LSM9DS1 Datasheet, PDF (24/72 Pages) –

LSM9DS1 functionality
LSM9DS1
3.5.2
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 by
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.
Figure 11. FIFO mode
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3.5.3
Continuous mode
Continuous mode (FIFO_CTRL (2Eh)(FMODE[2:0] = 110) provides continuous FIFO
update: as new data arrives the older is discarded.
A FIFO threshold flag FIFO_SRC (2Fh)(FTH) is asserted when the number of unread
samples in FIFO is greater than or equal to FIFO_CTRL (2Eh)(FTH4:0).
It is possible to route FIFO_SRC (2Fh)(FTH) to the INT1_A/G pin by writing in register
INT1_CTRL (0Ch) (INT1_FTH) = '1', or to the INT2_A/G pin by writing in register
INT2_CTRL (0Dh) (INT2_FTH) = '1'.
A full-flag interrupt can be enabled, (INT1_CTRL (0Ch) (INT_ FSS5)= '1’) when the FIFO
becomes saturated and in order to read the contents all at once.
If an overrun occurs, the oldest sample in FIFO is overwritten and the OVRN flag in
FIFO_SRC (2Fh) is asserted.
In order to empty the FIFO before it is full it is also possible to pull from FIFO the number of
unread samples available in FIFO_SRC (2Fh) (FSS[5:0]).
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