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transmit a response signal, the data sent from the data bus 40Bit SDA serial high byte is transmitted

first; data is sequentially transmitted high humidity, low humidity, high temperature, low temperature,

the parity bit , sent a message to trigger the end of data collection, collecting sensor automatically

transferred to the end of the sleep mode until the next traffic coming.

Detailed timing signal characteristics are shown in Table 10, a single bus communication timing

diagram shown in Figure 21.

Figure 21: AM2321 single bus communication timing

Note: The temperature and humidity data from the AM2321 host always read the previous measurement, the

measurement interval twice as long, please read twice in a row is the second time in the real-time temperature and

humidity values, while two read take a minimum interval 2S.

Table 10 : single bus signal characteristics

Symbol

Parameter

min

typ

max

unit

T be

Host starting signal low time

0.8

1

20

ms

T go

Host Bus release time

20

30

200

µ S

T rel

Response time low

75

80

85

µ S

T reh

Response time high

75

80

85

µ S

T low

Signal "0", "1" low time

48

50

55

µ S

T h0

Signal "0" High Time

22

26

30

µ S

T h1

Signal "1" High Time

68

70

75

µ S

T en

Sensor releases the bus time

45

50

55

µ S

8.3.4 Peripheral reading step example

Communication between the host and the sensor reads the data can be done through the

following three steps.

Step One:

AM2321 after power (power after AM2321 2S to wait to cross the unstable state, during the

reading device can not send any commands), test environment temperature and humidity data, and

record the data, then the sensor automatically transferred to a dormant state. The SDA data line

AM2321 by resistance and pulling high has been to maintain a high level, then the AM2321 SDA pin

is in the input state, always detect external signals.

Step Two:

Microprocessor I / O is set to output, while the output low and low retention time can’t be less

than 800us, typical values are pulled 1MS, then the microprocessor I / O is set to enter the state, the

release of the bus, Since the pull-up resistor, the microprocessor I / O data lines that AM2321 the

SDA also will go high, and so the host releases the bus, AM2321 sends a response signal, the output

Note: To ensure accurate

communication

of

the

sensor,

the

user

when

reading the signal, in strict

accordance with Table 10

and Figure 21, the design

parameters and timing

Aosong Guangzhou Electronics Co., Ltd.

Order Phone: 4006 305378

Enterprise QQ: 4006305378

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