Example Code for Arduino-Smart Watering System (Based on Easy IoT)

Hardware Preparation

• Arduino UNO board x 1
• IO Expansion board x1
• WiFi IoT module x1
• Soil Moisture Sensor x1
• Digital Relay Module x1
• Water Pump x1
• Wires

Software Preparation

• Arduino IDE
• Download and install the WiFi IoT Module Library. (About how to install the library?)

Wiring Diagram

Sample Code

 #include "DFRobot_WiFi_IoT_Module.h"
    #include <SoftwareSerial.h>
    int Relay = 3;
    //I2C mode
    DFRobot_WiFi_IoT_Module_I2C IoT;

    //I2C mode 
    DFRobot_WiFi_IoT_Module_I2C IoT;

    //You can change them based on your needs 
    const char *WIFI_SSID           = "hitest";         //WiFi account 
    const char *WIFI_PASSWORD       = "12345678";           //WiFi password 

    //Easy IOT English configuration 
    //const char *EASY_IOT_SERVER        = "iot.dfrobot.com";

    //EASY IoT Chinese configuration 
    const char *EASY_IOT_SERVER     = "iot.dfrobot.com.cn";    //IoT host address, no need to revise here 
    const char *EASY_IOT_PORT       = "1883";                  //IoT connect port, no need to revise here 
    const char *EASY_IOT_ID         = "smofVJDMR";             //Iot_id, the account recorded when creating device 
    const char *EASY_IOT_PWD        = "ymoBVJvMgz";            //Iot_pwd, the password recorded when creating device 
    const char *SUBSCRIBE_TOPIC     = "9qnYVJDMR";             //Subscribe a device, device number “9qnYVJDMR”
    const char *PUBLISH_TOPIC       = "9qnYVJDMR";             //Send data to the device, device number “9qnYVJDMR”
    const char *EASY_IOT_SEND_MESSAGE    = "Send_Message";

    /********************************************************************************************
    Function    : callback
    Description : print the subscribed IoT device number and message 
    Params      : topic: subscribed device number; message: subscribed device number message 
    Return      : 
    ********************************************************************************************/
    String data = "0";
    void callback(const char*topic,const char*message)
    {
     Serial.println("Receive [ " + (String)topic + "]," + "Message : " + (String)message);
     data = (String)message;
    }

    /********************************************************************************************
    Function    : getSoilHumidity
    Description : Get soil humidity value 
    Params      : 
    Return      : Current soil humidity 
    ********************************************************************************************/
    float getSoilHumidity()
    {
      uint16_t val;
      val = analogRead(A0);
      return val;
    }

    void setup(void){ 
      Serial.begin(115200);
      //Init communication port 
      while(IoT.begin() != 0){  
        Serial.println("init ERROR!!!!");
        delay(100);
      }
      Serial.println("init Success");
      //Connect to WiFi
      while(IoT.connectWifi(WIFI_SSID, WIFI_PASSWORD) != 0){  
        Serial.print(".");
        delay(100);
      }
      Serial.println("Wifi Connect SUccess");
      //Init MQTT and connect to IoT platform 
      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");
      //call callback function 
      IoT.setCallBack(callback); 
      //subscribe device SUBSCRIBE_TOPIC
      while(IoT.subscribe(SUBSCRIBE_TOPIC) != 0){
        Serial.print(".");
        delay(100);
      }
      Serial.println("Subscribe Topic Success");

      pinMode(13, OUTPUT);         //Set Pin13 as output
      digitalWrite(13, HIGH);     //Set Pin13 High
      pinMode(Relay, OUTPUT);     //Set Pin3 as output
    }

    static long timestamp = millis();
    void loop(void){

    IoT.loop();
      //Received command "1" from Easy IoT, set relay to high 
      if(strcmp(data.c_str(),"1") == 0){ 
        digitalWrite(Relay, HIGH);
        data = "0";

      }
    IoT.loop();
      //Received command "2" from Easy IoT, set relay to low
      if(strcmp(data.c_str(),"2") == 0){
         digitalWrite(Relay, LOW); 
        data = "0";
      }
      if(millis()-timestamp>5000){
        timestamp = millis();
        int Hum = getSoilHumidity();
      //When current soil humidity Hum<=100, send the current humidity to Easy IoT
        if(Hum <= 100){
          IoT.publish(PUBLISH_TOPIC, (String)Hum);
        }
      //When current soil humidity Hum>=300, send the current humidity to Easy IoT
        if(Hum >= 300){
          IoT.publish(PUBLISH_TOPIC, (String)Hum); 
        }
      } 
    }

Result

Upload the dectected soil moisture. The received message from Easy IoT is shown below:

Send command "1" from Easy IoT to water the plant(control the water pump by the relay module); command "2" for stopping watering.