Designing a simple and cheap temperature logger. Part 6: Video!!

I just finished developing my USB temperature logger and shot a video showing how it works. Here are the key figures:

  • Up to two months of logging with a single coin cell battery.
  • 30 000 timestamped temperature measurements.
  • Logging period from every 5 seconds to every 24 hours.
  • 0.5°C accuracy, 0.06°C resolution.
  • No driver, no software and no admin rights needed!
  • Compatible with any computer with USB port.
  • Automatic time synchronization with the computer.
  • Low cost design.

When plugged to a computer’s USB port, the logger appears as a normal USB drive. The temperature logging period is changed by editing a config.txt file. When this file is saved, the logger reads the periodicity (in seconds), synchronizes its clock to the computer’s date and time and starts to flash the LED to indicate it’s ready to log. Once removed from USB, the logging is started by pushing the button (the LED blinks three times). For every temperature measurement, the LED flashes.

Once plugged back to USB, the file DATA.CSV will contain all the temperature measurements and the corresponding date and time, TAB separated.

A future development could include a Li-Ion USB rechargeable battery, battery life monitoring, low power – long period logging mode.

If you’re interested by this project, don’t hesitate to contact me. Share if you like it!

19 thoughts on “Designing a simple and cheap temperature logger. Part 6: Video!!

  1. I’ve been looking to do a project that monitors body temperature over the course of a few days…

    Do you know of any temperature sensor that could be placed on the skin.. under the arm for example, and then wired to a controller for either local storage or remote transmission?

    • There are plenty. From the classic thermistor (most about the size of a grain of rice) to self contained A/D temperature sensing devices (about the size of a single 3 lead transitor).

    • I’m afraid I can’t answer just like that, as it really depends of the type of product you want to make. If it’s commercial, you’ll have to comply with the various regulations (an here it depends too, if it’s medical or just a gadget).
      If it’s just a hack project, then you can choose almost any sensor and figure out a case for it. You could even hack one of the cheap medical thermometers to get the sensor (and casing)

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  5. I need one of these for my middle school Earth Science class. Our plan, next year, is to build a balloon platform using latex party balloons to carry an altimeter and a thermometer to 1 mile high (or higher) and then return. We will want to log our data and create graphs, etc… I was looking to use an Arduino with a data shield and a thermistor, but the cost is prohibitive. How much would it take to create one of these? I have no experience with anything other than a breadboard and making an Arduino blink.

    • Well, you don’t need a 3rd gen Arduino to run your Arduino apps. You can get away cheaper by picking up the USB’less ones. You would then need either one of the 3rd gen Arduino’s USB interface or a stand alone USB interface to program the reduced cost Arduino. Also, you might get away w/only only an EEPROM and a serial-port-temperature sensor. But you might have to write your own Arduino drivers for these devices. Something that most Arduino users tend to avoid.

    • Hi!
      Is your project about the measurements or about making the altimeter and thermometer. In the first case, you’ll be better with cheap loggers from eBay (you can even double them for the price, to be sure to get data if one fails).
      If it’s about building the logging system, then yes, Arduino is supposed to be the easiest! (but run some tests to see if what you will send up there still works in a cold environment)

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  7. Hello Jean,

    I performed some tests, and energize the circuit only shows the name of the disk drive but the configuration file TXT, does not appear and the computer asks you to do to format the device.

    Could you give me any tips?

    Thank you.

    • You have to press the button and keep it pressed while plugging the logger to the USB port. That’s how the internal drive is formatted. You do that as well to start a new temperature logging.

      • Hello Jean,

        Thanks for the feedback, good performed the procedure, the LED will be direct access, should I wait a while?

        After the LED got direct access, the mobile unit no longer appears, is that correct?

        How else could do the test?

        Thank you,

  8. hi want to build this kind of datalogger but with an STM microcontroller and sd card for storage but I don’t understand how to create a USB instance .e.g like when I plug the USB how the sd card read as a normal sd card like sd card reader use. help me out

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