RT-Thread STM32F407 PWM

为了展示PWM效果，这里用ADC来采集PWM输出通道的电平变化

• 第一步，进入RT-Thread Settings配置PWM驱动
  

• 第二步，进入board.h，打开PWM宏
  

• 第三步，进入STM32CubeMX，配置时钟及PWM
  
  

• 第四步，回到RT-Thread Studio，编译发现程序报错
  

• 第五步，双击错误定位到具体位置，屏蔽相关错误，再次编译，发现错误消失
  

• 第六步，添加构建CubeMX生成的tim.c
  

• 第七步，进入main.c，查找PWM设备，设置PWM周期和脉冲宽度，并使能PWM

struct rt_device_pwm *pwm_dev=(struct rt_device_pwm *)rt_device_find(“PWM3”);

rt_pwm_set(pwm_dev, 3, period, pulse);      /* 周期为period、脉宽为pulse */
rt_pwm_enable(pwm_dev, 3);    /* 使能通道3 */
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• 第八步，设置脉宽变化，方便ADC采样查看

   if (dir)
   {
       pulse += 500;      /* 从0值开始每次增加5000ns */
   }
   else
   {
       pulse -= 500;      /* 从最大值开始每次减少5000ns */
   }
   if (pulse >= period)
   {
       dir = 0;
   }
   if (0 == pulse)
   {
       dir = 1;
   }       

rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
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第九步，ADC采样

value = rt_adc_read(adc_dev, ADC_DEV_CHANNEL);   /* 读取采样值 */
vol = value * REFER_VOLTAGE / CONVERT_BITS;   /* 转换为对应电压值 */
rt_kprintf("%d --- %d.%02d \n", value,vol / 100, vol % 100);
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综上，main.c

#include 
#include 
#include 
#include 

#define DBG_TAG "main"
#define DBG_LVL DBG_LOG

#define ADC_DEV_NAME        "adc1"      /* ADC 设备名称 */
#define ADC_DEV_CHANNEL     1           /* ADC 通道 */
#define REFER_VOLTAGE       330         /* 参考电压 3.3V,数据精度乘以100保留2位小数*/
#define CONVERT_BITS        (1 << 12)   /* 转换位数为12位 */

#define PWM_DEV_NAME        "pwm3"  /* PWM设备名称 */
#define PWM_DEV_CHANNEL     3       /* PWM通道   PB1 */
struct rt_device_pwm *pwm_dev;      /* PWM设备句柄 */

int main(void)
{
    /*ADC*/
    rt_adc_device_t adc_dev;
    rt_uint32_t value, vol;

    /*PWM*/
    rt_uint32_t period, pulse, dir;
    period = 500000;    /* 周期为0.5ms，单位为纳秒ns */
    dir = 1;            /* PWM脉冲宽度值的增减方向 */
    pulse = 0;          /* PWM脉冲宽度值，单位为纳秒ns */

    adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);  /* 查找设备 */
    if (adc_dev == RT_NULL)
    {
        rt_kprintf("adc sample run failed! can't find %s device!\n", ADC_DEV_NAME);
        return RT_ERROR;
    }
    else {
        rt_kprintf("find %s success!\n",ADC_DEV_NAME);
    }
    rt_adc_enable(adc_dev, ADC_DEV_CHANNEL);



    /* 查找设备 */
    pwm_dev = (struct rt_device_pwm *)rt_device_find(PWM_DEV_NAME);
    if (pwm_dev == RT_NULL)
    {
       rt_kprintf("pwm sample run failed! can't find %s device!\n", PWM_DEV_NAME);
       return RT_ERROR;
    }
    /* 设置PWM周期和脉冲宽度默认值 */
    rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
    /* 使能设备 */
    rt_pwm_enable(pwm_dev, PWM_DEV_CHANNEL);

    while (1)
    {
       rt_thread_mdelay(100);
       if (dir)
       {
           pulse += 500;      /* 从0值开始每次增加5000ns */
       }
       else
       {
           pulse -= 500;      /* 从最大值开始每次减少5000ns */
       }
       if (pulse >= period)
       {
           dir = 0;
       }
       if (0 == pulse)
       {
           dir = 1;
       }

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

       /* 读取采样值 */
       value = rt_adc_read(adc_dev, ADC_DEV_CHANNEL);
       /* 转换为对应电压值 */
       vol = value * REFER_VOLTAGE / CONVERT_BITS;
       rt_kprintf("%d --- %d.%02d \n", value,vol / 100, vol % 100);

    }
    return RT_EOK;
}

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实测如下：