Introduction: On-line Charting (logging) of Temperature Measurements

Picture of On-line Charting (logging) of Temperature Measurements

Hi!, this is my Internet of things (IoT) project with Arduino

What is needed:
1 x Arduino Uno (or compatible)
1 x Arduino EtherNet Shield (or compatible)
1 x Temperature sensor for Arduino (I used “DHT21” compatible)

Step 1: Soldering...

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Connect your temperature sensor to Arduino Uno board, you should find instruction for the exact sensor you use, for example the sensor I used is connected as follows:

red wire to pin “5V”,
black wire to pin “GND”
yellow wire to pin “2” (or any other digital input pin),

I soldiered the wires to “pin rows” so that it’s easier to attach it to Arduino

Step 2: Testing the Sensor...

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Start Arduino IDE and make sure that you have appropriate library for your temperature sensor at hand, for example, for my sensor (“DHT21” compatible), I found the library from Rob Tillaart working very well, write some code so that the sensor’s readings are printed out to the Serial terminal – run this to make sure the sensor is working properly

Step 3: Connecting to Web...

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Now it gets interesting. In order to make sensor’s readings accessible via Web, you’ll need to use an “Internet of things” solution that supports Arduino. I find the feoWeb service quite helpful for that: On their web-page, when you log-in you’ll find the needed library for Arduino, download it and copy it to the Arduino/lib folder (on Windows typically here: c:\Program Files (x86)\Arduino\lib\). Use instructions from feoWeb to adapt the source code you wrote in previous step (there is a handful of steps needed and I don’t want to repeat them here), in the end my main loop looked like this.

In screenshot, notice the call to ”feoWebVarSetAsFloat”, this is effectively the place where the sensor data is submitted to the web

Step 4: Visualizing It...

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And with the related feoWeb screen designer you should be able to see loggings of your sensor in any web browser

Step 5: Putting It Into a Nice Box...

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Put it into a box and fix it to a wall;
That’s it, now expand the system with additional sensors and actuators :)

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