Temperature and Humidity sensor (DHT11/DHT22)

Software

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

This sensor sleeps most of the time. You can change the sleep interval by updating SLEEP_TIME define at the top of the file.

Wire things up

Follow the instructions in ConnectingRadioModule to connect radio module.

To connect the DHT22 sensor to the Arduino board follow these instructions:
Pin1. Connect VCC of the DHT22 sensor to +5V
Pin2. Connect Data to digital pin 3 of the Arduino board
Pin3. Not used.
Pin4. Connect to Ground

Use also need a pull up resistor between +5V and Data. See picture below.

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 DHT22 Temperature and Humidity sensor (there also exist a cheaper humidity sensor called DHT11 that is less accurate but half the price).
​http://www.aliexpress.com/item/1pcs-DHT22-digital-temperature-and-humidity-sensor-Temperature-and-humidity-module-AM2302-replace-SHT11-SHT15-Free/1031321543.html

TOTAL SENSOR PRICE: $7,6 (arduino + radio) + $4,99 (DHT22) = $12,6