Low cost and ultra-low power monitoring of soil moisture

Within the TETRA project LoCo, aiming to make the commissioning and deployment of sensor networks a lot easier, the TELEMIC research group at KU Leuven has developed a low cost low entry and ultra-low power LoRa network — “uLoRa”. uLoRa sensor nodes come with a moisture sensor that keeps in touch with your plants.

By KU Leuven, departement Elektrotechniek (ESAT)

LoRa technology

Wireless technologies penetrate all layers of our daily lives and have revolutionized the way our society works. Particularly, the “Internet of Things” (IoT) is rising as new communication paradigm embedding tiny wireless transceivers into anything. Compared with other available technologies for IoT, such as Sigfox, NB-IoT and LTE-M, LoRa offers a very compelling mix of features: long range, low power, reasonable number of transmissions and an open-source LoRaWAN (LoRa wide area network) network-server. LoRa operates on the 868MHz free ISM band in Europe, making it a convenient choice for large and small companies and private users as well. A LoRa gateway can cover an urban city with a radius around 5 Km. LoRa is designed by Semtech who now builds the LoRa technology into chipsets.

Telemic LoRa solution

While LoRa networks are rolled out, the availability of applications and very cheap and low power sensors is still not yet at scale. TELEMIC new implementation –uLoRa can be deployed at scale because of the low cost, low power consumption and over the air activation, while taking advantage of The Things Network or alternatively by using a self-deployed LoRa database. The Things Network is a global community building a global Internet of Things data network based on LoRaWANuLoRa node with moisture sensor

uLoRa node with moisture sensor

The uLoRa node is designed to be low cost and ultra-low power, aiming to be suitable for massive deployment. The hardware of the uLoRa node can be divided into three parts: the processor, the RF front-end, and moisture sensor. Now by planting the uLoRa node with the embedded moisture sensor into the soil of your plants, you can have a real-time monitoring on the water level of your plants and subsequently know when you have to water them.

uLoRa prototype

 

TELEMIC LoRaWAN gateway

A LoRaWAN gateway consists of a LoRaWAN mCard 868MHz from MultiTech, a USB to Mini PCIe converter and an embedded Linux pc. The software for driving the gateway and handling all the received messages is written by Semtech. Subsequently, we run the message forwarder code on the embedded Linux pc in order to make them accessible from the own database or from The Things Network.

 

Telemic gateway

 

 

In addition to moisture sensors that keeps in touch with your plants, uLoRa also has the following advantages:

  • Ultra-low power: uLoRa is built around ARM processor from STM32L0 which is known as the best family in terms of power consumption. Moreover, the software has been optimized to minimize both RF transceiver and processor power consumption.
  • Low cost: the cost of hardware of a uLoRa node is only about 13 euros (including the battery), making it much cheaper than other LoRa nodes available on market.
  • Open-Source: both the hardware and software designs and implementations of the uLoRa platform are open to the research society (Please visit our repository on Github).

For more information about our deployment please check our repository on Github or contact the project coordinators: Jean Pierre Goemaere, Sofie Pollin or Lieven De Strycker.