Temperature Monitor With ESP8266 - IoT




This project will help you create a temperature monitor using an ESP8266 SoC and a temperature sensor (DS18B20) with next capabilities:

  • Measure Temperature
  • Send an email if temperature goes under a threshold
  • Monitor temperature and set threshold from a mobile App

To complete this project you will have to create three things

  • Hardware - Basically you have to hook up the temperature sensor to the ESP8266 board and upload the Arduino code.
  • Cloud device - Create the logic that drives the decision making using the IC2Cloud platform www.ic2cloud.com
  • Mobile App - Create the mobile App using AppInventor to monitor and control your temperature appinventor.mit.edu

This project can be easily extended to monitor different thresholds and if combined with an actuator it can control a heating/cooling system.

Step 1: Get Your Materials

To complete this project you need a few things

  • A ESP8266 board. I recommend the Adafruit HUZZAH ESP8266 board. The main advantages are:
    • You get a FCC certified ESP8266 board
    • The ESPB8266 board has multiple pins exposed on the PCB
    • It has a voltage regulator on the board
    • It has buttons to trigger programming mode
  • A temperature sensor. I used a DS18B20 from DealExtreme
  • Some female to female cables
  • And optional if you want to make the module stand alone a USB connector and a USB power supply....and an enclosure.
  • To upload the Arduino code on the ESP8266 board you need a programming cable. I recommend this one from Adafruit.

Step 2: Wiring

The wiring is very simple. You have a TOP VIEW diagram here that shows you how to do it. To be more specific you need to do three connections:

  • DS18B20 - Vcc Pin ---> HUZZAH ESP8266 - 3V Pin
  • DS18B20 - GND Pin ---> HUZZAH ESP8266 - GND
  • DS18B20 - Data Pin ---> HUZZAH ESP8266 - #4 Pin

To be able to program it you need to connect as the programming cable too. If you use the Adafruit cable I recommend then you just plug it in with the black wire to the GND pin as shown in the picture above. For more details how to program HUZZAH board with Arduino please go to Adafruit website.

Step 3: Prepare Development Environments

To program this project you will need three development environments:

Arduino IDE for ESP8266 - You will use this to create the "firmware" for your hardware. To set-up this please follow the tutorial on the Adafruit website.

IC2Cloud Device Builder - You need this to create the monitoring code. To set-up this go to www.ic2cloud.com and register. Once you did that go to this section to create an API password.

App Inventor - You need this to create your mobile App (Android). To set-up this please go to App Inventor website and press the button Create Apps. Follow the instructions on the website. You might need a Gmail address to authenticate there.

It might sound complicated but it is fairly fast to execute all these steps.

Step 4: Program the Hardware

To program the HUZZAH board I have opted for Arduino. A lot of people are familiar with this and considering the simplicity of the code I think it can do the job quite well. I assume you followed the instructions from Adafruit tutorial mentioned in the previous step.

I also assume you followed instructions to set-up you IC2Cloud account and the API access.

Once you did that please download the code I provide here (Temperature.ino file from the ZIP file) and load it in the Arduino IDE. You have to modify a few things in the code to make it work

1. Modify "wifi ssid" string with your wifi SSID.

2. Modify "wifi password" string with your wifi password.

3. Modify "authentication" string with your authentication string for IC2Cloud API. Basically you have to append your user name, colon sign and password and encode the whole string using base 64 encoding. You can use this site www.base64encode.org to do that. For example if your user name is "user" and your password is "password" then you create this string:


and encode it using the tool from the link above. You should get


The password is the Api Password and not your login password. The user is your email you use for login.

There is one more thing that we recommend to change (but let's not do it until you understand the inner workings of the entire project) is the device Id.

Last thing is to compile and upload the code on your ESP board. I assume you are familiar with Arduino IDE and once you are properly set up for the ESP board this should be easy.

Step 5: Verify Communication With the Cloud

Once you completed the previous step it is recommended that you verify the communication with the cloud.

If you are familiar with the debug in Arduino please use serial communication to check if everything is OK. You can also go to the Signal Manager on the IC2Cloud website to test if the TEMPERATURE signal is sent to the cloud. The picture above shows you how to do it.

Please be aware that the signal is sent every few seconds.

If this is working properly then your hardware is up and running.

Step 6: Create the Cloud Device

Using the IC2Cloud Device Builder import the BasicSecurity.vcd file on the online IDE. You should see the picture above. The steps you need to do are:

  • Set your own email address as destination.
  • Save the Device with a Name (Le's say "Temperature Monitor").

The logic is fairly simple. The cloud device will read the TEMPERATURE and THRESHOLD and it will send an email if the temperature goes under the threshold. The THRESHOLD signal is set by the mobile application you will create in the next step.

