LPS25HB Datasheet, PDF (14/40 Pages) STMicroelectronics – MEMS pressure sensor: 260-1260 hPa absolute digital output barometer

FIFO
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FIFO
LPS25HB
The LPS25HB embeds 32-slot data FIFO to store the pressure output values. The FIFO
allows consistent power saving for the system, since the host processor does not need to
continuously poll data from the sensor, but it can wake up only when needed and burst the
significant data out from the FIFO.
This buffer can work according to seven different modes: Bypass mode, FIFO mode, Stream
mode, Stream-to-FIFO mode, Bypass-to-Stream mode, Bypass-to-FIFO mode and FIFO
Mean mode.
The FIFO buffer is enabled when the FIFO_EN bit in CTRL_REG2 (21h) is set to '1' and
each mode is selected by the F_MODE[2:0] bits in FIFO_CTRL (2Eh).
FIFO threshold status, FIFO overrun events and the number of unread samples stored are
available in the FIFO_STATUS (2Fh) register and can be set to generate dedicated
interrupts on the INT_DRDY pin in the CTRL_REG4 (23h) register.
Bypass mode
In Bypass mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '000'), the FIFO is not
operational and it remains empty.
FIFO mode
In FIFO mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '001'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h) are stored in
the FIFO.
A watermark interrupt can be enabled (STOP_ON_FTH bit set to '1' in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
bits of FIFO_CTRL (2Eh). The FIFO continues filling until it is full (32 slots of data for
pressure output). When full, the FIFO stops collecting data.
Stream mode
In Stream mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '010'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h) are stored in
the FIFO. The FIFO continues filling until it's full (32 slots of data for pressure output). When
full, the FIFO discards the older data as the new arrive. A watermark interrupt can be
enabled and set as in FIFO mode.
Stream-to-FIFO mode
In Stream-to-FIFO mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '011'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h) PRESS_OUT_L (29h) and PRESS_OUT_XL
(28h) are stored in the FIFO.
A Watermark interrupt can be enabled (STOP_ON_FTH bit set to '1' in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
DocID027112 Rev 2