Motion Sensor

Software

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

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 motion sensor to digital input 3 of Arduino board. Connect VCC to +5V of the Arduino board. GND to GND. Use the trimpot Sx on sensor to set sensitivity. Trimpot Tx tunes how long the sensor should be triggered (5sec min - 200sec max).

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 Motion sensor
​http://www.aliexpress.com/item/Freeshipping-PIR-Sensor-Human-Body-detecting-module-Pyroelectric-HC-SR501-For-Arduino-MCU/967005480.html

TOTAL SENSOR PRICE: $7.6 (arduino + radio) + $1.7 (motion sensor) = $9.3