LPS35HW Datasheet, PDF (16/48 Pages) STMicroelectronics – Embedded temperature compensation

FIFO
4.2
FIFO mode
LPS35HW
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.
16/48
DocID029129 Rev 1