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command line with the sensor address, the sensor was to receive, and read the information in

accordance with the function codes and requirements; then the results (data) is sent back to the host.

The information returned includes the function code, and after execution of the data CRC code (the

user may read the CRC, can be sent directly to a stop condition).

◎Communication slave address

AM2321 sensors each address are the same, and is 0xB8. So on the same bus can only hang the

AM2321 sensors, sensor signal only after receiving the start and with itself will respond to the same

address.

◎Communication I C function code

Function code is the first byte of each communication message frame transmission. I C _Mod

Bus communication rules, define the function code is 1-127. As host requests sent by function code

tells the slave what action should be performed. As a slave response, the slave returns the function

code sent from the host to the function code, as it indicates that the response from the host machine

and have been related operations. I C _Mod Bus part of the function codes are listed in Table 7.

Table 7:C Mod Bus part of the function code

Function Code

Definitions

Operation (binary)

0x03

Reading Register Data

Read one or more data registers

0x10

Write Multiple Registers

Multiple sets of binary data to write multiple registers

◎C communication data area

The data area includes required by the sensor returns what information or what action to

perform. This information may be data (such as: temperature, humidity, the sensor device

information, the user writes data, etc.), the reference address. For example, function code 03 tells the

host through the register value returned by the sensor (including the start address of the register to be

read and the read length register), the returned data comprises data length and the content of the

register data register.

Sensor uses a custom I

C-Mod bus communication protocol used by the master

communication command (function code 03), which could be read its data register, the data register

table in Table 8. Sensor data register stores the temperature and humidity values and the

corresponding sensor device information and other related signals; each data register is a single byte

(8 bits) of binary data; once read data up to 10 sensor registers more than read length, the sensor will

return the corresponding error code. The error code information, see Schedule 1.

Table 8: AM2321 Data Register Table

Register

information

Address

Register information

Address

Register information

Address

Register

information

Address

High humidity

0x00

Model High

0x08

Users register a high

0x10

Retention

0x18

Low humidity

0x01

Model Low

0x09

Users register a low

0x11

Retention

0x19

High temperature

0x02

The version number

0x0A

Users register 2 high

0x12

Retention

0x1A

Low temperature

0x03

Device ID (24-31) Bit

0x0B

Users register 2 low

0x13

Retention

0x1B

2

2

2

2

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