Data Sheet

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6、Typical circuit
Microprocessor and DHT11 of connection typical application circuit as shown above, DATA pull the
microprocessor I / O ports are connected.
1. Typical application circuit recommended in the short cable length of 20 meters on the 5.1K
pull-up resistor, the resistance of greater than 20 meters under the pull-up resistor on the lower of the
actual situation.
2. When using a 3.5V voltage supply cable length shall not be greater than 20cm. Otherwise, the line
voltage drop will cause the sensor power supply shortage, caused by measurement error.
3. Each read out the temperature and humidity values are the results of the last measurement For
real-time data, sequential read twice, but is not recommended to repeatedly read the sensors, each
read sensor interval is greater than 5 seconds can be obtainedaccurate data.
7、Serial communication instructions (single-wire bi-directional)
◎Single bus Description
DHT11 uses a simplified single-bus communication. Single bus that only one data line, the system
of data exchange, control by a single bus to complete. Device (master or slave) through an open-drain
or tri-state port connected to the data line to allow the device does not send data to release the bus,
while other devices use the bus; single bus usually require an external one about 5.1kΩ pull-up resistor,
so that when the bus is idle, its status is high. Because they are the master-slave structure, and only
when the host calls the slave, the slave can answer, the host access devices must strictly follow the
single-bus sequence, if the chaotic sequence, the device will not respond to the host.
◎Single bus to transfer data defined
DATA For communication and synchronization between the microprocessor and DHT11, single-bus
data format, a transmission of 40 data, the high first-out.