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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.

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, RHT05 change from standby-status to running-status. When MCU finishs sending

the start signal, RHT05 will send response signal of 40-bit data that reflect the relative humidity and temperature

to MCU. Without start signal from MCU, RHT05 will not give response signal to MCU. One start signal for one

response data from RHT05 that reflect the relative humidity and temperature. RHT05 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 RHT05 and RHT05 send response signal to MCU

Data-bus's free status is high voltage level. When communication between MCU and RHT05 begins, MCU will

pull low data-bus and this process must beyond at least 1~10ms to ensure RHT05 could detect MCU's signal, then

MCU will pulls up and wait 20-40us for RHT05's response.

When RHT05 detect the start signal, RHT05 will pull low the bus 80us as response signal, then RHT05 pulls up

80us for preparation to send data. See below figure: