LoRaWAN Capacitive Soil Moisture/Water content, Temperature and EC sensor

The PM-WCS-3 family sensors is low-cost, accurate soil moisture sensor for monitoring water content, electrical conductivity and temperature of soil.

Features:

• Dust and water proof, every sensor is tested by submerging it in to the water, battery box grade: IP65.

• LoRaWAN class A device, may be activated with OTAA or ABP for any LoRaWAN network supporting EU868.

• Setup via USB CDC-ACM virtual COM port.

• Android application for USB setup and free online monitoring via The Things Network gateways.

• Demo Tinovi zerver.io cloud console for graphs and configurable event triggers

Data output

Format what you are usually getting from LoRaWAN is hex string, which you have to convert to bytes. Then data output is in binary format is total 9-byte long:

1. 2-byte 16-bit signed integer (divide by 100) Dielectric permittivity (ε) (Temperature corrected) resolution: 0.1ε (avg.Tolerance 5%) and range 1 (air) to 80 (water)

2. 2-byte 16-bit signed integer (divide by 100) Electrical Conductivity (dS/m) resolution: 0.01 mS/m (avg.Tolerance 20%)

3. 2-byte 16-bit signed integer (divide by 100) Temperature (°C) resolution: 0.1°C and range: -20 to 60°C (avg.Tolerance 3%)

4. 2-byte 16-bit signed integerVolumetric Water Content (%) resolution:0.1% and range: 0 – 100% VWC Note: VWC is calculated from dielectric permittivity by Topp equation (Topp et al, 1980): θ = 4.3 ⋅ 10−6ε3 − 0.00055ε2 + 0.0292ε − 0.053)

5. 1-byte Battery voltage percent: measures battery voltage and calculates percentage from 2v to 5v; To calculate actual battery voltage use equition: 2+0.03(battery reading). for example if battery measurement shows 50% ,then actual voltage is 2+0.0350=3.5v resolution: 1% and range: 2v – 0% to 5v – 100%

LoRaWAN Downlink message to update data sending interval

Device supports LoRaWAN downlink message for device sleep time (data sending interval) adjustment. Message should contain 5 bytes, 1st byte is Ox01 and following 4 bytes is unsigned 32-bit integer time in seconds to sleep. For example sending HEX 010000000A will set interval to 10 seconds, but 0100000E10 will set interval to 3600 secs = 1 hour.

Power supply

Sensor consumes max 0.3 mA in sleep mode, 12 mA in active mode and 150 mA in transmitting mode. Recommended battery is 3.6v ER14505. Sensor also may be powered from any 5v Micro-USB power source. After power up sensors wait 10 seconds for USB configuration session connection from android application or USB CDC terminal, if none is connected sensors turns off USB hardware and starts normal operation.

Sensor calibration via Android application

Get it on Google Play

1. remove battery, attach to phone
2. open application & wait for  USB connected status or connect
3. go to SETTINGS tab, 
4. hold sensor in the air - click button AIR
5. submerge sensor in the water or soil with water, click button WATER
6. go to MAIN tab, click "read" button to check calibrated values
7. To connect to LoRaWAN, disconnect from phone and connect to battery or any (other then android phone) Micro-USB power source.

Demo Online Monitoring via Android application

Get it on Google Play

For LoRaWAN sensors data is streamed online via LoRaWAN gateways connected to TTN.

To enable online monitoring via your The Things Network gateway and Tinovi default AppID you should:

• Click login in application main page, to signup with your google account.

• Attach LoRaWAN sensor to phone’s USB OTG port, wait for status USB Connected and go to soil sensor application’s settings tab.

• Click READ to read data from sensor or GENERATE button to generate new address data.

• Input your device’s name without white spaces and click REGISTER OTAA button, to register device to cloud.

• Your device should appear on main tabs sensor list. Chose your sensor in list to see data from sensor.

Soil Sensor Android application receives LoRaWAN sensors data via Tinovi zerver.io IoT cloud application. You may login to this dashboard tool using your google account and create nice dashboards to monitor your sensor data.

To connect to your TTN applicaiton:

1. create new OTTA device within your applcaiton in TTN console, let TTN genrate DeviceEUI and AppKey.
2. input from TTN DeviceEUI, AppEUI, AppKey to device config app and click "SET" button for each value.
3. device are not connecting to LoRaWAN while in configuration mode. After configuration you need to disconnect from configuration app and reconnect to new power source like battery or external Micro USB power supply.

Note: after you connected to your own TTN application, data from device are not sent any more to our Android application via TTN, because we have no access to your application on TTN. So you have to create your own app integration with TTN.

TTN application payload format:

```

var bytesToInt = function(bytes, dev) { var sign = bytes[0] & (1 << 7); var x = ((bytes[0] & 0xFF) << 8) | (bytes[1] & 0xFF); if (sign) { x = 0xFFFF0000 | x; } return x/dev; };

function Decoder(bytes, port) { var decoded = {}; decoded.e25=bytesToInt(bytes.slice(0,2),100); decoded.ec=bytesToInt(bytes.slice(2,4),10); decoded.temp=bytesToInt(bytes.slice(4,6),100); decoded.vwc=bytesToInt(bytes.slice(6,8),1); decoded.bat = bytes[8]; return decoded; }

```

Android application Features

• Demo Online LoRaWAN sensor monitoring via TTN connected gateways.

• 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

!WARNING please remove device battery before attaching device to USB port for configuration. Leaving battery with attached USB power supply may damage battery or your device’s USB port.

!WARNING LoRaWAN device waits for 10 seconds after power up for configuration terminal software connection. After terminal connection it remains in configuration mode until terminal software is disconnected.

!WARNING device joining mode OTAA or ABP is switched automatically on configuration when you setup OTAA or ABP parameter.

Get it on Google Play