AN2381 datasheet(21/47 Pages) STMICROELECTRONICS

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AN2381

Registers Description

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5.2

Control registers

5.2.1

CTRL_REG1 (20h)

Control register #1.

PD1, PD0 bits allow to turn on the device. The device is in power-down mode when PD1,

PD0= “00” (default value after boot). The device is in normal mode when either PD1 or PD0

is set to 1.

DF1, DF0 bits allow to modify the decimation factor of the internal digital filter thus selecting

the data rate at which acceleration samples are produced. The default value is 00 which

corresponds to a data-rate of 40Hz (decimation factor of 512). By changing the content of

DF1, DF0 to “01”, “10” and “11” the selected data-rate will be set respectively equal to

160Hz, to 640Hz and to 2560Hz which correspond to a decimation of 128, 32, 8

respectively.

ST bit is used to activate the self test function. When the bit is set to 1, an output change will

occur to the device outputs thus allowing to check the functionality of the whole

measurement chain.

Zen bit enables the Z-axis measurement channel when set to 1. The default value is 1.

Yen bit enables the Y-axis measurement channel when set to 1. The default value is 1.

Xen bit enables the X-axis measurement channel when set to 1. The default value is 1.

PD1

PD0

DF1

DF0

Zen

Yen

Xen

PD1,

PD0

Power Down Control. Default value: 00

(00: power down mode; x1, 1x: normal mode)

DF1,

DF0

Decimation Factor Control. Default value: 00

(00: decimate by 512

01: decimate by 128

10: decimate by 32

11: decimate by 8)

Self Test Enable. Default value: 0

(0: normal mode; 1: self test enabled)

Zen

Z-axis enable. Default value: 1

(0: channel disabled; 1: channel enabled)

Yen

Y-axis enable. Default value: 1

(0: channel disabled; 1: channel enabled)

Xen

X-axis enable. Default value: 1

(0: channel disabled; 1: channel enabled)

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