Multi Point Soil Humidity Measurement


Is there any public domain example to communicate between ESP8266-01 and an Aruino Pro Mini? Thanks for any guidance on the matter.

Kind regards.

The question is too broad to give a good answer. I would assume you are trying to add wifi to the Pro Mini? I would think a better bet would be to use one of the larger node MCU modules (with more I/O pins) and connect your sensors directly to the ESP, you shouldn’t need another CPU in the mix unless there is a size issue of some kind (and there are many different sizes of ESP modules.) That said a google search for “example to communicate between ESP8266-01 and an Aruino Pro Mini” brings up a bunch of articles, the first one of which repeats what I said above: use a larger node MCU instead of the pro mini by someone that has done something similar to what you appear to be doing.


Since this forum is for Fritzing, which focuses more on the physical level connections, some general options are serial (UART), I2C, SPI. Make sure your voltage levels match. A pro mini could be either 3V or 5V. If you are looking for code, other forums are much better. Same if you are adding wifi to to the pro mini. With that setup, it would have nothing to do with Fritzing, beyond the physical connections to the module.

Hello @vanepp & @microMerlin,

Apologies for jumping the gun. I should’ve done more homework before posting the question. Confession, I saw the board layout and thought that this was a complete project, so I submitted my PCB request to Ainsler. Then I starting digging in and realized that there are much better ways to handle multi sensor telemetry (and the Pro Mini is perhaps not optimal for this purpose). The sheer act of being able to get my first job through Ainsler was too much excitement for me! :grinning:

Sorry, please consider the issue closed (and when I Ainsler boards arrive I don’t mind mailing it to anyone upon request - I’ll pay for the shipping).

Kind regards.

I was about to suggest that the board may be useful anyway (I had not realized you were referring to a post in projects}, but looking at the post there is no software! The serial connection wiring is there in the .fzz file but no software for either the pro mini nor the esp and no indication of what humidity sensor it wants. You may be able to figure it out, or if you contact the poster he may have software, but it may be better to start from scratch.


Hello @vanepp,

Yes, your suggestion to start from scratch is the correct one. I was intrigued by the published idea but since there are multiple analog pins on most current boards the data acquisition part is widely published. The tricky part from my perspective is how to “irrigate” 5+ garden pots “asynchronously” since the demand for each garden pot (in my case) is different.

Here is the single garden pot flow arrangement under test.

Obviously, with multi point soil sensors single pump+meter could be more efficient if multiple tee with a solenoid value for each branch is available at the “hobbyist” level. The other option is have a moisture band range and if any pot falls below the lower limit just pump for a few cycles (based on empirical tests). Also, going above the band will simply result in an alert signal for manual intervention.

Thanks for reading my ramblings and for the feedback.

Kind regards.

There used to be 12V solenoid valves from coffee makers available for about $5 on ebay with tubing press fit outlets like the pump in the picture, but a quick search now doesn’t find any of them (the current ones are more robust, but with threaded output ports which would require costly fittings.) With an extra I/O pin and a relay driver that should allow you to select which plant gets water (assuming you can find the valves again of course :slight_smile: )


Thanks again! I will have the reading part (i.e. phase 1: from the sensors) done shortly.

Since, there will be occasional freezing conditions till mid-March (that is only an official prediction), I’ll use the lead time to plan for phase 2 with some relay arrangement.

Kind regards.

Found some similar to what I have:

about $5US ea. Don’t know why they didn’t show up earlier.


@vanepp, you been a big help! You’ve accelerated the development/construction plans significantly. Based on your suggestion, I’ve ordered a few of the solenoid valves because they’ll definitively do the job for my project.

Thanks again.

Kind regards.