RT-Thread STM32F407 PWM-编程知识

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

在这里插入图片描述

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 */

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);

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);

综上，main.c

#include <rtthread.h>
#include <rtdbg.h>
#include <rtdevice.h>
#include <board.h>#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;
}