RHT04 Datasheet, PDF (3/5 Pages) List of Unclassifed Manufacturers – Digital relative humidity & temperature sensor

Your specialist in innovating humidity & temperature sensors
response data from RHT04 that reflect the relative humidity and temperature. RHT04 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.
------------------------------------------------------------------------------------------------------------------------------------
1) Step 1: MCU send out start signal to RHT04 and RHT04 send response signal to MCU
Data-bus's free status is high voltage level. When communication between MCU and RHT04 begins, MCU will
pull low data-bus and this process must beyond at least 1~10ms to ensure RHT04 could detect MCU's signal, then
MCU will pulls up and wait 20-40us for RHT04's response.
When RHT04 detect the start signal, RHT04 will pull low the bus 80us as response signal, then RHT04 pulls up
80us for preparation to send data. See below figure:
------------------------------------------------------------------------------------------------------------------------------------
-3-