LPS001WP Datasheet, PDF (13/30 Pages) STMicroelectronics – MEMS pressure sensor 300-1100 mbar absolute digital output barometer

LPS001WP
6
Digital interfaces
Digital interfaces
The registers embedded inside the LPS001WP may be accessed through both the I²C and
SPI serial interfaces. The latter may be SW configured to operate either in 3-wire or 4-wire
interface mode.
The serial interfaces are mapped onto the same pads. To select/exploit the I²C interface, CS
line must be tied high.
PS pin select I²C or SPI interface.
If the I²C interface is disabled (PS pin connected to GND or logical ‘0’) and CS is kept high
Obsolete ^{Product(s) - Obsolete Product(s) 6.1}
(logical ‘1’), pin SDO and SDI are put in tri-state.
Table 7. Serial interface pin description
PIN Name
PIN Description
PS
CS
SCL/SPC
SDA/SDI/SDO
SA0/SDO
Protocol selection
I²C/SPI mode selection (logic 1: I²C mode; logic 0: I²C disabled)
SPI enable (chip select)
I²C serial clock (SCL)
SPI serial port clock (SPC)
I²C serial data (SDA)
SPI serial data input (SDI)
3-wire interface serial data output (SDO)
I²C less significant bit of device slave address (SA0)
SPI serial data output (SDO)
I²C serial interface
The LPS001WP I²C is a bus slave. The I²C is employed to write the data into the registers
whose content can also be read back.
The relevant I²C terminology is given in Table 8.
Table 8. Serial interface pin description
Term
Description
Transmitter
The device which sends data to the bus
Receiver
The device which receives data from the bus
Master
The device which initiates a transfer, generates clock signals, and terminates a
transfer
Slave
The device addressed by the master
There are two signals associated with the I²C bus: the serial clock line (SCL) and the serial
data line (SDA). The latter is a bi-directional line used for sending and receiving the data
to/from the interface. Both the lines are connected to Vdd through a pull-up resistor
embedded inside the LPS001WP. When the bus is free, both lines are high.
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