一、准备工作
二、编译代码
三、测试

3.PWM输出测试

该教程演示如何通过开发板的GPIO输出PWM波

一、准备工作

准备1块BearPi-Pico H3863开发板

二、编译代码

在Windows下编译操作

点击工具栏中的“系统配置”,打开配置界面.

选择Support PWM Sample

Application  --->
    [*] Enable Sample.
    [*]     Enable the Sample of peripheral.
    [ ]         Enable all the sample of peripheral, it's just for build.
    [ ]         Support ADC Sample.
    [ ]         Support BLINKY Sample.
    [ ]         Support BUTTON Sample.
    [ ]         Support I2C Sample.
    [ ]         Support PINCTRL Sample.
    [*]         Support PWM Sample.
                    PWM Sample Configuration  --->

按下"Save"键保存配置。
可在代码中修改高低电平时间，已达到输出不同占空比的PWM波

关键代码，位于application\samples\peripheral\pwm\pwm_demo.c

static void *pwm_task(const char *arg)
{
    UNUSED(arg);
    pwm_config_t cfg_no_repeat = {
        50,     //低电平
        200,    //高电平
        0,
        0,
        true
    };

    uapi_pin_set_mode(PWM_GPIO, PWM_PIN_MODE);  //设置引脚复用模式为PWM
    uapi_pwm_init();                            //初始化PWM 
    uapi_pwm_open(PWM_CHANNEL, &cfg_no_repeat); //开启PWM通道 

    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);
    uapi_pwm_unregister_interrupt(PWM_GROUP_ID);//取消注册PWM中断 
    uapi_pwm_register_interrupt(PWM_GROUP_ID, pwm_sample_callback);//注册PWM中断


    uapi_pwm_set_group(PWM_GROUP_ID, 1 << PWM_CHANNEL); //设置PWM通道对应的组 
    uapi_pwm_start(PWM_GROUP_ID);               //开启PWM


    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);

    uapi_pwm_close(PWM_CHANNEL);                //关闭PWM


    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);
    uapi_pwm_deinit();                          //去初始化PWM
    return NULL;
}

编译烧录固件
参考环境搭建教程编译烧录代码

在Ubuntu下编译操作

在MobaXterm中输入:
```
./build.py menuconfig ws63-liteos-app
```

选择Support PWM Sample

Application  --->
    [*] Enable Sample.
    [*]     Enable the Sample of peripheral.
    [ ]         Enable all the sample of peripheral, it's just for build.
    [ ]         Support ADC Sample.
    [ ]         Support BLINKY Sample.
    [ ]         Support BUTTON Sample.
    [ ]         Support I2C Sample.
    [ ]         Support PINCTRL Sample.
    [*]         Support PWM Sample.
                    PWM Sample Configuration  --->

按下"ESC"键退出并保存配置。
可在代码中修改高低电平时间，已达到输出不同占空比的PWM波

关键代码，位于application\samples\peripheral\pwm\pwm_demo.c

static void *pwm_task(const char *arg)
{
    UNUSED(arg);
    pwm_config_t cfg_no_repeat = {
        50,     //低电平
        200,    //高电平
        0,
        0,
        true
    };

    uapi_pin_set_mode(PWM_GPIO, PWM_PIN_MODE);  //设置引脚复用模式为PWM
    uapi_pwm_init();                            //初始化PWM 
    uapi_pwm_open(PWM_CHANNEL, &cfg_no_repeat); //开启PWM通道 

    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);
    uapi_pwm_unregister_interrupt(PWM_GROUP_ID);//取消注册PWM中断 
    uapi_pwm_register_interrupt(PWM_GROUP_ID, pwm_sample_callback);//注册PWM中断


    uapi_pwm_set_group(PWM_GROUP_ID, 1 << PWM_CHANNEL); //设置PWM通道对应的组 
    uapi_pwm_start(PWM_GROUP_ID);               //开启PWM


    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);

    uapi_pwm_close(PWM_CHANNEL);                //关闭PWM


    uapi_tcxo_delay_ms((uint32_t)TEST_TCXO_DELAY_1000MS);
    uapi_pwm_deinit();                          //去初始化PWM
    return NULL;
}

编译烧录固件
参考环境搭建教程编译烧录代码

三、测试

烧录固件后按下开发的复位按键，用示波器或者逻辑分析查看PWM输出引脚的PWM波，或者通过改变不同的占空比，观察开发板上的LED灯的亮度变化。