AOSONG DHT22 Temperature Humidity Sensor

Description
The DHT22 is a basic and low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the moisture and temperature with a digital signal output on the data pin (no analog input pins needed).
The first pin on the left is 3.3-5.5V power and the second pin connects to a data input pin and the right pin is connected to the ground. Although it uses a single-wire to send data, it is not compatible with Dallas one wire. In case you need multiple sensors, each one must have its own data pin.
In comparison with DHT11, this sensor is more precise, more accurate and works in a higher range of temperature/humidity, its temperature measuring range is from -40 to +80 degree Celsius with +-0.5 degrees accuracy, while the DHT11 temperature range is from 0 to 50 degrees Celsius with +-2 degrees’ accuracy. Besides, the DHT22 sensor has a better humidity measuring range, from zero to 100% with 2% accuracy, while the DHT11 humidity range is from 20 to 80% with 5% accuracy. But it is larger and more expensive.
They use the humidity sensing component to measure humidity which has two electrodes with moisture holding substrate between them. So as the humidity changes, the conductivity of the substrate changes or the resistance between these electrodes changes. This change in resistance is measured and processed by the IC which makes it ready to be read by a microcontroller.

Features
Model: DHT22
Input Voltage: 3.3V ~ 5.5V
Output Type: Digital
Temperature Range: -40°C ~ 80°C
Temperature Accuracy: +-0.5°C
Temperature Resolution: 0.1°C
Humidity Range: 0% ~ 100% RH
Humidity Accuracy: +-2% RH
Humidity Resolution: 0.1%
Interface: 1 wire
Pin Number: 4 Pins
Size: 25.1mm x 15.1mm x 7.7mm

Pinout:
(When the Sensor is kept facing you, the leftmost pin is Pin 1)
VDD: power supply (3.5V - 5.5V)
SDA: serial data - bidirectional 
NC: NC
GND: GND