Datasheet

Preliminary Data Sheet
BMA400
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Confidential
BST-BMA400-DS000-00 | Version 0.1 | November 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.
Under-read
In case the FIFO is under-read (not all frames were taken from the FIFO, but the last frame read was
read entirely), the next readout will continue at the frame that was just about to be sent.
Partial frame read
In case the FIFO is under-read and a partial data frame read occurred (not all frames were taken from
the FIFO, and the last frame read was not read entirely), the entire last data frame is repeated upon
the next read access.
When fifo_stop_on_full=‘0’ oldest frames are overwritten when new frames are available and the FIFO
is full.
When this happens, the partially read data frame is not repeated but the oldest frame available in the
memory is sent instead.
Sensortime frame is not repeated when it is read only partially.
If the read of a frame is interrupted during the frame's last byte read, this partial read is not recognized
and the frame is discarded like a fully read frame.
Over-read
If the burst read continues after all frames have been read out, a sensortime frame is sent after the
FIFO becomes empty during a burst read operation if fifo_time_en=’1’. After that or when FIFO was
completely read, the empty frame is returned as long as the burst read is active.
Reading nearly-empty FIFO
FIFO contains a reading cache buffer for a complete frame. When there is only one unread byte left in
the reading buffer, the FIFO starts prefetching the next frame from the memory to be ready for burst
reading if there is any further frame, or it evaluates itself as empty.
If new data frames/config frames are written to the FIFO before this reading event, the FIFO will
behave as containing one further frame and the new frame will be made available for reading as the
next frame. If new data/config frames are written to the FIFO after the moment when "only one unread
byte is left in the buffer", then user will see the FIFO as empty after the current frame will be finished.
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