hal_conf.h 文件是在 drivers 文件夹中，不是上一步生成的那个。

![hal_conf.png](https://oss-club.rt-thread.org/uploads/20210128/917fdf2b71fe514897aaf25e0ad070f5.png)

3、打开 RT-Thread Setting，勾选 “使用 PWM 设备驱动程序” 项。

![rt-settings.png](https://oss-club.rt-thread.org/uploads/20210129/2dc37e1d29014c7ecd1f180c38e12859.png)

4、添加 PWM 使能。在 board.h 文件中，添加 BSP_USING_PWM2 的宏定义。

![board.png](https://oss-club.rt-thread.org/uploads/20210128/fbcdac4090e242c9301dd2a3d97530b5.png)

5、使能 pwm 通道。打开 /drivers/include/config/pwm_config.h ，将 PWM2_CONFIG 的通道值改为 8 。此处若不更改，drv_pwm.c 中的 stm32_hw_pwm_init 函数将进行无通道的初始化。通道数是按照 bit 位区分，所以 4 通道应该修改为 8。

![pwm_config.png](https://oss-club.rt-thread.org/uploads/20210128/76b81d703d9fff5a5dfa3ff87acfa98a.png)

6、参考官方 pwm 例程，编写呼吸灯代码，并删除 main 函数中 led 部分代码，以免冲突。

```
/*
 * Copyright (c) 2006-2020, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2020-12-23     mgcheng       the first version
 */

#include <rtthread.h>
#include "rtdevice.h"
#include "board.h"

#define DBG_TAG     "breath led"
#define DBG_LVL     DBG_LOG
#include    <rtdbg.h>

#define PWM_DEV_NAME        "pwm2"
#define PWM_DEV_CHANNEL     4
#define BREATH_LED_THREAD_PRIORITY     25
#define BREATH_LED_THREAD_STACK_SIZE   512
#define BREATH_LED_THREAD_TIMELICE     5

struct rt_device_pwm *pwm_dev;      //pwm 设备句柄
static rt_uint32_t period = 1000000;   //周期为 1ms，单位为 ns
static rt_uint32_t pulse = 0;       //pwm 脉冲宽度值的增减方向
static rt_uint32_t scale = 2500;   //脉宽调整分辨率

ALIGN(RT_ALIGN_SIZE)
static rt_uint8_t breath_led_thread_stack[ BREATH_LED_THREAD_STACK_SIZE ];

static void breath_led_thread_entry(void *parameter)
{
    static rt_uint32_t dir = 1;

for(;;)
    {
        if(dir) //脉宽增加
        {
            pulse += scale;
            if(pulse >= period)
            {
                pulse = period;
                dir = 0;
            }
        }
        else
        {
            pulse -= scale;
            if(pulse <= period/2)
            {
                 pulse = period/2;
                 dir = 1;
            }
        }
        rt_thread_mdelay(5);
        rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
    }
}

int breath_led_init(void)
{
    static struct rt_thread breath_led_thread;
    rt_err_t result;

pwm_dev = (struct rt_device_pwm *)rt_device_find(PWM_DEV_NAME);
    if(pwm_dev == RT_NULL)
    {
        rt_kprintf("can't find %s device!\n", PWM_DEV_NAME);
        return RT_ERROR;
    }

rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
    rt_pwm_enable(pwm_dev, PWM_DEV_CHANNEL);

result = rt_thread_init(&breath_led_thread,
                            "breath_led",
                            breath_led_thread_entry,
                            RT_NULL,
                            (rt_uint8_t*)&breath_led_thread_stack[0],
                            BREATH_LED_THREAD_STACK_SIZE,
                            BREATH_LED_THREAD_PRIORITY,
                            BREATH_LED_THREAD_TIMELICE);

if(RT_EOK == result)
    {
        rt_thread_startup(&breath_led_thread);
    }

return RT_EOK;
}
INIT_APP_EXPORT(breath_led_init);

```

7、编译下载

![Video_20210129_103418_217.gif](https://oss-club.rt-thread.org/uploads/20210129/af491fb27f8ac783aa76f940753f78c5.gif)