使用RT-Thread Studio + CubeMX开发项目（二）：使用pwm

摘要：本文主要记录如何使用 RT-Thread Studio + CubeMX 来配置 STM32 上的 PWM 器件。

第一步、利用 RT-Thread Studio 配置 PWM 相关代码（接着 UART2 项目进行）

首先在 board.h 中官方给出了如何在 rtt 中使用 pwm。

STEP 1：RT-Thread Settings 中打开 PWM 驱动支持。

STEP 2：在 board.h 中定义相关宏，这里注意 “BSP_USING_PWM1_CH1 ”，这个也是需要的，可以看。

/** if you want to use pwm you can use the following instructions.
 *
 * STEP 1, open pwm driver framework support in the RT-Thread Settings file
 *
 * STEP 2, define macro related to the pwm
 *                 such as     #define BSP_USING_PWM1
 *
 * STEP 3, copy your pwm timer init function from stm32xxxx_hal_msp.c generated by stm32cubemx to the end if board.c file
 *                 such as     void HAL_TIM_Base_MspInit(TIM_HandleTypeDef* htim_base)  and
 *                             void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
 *
 * STEP 4, modify your stm32xxxx_hal_config.h file to support pwm peripherals. define macro related to the peripherals
 *                 such as     #define HAL_TIM_MODULE_ENABLED
 *
 */

/*#define BSP_USING_PWM1*/
/*#define BSP_USING_PWM2*/
/*#define BSP_USING_PWM3*/

#define BSP_USING_PWM1
#define BSP_USING_PWM1_CH1

下面是源码中对 “BSP_USING_PWM1_CH1” 的使用：

static void pwm_get_channel(void)
{
#ifdef BSP_USING_PWM1_CH1
    stm32_pwm_obj[PWM1_INDEX].channel |= 1 << 0;
#endif
#ifdef BSP_USING_PWM1_CH2
    stm32_pwm_obj[PWM1_INDEX].channel |= 1 << 1;
#endif

......

#ifdef BSP_USING_PWM9_CH4
    stm32_pwm_obj[PWM9_INDEX].channel |= 1 << 3;
#endif
#ifdef BSP_USING_PWM12_CH1
    stm32_pwm_obj[PWM12_INDEX].channel |= 1 << 0;
#endif
#ifdef BSP_USING_PWM12_CH2
    stm32_pwm_obj[PWM12_INDEX].channel |= 1 << 1;
#endif
}

STEP 3：使用 cubemx 生成，pwm 的初始化相关代码 HAL_TIM_Base_MspInit 和 HAL_TIM_MspPostInit (只需要修改红色标记就可以，其他的我们使用 rtt 中提供的 API 来修改就好，drv_pwm_set 函数中会根据用户需要的周期和占空比自动计算相应的参数)，并拷贝到 board.c 中。

 static rt_err_t drv_pwm_set(TIM_HandleTypeDef *htim, struct rt_pwm_configuration *configuration)
 {
     rt_uint32_t period, pulse;
     rt_uint64_t tim_clock, psc;
     /* Converts the channel number to the channel number of Hal library */
     rt_uint32_t channel = 0x04 * (configuration->channel - 1);

 		... ...

     /* Convert nanosecond to frequency and duty cycle. 1s = 1 * 1000 * 1000 * 1000 ns */
     tim_clock /= 1000000UL;
     period = (unsigned long long)configuration->period * tim_clock / 1000ULL ;
     psc = period / MAX_PERIOD + 1;
     period = period / psc;
     __HAL_TIM_SET_PRESCALER(htim, psc - 1);

     if (period < MIN_PERIOD)
     {
         period = MIN_PERIOD;
     }
     __HAL_TIM_SET_AUTORELOAD(htim, period - 1);

     pulse = (unsigned long long)configuration->pulse * tim_clock / psc / 1000ULL;
     if (pulse < MIN_PULSE)
     {
         pulse = MIN_PULSE;
     }
     else if (pulse > period)
     {
         pulse = period;
     }
     __HAL_TIM_SET_COMPARE(htim, channel, pulse - 1);
     __HAL_TIM_SET_COUNTER(htim, 0);

