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5. Electrical connection diagram:

6. Operating specifications:

(1) Power and Pins

Power's voltage should be 3.3-6V DC. When power is supplied to sensor, don't send any instruction to the sensor

within one second to pass unstable status. One capacitor valued 100nF can be added between VDD and GND for

wave filtering.

(2) Communication and signal

MaxDetect 1-wire bus is used for communication between MCU and RHT03. ( 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 RHT03 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.

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, RHT03 change from standby-status to running-status. When MCU finishs sending

the start signal, RHT03 will send response signal of 40-bit data that reflect the relative humidity and temperature