Currently i am able to send the 2 decimal data to thingspeak field. But i stuck on how to write 3 decimal places data to that field. Hope u guys can help.Here is my coding. #include PubSubClient.h // library used to publish the data through mqtt broker #include WiFiEsp.h // library for ESP8266 wifi #include EEPROM.h // library that GravityTds use #include GravityTDS.h // library that GravityTds use #include OneWire.h // Include the libraries for temperature #include DallasTemperature.h // Include the libraries for temperature #include SoftwareSerial.h // library for software serial to display output on the serial monitor

#define TdsSensorPin A1 // set TdsSensorPin at pin A1 #define temperaturePin 2 // temperature sensor is connected into pin 2 on the Arduino

OneWire oneWire(temperaturePin); // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs) DallasTemperature tempsensor(&oneWire); // Pass our oneWire reference to Dallas Temperature. GravityTDS gravityTds; // define the gravityTds SoftwareSerial Esp8266(5, 6); // Rx, Tx set communication pin for esp8266 to uno WiFiEspClient Esp8266wifi; // set the esp8266 for the mqtt broker connnection PubSubClient client(Esp8266wifi); // set the esp8266 for the mqtt broker connnection

unsigned long previousMillis1 = 0; // used to delay without delay the system for sensor data unsigned long previousMillis2 = 0; // used to delay without delay the system for the send data to thingspeak float temperature; // variable to store temperature value int tdsValue; // variable to store tds value float EC; // variable to store EC value

char ssid[] = ""; // your network SSID (name) char pass[] = ""; // your network password int status = WL_IDLE_STATUS; // the Wifi radio's status String clientName="ESP-Thingspeak";

//char* topic="channels/<channelID/publish/<channelAPI> char* topic = "channels/1244171/publish/FOZYSFXXS4P6DE5N"; // topic to be published to the thingspeak with channel id and api code char* mqtt_server = "mqtt.thingspeak.com"; // set the server for the mqtt of thingspeak

void setup()

{

    Serial.begin(9600);                   // 9600 is the baud rate for the data to display to the serial monitor
    Esp8266.begin(9600);                  //9600 is the baud rate for the srial data connection of esp8266
    WiFi.init(&Esp8266);

    client.setServer(mqtt_server, 1883);  // set mqtt broker server and port
    tempsensor.begin();                   // begin temperature sensor library
    gravityTds.setPin(TdsSensorPin);      // set pin tds at declared variable TdsSensorPin
    gravityTds.setAref(5.0);              //reference voltage on ADC, default 5.0V on Arduino UNO
    gravityTds.setAdcRange(1024);         //1024 for 10bit ADC;4096 for 12bit ADC                // arduino uno adc level  is a 10-bit ADC   
    gravityTds.begin();                   //initialization

    InitWiFi();   //call function to intialize wifi

Serial.print("Connecting to ");               // display on serial monitor
Serial.print(mqtt_server);
Serial.print(" as ");
Serial.println(clientName);

if (client.connect((char*) clientName.c_str()))                   // connect to the thingspeak with the client name
{
  Serial.println("Connected to MQTT broker");

    if (client.publish(topic, "Test send data"))                   // Test send data to the thingspeak
    {
      Serial.println("Testing send data succes");
    }
    else {
      Serial.println("Testing send data failed");
    }
  }
  else {
    Serial.println("MQTT connect failed");
    Serial.println("Will reset and try again...");
    abort();
  }

}

//this function is only for the initialization of the esp8266 to connect to the network & mqtt  and  initialize the sensor 

void loop(){ unsigned long currentMillis = millis(); //timer start

checkconnection();                             // calling function to check the connection

if (currentMillis - previousMillis1 >= 2000)  //delay without causing system delay
{

    previousMillis1 = currentMillis;       

    sensordata();                               // calling fucntion of the sensor data  
  }

if (currentMillis - previousMillis2 >= 2000) //delay without causing system delay
{

    previousMillis2 = currentMillis;       

senddata();                                   // calling fucntion to send data         // send one set of data in 2 seconds
}

}

void sensordata() { tempsensor.requestTemperatures(); // get temperatures temperature = tempsensor.getTempCByIndex(0); // set variable to the temperature sensor output gravityTds.setTemperature(temperature); // set the temperature and execute temperature compensation gravityTds.update(); //sample and calculate tdsValue = gravityTds.getTdsValue(); // then get the value of TDS EC = gravityTds.getEcValue()/1000; // get EC value Serial.println(temperature); // display sent data Serial.println(tdsValue); Serial.println(EC,3); Serial.println("Data Sent"); }

void senddata() {

String payload="field1=";     // payload to send to thingspeak using mqtt broker
payload+=temperature;         // field1=temperature&field2=tdsValue&field3=EC&status=MQTTPUBLISH
payload+="&field2=";          //// field1=26.9&field2=120&field3=0.2&status=MQTTPUBLISH
payload+=tdsValue;
payload+="&field3=";          //// field1=26.9&field2=120&field3=0.2&status=MQTTPUBLISH
payload+=EC,3;
payload+="&status=MQTTPUBLISH";

if (client.connected())         // if client connected
{
  Serial.println("Sending data ");

    if (client.publish(topic, (char*) payload.c_str()))   // send data to the thingspeak, topic (the channel id and channel api) -- payload is the data from sensor that will be sent to the thingspeak
    {
      Serial.println(temperature);                          // display sent data
      Serial.println(tdsValue);      
      Serial.println(EC,3);      
      Serial.println("Data Sent");
    }
    else 
    {
      Serial.println("Publish failed");
    }
}
}

void checkconnection() /// check connection if disconnected try to reconnect wifi and mqtt broker {

   if  ( status != WL_CONNECTED)
 Serial.println("Wifi Disconnected");
 {
  while ( status != WL_CONNECTED)
 {
  InitWiFi();                   // call function to start wifi // reconnect wifi
  }
 }

if (!client.connected())                  // if mqtt broker disconnected from thingspeak
{
   Serial.println("MQTT Disconnected");
 while (!client.connected())                    // while mqtt broker disconnected from thingspeak
{
 if (client.connect((char*) clientName.c_str()))          // reconnect to the server
{
  Serial.println("MQTT connected");
}
else 
{
  Serial.println("MQTT connect failed");
  Serial.println("Will reset and try again...");

}
}
}

} void InitWiFi() { // check for the presence of the module if (WiFi.status() == WL_NO_SHIELD) { Serial.println("WiFi module not present"); // don't continue // don't continue while (true); //keep looping until it detect esp8266 module }

// attempt to connect to WiFi network
while ( status != WL_CONNECTED) {
  Serial.print("Attempting to connect to WPA SSID: ");
  Serial.println(ssid);
  // Connect to WPA/WPA2 network
  status = WiFi.begin(ssid, pass);
}

// print your WiFi ESP8266 IP address
IPAddress ip = WiFi.localIP(); 
Serial.print("IP Address: ");
Serial.println(ip);

    // print the SSID of the network you're attached to
  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());

    // print the received signal strength
  long rssi = WiFi.RSSI();
  Serial.print("Signal strength (RSSI): ");
  Serial.println(rssi);
  delay (5000);
}