LSM6DB0 datasheet(26/66 Pages) STMICROELECTRONICS

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Accelerometer and gyroscope functionality

LSM6DB0

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FIFO_SRC (2Fh) (FTH) goes to '1' when the number of unread samples (FIFO_SRC (2Fh)

(FSS5:0)) is greater than or equal to FTH [4:0] in FIFO_CTRL (2Eh). If FIFO_CTRL (2Eh)

(FTH[4:0]) is equal to 0, FIFO_SRC (2Fh) (FTH) goes to ‘0’.

FIFO_SRC (2Fh) (OVRN) is equal to '1' if a FIFO slot is overwritten.

FIFO_SRC (2Fh) (FSS [5:0]) contains stored data levels of unread samples. When FSS

[5:0] is equal to ‘000000’, FIFO is empty, when FSS [5:0] is equal to ‘100000’, FIFO is full

and the unread samples are 32.

The FIFO feature is enabled by writing '1' in CTRL_REG9 (23h) (FIFO_EN).

To guarantee the correct acquisition of data during the switching into and out of FIFO mode,

the first sample acquired must be discarded.

7.2.1

Bypass mode

In Bypass mode (FIFO_CTRL (2Eh)(FMODE [2:0]= 000), the FIFO is not operational and it

remains empty.

Bypass mode is also used to reset the FIFO when in FIFO mode.

As described in Figure 9, for each channel only the first address is used. When a new data

is available the old data is overwritten.

Figure 9. Bypass mode

7.2.2

FIFO mode

In FIFO mode (FIFO_CTRL (2Eh) (FMODE [2:0] = 001) data from the output channels are

stored in the FIFO until it is overwritten.

To reset FIFO content, Bypass mode should be selected by writing FIFO_CTRL (2Eh)

(FMODE [2:0]) to '000'. After this reset command, it is possible to restart FIFO mode, writing

FIFO_CTRL (2Eh) (FMODE [2:0]) to '001'.

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

setting the STOP_ON_FTH bit in CTRL_REG9 (23h). If the STOP_ON_FTH bit is set to '1',

FIFO depth is limited to FIFO_CTRL (2Eh)(FTH [4:0]) + 1 data.

A FIFO threshold interrupt can be enabled (INT_OVR bit in INT1_CTRL (0Ch) ) in order to

be raised when the FIFO is filled to the level specified by the FTH[4:0] bits of FIFO_CTRL

(2Eh). When a FIFO threshold interrupt occurs, the first data has been overwritten and the

FIFO stops collecting data from the input channels.

x31

y31

z31

xi,yi,zi

empty

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