ATH25 Data Sheet

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Version:V1.0 —— May 2021

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Figure 9. Timing diagram of digital input / output

The abbreviations are explained in Table 8. The thicker SDA line is controlled by the sensor,

and the ordinary SDA line is controlled by the single-chip microcomputer. Please note that the

SDA valid read time is triggered by the falling edge of the previous conversion.

Table 8. Timing characteristics of I²C fast mode digital Inputs / outputs

The meaning is shown in Figure 9. Unless otherwise noted

7 Sensor Communication

ATH25 uses standard I²C protocol for communication. For information about the I²C protocol

other than the following chapters, please refer to the following website: www.aosong.com

provides a sample program for reference.

7.1 Start the Sensor

The first step is to power up the sensor with the selected VDD supply voltage (range between

2.2V and 5.5V). After power-on, the sensor needs less than 100ms stabilization time (SCL is

high at this time) to reach the idle state and it is ready to receive commands sent by the host

(MCU).

7.2 Start/Stop Sequence

Each transmission sequence starts with the Start state and ends with the Stop state, as shown

in Figure 10 and Figure 11.

Figure 10. Start transmission status (S)

When SCL is high, SDA is converted from high to low. The start state is a special bus state

controlled by the master, indicating the start of the slave transfer (after Start, the BUS is

generally considered to be in a busy state).