LSM303AGR datasheet(40/68 Pages) STMICROELECTRONICS

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Digital interfaces

LSM303AGR

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DocID027765 Rev 5

6.2.2

Accelerometer SPI read in 3-wire mode

3-wire mode is entered by setting the CTRL_REG4_A (23h) (SPI_ENABLE) bit equal ‘1’

(SPI serial interface read enable).

Figure 13. Accelerometer SPI read protocol in 3-wire mode

The SPI read command is performed with 16 clock pulses:

bit 0: READ bit. The value is 1.

bit 1: MS bit. When 0, does not increment the address; when 1, increments the address in

multiple reads.

bit 2-7: address AD(5:0). This is the address field of the indexed register.

bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).

A multiple read command is also available in 3-wire mode.

6.2.3

Magnetometer SPI write

Figure 14. Magnetometer SPI write protocol

The SPI write command is performed with 16 clock pulses. The multiple byte write

command is performed by adding blocks of 8 clock pulses to the previous one.

bit 0: WRITE bit. The value is 0.

bit 1-7: address AD(6:0). This is the address field of the indexed register.

bit 8-15: data DI(7:0) (write mode). This is the data that is written inside the device (MSb

first).

bit 16-... : data DI(...-8). Further data in multiple byte writes.

SPC

SDI

D I7D I6

D I5D I4

DI3DI2

DI1DI0

AD5 AD 4 AD 3 AD2 AD 1 AD0

AD6

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