RHT-02 Ver la hoja de datos (PDF) - Unspecified
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RHT-02 Datasheet PDF : 6 Pages
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(2) Communication and signal
MaxDetect 1-wire bus is used for communication between MCU and RHT02. ( MaxDetect 1-wire bus is
specially designed by MaxDetect Technology Co., Ltd. , it's different from Maxim/Dallas 1-wire bus, so it's
incompatible with Dallas 1-wire bus.)
Illustration of MaxDetect 1-wire bus:
DATA=16 bits RH data+16 bits Temperature data+8 bits check-sum
Example: MCU has received 40 bits data from RHT02 as
0000 0010 1000 1100 0000 0001 0101 1111 1110 1110
16 bits RH data
16 bits T data
check sum
Here we convert 16 bits RH data from binary system to decimal system,
0000 0010 1000 1100 → 652
Binary system
Decimal system
RH=652/10=65.2%RH
Here we convert 16 bits T data from binary system to decimal system,
0000 0001 0101 1111 → 351
Binary system
Decimal system
T=351/10=35.1℃
When highest bit of temperature is 1, it means the temperature is below 0 degree Celsius.
Example: 1000 0000 0110 0101, T= minus 10.1℃
16 bits T data
Sum=0000 0010+1000 1100+0000 0001+0101 1111=1110 1110
Check-sum=the last 8 bits of Sum=1110 1110
When MCU send start signal, RHT02 change from standby-status to running-status. When MCU finishs sending
the start signal, RHT02 will send response signal of 40-bit data that reflect the relative humidity and temperature
to MCU. Without start signal from MCU, RHT02 will not give response signal to MCU. One start signal for one
response data from RHT02 that reflect the relative humidity and temperature. RHT02 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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MaxDetect Technology Co., Ltd.
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Thomas Liu (Sales Manager)
Email: thomasliu198518@yahoo.com.cn , sales@humiditycn.com
http://www.humiditycn.com
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