Smartphone data logger for meters and sensors created by Christiania Nabovarme

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The MeterLogger is an offline datalogger with online sync possibilities
It uses a custom audio dongle for communication with devices.
The concept is to make it easy to gather data from a wide range of heating/electricity/gas meters and store them on your smartphone for viewing and sharing.
Simply plug in the dongle, choose your device from the list, make a new sample and decide further actions (save, share, sync etc)


In Christiania (freetown in Denmark) we have an off-grid heating infrastructure running with wooden pellet stoves. To send out bills we need to be able to read the meters installed at all households in a fast and easy manner.

Before we used pen and paper and sampled only once a year but now every household can sample their meter and report back to the central with fresh and more frequent samples.

We can also use the MeterLogger to sample gas combustion in the stoves using IR between the dongle and the Testo Gas Probe.

The meterLogger will have a great impact in the daily lives of our sub 1000 citizens!

MeterLogger is:

Meterlogger is composed of a dongle and an app running on a iphone.

The connection between the two is standard stereo/mic audio cable and the dongle runs leaches power through the same connection.

The dongle takes care of translation between audio and IR but the business logic is embedded in the app running on the phone.

The app takes care of checksumming if the chosen meter supports it.

Currently supported devices/meters/sensors:

Tested and working:

Kamstrup Multical 601 

Kamstrup Multical 3 

Kamstrup Multical

Testo Gas Probe 310


The project is licensed under GPL and uses the New BSD License licensed Arms22 softmodem library for audio communication.

For more info on arms22 see:

  • First demo video

    johannesgj06/25/2014 at 13:58 0 comments

    Link to video:

    Our first video is a small overview of the components.

    Iphone connected with audio jack to our breadboard prototype (pcb prototype comming next week or so) 

    The breadboard prototype has a wire with IR transceiver positioned atop the Kamstrup heating meter ( see white ribbon cable and improvised supporting "op" box)

    The app starts in device list mode and we select the demo device. We see that the PIC mcu interprets the audio via the red debug leds on the breadboard.

    We then via same red leds see that the Kamstrup answers and in the end we see the refreshed view on the iphone app.

    GPL licensed source files for HW and SW are available at

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Adam Fabio wrote 07/01/2014 at 05:29 point
So IR Form the meter to the logger, then audio from the logger to phone/computer etc. I think I get it! Great entry johannesgj! Thanks for entering The Hackaday Prize!
Be sure to add some updates if you add more meters!

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