Datasheet

Preliminary Data Sheet
BMA400
Page 34 /
Confidential
BST-BMA400-DS000-00 | Version 0.1 | November 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.
fh_param<2/1/0> indicate whether Z, y or x axis data are stored.
Thus, fh_param<3:0> allows to calculate the amount of data payload following the header.
The maximal payload is 6 bytes if all axes are enabled and 12bits are stored.
3bytes payload are needed if all axes are enabled and 8bits are stored.
A lesser amount of data is required if one or two axes are disabled.
As an example, data frames with 12bit and 8bit resolution are shown below, all axes enabled
Bit
7
6
5
4
3
2
1
0
Header
1
0
0
1: 12bit
1: Z
1: Y
1: X
0
data
unused
acc_x<3:0>
acc_x<11:4>
unused
acc_y<3:0>
acc_y<11:4>
unused
acc_z<3:0>
acc_z<11:4>
Bit
7
6
5
4
3
2
1
0
Header
1
0
0
0: 8bit
1: Z
1: Y
1: X
0
data
acc_x<11:4>
acc_y<11:4>
acc_z<11:4>
A FIFO empty frame is a sensor data frame, this is what the header indicates (fh_mode=b10).
fh_param<2:0>=b000 shows that the frame delivered is an empty frame and contains 1 data byte of value
0x00 after the header.
This kind of frame is delivered if the last frame in the FIFO was already read out or if the FIFO is empty. The
format is shown below.
Bit
7
6
5
4
3
2
1
0
Header
1
0
0
0
0
0
0
0
Data
0
0
0
0
0
0
0
0
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Confidential and under NDA
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Confidential and under NDA