动手实践：WiFi IoT模块控制小转盘 🤖✨

模块买到手好几天了，乘周末有时间开箱上电试试。

WiFi IoT模块开箱上电之小转盘图1

材料：DFRduino UNO R3一枚、IO 传感器扩展板 V7.1一枚、Gravity：WIFI IoT模块一枚、DMS-MG90舵机一枚。

打算从EasyIoT上向设备发送字符，控制舵机转起来，一个简单的小转盘，协议用MQTT。

WiFi IoT模块开箱上电之小转盘图2

WiFi模块拨到I2C模式，连接扩展板I2C端口。舵机连接数字端口9。在https://github.com/DFRobot/DFRobot_WiFi_IoT_Module下载库文件（我下载的是ZIP格式）。

WiFi IoT模块开箱上电之小转盘图5

下面处理代码部分，涉及ID/密码的地方我用星号代替。

#include <Servo.h>
#include <SoftwareSerial.h>
#include "DFRobot_WiFi_IoT_Module.h"

DFRobot_WiFi_IoT_Module_I2C IoT;

Servo myservo;
int pos = 0;

String flag01 = ""; // compare if new data sent from EasyIoT

// WiFi SSID and password
const char *WIFI_SSID                       = "Linksys19544";
const char *WIFI_PASSWORD          = "********";

// setup EasyIoT essential parameters
const char *EASY_IOT_SERVER        = "iot.dfrobot.com.cn";
const char *EASY_IOT_PORT            = "1883";
const char *EASY_IOT_ID                  = "********";
const char *EASY_IOT_PWD             = "********";
const char *SUBSCRIBE_TOPIC        = "auwZY6AWg";
const char *PUBLISH_TOPIC             = "auwZY6AWg";
const char *EASY_IOT_SEND_MESSAGE  = "";

String receiveMessage = "";

// setup CallBack function (for listening info sent by EasyIoT)
void callback(const char *topic, const char *message)
{
  receiveMessage = (String)message;
}

// main initialization
void setup() 
{
   Serial.begin(115200);

   // initialize IoT port
   while(IoT.begin() != 0)
   {  
     Serial.println("IoT init ERROR!!!!");
     delay(100);
   }
   Serial.println("IoT init Success");

   // connect to WiFi
   while(IoT.connectWifi(WIFI_SSID, WIFI_PASSWORD) != 0)
   {  
     Serial.print(".");
     delay(100);
   }
   Serial.println("Wifi Connect Success");

   // initialize MQTT (EasyIoT)
   while(IoT.MQTTBegin(EASY_IOT_SERVER, EASY_IOT_PORT, EASY_IOT_ID, EASY_IOT_PWD) != 0)
   {
     Serial.print(".");
     delay(100);
   }
   Serial.println("MQTT Connect Success");

   // invoke callback function for listening
   IoT.setCallBack(callback);

   // subscribe a topic (listening info from this device)
   while(IoT.subscribe(SUBSCRIBE_TOPIC) != 0)
   {
     Serial.print("?");
     delay(100);
   }
   Serial.println("Subscribe Topic Success");

   // initial servo to 0 degree
   myservo.attach(9);
   myservo.write(pos);
   delay(15);
   pinMode(13, OUTPUT);
   digitalWrite(13, HIGH);
  }

// regular works
void loop()
{
   if(strcmp(flag01.c_str(), receiveMessage.c_str()) !=0)
   {
     flag01 = doJob(receiveMessage);
   }
   IoT.loop();
   delay(100);
  }
  String doJob(String code)
 {
     if (code.equals("1"))
    {
       pos = 0;
       myservo.write(pos);
       delay(15);
    }
   if (code.equals("2"))
   {
     pos = 45;
     myservo.write(pos);
     delay(15);
   }
   if (code.equals("3"))
   {
     pos = 90;
     myservo.write(pos);
     delay(15);
   }
   if (code.equals("4"))
   {
     pos = 135;
     myservo.write(pos);
     delay(15);
   }
   if (code.equals("5"))
   {
     pos = 180;
     myservo.write(pos);
     delay(15);
   }
   return code;
}
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