USB Non-Contact Capacitive Soil Moisture/Water content, Temperature sensor

Features

• Android and Raspberry Pi client demo software.

• Dust and waterproof

• Low cost and easy to use.

• Fairly accurate readings

• Calibration functions for EC and Dielectric permittivity

• USB CDC-ACM virtual COM port and 115200 baudrate.

Connecting

The sensor is equipped with a standard 2.9 meters long USB 2.0 cable. You may connect lots of sensors using a USB hub. To identify sensors there is an option to set a unique 8 character device id and application id. See documentation for more information.

On linux sensor will be detected as /dev/ttyACM0 ... /dev/ttyACMx

For linux permissions settings please consult

On Linux you may use minicom utility to configure the sensor.

For windows, PuTTY may be used.

We recommend Android mobile application for sensor setup and data reading/storage.

USB interface data format

PM-WCS-3-USB data output prints comma-separated values (CSV) sequenced as described below.

1. Dielectric permittivity (ε) (Temperature corrected) resolution: 0.1ε (avg. Tolerance 5%) and range 1 (air) to 80 (water)

2. Electrical Conductivity (dS/m) resolution: 0.01 dS/m (avg.Tolerance 20%)

3. Temperature (°C) resolution: 0.1°C(Tolerance 3%) and range: -20 to 60°C

4. Degree of water saturation in the soil (%) resolution:0.1% (avg.Tolerance 5%) and range: 0 – 100%

5. Volumetric water content - VWC calculation from Dielectric permittivity ε. VWC = 0.002974 * pow(ε,2) + 0.07424 * ε -1.295;

Optionally you may set up EPOCH time (Table 3.2.1 command: “time”) in seconds and there will be time parameter added in front. See documentation for more information.

Redirecting sensor reading data to file on Linux systems

You can write a simple script to start log sensor USB data to a CSV file.

This sample is written for Raspberry Pi, Debian, Ubuntu Linux, before executing the script you have to install minicom: sudo apt-get install minicom

!/bin/bash

sensor serial port name

PT=”/dev/ttyACM0″

sudo stty -F $PT speed 115200 cs8 -cstopb -parenb -echo raw

setup current time

echo -ne “time $(date +%s)\r” > $PT

set time period 5 seconds in milliseconds and start logging

echo -ne “millis 5000\r” > $PT

flush some output

timeout 2s cat $PT

print output to file

cat $PT > swout.csv 2>&1 &

Monitoring via Android application

Get it on Google Play

Android application Features

• Setup USB and LoRaWAN soil sensors

• Write USB and LoRaWAN sensor data to phone memory

• View data on charts and export to CSV

• Open Source Android application located there

Read documentation for more information.