AM2302 / DHT22 humidity and temperature sensor pinout

The AM2302 measures relative humidity and temperature and sends a 40-bit frame over a single data wire.

Four-position sensor interface

4 contacts Current package

Aosong / ASAIR ·

Four-position sensor interface

Front view with the vented face toward you and leads below. Pin 1 is at the left.

Supply return · Ground

Connect to the common ground plane or bench return.

Aosong / ASAIR AM2302 Technical Manual V1.0, pp. 4–6.

Pin	Signal	Direction	Function
1	VDD Supply input	Supply input	Device supply. Place the bypass capacitor close to this pin.
2	SDA Bidirectional	Bidirectional	Aosong single-wire pulse timing interface. The host pulls the line low to request data, then releases it.
3	NC None	None	No internal connection. Leave electrically open unless the package notes specify otherwise.
4	GND Supply return	Supply return	Connect to the common ground plane or bench return.

The sensor replies with two humidity bytes, two temperature bytes, and an additive checksum.

Parameter	Limit	Conditions and source
Supply3.3–5.5 V	3.3–5.5 V	The example uses a shared 5 V logic and supply rail. Aosong / ASAIR AM2302 Technical Manual V1.0, pp. 4–6.
Host start pulse1 ms low	1 ms low	Release the line afterward and measure the sensor’s response. Aosong / ASAIR AM2302 Technical Manual V1.0, pp. 4–6.
Sample intervalMore than 2 s	More than 2 s	Wait after power-up and leave time between requests. Aosong / ASAIR AM2302 Technical Manual V1.0, pp. 4–6.

Aosong also markets AM2302 as DHT22. This map shows the four positions in the manufacturer manual. Pin 3 carries no signal.

AM2302 manufacturer documentation· Aosong / ASAIR AM2302 Technical Manual V1.0, pp. 4–6.