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  • Author Author: fvan
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Simple thermometer using Arduino Micro and OLED display

fvan

A colleague recently made an Arduino-based thermometer to measure how hot it gets in the office. I thought I'd recreate and document the project with the components I have at hand image

 

Circuit

 

The circuit is based around the TMP36 temperature sensor. It's cheap, easy to use and doesn't require any external calibration. The voltage output is linearly proportional to temperature in degrees Celsius, making the conversion easy to calculate.

Any Arduino or microcontroller having at least one analog input pin can be used to make the reading. Finally, some form of display is required. This could be a 7-segment display, a character LCD or even an OLED display.

 

I'll be using an Arduino Micro combined with a small OLED display.

 

The resulting circuit is the following:

image

 

Code

 

The temperature sensor can be used without any additional libraries, the analogRead() function and some math will do the trick.

 

The OLED display however, requires two libraries:

 

The completed code looks as follows (comments in the code for explanation):

 

 

Result

 

Now I finally know how hot it is in my room ... Outside temperature is not bad either image

imageimage

 

Extra

 

As requested in the comments, I have made an updated version of the above project. It includes a button to toggle between degrees C, F and K.

 

All temperatures are calculated, and a button connected to an interrupt pin is used to toggle the displayed value.

 

The updated code:

 

 

Some pics:

 

imageimage

  • Better late than never.

    Very good - for a newcomer to OLEDs, this was just what I was after.

    I am going to fit two of these to a fridge and a freezer. I suspect that the temperature control of the fridge thermostat is  pretty poor with swings between 1-degree C and 10-degrees C.

    This will be the basis of a new fridge thermostat. I was using the TMP36 for the freezer which it's ideal for.

    My setup is 1.3" 128 x 64 OLED from Lamnu (?) on Amazon and has SPI as well as I2C. As reviewers have noted, documentation is next to useless.

    So for I2C, remove the 4K7 SMD resistor marked SPI and short out the I2C pads (not the SPI as well). Subtstitute SD1106 for SSH1306 libraries and change references accordingly.

    On Nano or Uno, use A4 for SDA and A5 for SCL.

    I like the averaging and the fact that I didn't have to code for negative values.

    The only problem I had was with the I2C address - I tried Nick Gammons' address finder sketch, but it couldn't find it. Is this because the SSH1106 chip doesn't support full read/write?

    However, 0x3D worked for the 128 x 64

    Thanks a lot.

  • in reply to fvan

    Oh right,

     

    I saw on link you provided me that for Micro board, interrupt 4 is on pin 7.

    Now everything makes sense, because I could not find a link between interrupt pin and button pin.

     

    Thank you.

  • in reply to Former Member

    Trying to remember ...

     

    I think it just means interrupt 4 is on pin 7. See https://www.arduino.cc/en/Reference/AttachInterrupt  for more info on the interrupt.

  • Hi Frederick,

    first of all thank you for this project, it's perfect for my needs.

    I have one question for 2nd code - with button.

    I'm confused with this line:

    attachInterrupt(4, debounce, FALLING); - instead of 4, do we maybe must use pin 7 for interrupt? If no, can you please explain me then connection between pin7 (button) and pin4.

    Thank you very much.

    P.S. I'm new to this and learning every day...

  • in reply to clem57

    ... and for doing that in these harsh hot conditions!