Board Mount Pressure Sensor

AMS 6915 SERIES

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Datasheet AMS 6915

– Rev. 2.0

9/13

DATA READOUT VIA THE I2C-INTERFACE

The digital output values for pressure (14-bit value) and temperature (11-bit value) are read from

AMS 6915

’s output register via AMS 6915’s I²C-interface. The data readout, which is illustrated in Figure 4, is

done byte by byte.

A data request from the I²C-master always initializes the data transfer via the I²C-bus. For this purpose the

I²C-master generates a start condition on the I²C-bus lines. Following the start condition the I²C-master then

sends the addressing byte containing the 7-bit slave address of the AMS 6915 (programmed to

0x28Hex = 0101000bin at the factory) and the data direction bit R = 1 which indicates a data request. The

selected pressure sensor first answers with an acknowledge bit. The selected sensor then starts the data

transfer from the output register.

For pressure and temperature value readout four data bytes are transmitted from the pressure sensor to the

I²C-master. The two bytes for the current digital pressure value are sent first, followed by the two bytes for

the current digital temperature value, always beginning with the most significant byte. On each transferred

data byte the I²C-master sends an acknowledge bit confirming the correct receipt of data. After the fourth

data byte, the receiving master generates a no acknowledge bit and the pressure sensor is set to inactive.

The I²C-master shuts down the data transfer by sending a stop condition.

The last 6 bits of the first data byte and the 8 bits of the second data byte always beginning with the most

significant bit give the 14-bit pressure value. The 8 bits of the third data byte and the first 3 bits of the fourth

data byte give the 11-bit temperature value.

For pressure value readout only it is possible to stop the data transfer after two data bytes. In this case the

I²C-master sends a no acknowledge bit after the second data byte and shuts down the data transfer by

sending a stop condition.

Figure 4: Data readout of the digital pressure and temperature values