Data Sheet

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external approximately 5.1kΩ pull up resistor, so that when the bus is idle, the state is high. Because
they are master-slave structure, only the host calls a slave, a slave to answer, so the host access
devices must strictly follow the sequence of a single bus, if there is a sequence of confusion, the
device will not respond to the host.
◎Single bus transfer data bit definition
DATA is used for communication between the microprocessor and DHT11 and
synchronization, single-bus data format, a 40-bit data transfer, high first-out.
Data formats:
8bit humidity integer data + 8bit decimal data +8 bit temperature and humidity data + 8bit
temperature decimal integer data +8 bit parity bit.
Note: The fractional portion wherein the temperature and humidity of 0.
◎Parity bit data definition
"8bit humidity decimal integer data + 8bit humidity temperature data +8 bit decimal integer
data + 8bit temperature data" 8bit parity bit is equal to the result of the end of eight.
Example One：40 receives the data to:
0011 0101 0000 0000 0001 1000 0000 0000 0100 1101
High humidity 8 Low humidity 8 High temperature 8 Low temperature 8 Parity bit
Calculated as follows:
0011 0101+0000 0000+0001 1000+0000 0000= 0100 1101
Receive data is correct:
Humidity: 0011 0101=35H=53%RH
Temperature:0001 1000=18H=24℃
Example Two: The received data is 40:
0011 0101 0000 0000 0001 1000 0000 0000 0100 1001
High humidity 8 High humidity 8 High temperature 8 High temperature 8 Parity bit
Calculated as follows:
0011 0101+0000 0000+0001 1000+0000 0000＝ 0100 1101
01001001 is not equal to 01001101
The received data is not correct, give up, again receiving data.
◎Data Timing Diagram
Hosts (MCU) after sending a start signal, DHT11 transition from a low-power mode to
high-speed mode, the host until after the end of the start signal, DHT11 send a response signal, send
40bit data acquisition and trigger a letter. Signal transmission shown in fig.