100% Correct 😁

Hi there. thanks for the reply - there is a lot to consider!!

I think i have understood that one option is to use a "crappy resistive sensor" 😁, but replace the copper with stainless steel. I am likely to get slight fluctuations due to temperature.

Grazie

Mathew

Ciao,

SlowWire has passed the testing phase, it is listed in my shop now:

https://www.tindie.com/products/angelova/digital-soil-moisture-sensor/

Unfortunately I sold the few I had as options to the Hat Boards. I don't know If I would sell separately from the boards, because I don't feel comfortable when the shipment costs more than the product itself.

In my setup I'm using both the stainless steel sensors and the capacitive sensor, Have to say that the Stainless steel sensor is more sensitive but it is also quite sensitive to the temperature, but in my opinion it is still doing a good job :).

The Hat board without the embedded hardware for the direct connection to the probe needs an additional piece of hardware that is sold together with the crappy resistive sensors as in picture below (the small board).

On one side there is the probe connection, on the other side the GND, 5v, Analog.

You can chose any of the 0-5v analog input of the board.

I also have this in my setup and it is working well.

Below an example of Resistive Sensor in yellow and Capacitive Sensor in Blue. As we can see, the Resistive sensor is fluctuating with the daily temperature change while the capacitive sensor reading is more stable.

Ciao,

(Rev. 10.3 HAT)

I think it's right to jump in on this thread for more chat on soil sensors. Hope that's OK?

Firstly, how's Slow Wire going? 😉

In the meantime, I'm think about how to set up soil moisture measurement to get accurate results. It looks like using stainless steel is the best way to go. My Rev 10.3 HAT does not have the additional Hygro components, so what's the best option for me? I'm a bit confused!

BTW, this is a great project. Thanks for all your effort, and congratulations on the interest it has received.

Mathew

Thanks for the update, really appreciated!

In case of any configuration question or info I'll be happy to support.

Note: Just for info, I have noticed that the resistive hygrometers interfere with each other if they are in same pot, or close to each other. This will make the reading biased.

Hi Goran,

Thanks for the feedback,

Yes I'm working on a capacitive soil moisture sensor which will directly connect to the raspberry PI digital pins.

Now I'm in the testing phase to check the sensor stability and it seems that everything is working well.

During the initial testing I realized that the I2C interface cannot support cable length more than about 1 meter. So I decided to build my own digital protocol for the communication with the sensor, which I called "SlowWire" which of course I'll make it open source.

The "SlowWire" requires only one wire for the signalling and can support length exceeding 3 meters (I did not test the max cable length yet but I expect to be of the order of 5+ meters).

For this sensor 3 wires will be required, GND , +5v, and one GPIO for each sensor.

As far as you have GPIO pins available on your raspberry you can add more of these sensors.

I hope to make it more affordable than many other sensors in the market today.

Last thing if possible, as I'm quite curious, can you post a screenshot of the hygrometers data graph?

Cheers, Angelo

Hi Goran,

Sorry for the misunderstanding but the board that I sell by default does not have the electronics to support the hygro1-4 output. I include the electronics for it only for the customized version. So your connection on the hygro ports is not going to work, but it can work connecting it to the analog ports.

In another post I show how to connect that type of hygrometers, here the link:

https://hydrosys4.wixsite.com/hydrosys4forum/forum/hardware-discussion/hydrometer-using-te215-soil-moister-sensor

(please consider that this type of sensors is not going to last long into the soil)

Regarding the product in the link you have indicated, I never tested it, anyway seems that it has an analog output compatible with the board.

What about the other wires connected to the other analog ports? are they capacitive hygrometers?

Regards,

Angelo

Hi There,

Can you show a picture with the connection of the hygrometer to the board?

Thanks