Aosong Electronics Co.,Ltd

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Your specialist in innovating humidity & temperature sensors

5. Electrical connection diagram:

6. Operating specifications:

(1) Power and Pins

Power's voltage should be 3.3-6V DC. When power is supplied to sensor, don't send any instruction to the sensor

within one second to pass unstable status. One capacitor valued 100nF can be added between VDD and GND for

wave filtering.

(2) Communication and signal

Single-bus data is used for communication between MCU and DHT22, it costs 5mS for single time

communication.

Data is comprised of integral and decimal part, the following is the formula for data.

DHT22 send out higher data bit firstly!

DATA=8 bit integral RH data+8 bit decimal RH data+8 bit integral T data+8 bit decimal T data+8 bit check-sum

If the data transmission is right, check-sum should be the last 8 bit of "8 bit integral RH data+8 bit decimal RH

data+8 bit integral T data+8 bit decimal T data".

When MCU send start signal, DHT22 change from low-power-consumption-mode to running-mode. When MCU

finishs sending the start signal, DHT22 will send response signal of 40-bit data that reflect the relative humidity

Thomas Liu (Business Manager)

Email: thomasliu198518@yahoo.com.cn

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