DHT22 View Datasheet(PDF) - Unspecified
Part Name
Description
MFG CO.
'DHT22' PDF : 10 Pages View PDF
Aosong Electronics Co.,Ltd
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Your specialist in innovating humidity & temperature sensors
and temperature information to MCU. Without start signal from MCU, DHT22 will not give response signal to
MCU. One start signal for one time's response data that reflect the relative humidity and temperature information
from DHT22. DHT22 will change to low-power-consumption-mode when data collecting finish if it don't receive
start signal from MCU again.
1) Check bellow picture for overall communication process:
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Host computer send out
start signal.
Data transmission finished,
Sensor send out
and RL pull up bus's voltage
response signal. Output data: 1bit"0"
for next transmission
Pull up and wait
Host's signal
response from sensor
Pull up voltage and get
ready for sensor's output.
Sensor's signal Output data: 1bit "1"
Sensor pull down
bus's voltage
Single-bus output
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2) Step 1: MCU send out start signal to DHT22
Data-bus's free status is high voltage level. When communication between MCU and DHT22 begin, program of
MCU will transform data-bus's voltage level from high to low level and this process must beyond at least 1ms to
ensure DHT22 could detect MCU's signal, then MCU will wait 20-40us for DHT22's response.
Check bellow picture for step 1:
6
Thomas Liu (Business Manager)
Email: thomasliu198518@yahoo.com.cn
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