Wireless IoT Soil Moisture Sensor
How the platform works
Connecting the Moisture sensor to the mcModule
Pins Used
Programming the mcModule to check soil moisture
Viewing the incoming information on Android
Youtube Video
Sending soil moisture information to other applications

Published February 28, 2017 © GPL3+

Wireless IoT Soil Moisture Sensor Using mcThings!

Coin-cell operated, wireless IoT soil moisture sensor using mcThings! Alerts, status levels, temperature!

BeginnerFull instructions provided2 hours3,300

Things used in this project

Hardware components

mcThings mcModule120 Dev Kit

We recommend the kit as it provides everything you need to get started! (Not required but you will need at least one mcModule, one mcGateway and an mcDongle)

mcThings mcMod120 Module

Make sure you have updated your modules to the latest firmware

mcThings mcGateway110

Make sure you have updated your gateway to the latest firmware

mcThings mcDongle

Required to completed firmware updates on the mcModules and mcGateway

Resistor 100k ohm

Used as a voltage divider

Female/Female Jumper Wires

These aren't the ones we used, but just to add it to the list of components required

Soil Moisture Sensor

These can be purchased at many different sites for a very inexpensive price.

Hammond Plastic Enclosure (1551 Series)

We purchased them from a local electronic store.

Android device

Software apps and online services

mcThings mcStudio

IFTTT Maker service

IOT MQTT Dashboard (Android App)

MQTT

Hand tools and fabrication machines

Soldering iron (generic)

Story

Wireless IoT Soil Moisture Sensor

To showcase an easy example of some of the impressive things that you can do with the mcThings IoT Platform, we created a little wireless low-power soil moisture sensor! In this project we'll show you an example of sending soil moisture status, battery voltage and temperature (using the built-in temperature sensor) to an MQTT client on Android. Feel free to use the below and send the information to other applications or services as you can send information to the cloud with using IFTTT and MQTT!

How the platform works:

The mcThings platform includes 2 main components: mcModules and mcGateways. A powered and connected mcGateway creates the mcAir network (up to 200m range under optimal conditions) and bridges the information between the mcModules (within range) to and from the Internet. Using the IDE (mcStudio) and mcScript (ultra-low power programming language - a subset of VB.NET) allows you to wirelessly connect, debug and program modules with your customized scripts.

Note - You also require an mcDongle to complete firmware updates on the modules/devices and gateways! We recommend looking at the mcModule120 Dev kit which includes everything you need to get going!

How the mcThings platform works

Connecting the Moisture sensor to the mcModule:

We acquired some inexpensive soil moisture sensors and then connected them to a couple of mcModules (Note - The modules shown below are mcMod110, end of life now, but this project is the exact same using the new mcMod120).

We started by attaching and sealing the moisture sensor into an enclosure. We made sure to make it a tight fit for the sensor and then sealed it nicely as it would be exposed to the elements. After the sensor was in in place, we then connected two flexible and short female jumpers:

We then soldered a couple of pins into the mcModule along with a 100k resistor for the voltage divider. You could easily connect the sensor directly to the module using male to female jumpers as well. We added pins to the module so that you can 'unplug' and remove the module from the enclosure if need be.

Pins Used

Moisture Sensor: PIN 0 & GND

Resistor: PIN 6 & PIN 0

Backside of the module. Watch the Youtube video for a closer and better view of the wiring

We then connected the sensor to the mcModule, added a battery and closed it up!

We suggest putting the UID of the module on the back of the enclosure for easy identification

Programming the mcModule to check soil moisture

After working out the soil moisture variables (see YouTube video at the bottom) using the wireless debugging feature in mcStudio, we loaded the code onto the module and put into a planter. We programmed the module to check the soil moisture every 30 seconds as well as the temperature every minute and then send that information via MQTT to our broker, CloudMQTT.

The module is also programmed to check the temperature every minute and also relay that information via MQTT to our broker.

We also programmed the module to check its battery level every 2 hours and send a notification to a smartphone using IFTTT by setting up an applet to receive the information from the module and then alert on Android (using the IFTTT Android app) if the low-battery message was received.

*Note - we programmed to check the soil every 30 seconds, the battery voltage every 2 hours and temperature every 60 seconds for the purposes of this example but in real-life and for a long battery life, you could easily set the intervals to only a couple of times per day or mix and match your intervals with the different variables you are measuring to tailor the information to your needs

Viewing the incoming information on Android

Using an Android MQTT App called IoT MQTT Dashboard we are able to see the incoming information from this device. There are many other great MQTT apps in the Google Play store that you should check out!

Note - We had other mcModules reporting variables into the app including a rain sensor device!

Youtube Video!

Sending soil moisture information to other applications

Using MQTT and IFTTT, you can send information to tons of different applications! (Check out a LIVE real-time dashboard with mcModules using Losant - We show you how to do setup this dashboard in one of our other Hackster projects)

There are examples on our YouTube channel and also from other users within our forum. Watch for upcoming projects where we'll send data to some of our partners such as Losant and thethings.io!

Please join our Hub here on Hackster as a member so you can keep up with the many projects we are posting shortly!

Thanks for reading!

Code

Code

Define PinMode Pin0 As AnalogInput Alias MoistureLevel 
Define PinMode Pin6 As DigitalOutput Alias enableMoistureLevel 
    
    Class RainSensor         
        Shared Event measureMoisture() RaiseEvent Every 30 Seconds 
            enableMoistureLevel = True 'turn on voltage divider 
            Thread.Sleep(40000) 'sleep 40ms for voltage to stabilize
            Dim voltage As Short = MoistureLevel
            Dim payload As ListOfByte = New ListOfByte
            Dim payString As String = "" 
            If voltage > 1500 Then
                payString = "Dry - I NEED WATER"
            ElseIf voltage <= 1499 And voltage >= 600 Then
                payString = "Fairly Moist" 
            ElseIf voltage <= 599 And voltage >= 335 Then
                payString = "Moist" 
            ElseIf voltage < 355 Then 
                payString = "OVERWATERED"
            Else 
            End If 
            enableMoistureLevel = False 'turn off voltage divider
            payload.Add(payString)
            Lplan.Publish("mcThings/MoistureLevel", payload)
        End Event
        Shared Event sendMQTT() RaiseEvent Every 1 Minutes 
            Dim payload As ListOfByte = New ListOfByte() 
            Dim TempC As Float = TempSensor.GetTemp
            Dim TempString As String = TempC.ToString() 
            payload.Add(TempString) 
            Lplan.Publish("mcThings/GardenTemp", payload) 
        End Event
        Shared Event measureVoltage() RaiseEvent Every 2 Hours
            Dim BattVolt As Short = Device.BatteryVoltage
            If BattVolt < 2200 Then 
            Lplan.IFTTT("YOURIFTTTKEYHERE", "MoistureSensorBatt")
            Else
  
            End If
        End Event
    End Class

Credits

mcThings

17 projects • 70 followers

Use mcThings to quickly & easily create, test and deploy IoT solutions for industrial, business/commercial and individual needs!

Thanks to mcThings Team.

Wireless IoT Soil Moisture Sensor Using mcThings!