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

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

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!

Using MQTT and IFTTT, you can send information to tons of different applications! (Check out a LIVE real-time dashboard with mcModules using Losant)

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!

Thanks for reading!

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