Soil Moisture Cinibar by repatten

Domoticz

The sketch does not correspond to the sensor shown in the images. It is much better to use the 2-pin sensors and drive them directly using digital outputs. Search for FC28 (better) or YL-69 in ebay or amazon. I use a voltage divider with a 10k resistor I've been using the alternating polarity approach on about 20 sensors, with perfect results and no signs of corrosion after around 6 months. I run some tests to determine the effect of measuring time and finally came up with 5ms with no averaging. The batteries last for months; I'm not sure how many since I haven't yet had to replace any (status led removed from 3.3v arduino mini pro board). As a reference, I tested a rain sensor (same principle) with no alternating current and as soon as a drop of water touched the tracks, small bubbles were produced with indicated that electrolysis was taking place. The effect could be seen on the tracks after just a couple of minutes. I'm attaching my sketch below. It reports battery level in addition to moisture. It uses the development branch of the mysensors library in order to use the new version of the rfm69 drivers with RSSI ATC - which btw works more than perfect. I'm using Domoticz which includes a predefined device for moisture. This device uses the centibar scale, so I calibrated my sensors in % moisture and then convert to cb.