Lora Soil Moisture Sensor V3

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The Lora soil moisture sensor V3 is based on Atmel's Atmega328P, it collects local air temperature/ humidity with sensor AHT10, and detects the soil humidity with capacitor-humility measurement solution. It can transmit the local environment data to the gateway or devices with the Lora communication, and it suits for the applications such as smart-farm, irrigation, agriculture, etc.

In applications, always you do not need to check the air/soil state continuously, have a test of them for few seconds after then minutes/hours sleeping is normally Ok for most projects. To save power, there the Air/ Soil measuring functional could be shut down in the working, so they can be only powered ON a short time and then a long time power off. With MCU in sleeping mode and low power consumption Lora module, this module can work with 2 AAA batteries for more than one year. Besides, this sensor is coated with waterproof paint, which makes it working longer in wet soil.

This is the V3 version of the Lora soil moisture sensor, you can check here for the previous one.


  • Classic ATMEL AVR 8-bit Atmega328P, with Arduino Pro Mini(3.3V/8M bootloader pre-loaded)
  • Capacitor-humility measurement.
  • AHT10 temperature and humidity sensor.
  • Working with 2 AAA batteries for more than one year.
  • 3D printed case.
  • Waterproof coating.
  • Can be used directly without secondary programming.

What is hardware changed

Lora Soil Moisture Sensor V3 102.jpg Lora Soil Moisture Sensor V3 103.jpg
At the V2 version, the 555 IC will generate square ware that the ware into low pass filter composed of a resistor and a capacitor made by soil and PCB probe. As the moisture of the soil changes, the equivalent voltage of the capacitor will change. So the moisture can be measured by detecting the voltage of the capacitor.
As the picture showed, the difference between the V2 and V3 is the generator of the square ware. V3 generates the square wave by the MCU replaced the 555 IC, it can get the same effect as V2. Besides, removing the 555 IC will reduce the power consumption that will increase the battery life.

Power consumption

Lora Soil Moisture Sensor V2 Lora Soil Moisture Sensor V3
Standby Current 680uA 7.3uA
Service life (two AAA Batteries) About 30 days About 2 years or more


When the sensor is used in the wet soil for a long time, the PCB part buried in the ground would be more and more damper, and it would cause the inaccuracy of measurement at the end of the detection. To improve the measurement accuracy and extend the service life, we made a waterproof coating for it, that can provide waterproof protection and slow down the PCB spoilage.


In order to meet the requirement of the low power consumption, we provide the firmware for the low consumption and the firmware has been uploaded to the sensor before shipping. So you can use the sensor directly after unpacking it.

  • The firmware is available on Github.
  • When you power the sensor with 2 AAA batteries, it will transmit the soil moisture measuring through LoRa communication. Then the sensor will enter the sleep mode and wake up to work in 75 minutes.