Datasheet

Preliminary Data Sheet

BMA400

Page 32 /

Confidential

BST-BMA400-DS000-00 | Version 0.1 | November 2017 Bosch Sensortec

BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice.

FIFO read out

The FIFO can be read out via FIFO_DATA register in a single burst read, this allows a complete

reading of the FIFO content within one burst read transaction.

FIFO read out is not supported in Sleep mode.

FIFO read out is supported in normal and Low-power mode if FIFO_PWR_CONFIG.fifo_read_en =

‘1’. The minimum delay T

fifo_read

has to be applied between the write command of

FIFO_PWR_CONFIG.fifo_read_en =‘1’ and the start of FIFO read. Don’t read the FIFO when

FIFO_PWR_CONFIG.fifo_read_en =‘0’.

FIFO overflow behavior

A FIFO overflow occurs if the FIFO is full and a new data is to be written to the FIFO. FIFO full

means free space is less than maximum frame length of 9 bytes. The largest frame is 7 bytes long,

however each time FIFO is written (at the end of the measurement), 9 bytes can be written to the

FIFO in total, consisting of 2 frames: one with the measurement results (maximum of 7 bytes), and

configuration change frame consisting of 2 bytes. The definition of the full interrupt uses 9 bytes limit

to give the host system time to react to it before the FIFO overflows.

In case of overflow the FIFO can either stop recording data or overwrite the oldest data. The

behavior is controlled by register fifo_stop_on_full.

Streaming mode, fifo_stop_on_full = ’0’: if the new frame does not fit inside the remaining free space

in the FIFO RAM, FIFO will repeatedly delete the oldest frame until it creates enough space for the

new one.

FIFO stop-on-full mode, fifo_stop_on_full = ’1’: The newest frame is discarded.

Normal operation resumes if the FIFO full condition no longer persists.

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Seeed Studio

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Seeed Studio

Confidential and under NDA