Relay Actuator

Software

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

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.

Wire things up

Follow the instructions in ConnectingRadioModule to connect radio module.

Connect the IN1 and IN2 of relay to digital pin 3,4 of Arduino board. Connect VCC to +5V of the Arduino board. GND to GND. I Used a dual relay module. But the code can easily be adapted to handle more or less relays by modifying RELAY_1 (which digital input first relay is connected to) and NUMBER_OF_RELAYS defines at the top of the sketch code.

Hardware - Purchase guide

This is the stuff you need to purchase to build the RelayActuator. 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 4 extra Female->Male for your relay module)
​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 Relay module
​http://www.aliexpress.com/item/5V2-CHANNEL-RELAY-MODULE-FOR-ARDUINO-PIC-ARM-DSP-AVR-ELECTRONIC-SCA-1720/933830812.html

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

TOTAL SENSOR PRICE: $3,99 + $0.93 + $0,6 + $3,24 = $7,26

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