Once that is done you need to start this cloud device.

Go to the Device Manager on the IC2Cloud site and press the button start next to it. You should get a confirmation the device is started and it runs.

Step 7: Create the Mobile App

Using App Inventor from MIT you will create the mobile application. Once you are set-up with App Inventor you can go and import the Temperature.aia file. Once you open the project you should see the user interface designer. Switch to blocks section and you will see the picture above.

The only thing you need to change is your authentication string you have created in the previous steps.

The password is the Api Password and not your login password. The user is your email you use for login.

Once that is done you can build and download the App on your phone and you have everything ready. Follow the instructions on the App Inventor site how to execute the steps.

Step 8: Using the Temperature Monitor

Open the mobile application you have created and you are gong to get a screen like the one above.

Here you can see your temperature from the sensor and the current threshold.

You can change the temperature threshold by using the slider.

Whenever temperature goes under threshold the system will send you an email.

This concludes the project. You have a temperature monitor IoT style ;-)

You can improve it. Here you have a few ideas:

  • Add multiple sensors.
  • Create different thresholds
  • ...and whatever you come up with ;-)

Anyway, if you managed to get to this point then you have the basic skeleton of a temperature monitor that will notify you whenever the temperature is going down.

Please keep in mind this is experimental and you need to make your own judgements how you use this project.

Good luck!

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30 Discussions


5 months ago

I have made the project Temperature Monitor With ESP8266 - IoT and it works until step 6. App invertor simulator and mobile appers the error 1101: Unable to get a response with specified URL: https: //Ic2pro.com/Wire/connector/get? id = 111-222-444 & Temperature.
Have sombody an idea what is the problem!?

Many Thanks!

3 replies

Reply 5 months ago

Hallo! Gibt es schon die Lösung dazu? Ich habe genau das gleiche Problem Danke.


Reply 5 months ago

Hallo OttL8,
Ich habe das gemacht was JoelD107 geschrieben hat, und es hat sofort funktioniert.


Reply 5 months ago

I found the solution. As said before, we must add "www." ahead of "ic2pro.com/Wire ..." and use a unique identifier (devId), in the "Block" section and for "Non-visible components" in the "Designer" section.


5 months ago on Step 8

Hi JoëlD107,
Many Thanks, for your tip, it worked well.
Best Regards


Question 9 months ago

I am new in ESP8266.

I have a NodeMCU ESP-12 board.

I registered on the IC2Cloud. On the form I added my name, screen name and email address. I have setup my IC2Cloud account and the API access. I have set my router access to the arduino code. At the www.base64encode.org I wrote my SCREEN name:API password. I paste this string to the code in the authentication row. I created Cloud Device too.

I compiled and uploaded the code to the ESP board. The NodeMCU works well. The Arduino´s Serial Monitor shows the temperature, but does not connected to the cloud. The Signal manager do nothing.

What did I do wrong? Screen name is the good user name?

In the code the host address is www.ic2pro.com. Not www.ic2cloud.com. Is that good?

1 answer

Answer 8 months ago

Seems like we are experiencing the same problem.
Have you found a solution yet?


Tip 1 year ago on Step 4

the current (May 2018) downloadable appinventor stuff for this project ,.. fails with URL errors,.. I fixed this by adding "www" to the www.ic2pro.com lines,... and adding my devID to the same lines.. after this correction,.. the project works really well,.. nice One!!


2 years ago

What would it take to make it alert on rise of temperature?


2 years ago

Well if anyone is still interested, the cloud based device manager appears to be up and running again!


3 years ago

Hi. Is anyone else having a problem with running devices in the cloud? When I open device manager and click on START the indicator goes yellow, then red, then it just hangs and I have to close the browser. When I go back in the device may show as ON or it may not but it never shows RUN.


3 years ago

Hello, i can do it so far until Step 4.
but in Step 5, i found error when running the program.
the error sounds like this,
"#error "Please define I/O register types here"
anyone can help?
Thank you.

2 replies

Reply 3 years ago

Even i am getting the same error. Any updates yet? did you resolve?


3 years ago

How can i get the ESP8266WiFIi.h and onewire.h?

1 reply

Reply 3 years ago

You can get it from here: http://playground.arduino.cc/Learning/OneWire


3 years ago

how did this work for anyone. kept getting ERR1, data pin for the DS18B20 is the middle pin. looks like i cooked mine after connecting 5 volts to that pin (5 volts is acceptable). Should I have looked it up ... yes. but still.


3 years ago

Great write-up, thanks for all the information!

I'm using an ESP8266 ESP-1 so I'm connecting the data line from the temp sensor to GPIO2. What do I change in the code?

Thanks for any help!