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Figure 1 13 3: AM2321 typical application circuit I2C bus and timing diagram

Table 6 : AM2321 sensor C interface characteristics

Symbol

Parameters

Standard C mode

Unit

min

Max

SCL clock frequency

100

kHz

T w (SCLL)

SCL Clock low time

4.7

μs

T w (SCLH)

SCL Clock high time

4.0

T s u (SDA)

SDA Settling time

250

ns

T h (SDA)

SDA Data hold time

0

[1]

T r (SDA)

T r (SCL)

SDA and SCL Rise time

1000

T f (SDA)

T f (SCL)

SDA and SCL Fall Time

300

T h (STA)

Start condition hold time

4.0

μs

T s u (STA)

Repeated Start condition setup time

4.7

T s u (STO)

Stop condition setup time

4.0

μs

T w (STO:STA)

Stop to Start condition time (bus idle)

4.7

μs

C b

Capacitive load for each bus

400

P F

8.2.3 Communication protocol

I C protocol AM2321 sensor is based on the standard I C bus protocol, the reference to the

Mod Bus protocol, according to AM2321 sensor itself features a combination of I C Mod Bus

agreement. Specific format is as follows:

◎Communication data (information frame) format

◎Communication and information transfer process

When a command is sent by the sending communication device (host) to the sensor, the

2

2

2

I

C

data+W/R

Function Code

Data Area

CRC

1byte

1 byte

N-byte

16-bit CRC (cyclic redundancy code)

2

Data formats:

Data length:

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