DAC

#DAC API

API	说明
DAC.open(id)	功能：打开dac 参数： id:和板级配置文件中的id保持一致 返回值：成功：回资源handle，失败：-1
DAC.close(handle)	功能：关闭dac 参数： handle:资源handle，为DAC.open的返回值; 返回值：0=ok other=fail
DAC.setVol(handle,vol)	功能：设置dac输出电压 参数： handle:资源handle，为DAC.open的返回值;             vol：电压值 返回值：0=ok other=fail
DAC.getVol(handle)	功能：获取当前dac电压; 参数： handle:资源handle; 返回值：电压值;

#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; <span data-type="color" style="color:#F5222D">类型：</span>string </div> <div data-type="p"> <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：number <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;voltage&quot;</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"><span data-type="color" style="color:#F5222D">功能：</span>默认输出电平; </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>依据实际情况进行配置；</div> </td> <td rowspan="1" colSpan="1"> <div data-type="p"></div> </td> </tr> </tbody>

#板级配置示范

/*apps/js/board_config.json*/
{

	"DAC":[
		{
		"id":"led",
		"port":1,
		"voltage":255
		}
	]

}

#ESP32之LED模块

#硬件

1)esp32Kit开发板 2)LED模块

#接线

EPS32 IO25引脚 连接 LED模块的正极； EPS32 GND引脚 连接 LED模块的负极；

#配置

/*apps/js/board_config.json*/
{

	"DAC":[
		{
		"id":"led",
		"port":1,
		"voltage":255
		}
	]

}

#代码

var led_handle = DAC.open('led');
var cur_voltage = DAC.getVol(led_handle);
console.log('cur_voltage:'+cur_voltage);
setInterval(function(){

	cur_voltage  = cur_voltage + 1;
	if(cur_voltage >= 255){
		cur_voltage = 0;
	}
	DAC.setVol(led_handle,cur_voltage);
},50);

#现象

LED亮度由弱变强，当低于某个值是，LED完全熄灭；

#TODO

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