LPS35HW datasheet(16/48 Pages) STMICROELECTRONICS

16 / 48 page

FIFO

LPS35HW

16/48

DocID029129 Rev 1

4.2

FIFO mode

In FIFO mode (FIFO_CTRL(FMODE2:0) = 001) data from the output

PRESS_OUT_H(2Ah), PRESS_OUT_L(29h), PRESS_OUT_XL(28h) and

TEMP_OUT_H(2Ch), TEMP_OUT_L(2Bh) are stored in the FIFO until it is overwritten.

To reset FIFO content, Bypass mode the value '000' must be written in

FIFO_CTRL(FMODE2:0). After this reset command it is possible to restart FIFO mode

writing the value '001' in FIFO_CTRL(FMODE2:0).

FIFO buffer memorizes 32 levels of data but the depth of the FIFO can be resized by

setting the CTRL2(STOP_ON_FTH) bit. If the STOP_ON_FTH bit is set to '1', FIFO depth

is limited to FIFO_CTRL(WTM4:0) + 1 data.

A FIFO threshold interrupt can be enabled (F_OVR bit in CTRL3(12h) in order to be raised

when the FIFO is filled to the level specified by the WTM4:0 bits of FIFO_CTRL(14h).

When a FIFO threshold interrupt occurs, the first data has been overwritten and the FIFO

stops collecting data from the input pressure and temperature.

Figure 7: FIFO mode

4.3

Stream mode

Stream mode (FIFO_CTRL(FMODE2:0) = 010) provides continuous FIFO update: as new

data arrive, the older is discarded.

Once the entire FIFO has been read, the last data read still remains in the FIFO and hence

once a new sample is acquired, the FIFO_STATUS(FSS5:0) value rises from 0 to 2.

An overrun interrupt can be enabled, CTRL3(F_OVR) = '1', in order to inform when the

FIFO is full and eventually read its content all at once. If an overrun occurs, the oldest

sample in FIFO is overwritten, so if the FIFO was empty, the lost sample has already been

read.

LPS35HW 데이터시트(PDF) 16 Page - STMicroelectronics