Soil Moisture Sensor

Software

You can download the Arduino sketch ​here.

This sensor sleeps most of the time. If interrupt on digital input occurs it wakes up and transmits the change.

Wire things up

Follow the instructions in ConnectingRadioModule to connect radio module.

Connect the digital out of the moisture sensor to digital input 3. If you instead want to use digital input 2. Update DIGITAL_INPUT_SOIL_SENSOR in sketch code accordingly. Connect VCC to +5V or +3.3V of the Arduino board. Use the trimpot to set moist level that should trigger "alarm".

If you want to use the analog output from the sensor you'll have to rewrite the code and use some other device type that can show the actual analog value.

Hardware - Purchase guide

To build this sensor you'll need one arduino + radio specified in the base kit found here:
http://code.mios.com/trac/mios_arduino-sensor/wiki/WikiStart#Buyingguide

With the following additional parts:
1x ​Moisture sensor

TOTAL SENSOR PRICE: $7.6 (arduino + radio) + $2.9 (moisture sensor) = $10.5