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2. Week 02

This week I worked on a temperature sensor that displays the temperature wirelessly on a smartphone.

sample photo

Description of my wireless sensor

To implement my project I used the following parts:

  • ESP8266 as a transmitter sample photo

  • DHT11 temperature sensor sample photo sample photo

  • Arduino IDE for programming

  • Mobile hotspot of my iPhone as a WiFi network

  • HTML page to display the temperature

The following functionality was implemented:

As shown below, the ESP8266 records the temperature at the sensor. The temperature is displayed on an HTML page. The address of the page can be saved as a bookmark in the Internet browser. The ESP8266 automatically connects to the smartphone’s hotspot.

sample photo

The following decisions and problem solutions were made within the project:

  • The ESP8266 has a built-in WIFI module and therefore - unlike many Arduino boards, for example - does not require an additional WIFI module. In addition, the ESP8266 costs just under 1 euro with a corresponding volume discount. However, it should be noted that only one analog input is available.

  • The ESP8266 can connect to a specified WIFI network or create its own WIFI hotspot to connect to. In the school FabLab, it would probably make sense to set up the school’s WIFI network. If you want to be as flexible as possible, it makes sense to use the ESP8266 as a hotspot. For my project, I implemented it so that the ESP8266 connects to the hotspot on my smartphone.

  • The temperature value is transferred via an HTML page that I can access with my browser (Safari). Alternatively, you could use a paid app (e.g. BLYNK), but I want to make the project as open as possible.

sample photo

  • Since I only wanted to show the basic feasibility, I decided not to build a housing for the transmitter unit. This would be easily possible with the 3D printer. By using a battery, the device can be operated independently of the mains. The range is sufficient, for example, to operate the device as an outdoor sensor.

Here is the code I created for the arduino-IDE:

#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>
#include <ESP8266WebServer.h>
#include <DHT.h>

#define DHTPin 5          
#define DHTTYPE DHT11

DHT dht(DHTPin, DHTTYPE);

ESP8266WebServer server(80);

const char* ssid = "iPhone NIXF";
const char* password = "12345678";
const char* dns_name = "Temp";


void reportValue();

void setup ()
{
 pinMode(A0, INPUT);
 Serial.begin(115200);
 Serial.println("ESP gestartet");

 WiFi.begin(ssid, password);

 Serial.print("Verbindung wird hergestellt");
 while (WiFi.status() != WL_CONNECTED)
 {
  delay(500);
  Serial.print(".");
 }
 Serial.println(); 

 Serial.print("Verbunden! IP-Adresse: ");
 Serial.println(WiFi.localIP());

 if (MDNS.begin(dns_name)){
  Serial.println("DNS gestartet, erreichbar unter: ");
  Serial.println("http://" + String(dns_name)+".local/");
 }


 server.onNotFound([](){
  server.send(404, "text/plain", "Link wurde nicht gefunden!");
 });

 server.on("/", indexHTML);
 server.on("/temp", reportValue); 

 server.begin();
 Serial.println("WebServer gestartet.");
}

void loop(){
  server.handleClient();
  MDNS.update();
}

void reportValue(){
  String temperature = String(dht.readTemperature(),1);
  Serial.println(temperature);
  server.send(200, "text/plane", temperature);
}

void indexHTML() {    
  server.send(200, "text/html", 
  "<!DOCTYPE html>\
  <html>\
  <head>\
  <title>Temperaturanzeige</title>\
  <meta http-equiv='content-type' content='text/html'; charset='utf-8'>\
  <style>\
  body { background-color: #585858; font-size: 50px; font-family: Arial, Helvetica, Sans-Serif; color: #F2F2F2; margin-left: 40px; }\
  h1 { color: #2ECCFA; margin-top: 50px; margin-bottom: 0px; }\
  h2 { font-size: 20px; margin-top: 0px; margin-bottom: 50px; }\
  #temp { width: 230px; height: 80px; border: 5px solid #F2F2F2; text-align:center; padding: 1px; color: #9AFE2E; background-color: #000000; font-size: 60px; }\
  </style>\
  </head>\
  <body>\
  <h1>Temperaturanzeige</h1>\
  <h2>EBGS</h2>\
  <table><tr><td>Aktuelle Temperatur:&nbsp;</td>\
  <td id='temp'><span id='temperature'>-</span>°C</td></tr></table>\
  <script>\
  setInterval(function() {\
    getData();\
  }, 1000);\
  function getData() {\
    var xhttp = new XMLHttpRequest();\
    xhttp.onreadystatechange = function() {\
      if (this.readyState == 4 && this.status == 200) {\
        document.getElementById('temperature').innerHTML = this.responseText;\
      }\
    };\
    xhttp.open('GET', 'temp', true);\
    xhttp.send();\
  }\
  </script>\
  </body>\
  </html>\
  ");
}

Reflecting Questions

What are some opportunities in your context to work within your local community? Who you could collaborate with? How? What should happen to succeed in the collaboration?

Since our school is under municipal supervision, cooperation with the municipality is obligatory. For example, structural changes must be discussed with the municipality and commissioned by it. Apart from this obligatory cooperation, there are also other possibilities for cooperation. For example, we have an anniversary with our twin town Agen in France. Here we are working with city representatives to design part of the program in the Fablab that is planned as part of the celebrations.

What are the next steps in development further a makerspace in your school? How do you envision the maker space?

We have already set up a makerspace in our school. Less than a year passed from the initial idea in early 2024 to the inauguration of the School FabLab in January 2025. The focus of the first phase was on providing the space and equipping it with the necessary machines and equipment. Currently, different groups of students are working in the FabLab as part of working groups, and we have already implemented individual projects - e.g. with primary schools. What we need to do next is to establish a reliable team and focus more on the educational side of the work in the FabLab. Open times during which students can simply come along and implement their projects are particularly important to us. That is what we definitely want to implement next.

What is the potential of physical computing and IoT for your teaching? Do you have any ideas on how you are planning to integrate those techniques in your context?

This area is very important to me and we are planning a series of project ideas for our School Fablab. It is particularly important to us that the students can still understand the function of these systems well and can design them very freely. That is why we want to find the simplest possible options - as in the project shown here - even if the solutions may seem less professional than, for example, a self-designed app, where the students’ activity is limited to clicking elements together. We are more concerned with the students understanding what they are doing. It is also very important that the students can take their projects home and use them there. This makes it necessary to limit the costs, as our students have to pay for most of their projects themselves. A project like the temperature sensor described here could be realized for less than 5 euros including housing and battery, which is an acceptable price for our students.