Datasheet

Bosch Sensortec
| BMI088 Data sheet
14 |
48
Modifications reserved | Data subject to change without notice
Document number: BST-BMI088-DS001-1
3
Revision_1.3_05201
8
4.1.2 Power Modes: Gyroscope
The gyroscope has 3 different power modes. Besides normal mode, which represents the fully
operational state of the device, there are 2 energy saving modes: suspend mode and deep-suspend
mode.
After power-up gyro is in normal mode so that all parts of the device are held powered-up and data
acquisition is performed continuously.
In suspend mode the whole analog part is powered down. No data acquisition is performed. While in
suspend mode the latest rate data and the content of all configuration registers are kept. The registers
can still be read (though they are not updated).
Suspend mode is entered by writing 0x80 to the register GYRO_LPM1. It can be left by writing 0x00 to
GYRO_LPM1 or by a soft reset (see 4.9).
Although write access to registers is supported at the full interface clock speed (SCL or SCK), a waiting
period must be inserted between two consecutive write cycles (please refer also to section 9.2.1).
In deep suspend mode the device reaches the lowest possible power consumption. Only the interface
section is kept alive. No data acquisition is performed and the content of the configuration registers is
lost.
Deep suspend mode is entered by writing 0x20 to the register GYRO_LPM1. It can be left by writing
0x00 to GYRO_LPM1 or by a soft reset (see 4.9).
Please note, that all application specific settings, which are not equal to the default settings, must be re-
set to its designated values after leaving deep-suspend mode.
Note: after POR or soft-reset, or when switching between the different power modes, the gyroscope
sensor needs up to 30ms time to reach the new state. Any communication with the sensor during this
time should be avoided.
4.2 Sensor Data
The width of the gyroscope and accelerometer sensor data is 16 bits (11 bits for the temperature sensor)
given in two’s complement representation.
The bits for each axis are split into an MSB upper part and an LSB lower part. Reading the sensor data
registers shall always start with the LSB part. In order to ensure the integrity of the sensor data, the
content of an MSB register is locked by reading the corresponding LSB register (shadowing procedure).
For details regarding the registers and the interpretation of the data found in these registers see:
• chapter 5.5.2 for the gyroscope part
• chapter 5.3.4 or the accelerometer part
• chapter 5.3.7 for the temperature sensor
The burst-access mechanism provides an efficient way to read out the angular rate data in I
2
C or SPI
mode. During a burst-access, the sensor automatically increments the starting read address after each
byte. The burst-access allows data to be transferred over the I
2
C bus with an up to 50% reduced data
density. The sensor data (angular rate or acceleration data) in all read-out registers is locked as long as
the burst read access is active. Reading the sensor data registers of each gyroscope and accelerometer
part in burst read access mode ensures that the sensor values in all readout registers belong to the
same sample.