LPS22HH datasheet(17/59 Pages) STMICROELECTRONICS

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LPS22HH

FIFO

The LPS22HH embeds 128 slots of 40-bit data FIFO to store the pressure and temperature

output values. This 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 six different modes:



Bypass mode



FIFO mode



Continuous (Dynamic-Stream) mode



Continuous (Dynamic-Stream)-to-FIFO mode



Bypass-to-Continuous (Dynamic-Stream)



Bypass-to-FIFO mode

The FIFO buffer is enabled when a configuration different from all bits '0' are written in

FIFO_CTRL (13h) and each mode is selected by the TRIG_MODES bit and F_MODE[1:0]

bits in FIFO_CTRL (13h). Programmable FIFO threshold status, FIFO overrun events and

the number of unread samples stored are available in the FIFO_STATUS1 (25h) and

FIFO_STATUS2 (26h) registers and can be set to generate dedicated interrupts on the

INT_DRDY pad using the CTRL_REG3 (12h) register.

FIFO_STATUS2 (26h)(FIFO_WTM_IA) goes to '1' when the number of unread samples

(FIFO_STATUS1 (25h)(FSS[7:0]) is greater than or equal to WTM[6:0] in FIFO_WTM

(14h). If FIFO_WTM (14h)(WTM[6:0]) is equal to 0, FIFO_STATUS2 (26h)(FIFO_WTM_IA)

stays at '0'.

FIFO_STATUS2 (26h)(FIFO_OVR_IA) is equal to '1' if a FIFO slot is overwritten.

FIFO_STATUS1 (25h)(FSS[7:0]) contains stored data levels of unread samples; when

FSS[7:0] is equal to ‘00000000’, FIFO is empty; when FSS[7:0] is equal to ‘10000000’,

FIFO is full and the unread samples are 128.

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