Datasheet

- 23 -

T h0

Signal "0" High Time

µ S

T h1

Signal "1" High Time

µ S

T en

Sensor releases the bus time

µ S

Note: To ensure quasi-sensor indeed communication, the user reads the letter when number,

strictly in accordance with table 10 and the parameters in figure 21 program design.

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:

AM2320 after power (power after AM2320 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

AM2320 by resistance and pulling high has been to maintain a high level, then the AM2320 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 AM2320 the

SDA also will go high, and so the host releases the bus, AM2320 sends a response signal, the output

low as 80 microseconds response signal, followed by 80 microsecond high output peripheral is ready

to receive data notification signal transmitter 22 shown in fig.

Figure 22: Single-bus timing diagram decomposition

Step Three:

AM2320 After sending the response, followed by a continuous serial data bus SDA data output

40, the microprocessor 40 receives the data according to I / O level changes.

Bit data "0" in the form: low high 50 microseconds plus 26-28 microseconds;

Bit data "1" format: LOW HIGH plus 70 microseconds 50 microseconds;

Bit data "0", the bit data "1" signal format shown in Figure 23.