Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, a web toolkit designed to help citizens, conservation practitioners, municipal decision-makers, researchers, educators, and students advance knowledge and stewardship of fresh water. New to EnviroDIY? Start here

Welcome to EnviroDIY

Welcome to our blog on dataloggers, sensors, and other open source hardware projects.  We have created this site as a way of sharing our ideas, designs, and source code so other researchers and hobbyists can follow along with what we are developing.  Hopefully this will be a collaborative effort where we can trade knowledge and build some innovative new hardware projects together.

During the first week of December 2012, I will be presenting a poster and showcasing some of our hardware at the American Geophysical Union’s Fall Meeting in San Francisco.  Last year we presented our preliminary ideas and got tremendous support and interest from all over the world.  Now that our loggers and other devices have been deployed in various weather and locations, and in use for more than a year, the hardware is now past the “prototype” phase, and we’re ready to share the details of our projects.  In the coming weeks and months, this blog will serve as our way of sharing those designs, along with tips and tricks we’ve learned in the past two years of Arduino development.

In the past year, I have gotten emails requesting information and help from many people, and most of the questions have been about the same topics.  In order to make it easier for other people to follow along, please post your basic questions here on this blog, preferably in the forum most related to your topic.  You can still email me if you have a specific question or request for more information on a topic you’d like to see discussed here.


  1. Thanks for your efforts and sharing on these sensors and networks!

    How do I switch or read the different outputs from a Decagon soil moisture and temp sensor on the Arduino serial monitor? I am able to read analog voltage out that is tied to temp, but I am not sure how to get the voltage for the moisture sensor. There is only 1 data wire (obviously) so is there a pattern in the Vout or do I need to tell the sensor to switch? Thanks for the help!

  2. That’s a good question. I have had several requests for information about how to interface Arduino circuits with sensors from Decagon Devices. That will be one of the first topics I’ll tackle in the next couple of days. What type of soil moisture probe are you using?

    • I am using the Decagon EC-TM, the forerunner to the 5TM. Here is a brief discussion on these sensors’ communication from the Decagon forums: http://www.decagon.com/forums/soil-moisture/show/33

      Also, p.27 of this document talks about some EC-TM comm details.

      Thanks much!

      • Sorry, here’s the link to that document:


        • According to the manual, the EC-TM probes behave the same as the 5TM probes except that they do not have temperature. On the probes there are 3 wires – one is ground, one is excitation, and one is the digital signal from the sensor. Basically you send a quick pulse on the excitation line and a serial data string can be read on the data line. The Arduino board will have to parse the string to get a raw value and then apply that value to a formula to calculate water content. The code I’ve been using can do all that, and I’ll be posting it here very soon.

          • First thanks for all your effort!
            I am very new to Arduino, and I would love to hook up a sensor, but I don’t want to take any unnecessary risks.
            I was wondering if you could post or email the code that you have which connects a Decagon sensor to an Arduino.
            Do you send the excitation through the voltage wire, and then connect the digital signal from the sensor to the RX pin on the Arduino? This seems reasonable, but I am also unsure about how to communicate with the sensor in order to establish SDI identifications.

            Thanks for any help you can provide!

  3. Dear, great work! thanks for sharing your ideas/work
    I have many hydra-probe II and watermar soil moisture sensors and I would like get and store the sensed data using Aarduino.
    Now I am testing FC-28 soil moisture probe connected to arduino uno and I am loggind it, but I would like to add some commercial and commonly used sensors like hydra probe and watermark. Could you give me (us) some help or information about this, please?
    I work in a environmental reserch centre (called ceneha) from Argentina and we need avoid prohibitive costs.
    Thanks in advance.
    Sorry by my bad english.

  4. Thank you for sharing works that you’ve been doing with Arduino.
    I am particularly interested in the storage side of your data collection process. I have read through your AGU2012 poster where you’ve mentioned that the incoming live streaming data CAN be displayed on a computer, stored in a database, etc. I am curious to know what you have effectively done to handle the incoming data at the base station.
    Can you provide more details about this?
    Thank you.

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