- 10 -

Figure 12: I2 C bus master basic format for receiving data from a machine

8.2 AM2321 sensor I C communication protocol

AM2321 serial interface for the I C bus, in full accordance with I C standard protocols

addressing, can be directly linked to the I C bus. AM2321 sensor I C address of the c(SLAVE

ADDRESS) 0xB8, on the basis of I C standard protocol on the bus, based on Mod Bus protocol,

developed a unique communication protocol, reducing the transmission error rate. When micro

controller read AM2321 sensors strict accordance with AM2321 sensor I

communication protocol design and timing.

8.2.1 I C Interface Description

AM2321 digital temperature and humidity sensor as a communication from the machine, and

the host (user microprocessor) between uses the standard I

C bus mode. For the accurate

measurement of humidity, temperature and humidity to reduce the impact of, AM2321 sensors

during non-working, automatically become dormant, in order to reduce public consumption, to

reduce the impact sensor self-heating of the ambient humidity values. AM2321 uses passive mode,

which hosts the wake sensor by instruction, and then send the appropriate commands to read the

appropriate temperature and humidity values; After the communication, the sensor triggers a

temperature and humidity acquisition; Therefore, if there is no time to read the sensor, please read

two consecutive second sensor (minimum interval of two reads 2s), is the latest in a second

measurement; after the acquisition sensor automatically become dormant. The next time you need to

read the host sensor, sensors need to reawaken. It should be noted that the host communication from

start to finish, for a maximum of 3s. If communication is not completed within 3s, sensors

automatically end communication, automatically become dormant again as the host read sensors,

needed to re-send a wakeup command.

8.2.2 interface Features

This section describes the I C interface characteristics AM2321 sensor, if you want to get the

best communication with the sensor results, designed in strict compliance with the conditions of

Figure 13 and Table 6 design.

2

2

2

2

2

2

2

2

2

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