[Vision Board创客营] PWM模块实践

发布于 2024-05-05 15:07:58 浏览：267 订阅该版

1. PWM简介
	PWM(Pulse Width Modulation , 脉冲宽度调制) 是一种对模拟信号电平进行数字编码的方法，通过不同频率的脉冲使用方波的占空比用来对一个具体模拟信号的电平进行编码，使输出端得到一系列幅值相等的脉冲，用这些脉冲来代替所需要波形的设备。
2. 开发环境搭建
	开发环境搭建主要参考开发板环境搭建手册：https://docs.qq.com/doc/DY2hkbVdiSGV1S3JM
3. PWM模块配置过程
- 基于vision board新建rt-thread studio 模板工程

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20240505/8af04d86d4e042f5ca725c74cc6dce05.png.webp)
- 在RT-Thread Settings里面对GPT进行使能,这里因为开发板树莓派接口中有一个引脚是连到GPT12的所以使能GPT12

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20240505/d790c66435258eb5e5123f3d1d26e2ef.png)
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20240505/1985f8ef20a6a63977c8e6bb9d243c17.png)
- 在RA Smart Configurator 中对芯片底层进行配置

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20240505/8af59ddaba35b9192bfd53fcb91b33b8.png.webp)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20240505/48abdd1080c247f3c1595bec79a370ea.png.webp)
最后生成代码
4.配置代码编写

```c
#include <rtthread.h>
#include <rtdevice.h>
#include "hal_data.h"

#define LED_PIN    BSP_IO_PORT_01_PIN_02 /* Onboard LED pins */
#define PWM_DEV_NAME        "pwm12"  /* PWM 设备名称 */
#define PWM_DEV_CHANNEL     0       /* PWM通道 */
struct rt_device_pwm *pwm_dev;      /* PWM 设备句柄 */
void hal_entry(void)
{
    rt_kprintf("\nHello RT-Thread!\n");
    //drv_pwm_control();

rt_uint32_t period, pulse;

period = 500000;    /* 周期为0.5ms，单位为纳秒ns */
    pulse = 250000;          /* PWM脉冲宽度值，单位为纳秒ns */
    /* 查找设备 */
    pwm_dev = (struct rt_device_pwm *)rt_device_find(PWM_DEV_NAME);
    /* 设置PWM周期和脉冲宽度默认值 */
    rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);

rt_pwm_enable(pwm_dev, PWM_DEV_CHANNEL);

while (1)
    {
        rt_pin_write(LED_PIN, PIN_HIGH);
        rt_thread_mdelay(500);
        rt_pin_write(LED_PIN, PIN_LOW);
        rt_thread_mdelay(500);
    }
}

```
输出频率为2k,占空比50%的方波

![screenshot_9809d35b9fc9167aa13294eeefda390.jpg](https://oss-club.rt-thread.org/uploads/20240505/5cfeba8ee83b12845f3d5992071ee0a3.jpg.webp)