AN4650 datasheet(75/102 Pages) STMICROELECTRONICS

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AN4650

First-in first-out (FIFO) buffer

102

8.1.2

FIFO_CTRL2 (07h)



TIMER_PEDO_FIFO_EN enables step counter and time stamp data to be stored as

the 4th FIFO data set. The content of the 6 bytes stored in the FIFO when this bit is set

to 1 is described in Section 8.8.



TIMER_PEDO_FIFO_DRDY. When this bit is set to 1 and the DATA_VALID_SEL_FIFO

bit in the MASTER_CONFIG register is set to 0, all the data are stored in the FIFO

every time a new step has been detected by the step counter. See Section 8.3 for

details.



FTH_[11:8] contains the upper part of the FIFO threshold level. For the complete

threshold level configuration, consider also the FTH_[7:0] bits in the FIFO_CTRL1

8.1.3

FIFO_CTRL3 (08h)

The FIFO_CTRL3 register contains the accelerometer and gyroscope FIFO decimation

factors, used to choose if the data of these sensors have to be stored in the FIFO and at

which rate they are stored.

When the DEC_FIFO_GYRO[2:0] bits are set to 000b, the 1st FIFO data set (reserved for

gyroscope data) is not stored in the FIFO. When the DEC_FIFO_XL[2:0] bits are set to

000b, the 2nd FIFO data set (reserved for accelerometer data) is not stored in the FIFO.

Note:

It’s required to set at least one of the four decimation factors to 1 (no decimation).

Table 54. FIFO_CTRL2 register

TIMER_PE

DO_FIFO_

TIMER_PE

DO_FIFO_

DRDY

FTH_11

FTH_10

FTH_9

FTH_8

Table 55. FIFO_CTRL3 register

DEC_FIFO

_GYRO2

DEC_FIFO

_GYRO1

DEC_FIFO

_GYRO0

DEC_FIFO

_XL2

DEC_FIFO

_XL1

DEC_FIFO

_XL0

Table 56. Gyroscope FIFO decimation setting

DEC_FIFO_GYRO [2:0]

Configuration

000

Gyroscope sensor not in FIFO

001

No decimation

010

Decimation with factor 2

011

Decimation with factor 3

100

Decimation with factor 4

101

Decimation with factor 8

110

Decimation with factor 16

111

Decimation with factor 32

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