Datasheet

Bosch Sensortec
| BMI088 Data sheet
34 |
48
Modifications reserved | Data subject to change without notice
Document number: BST-BMI088-DS001-1
3
Revision_1.3_05201
8
The following figure shows the definition of the SPI timings:
t
SDI
_hold
t
SCKH
t
CSB_hold
t
CSB_setup
t
SDI_setup
t
SCKL
t
SDO_OD
CSB
SCK
SDI
SDO
Figure 2: SPI timing diagram
The SPI interface of the BMI088 is compatible with two modes, ´00´ and ´11´. The automatic selection
between [CPOL = ´0´ and CPHA = ´0´] and [CPOL = ´1´ and CPHA = ´1´] is controlled based on the
value of SCK after a falling edge of CSB (1 or 2).
6.1.1 SPI interface of gyroscope part
For single byte read as well as write operations, 16-bit protocols are used. The SPI interface also
supports multiple-byte read operations (burst-read).
The communication starts when the CSB (1 or 2) is pulled low by the SPI master and stops when CSB
(1 or 2) is pulled high. SCK is also controlled by SPI master. SDI and SDO (1 or 2) are driven at the
falling edge of SCK and should be captured at the rising edge of SCK.
The data bits are used as follows:
• Bit #0: Read/Write bit. When 0, the data SDI is written into the chip. When 1, the data
SDO from the chip is read.
• Bit #1-7: Address AD(6:0).
• Bit #8-15: when in write mode, these are the data SDI, which will be written into the
address. When in read mode, these are the data SDO, which are read from the
address.
Multiple read operations (burst-read) are possible by keeping CSB low and continuing the data transfer
(i.e. continuing to toggle SCK). Only the first register address has to be written. Addresses are
automatically incremented after each read access as long as CSB stays active low.
6.1.2 SPI interface of accelerometer part
In case of read operations of the accelerometer part, the requested data is not sent immediately, but
instead first a dummy byte is sent, and after this dummy byte the actual reqested register content is
transmitted.