LSM303AGR Datasheet, PDF (40/68 Pages) STMicroelectronics – ultra-low-power 3D accelerometer and 3D magnetometer

Digital interfaces
LSM303AGR
6.2.2
6.2.3
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
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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.
Magnetometer SPI write
Figure 14. Magnetometer SPI write protocol
CS
SPC
SDI
RW
D I7 D I6 D I5 D I4 DI3 DI2 DI1 DI0
AD6 AD5 AD 4 AD 3 AD2 AD 1 AD0
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.
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