Datasheet

Data Sheet
BMA456
Page 28
BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to third parties.
BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Skip Frame (fh_parm=0x0):
In the case of FIFO overflows, a skip_frame is prepended to the FIFO content, when read out next
time. The data for the frame consists of one byte and contains the number of skipped frames. When
more than 0xFF frames have been skipped, 0xFF is returned. A skip frame is expected always as first
frame in a FIFO read burst. A skip frame does not consume memory in the FIFO.
Sensortime Frame (fh_parm=0x1):
The data for the sensortime frame consists content of the Register SENSORTIME_0 to
SENSORTIME_2 when the last byte of the last sample frame was read. A sensortime frame is always
expected as last frame in the FIFO. A sensortime frame is only sent if the FIFO becomes empty during
the burst read. A sensortime frame does not consume memory in the FIFO. Sensortime frames are
enabled (disabled) by setting FIFO_CONFIG_0.fifo_time_en to 0b1 (0b0).
Fifo_Input_Config Frame (fh_parm=0x2):
Whenever the filter configuration of the FIFO input data sources changes, a FIFO input config frame
is inserted into the FIFO, before the configuration change becomes active. E.g. when the bandwidth
for the accelerometer filter is changed in Register ACC_CONF, a FIFO input config frame is inserted
before the first frame with accelerometer data with the new bandwidth configuration. The FIFO input
config frame contains one byte of data with the format
Bit
7
6
5
4
3
2
1
0
Content
reserved
aux_
if_ch
aux_
conf_ch
reserved
reserved
acc_
range_ch
acc_
conf_ch
aux_if_ch: A write to Register AUX_IF_CONF, AUX_RD_ADDR, or AUX_WR_ADDR becomes active.
aux_conf_ch: A write to Register AUX_CONF becomes active.
acc_range_ch: A write to Register ACC_RANGE becomes active.
acc_conf_ch: A write to Register ACC_CONF or acc_FIFO_filt_data or acc_FIFO_downsampling in
Register FIFO_DOWNS becomes active.
Sample Drop Frame
A sample drop frame has always one byte payload, defined through
Bit
7
6
5
4
3
2
1
0
Content
reserved
aux_drop
reserved
acc_
drop
Sample drop frame will be inserted after a Fifo_Input_Config frame at the ODR tick at which the sample
was dropped and only if no other sensor provides a valid sample at this ODR tick. If another sensor
provides valid data, the data of this sensor is just not included and the appropriate header bit of the
data frame is not set.