ISM303DAC datasheet(37/80 Pages) STMICROELECTRONICS

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ISM303DAC

Functionality

4.4.2

FIFO mode

In FIFO mode (FIFO_CTRL_A (25h) (FMODE [2:0])= 001) data from the X, Y and Z

channels are stored in the FIFO until it is full, when 256 unread samples are stored in

memory, data collecting is stopped.

To reset the FIFO content, Bypass mode should be written in the FIFO_CTRL_A (25h)

restart FIFO mode, writing the value '001' in FIFO_CTRL_A (25h) (FMODE [2:0]).

The FIFO buffer can memorize 256 slots of X, Y and Z data.

4.4.3

Continuous mode

Continuous mode (FIFO_CTRL_A (25h) (FMODE[2:0] = 110) provides a continuous FIFO

update: when 256 unread samples are stored in memory, as new data arrives the oldest

data is discarded and overwritten by the newer.

A FIFO threshold flag FIFO_CTRL_A (25h) (FIFO_FTH) is asserted when the number of

unread samples in FIFO is greater than or equal to FIFO_THS_A (2Eh) (FTH[7:0]).

It is possible to route FIFO_CTRL_A (25h)(FTH) to the INT1 pin by writing the INT1_FTH bit

to '1' in register CTRL4_A (23h) or to the INT2 pin by writing the INT2_FTH bit to '1' in

If an overrun occurs, the oldest sample in FIFO is overwritten and the FIFO_OVR flag in

FIFO_SRC_A (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_A (2Fh) and FIFO_SAMPLES_A (30h) (Diff[8:0]).

4.4.4

Continuous-to-FIFO mode

In Continuous-to-FIFO mode FIFO_CTRL_A (25h) (FMODE [2:0] = 011), FIFO operates in

Continuous mode and FIFO mode starts upon an internal trigger event. When the FIFO is

full, data collecting is stopped.

Figure 10. Continuous-to-FIFO mode

x31

y31

z31

xi,yi,zi

Continuous Mode

FIFO Mode

Trigger event

x31

y31

z31

xi,yi,zi

x30

y30

z30

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