Datasheet
Data Sheet
BMA456
Page 24
BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec
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BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
4.5. FIFO
The device supports the following FIFO operating modes:
Streaming mode: overwrites oldest data on FIFO full condition
FIFO mode: discards newest data on FIFO full condition
The FIFO depth is 1024 byte and supports the following interrupts:
FIFO full interrupt
FIFO watermark interrupt
FIFO is enabled with FIFO_CONFIG_1.fifo_acc_en=0b1 (0b0= disabled). To enable the FIFO for the
auxiliary interface (magnetometer) set FIFO_CONFIG_1.fifo_aux_en=0b1 (0b0=disabled).
Frames
The FIFO captures data in frames, which consist of a header and a payload. The FIFO can be
configured to skip the header (headerless mode) in which case only payload is stored.
In header mode (standard configuration) each regular frame consists of a one byte header
describing properties of the frame, (which sensors are included in this frame) and the data
itself. Beside the regular frames, there are control frames.
In headerless mode the FIFO contains sampled data only.
Header mode
The header has a length of 8 bit and the following format:
Bit
7
6
5
4
3
2
1
0
Content
fh_mode<1:0>
fh_parm<3:0>
fh_ext<1:0>
These fh_mode and fh_parm and fh_ext fields are defined below
fh_mode<1:0>
Definition
fh_parm <3:0>
fh_ext<1:0>
0b10
Regular
Enabled sensors
Tag of INT2 and INT1
0b01
Control
Control opcode
0b00 and 0b11
Reserved
Na
f_parm=0b0000 is invalid for regular mode, a header of 0x80 indicates an uninitialized frame.
In a regular frame, fh_parm frame defines which sensors are included in the data part of the frame.
The format is
Name
fh_parm<3:0>
Bit
3
2
1
0
Content
Reserved
FIFO_aux_data
Reserved
FIFO_acc_data