Datasheet
Bosch Sensortec
| BMI088 Data sheet
33 |
48
Modifications reserved | Data subject to change without notice
Document number: BST-BMI088-DS001-1
3
Revision_1.3_05201
8
In order to allow for the correct internal synchronisation of data written to the BMI088, a wait time of at
least 2 µs (normal mode) or 1000 µs (suspend mode) must be followed.
6.1 Serial Peripheral Interface (SPI)
The behavior of the SPI interface is slightly different between gyroscope part and accelerometer part:
• Initialization phase: as described in chapter 3, the interface of the gyroscope part is selected by
the level of the PS pin. In contrast to this, the accelerometer part starts always in I
2
C mode
(regardless of the level of the PS pin) and needs to be changed to SPI mode actively by sending
a rising edge on the CSB1 pin (chip select of the accelerometer), on which the accelerometer
part switches to SPI mode and stays in this mode until the next power-up-reset.
To change the sensor to SPI mode in the initialization phase, the user could perfom a dummy
SPI read operation, e.g. of register ACC_CHIP_ID (the obtained value will be invalid).
• In case of read operations, the SPI interface of the accelerometer part does not send the
requested information directly after the master has send the corresponding register address,
but sends a dummy byte first, whose content is not predictable. Only after this dummy byte the
desired content is sent. (This dummy byte procedure does not apply to the gyroscope part.)
Please find more details below in section 6.1.2.
The timing specification for SPI of the BMI088 is given in the following table:
Table 12: SPI timing
Parameter
Symbol
Condition
Min
Max
Units
Clock Frequency f
SPI
Max. Load on SDI or SDO =
25pF
10 MHz
SCK Low Pulse
t
SCKL
45
ns
SCK High Pulse
t
SCKH
45
ns
SDI Setup Time
t
SDI_setup
20
ns
SDI Hold Time
t
SDI_hold
20
ns
SDO Output Delay
t
SDO_OD
Load = 25pF
30
ns
Load = 250pF,
VDDIO > 2.4V
40
ns
CSB Setup Time
t
CSB_setup
40
ns
CSB Hold Time
t
CSB_hold
40
ns
Idle time between write
accesses
t
IDLE_wacc
normal mode
2
µs