DHT22 digital temperature and humidity sensor module for Raspberry Pi and Arduino
The DHT22 is a basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed). Its fairly simple to use, but requires careful timing to grab data.
Simply connect the first pin on the left to 3-5V power, the second pin to your data input pin and the right most pin to ground.
If you are connecting to the Pi Power Board then that is all you need to do as the pull up resistor is already in place
However if you are going to use this on another IOT device you will need a 4.7K – 10K pull up resistor that connects the 3-5V wire and the signal wire. The sensor will work without this but will be less reliable