AM2302 Humidity and Temperature Sensor Module

The AM2302 (DHT22) is a calibrated relative humidity and temperature sensor module with a single data line for data exchange.  It has a small micro controller which uses a proprietary protocol.

AM2302 sensor module

Pin Out:
1. VDD 3.3V to 6V
2. DATA
3. N/C (not connected)
4. GND

Measurement:

• Humidity: 0 to 100% 
• Temperature: -40 to 125 degrees Celsius

Accuracy:

• humidity+-2%RH(Max+-5%RH)
• temperature+-0.2Celsius

In applications, an external pull-up resistor, about 10 - 5kΩ, is often required. Sometimes this resistor is already integrated in the module, sometimes its necessary to add it.

Arduino IDE

Numereous Arduiono IDE libraries exist for the DHTxx family of modules.  For ESP8266 try https://github.com/beegee-tokyo/DHTesp which disables task switching during reads to ensure timings are not affected.