LPS25HB datasheet(15/40 Pages) STMICROELECTRONICS

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LPS25HB

FIFO

bits of FIFO_CTRL (2Eh).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. Once a

trigger event occurs, the FIFO starts operating in FIFO mode. A trigger event can be

configured in INTERRUPT_CFG (24h).

4.5

Bypass-to-Stream mode

In Bypass-to-Stream mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '100'), the FIFO is in

Bypass mode until a trigger event occurs and the FIFO starts operating in Stream mode. A

trigger event can be configured in INTERRUPT_CFG (24h).

4.6

FIFO Mean mode

In FIFO Mean mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '110'), the pressure data are

not directly sent to the output register but are first stored in the FIFO to calculate the

average. In this mode the FIFO is used to implement a moving average of the pressure data

with a 2, 4, 8, 16 or 32 sample set by changing the watermark defined by the

WTM_POINT[4:0] bits of FIFO_CTRL (2Eh) (refer to Table 8).

There are two possible ways of providing the output pressure data averaged by FIFO:

If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to '0', the output is at the same

ODR of the data coming from the sensor;

If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to '1', the output is decimated

(@1 Hz when ODR = 4 or 2; @1.04 Hz when ODR=3).

Please note that when using the FIFO Mean mode it is not possible to access the FIFO

content.

4.7

Bypass-to-FIFO mode

In Bypass-to-FIFO (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '111'), the FIFO is in Bypass

mode until a trigger event occurs and the FIFO starts operating in FIFO mode. A trigger

event can be configured in INTERRUPT_CFG (24h).

Table 8. Running average sample size

WTM_POINT[4:0]

FIFO_MEAN_MODE sample size

00001

2-sample moving average

00011

4-sample moving average

00111

8-sample moving average

01111

16-sample moving average

11111

32-sample moving average

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