Data Sheet

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◎Peripherals read steps
Communication between the master and slave can be done through the following steps (peripherals
(such as microprocessors) read DHT11 the data of steps).
Step 1:
After power on DHT11 (DHT11 on after power to wait 1S across the unstable state during this period
can not send any instruction), the test environment temperature and humidity data, and record the data,
while DHT11 the DATA data lines pulled by pull-up resistor has been to maintainhigh; the DHT11 the
DATA pin is in input state, the moment of detection of external signals.
Step 2:
Microprocessor I / O set to output at the same time output low, and low hold time can not be less
than 18ms, then the microprocessor I / O is set to input state, due to the pull-up resistor, a
microprocessor/ O DHT11 the dATA data lines also will be high, waiting DHT11 to answer signal, send
the signal as shown:
Host sends a start signal
Step 3:
DATA pin is detected to an external signal of DHT11 low, waiting for external signal low end the
delay DHT11 DATA pin in the output state, the output low of 80 microseconds as the response signal,
followed by the output of 80 micro-seconds of high notification peripheral is ready to receive data, the
microprocessor I / O at this time in the input state is detected the I / O low (DHT11 response signal), wait
80 microseconds highdata receiving and sending signals as shown:
Step 4:
Output by DHT11 the DATA pin 40, the microprocessor receives 40 data bits of data "0" format: the
low level of 50 microseconds and 26-28 microseconds according to the changes in the I / O levellevel,
bit data "1" format: the high level of low plus, 50 microseconds to 70 microseconds. Bit data "0", "1" signal
format as shown: