RHT01 Datasheet, PDF (3/5 Pages) List of Unclassifed Manufacturers – Digital relative humidity & temperature sensor

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Without start signal from MCU, RHT01 will not give response signal to MCU.
One start signal for one response data from RHT01 that reflect the relative humidity and temperature.
RHT01 will change to standby status when data collecting finished if it don't receive start signal from MCU again.
See below figure for overall communication process, the interval of whole process must beyond 2 seconds.
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1) Step 1: MCU send out start signal to RHT01 and RHT01 send response signal to MCU
Data-bus's free status is high voltage level. When communication between MCU and RHT01 begins, MCU will
pull low data-bus and this process must beyond at least 1~10ms to ensure RHT01 could detect MCU's signal, then
MCU will pulls up and wait 20-40us for RHT01's response.
When RHT01 detect the start signal, RHT01 will pull low the bus 80us as response signal, then RHT01 pulls up
80us for preparation to send data. See below figure:
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