IoT meteo station

In this page you will see how I built the first IoT device to use to test the Miniservice environment. This device constantly save the temperature using a meteo service available on the internet

If you need additional specific information about this topic or if you want to look it personally please write an email

In order to test miniservice functions I decided to build a smart sensor able to connect to the internet and to store in the Miniservice Cloud a temperature value collected every X mins.

The development of such similar component will allow me to test the stability of the code built to run miniservice environment, the stability of the database and the high availability of the infrastructure. Another big advantage will be the possibility to build usefull libraries and structures that I have been able to make available to be downloaded and to simplify the development of any IoT device interfacing with miniservice environment.

To build an easy IoT device using my competences I chose to continue to use the arduino IDE. Arduino IDE is easy to use, is C++ compliant, manages a great amount of prototyping boards and has a tremendous amount of libraries built to integrate a massive set of devices.

In order to work with the Arduino framework you can use both the standard Arduino Framework or different additional IDE like Platformio or Visual Micro.

If you want to better understand what is an Arduino IDE see my tutorial.
If you need some instructions on how to manage libraries in Arduino framework see here.

Once decided the framework and the development environment, you need to select a valid device to use for your application. You can decide to use a standard arduino board adding wifi capabilities or you can decide to use a board with a wifi module integrated directly on it. In both cases the chipset to use to connect to a wifi APNs is an ESP8266. This chipset family is the most common one to build integrated IoT application. Obviously, for such similar chip you will find toons of libraries available on internet ready to be installed and to be used in your project.

If you decide to use an Arduino board you need to buy a separate ESP8266 component that you will connect to the TX and RX channel of your arduino. The ESP8266 board acts exactly as a modem. It connects with a serial port and receive AT commands in order to activate the TCP layer to use to run protocols like HTTP, FTP and so on.

This configuration is more stable because it allows you to use all the power of an arduino board (memory, pins, libraries, features etc.). On the other side there is an important consideration while connection Arduino with the ESP 8266 board. The first one (except for some models) works with 5V on TX and RX pins. The second one (ESP 8266) works with 3.3V. For this reason, in theory, you should never connect those two components directly. You should use a voltage divider or a bidirectional component able to reduce the voltage in one direction and increase it in the opposite one.

How to connect an ESP8266 to an Arduino board using a voltage divider component

Once this issue has been solved then this is the solution that gives you more flexibility and capability in term of sensors and connections you can use contemporary.

In case you need to build a basic IoT service with just one or two sensors or with a sensor and an Oled display (for example) then there is an easy solution. You can use a board called: "NodeMcu"

To perform my test the solution based on a nodeMCU board was the perfect one. Using this board you have everithing already built in and you can use the arduino development environment as for any other card (remember to add this board from the board manager in the preference menu of the standard arduino IDE).

To retrieve the temperature the sensor I used is a DHT11, but you can use also a DHT22 (more detailed) or any other sensor. To download this library you can use our Download area

To run the ESP8266 capabilities of the NodeMCU board, you need, in any case, to use the right libraries. Your code will need to include the following headers:

                #include "ESP8266WebServer.h"
                #include "ESP8266WiFi.h"
                #include "dht11.h"
                #include "ESP8266HTTPClient.h"

The first version of the IoT module was very basic. I decided to not use any Oled Display to show the connection status. I simply used two leds a white one and a red one.
The algorithm is very easy and uses the EPROM chipset installed on the board to store configuration data.

        Start and retrieve the APN information stored into the EPROM of the NodeMCU
        Try to connect to the APN
        IF YES then activate the white led and start sending information every five minutes to the  Miniservice temperature service
            Activate a web server and if requested display the same temperature you read
        IF NO then activate the RED led and start your APN (became an access point)
            Open a web server and wait for a connection
            Once a connection has been estabilished then ask for a new APN and a new password and store these info into the eprom
            reset the board and start from scratch

The connections look like in the following picture:

IoT Temperature sensor connection picture

The IoT device fits perfectly in a case I draw and printed with my printerina 3D printer. If you want you can download the STL files from our Download area

IoT Temperature sensor case

This is the function I built in order to test if the wifi connection, using the settings stored in the EPROM, has been successufully performed:

        bool testWifi(void) {
            int c = 0;
            WiFi.begin(esid.c_str(), epass.c_str());

            Serial.println("Waiting for Wifi to connect");
            while ( c < 20 ) {
                if (WiFi.status() == WL_CONNECTED) { return true; }
            Serial.println("Connect timed out, opening AP");
            return false;


Here the function you can use to send to the temperature Miniservice an auth request to receive a token used to store the temperature:

        String BuonevacanzeAuthenticate() {

            String SendString, payload, StrToken;
            HTTPClient http;
            SendString = "" + ObjectCode + "&&APP=" + SVCTemperature + "&&TAG=0&&LANIP=" + WiFi.localIP().toString();
            Serial.println("Sending = "+ SendString);
            //Send Data to Buonevacanze
            http.begin(SendString);  //Specify request destination
            int httpCode = http.GET();                                                                  //Send the request
            if (httpCode > 0) { //Check the returning code

                payload = http.getString();   //Get the request response payload
                StrToken = xmlTakeParam(payload,"Message");
                Serial.println("HashCode: " + StrToken);
                payload = "Not Authorized";

            http.end();   //Close connection
            return payload;


Read the temperature from the sensor is very easy:

            dht11 DHT;

            TempValue =;



Obviously SendMeteoValues Is the function I built to call the Temperature service once you have a valid token to use in this service categhory.

            void SendMeteoValues(String Token,int Temp,int Hum)

                String SendString, payload, StrToken;
                HTTPClient http;
                SendString = "" + Token + "&&TEMP=" + String(Temp) + "&&HUM=" + String(Hum) + "&&GEO=0";
                Serial.println("Sending = "+ SendString);

                //Send Data to Buonevacanze
                http.begin(SendString);     //Specify request destination
                int httpCode = http.GET();                                                                  
                if (httpCode > 0) {         //Check the returning code

                payload = http.getString();   //Get the request response payload
                StrToken = xmlTakeParam(payload,"ReturnMessage");
                Serial.println("Result: " + StrToken);

                http.end();   //Close connection


As described in the pages dedicated to Miniservices by, once those information have been stored you will have available also different services to manipulate them or to simply retrieve data stored in the central DB.
Another interesting functionality (not implemented for this occasion but available as service function), is the one to store a gps position linked to the temperature sent to the infrastructure. In this way you will be able to associate a position to a specific temperature.

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