AIS328DQ Datasheet, PDF (23/43 Pages) STMicroelectronics – High-performance ultra low-power 3-axis accelerometer

AIS328DQ
Digital interfaces
5.2.3
Note:
SPI read in 3-wire mode
3-wire mode is entered by setting to ‘1’ the bit SIM (SPI serial interface mode selection) in
CTRL_REG4.
Figure 11. SPI read protocol in 3-wire mode
CS
SPC
SDI/O
RW
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
MS AD5 AD4 AD3 AD2 AD1 AD0
The SPI read command is performed with 16 clock pulses:
bit 0: READ bit. The value is 1.
bit 1: MS bit. When 0, do not increment address; when 1, increment address in multiple
reading.
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).
Multiple read command is also available in 3-wire mode.
If AIS328DQ is used in a multi-SPI slave environment (several devices sharing the same
SPI bus), the accelerometer can be forced by software to remain in SPI mode. This
objective can be achieved by sending at the beginning of the SPI communication the
following sequence to the device:
a = read(0x17)
write(0x17, (0x80 OR a))
The programming of this register is a possibility to enhance the robustness of the SPI
system.
Doc ID 18160 Rev 3
23/43