LSM320HAY30 Datasheet, PDF (20/42 Pages) STMicroelectronics – MEMS motion sensor module: 3D digital accelerometer and 2D pitch and yaw analog gyroscope

Digital interfaces
6
Digital interfaces
LSM320HAY30
The registers embedded in the LSM320HAY30 may be accessed through both the I²C and
SPI serial interfaces. The latter may be software 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, the
CS line must be tied high (i.e. connected to Vdd_IO).
Table 7. Serial interface pin description
Pin name
Pin description
CS
SCL
SPC
SDA
SDI
SDO
SA0
SDO
SPI enable
I²C/SPI mode selection (1: I²C mode; 0: SPI enabled)
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 the device address (SA0)
SPI serial data output (SDO)
6.1
I²C serial interface
The LSM320HAY30 I²C is a bus slave. The I²C is employed to write data into registers
whose content can also be read back.
The relevant I²C terminology is given in the table below.
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 bidirectional line used for sending and receiving the data
to/from the interface. Both the lines are connected to Vdd_IO through a pull-up resistor
embedded inside the LSM320HAY30. When the bus is free, both the lines are high.
The I²C interface is compliant with fast mode (400 kHz) I²C standards as well as with normal
mode.
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