BMP388 datasheet(18/59 Pages) BOSCH

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Bosch Sensortec | BMP388 Datasheet

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Modifications reserved |Data subject to change without notice | Printed in Germany

Document number: BST-BMP388-DS001-07 Revision_1.7_112020

3.6.

FIFO Description

The BMP388 contains a 512 Bytes FIFO (first-in-first-out) data buffer. To enable data collecting in the FIFO, fifo_mode is set

at ‘1’ and data to be collected are defined through fifo_press_en and fifo_temp_en. The FIFO mode is disabled, when no

writing is defined which according to the following two cases:

•

fifo_mode=’0’

•

fifo_mode=’1’ and fifo_press_en=’0’ and fifo_temp_en=’0’

If the FIFO is disabled when FIFO byte count is greater than 0, no new frame is written to the FIFO, but FIFO is operational:

•

Frames already written in the FIFO remain stored and can be read out

•

FIFO interrupts and their corresponding statuses are still evaluated

•

after all bytes are read out, Sensortime (if enabled) and Empty frames are generated

•

FIFO can be flushed

3.6.1. FIFO input data

Storing of pressure and/or temperature measurement results is enabled by setting fifo_press_en=’1’ and fifo_temp_en=’1’

respectively. Storing of data can be enabled or disabled on a per-channel basis in any combination. Filtered or unfiltered data

are stored to the FIFO; if data_select=”01”, filtered data are stored, otherwise unfiltered data are stored to the FIFO. The

Number of bytes available in FIFO is readable through fifo_length_1<0> (MSBs) and fifo_length_0<7:0> (LSBs) registers.

The FIFO byte count registers fifo_length_0 and fifo_length_1 are updated only when a full frame has been written to FIFO

and is available for read-out. FIFO byte count registers are also updated after each full-frame read from the FIFO.

FIFO byte count registers increment or decrement is equal to frame length; intermediate increments (corresponding to a

partial frame) are not readable.

3.6.2. FIFO data sampling selection

The FIFO input data rate is reduced by selecting a down-sampling factor in register fifo_subsampling. Down-sampling factor

ranges from 1 to 128 and is equal to 2fifo_subsampling. Down-sampling is applied in the normal mode only and is aligned to the

measurement timing grid. Down-sampling counter is reset and data saved to the FIFO at the end of the first measurement

when a transition from sleep mode to normal mode occurs.

3.6.3. FIFO read out

FIFO is read out via fifo_data register. FIFO reads are never blocked, however an ongoing read from the FIFO does not block

writing to the FIFO.

During burst read, the address counter stops incrementing when fifo_data address is reached; this allows a complete reading

of the FIFO content within one burst read transaction.

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