PWM

#PWM API

API	说明
PWM.start(id)	功能：配置和启动PWM 参数： id:和板级配置文件中的id保持一致 freq:频率 duty:占空比 返回值：成功:返回资源handle,失败:-1
PWM.getDuty(handle)	功能：获取当前pwm周期 参数：handle:资源handle，为PWM.open的返回值; 返回值：占空比值
PWM.setDuty(handle，duty)	功能：配置duty 参数： handle:资源handle，为PWM.open的返回值; duty:占空比值 返回值：0=ok other=fail
PWM.getFreq(handle)	功能：获取当前pwm频率 参数：handle:资源handle，为PWM.open的返回值; 返回值：频率值
PWM.setFreq(handle, freq)	功能：配置freq 参数： handle:资源handle，为PWM.open的返回值; freq:频率 返回值：0=ok other=fail
PWM.stop(handle)	功能：停止PWM 参数： handle:资源handle，为PWM.open的返回值; 返回值：0=ok other=fail

#板级配置参数

参数名	类型/功能/值	说明
"id"	功能：资源唯一性标志; 类型：string <span data-type="color" style="color:#F5222D">值：</span>任意，保持数组内id值唯一;</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p">该id值和js层GPIO.open时的id值保持一致;</div> </td> </tr> <tr height="34px"> <td rowspan="1" colSpan="1"> <div data-type="p">&quot;port&quot;</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"><span data-type="color" style="color:#F5222D">功能：</span>端口值; </div> <div data-type="p"> <span data-type="color" style="color:#F5222D">类型：</span>number </div> <div data-type="p"> <span data-type="color" style="color:#F5222D">值：</span>和板级资源描述保持一致；</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p">该port值和HAL层API对应的port保持一致；</div> </td> </tr> <tr height="34px"> <td rowspan="1" colSpan="1"> <div data-type="p">&quot;freq&quot;</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"><span data-type="color" style="color:#F5222D">功能：</span>频率值; </div> <div data-type="p"> <span data-type="color" style="color:#F5222D">类型：</span>number </div> <div data-type="p"> <span data-type="color" style="color:#F5222D">值：</span>依据需求进行设置；</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"></div> </td> </tr> <tr height="34px"> <td rowspan="1" colSpan="1"> <div data-type="p">&quot;duty&quot;</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"><span data-type="color" style="color:#F5222D">功能：</span>占空比; </div> <div data-type="p"> <span data-type="color" style="color:#F5222D">类型：</span>number </div> <div data-type="p"> <span data-type="color" style="color:#F5222D"> 值：0-100；	占空比的范围是0-100，表示0%-100%

#板级配置示范

{
	"PWM":[
		{
		"id":"buzzer",
		"port":4,
		"freq":5000,
		"duty":50
		}
	]
}

#ESP32之无源蜂鸣器

#硬件

#接线

EPS32 IO4引脚 连接 无源蜂鸣器模块的'+'引脚； EPS32 GND引脚 连接 无源蜂鸣器模块的GND引脚；

#配置

/*apps/js/board_config.json*/
{
	"PWM":[
		{
		"id":"buzzer",
		"port":4,
		"freq":5000,
		"duty":50
		}
	]

}

#代码

/*samples/js/buzzer.js*/
print('buzzer uart test.....................');
var buzzer_handle=PWM.start('buzzer'); 
var cur_duty = PWM.getDuty(buzzer_handle);
console.log('cur_duty:'+cur_duty);
setInterval(function() {
	cur_duty += 1;
	if(cur_duty >= 100)cur_duty=0;
	PWM.setDuty(buzzer_handle,cur_duty);
}, 500);
print('end buzzer test........................');

#现象

蜂鸣器声音由弱到强转换。

#TODO

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