Datasheet

Data Sheet
BMA456
Page 45
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.
measurement of the auxiliary sensor using the auxiliary sensor forced mode and the data readout from
the auxiliary sensor (data mode).
In setup mode, the auxiliary sensor may be configured and trim data may be read out from the auxiliary
sensor. In the data mode the auxiliary sensor data are continuously copied into BMA456 registers and
may be read out from BMA456 directly over the primary interface. For a BMM150 magnetometer, these
are the auxiliary sensor data itself and Hall resistance, temperature is not required. The table below
shows how to configure these three modes using the registers PWR_CONF, PWR_CTRL, and
AUX_IF_CONF.aux_manual_en.
The auxiliary sensor interface mode may be enabled by setting bit IF_CONF.if_mode according to the
following table.
IF_CONF.if_mode
Result
0
Secondary IF disabled (default)
1
AuxIF enabled
The auxiliary sensor interface operates at 400 kHz. This results in an I2C readout delay of about 250
us for 10 bytes of data.
Setup mode (AUX_IF_CONF.aux_manual_en =0b1)
Through the primary interface the auxiliary sensor may be accessed using indirect addressing through
the AUX_* registers. AUX_RD_ADDR and AUX_WR_ADDR define the address of the register to
read/write in the auxiliary sensor register map and triggers the operation itself, when the auxiliary
sensor interface is enabled through PWR_CTRL.aux_en.
For reads, the number of data bytes defined in AUX_IF_CONF.aux_rd_burst are read from the auxiliary
sensor and written into the BMA456 Register DATA_0 to DATA_7. For writes only single bytes are
written, independent of the settings in AUX_IF_CONF.aux_rd_burst. The data for the I2C write to
auxiliary sensor must be stored in AUX_WR_DATA before the auxiliary sensor register address is
written into AUX_WR_ADDR.
When a read or write operation is triggered by writing to AUX_RD_ADDR and AUX_WR_ADDR,
STATUS.aux_man_op is set and it is reset when the operation is completed. For reads the DATA_0 to
DATA_7 contains the read data, for writes AUX_WR_DATA may be overwritten again.
Mode
AUX_IF_CONF.aux_manual_en
PWR_CONF.adv_power_save
PWR_CTRL.aux_en
No auxiliary
sensor
access
1
1
0
Setup mode
1
0
0
Data mode
0
x
1