Datasheet

Data Sheet
BMA456
Page 48
BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
Data mode (AUX_IF_CONF.aux_manual_en=0)
AUX_RD_ADDR.read_addr defines the address of the data register from which to read the number of
data bytes configured in AUX_IF_CONF.aux_rd_burst from AUX_0… AUX_7 data of the auxiliary
sensor. These data are stored in the DATA_0 up to DATA_7 register. The data ready status is set in
STATUS.drdy_aux, it is typically cleared through reading one of the DATA_0 to DATA_7 registers.
AUX_WR_ADDR.write_addr defines the register address of auxiliary sensor to start a measurement
in forced mode in the auxiliary sensor register map. The delay (time offset) between triggering an
auxiliary sensor measurement and reading the measurement data is specified in
AUX_CONF.aux_offset. Reading of the data is done in a single I2C read operation with a burst length
specified in AUX_IF_CONF.aux_rd_burst. For BMM150 AUX_IF_CONF.aux_rd_burst should be set to
0b11, i.e. 8 bytes. If AUX_IF_CONF.aux_rd_burst is set to a value lower than 8 bytes, the remaining
auxiliary sensor data in the Register DATA_0 to DATA_7 and the FIFO are undefined.
It is recommended to disable the auxiliary sensor interface (IF_CONF.if_mode=0b0) before setting up
AUX_RD_ADDR.read_addr and AUX_WR_ADDR.write_addr for the data mode. This does not put the
auxiliary sensor itself into suspend mode but avoids gathering unwanted data during this phase.
Afterwards the auxiliary sensor interface can be enabled (IF_CONF.if_mode=0b1) again.
Delay (Time Offset)
BMA456 supports starting the measurement of the sensor at the auxiliary sensor interface between
2.5 and 37.5 ms before the Register DATA are updated. This offset is defined in AUX_CONF.aux_offset.
If set to 0b0, the measurement is done right after the last Register DATA update, therefore this
measurement will be included in the next register DATA update.