AM2302 / DHT22 humidity and temperature sensor connection guide

AM2302 / DHT22 humidity and temperature sensor Four-position sensor interface wiring guide with power, signal assignments, and bench checks.

Four-position sensor interface

4 contacts Current package

Aosong / ASAIR ·

Required

Use a short cable and a 5 V host with a GPIO that can switch between driving low and high impedance. Pull the data wire up to the same 5 V supply.

Wait more than two seconds after power-up. Pull the data line low for the documented start time. Then release the line and look for the sensor response.
Check that the low eight bits of the sum of the first four bytes equal the fifth byte before decoding.
Decode humidity as an unsigned big-endian value in tenths of percent. Decode temperature as sign and magnitude in tenths of a degree Celsius.

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

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

Four-position sensor interface

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

Supply input · Power

Device supply. Place the bypass capacitor close to this pin.

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.