LSM303AGR datasheet(27/68 Pages) STMICROELECTRONICS

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LSM303AGR

Functionality

4.2.2

Accelerometer 6D / 4D orientation detection

The LSM303AGR includes 6D / 4D orientation detection which applies only to the

accelerometer.

In this configuration the interrupt is generated when the device is stable in a known

direction. In 4D configuration, detection of the position of the Z-axis is disabled.

4.2.3

Accelerometer activity/inactivity function

The Activity/Inactivity recognition function allows reducing the power consumption of the

accelerometer block in order to supply other smart applications and is applicable only to the

accelerometer block of the device.

When the Activity/Inactivity recognition function is activated, accelerometer is able to

automatically go to 10 Hz sampling rate and to wake up as soon as the interrupt event has

been detected, increasing the output data rate and bandwidth.

With this feature the system may be efficiently switched from/to low-power mode to full

performance depending on user-selectable positioning and acceleration events, thus

ensuring power saving and flexibility.

The Activity/Inactivity recognition function is activated by writing the desired threshold in the

Act_THS_A (3Eh) register. The high-pass filter is automatically enabled.

Table 16. Activity/Inactivity function control registers

When the acceleration becomes smaller than the threshold for at least the duration

(8*ACT_DUR+1)/ODR, the ODR [3:0] bits of CTRL_REG1_A (20h) are bypassed (Inactivity)

and internally set to 10 Hz (ODR [3:0] = 0010), but the content of the CTRL_REG1_A

(20h)(ODR [3:0]) bits are left untouched.

When the acceleration becomes greater than the threshold (Act_THS_A (3Eh)),

CTRL_REG1_A (20h) is restored immediately (Activity).

Once the Activity/Inactivity detection function is enabled, it will be applied to the INT_2 pin

by setting the CTRL_REG6_A (25h) (P2_ACT) bit to ‘1’.

To disable the Activity/Inactivity detection function, set the content of the Act_THS_A (3Eh)

1344

185

1620

100

5376

185

Table 15. Current consumption of operating modes (continued)

Operating

mode [Hz]

Low-power mode

(8-bit data output)

[μA]

Normal mode

(10-bit data output)

[μA]

High resolution

(12-bit data output)

[μA]

LSB value

ACT_THS_A

Full scale / 128 [mg]

ACT_DUR_A

8/ODR [s]

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