LIS2DUX12 datasheet(20/102 Pages) STMICROELECTRONICS

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5.1.5

Bypass-to-continuous mode

In bypass-to-continuous mode FIFO_CTRL (15h) (FIFO_MODE[2:0] = 100), data measurement storage inside

FIFO starts in continuous mode upon an edge trigger event.

The trigger event could be single/double/triple-tap, wake-up, free-fall, 6D interrupt or any combination of these

events, but every interrupt has to be routed to the corresponding pin to be used as a trigger. The sample that

generated the trigger is available in FIFO.

5.1.6

Bypass-to-FIFO

In bypass-to-FIFO mode FIFO_CTRL (15h)(FIFO_MODE_[2:0] = 111), data measurement storage inside FIFO

operates in FIFO mode when selected triggers are equal to 1, otherwise FIFO content is reset (bypass mode).

The trigger event could be single/double/triple-tap, wake-up, free-fall, 6D interrupt or any combination of these

events, but every interrupt has to be routed to the corresponding pin to be used as a trigger.

The sample that generated the trigger is available in FIFO.

5.1.7

FIFO reading procedure

When FIFO is enabled and the mode is different from bypass, reading the FIFO output registers return the oldest

FIFO sample set. Whenever these registers are read, their content is moved to the SPI/I²C/MIPI I3C® output

buffer.

The data stored in FIFO are accessible from dedicated registers and each FIFO word is composed of 7

bytes: one tag byte (FIFO_DATA_OUT_TAG (40h), in order to identify the sensor, and 6 bytes of fixed data

(FIFO_DATA_OUT registers from (41h) to (46h)).

The FSS[7:0] field in the FIFO_STATUS2 (27h) registers contains the number of words (1 byte TAG + 6 bytes

DATA) collected in FIFO.

Meta information about accelerometer configuration changes can be managed by enabling the CFG_CHG_EN bit

in FIFO_CTRL (15h).

The entire FIFO content is retrieved by performing a certain number of read operations from the FIFO output

registers until the buffer becomes empty (FSS[7:0] bits of the FIFO_STATUS2 (27h) register are equal to 0).

FIFO output data must be read with multiples of 7-byte reads starting from the FIFO_DATA_OUT_TAG (40h)

The rounding function (automatic wraparound) from address FIFO_DATA_OUT_Z_L (45h) and

FIFO_DATA_OUT_Z_H (46h) to FIFO_DATA_OUT_TAG (40h) is done automatically in the device, in order to

allow reading many words with a unique multiple read operation.

The recommended way to retrieve data from the FIFO is the following:

Read the FIFO_STATUS2 (27h) register to check how many words are stored in the FIFO. This information

is contained in the FSS[7:0] bits.

For each word in FIFO, read the FIFO word (tag and output data) and interpret it on the basis of the FIFO

tag.

Go to step 1.

5.1.8

FIFO empty condition

When FIFO is emptied, a dedicated FIFO tag value (equal to 00000) is used in order to recognize an empty

condition and no duplicated samples are read.

LIS2DUX12

FIFO

DS14071 - Rev 2

page 20/102

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