Soil Moisture Sensor

Software

You can download the Arduino sketch here:
http://code.mios.com/trac/mios_arduino-sensor/browser/trunk/Arduino/SoilMoistSensor

Before downloading the sketch to the Arduino you need to select a unique RADIO_ID (see top of sketch source code). The RADIO_ID must be unique in your radio network and is also used on the Vera side to distinguish between different sensors. After updating RADIO_ID and downloading the code you should be ready to go. This sensor sleeps most of the time. If interrupt on digital input occurs it wakes up and transmits 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

This is the stuff you need to purchase to build the SoilMoistSensor. Note that I've provided links to the things I bought during the development. You might find it cheaper somewhere else. Also note that you might need to buy like 10x of some items to get the price specified.

1x Cheap Arduino Nano without serial interface and usb connector
​http://www.aliexpress.com/item/16Pcs-Lot-Pro-Mini-Module-Atmega328-5V-16M-For-Arduino-Compatible-Nano/710613095.html

8x Dupont cable Female->Female (you might need 3 extra Female->Male for your moist sensor)
​http://www.aliexpress.com/item/New-Female-To-Female-40-pcs-Wire-Cable-Line-1p-1p-Pin-Connector-20cm-2-54mm/1045212486.html

1x NRF24L01+ wireless data transmission module 2.4Ghz
​http://www.aliexpress.com/item/Free-shipping-NRF24L01-wireless-data-transmission-module-2-4G-the-NRF24L01-5PCS-LOT-upgrade-version-New/603756080.html

1x Moist sensor
​http://www.aliexpress.com/item/Soil-Moisture-Sensor-Hygrometer-Module-for-Arduino-2560-UNO-1280-Free-Shipping-Wholesale/762036166.html

(You might later need some housing and transformer or battery compartment as well)

TOTAL SENSOR PRICE: $3,99 + $0.93 + $0,6 + $2.94 = $8,46

To download code to the cheapest Arduino Nano sensors (that is missing the serial USB port) you need to buy one of following as well. It is only attached while downloading code and can be reused between sensors.

1x Serial to USB adapter to download code to cheap Arduino Nanos
​http://www.aliexpress.com/item/Free-Shipping-FT232RL-USB-To-Serial-Adapter-Module-USB-TO-232-For-Arduino-Download-Cable/827218126.html