     /* Update frequency value */
     HAL_TIM_GenerateEvent(htim, TIM_EVENTSOURCE_UPDATE);

     return RT_EOK;
 }
 ```

- STEP 4：修改 stm32xxxx_hal_config.h 文件，打开 HAL 对相关功能的支持。

![](https://Zhangfan94.github.io/post-images/1610726601903.png)

- 需要在 pwm_config.h 文件中自己构建 PWM1_CONFIG ，否则使用 PWM1 时，编译报错。

 ```cpp
 #ifdef BSP_USING_PWM1
 #ifndef PWM1_CONFIG
 #define PWM1_CONFIG                             \
     {                                           \
        .tim_handle.Instance     = TIM1,         \
        .name                    = "pwm1",       \
        .channel                 = 0             \
     }
 #endif /* PWM1_CONFIG */
 #endif /* BSP_USING_PWM1 */
 ```

### 第二步、完善对 PWM 初始化及测试的代码

创建路径 “RttDemo\applications\service\pwm” 并创建文件 “PwmChanel1.h” “PwmChanel1.c”。

- “PwmChanel1.h” 内容如下：

```cpp
/*
* Change Logs:
* Date           Author       Notes
* 2020-10-23     ZhangFan     first version
*/

#ifndef _PWM_CHANEL_1_H_
#define _PWM_CHANEL_1_H_

#include <rtdevice.h>

rt_bool_t pwm_ch1_init();

/* 设置PWM1 的频率 */
rt_bool_t pwm_ch1_set_freq(rt_uint32_t freq);

/* 设置PWM1 的占空比 */
rt_bool_t pwm_ch1_set_duty(rt_uint32_t duty);

#endif //_PWM_CHANEL_1_H_

“PwmChanel1.c” 内容如下：

/*
 * Change Logs:
 * Date           Author       Notes
 * 2020-10-21     ZhangFan     first version
 */

#include "PwmChanel1.h"

/* log */
#define DBG_TAG    "PwmChanel1"
#define DBG_LVL    DBG_LOG
#include <rtdbg.h>

/* pwm chanel */
#define PWM_DEV_NAME        "pwm1"  /* PWM设备名称 */
#define PWM_DEV_CHANNEL     1       /* PWM通道 */
struct rt_device_pwm *pwm_dev;      /* PWM设备句柄 */

rt_uint32_t period = 500000000;     /* 周期为5ms，单位为纳秒ns */
rt_uint32_t pulse  = 250000000;     /* PWM脉冲宽度值，单位为纳秒ns */

rt_bool_t pwm_ch1_init()
{
    /* step 1、查找设备 */
    pwm_dev = (struct rt_device_pwm *)rt_device_find(PWM_DEV_NAME);
    if (pwm_dev == RT_NULL)
    {
        LOG_D("pwm run failed! can't find %s device!\n", PWM_DEV_NAME);
        return RT_FALSE;
    }

    /* step 2、设置PWM周期和脉冲宽度 */
    rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);

    /* step 3、使能 PWM 设备的输出通道 */
    rt_pwm_enable(pwm_dev, PWM_DEV_CHANNEL);

    return RT_TRUE;
}

/* 设置PWM1 的频率 */
rt_bool_t pwm_ch1_set_freq(rt_uint32_t freq)
{
    if(RT_EOK != rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, freq, pulse))
    {
        return RT_FALSE;
    }

    period = freq;

    return RT_TRUE;
}

/* 设置PWM1 的占空比 */
rt_bool_t pwm_ch1_set_duty(rt_uint32_t duty)
{
    if(RT_EOK != rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, duty))
    {
        return RT_FALSE;
    }

    pulse = duty;

    return RT_TRUE;
}

“main.c”函数内容：

#include <rtthread.h>

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

#include "SerialUart2.h"
#include "PwmChanel1.h"

int main(void)
{
    int count = 1;

    serial2_init(); /* 串口2初始化 */
    pwm_ch1_init(); /* PWM 初始化 */

    while (count++)
    {
        //LOG_D("Hello RT-Thread!");
        serial2_write("Hello RT-Thread!\r\n", sizeof("Hello RT-Thread!\r\n") - 1);
        rt_thread_mdelay(1000);
    }

    return RT_EOK;
}