Datasheet

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Figure14: I
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C sensors read the complete example of fig
◎I
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C read and write timing decomposition
Sensors read or write, you must follow these three steps, otherwise it will not communicate or
can’t read the correct data:
Step one: Wake Sensor
In order to reduce the humidity sensor errors caused by self-heating, the sensor in a
non-working state, dormant, so to read the sensor must wake sensor to transmit commands to read
and write, otherwise the sensor will not respond. It should be noted that, in the wake sensor, I
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C
address is sent, the sensor does not respond to ACK, but the host must send back an ACK clock
verify that the ninth SCL clock signal. Wake sensor operation is following instructions:
After the host sends a start signal is applied to the starting address, wait for sometime (waiting
time of at least 800 μs, the maximum 3ms; such as host hardware I
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C, you do not need to wait for
the hardware I
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C will automatically wait), and then sends a stop signal.
Namely: the starting signal +0 xB8 + wait (> 800us) + stop signal timing diagram shown in
Figure 15.
Figure 15: Wake Sensor
Step two : Send the read command or send written instructions
After the wake AM2320 sensors, can be fully in accordance with the standard read and write
timing I
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C, and the maximum speed supported 100Kb / s. Read the temperature and humidity of
example, as shown in Figure 16.
The host sends commands to: START +0 xB8 (SLA) +0 x03 (function code) +0 x00 (starting
address) +0 x04 (register length) + STOP
Figure 16: sending a read command example temperature and humidity
Steps three : To return the data read or confirmation signal
Send read / write command, the host is required to wait at least 1.5ms, and then sends a read
timing, reads return data example shown in Figure 17; must be noted that, when you read the data,
issued after the completion of I
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C address, wait at least 30 μs and then sent over the next serial