SDI-12 USB+Analog adapter vs stacking basic adapter with Analog extension board

If you wonder the pros and cons of these two options, here is a video for you.

SDI-12 USB+Analog adapter:

Pro: small form factor that is easy to work with
Con: no digital inputs for digital pulse from rain gauge or flow meter, no extension

SDI-12 USB adapter stacked with Analog extension board:
Pro: extendable with up to 4 hi-res analog addons and other addons such as extra SDI-12 terminals, 4-20mA sensor addon (coming out soon), and possibly a future GPS addon via the 6-pin header.
Con: device gets taller with the extension boards

Starting a weather station at

So this summer I’m thinking about starting a weather station at, after someone contacted me about possibly doing theirs with a MEGER Group weather station. So in order to post your own weather data, you need to register and add a device. There is a relatively old (3yr) tutorial on raspberry pi. Much has changed but it may still be useful if you go through it just to see what will be involved:

Anyway, here is a more updated but short version:

  1. Go to and register an account:
  2. Under “My Profile” you will find my devices:

3. Add a new weather station. Choose device as Raspberry pi and let the system choose default values for the rest. I gave a 5ft weather station height. Probably higher is better but again I don’t have a weather station yet.

Now under your devices you will se a device ID and a key. You will be able to use this information to post your data. Here is an example of the posting address that you can put in Python or just in your web browser:
Just replace XXXX and YYYY with your own wunderground weather station information and say post your humidity data, place the whole line in your web browser and you should get a success if everything is correct. You could add more more data with the & symbol between them, such as humidity=40&tempf=70 to post both humidity and temperature (in Deg F)

Here is a recent post that has all the different weather information you could post:

So my next step is to get some outdoor temperature and moisture sensors whether they are compatible with my SDI-12 adapter or not. I can run a separate Python script to post to and to for soil data. Stay tuned!

How do you analyze soil data?

That was actually a question from one of my customers. To be honest, I’m a physicist and engineer. I wish I knew more about soil science and agriculture but I’m open to anyone who is willing to share some knowledge. My basic understanding is if you can measure dielectric permittivity with the sensor. Then you can calculate volumetric water content with formulas the sensor manufacturers provide, for a few typical types of soil. Or you make your own calibration with your own soil, such as using a different method to measure VWC (baking the soil dry?) and correlate with dielectric permittivity so you develop your own formula. More specifically the question was about METER Group Teros 12 sensor. If you use this sensor or something similar, could you share a few lines of how you get VWC and/or other data from it? Any reference materials to point to? Thank you!