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Data sheet

BMA220

Page 10

BST-BMA220-DS003-08 | Revision 1.15 | August 2011 Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice.

4.1.2 Low-power mode configuration

The BMA220 supports a low-power mode. In this low-power mode, the chip wakes up

periodically, enables the interrupt controller and goes back to sleep if no interrupt has occurred.

The procedure is the following:

1. Wake-up.

2. Enable analog front-end and convert acceleration data until the low-pass filters have

settled.

3. Enable integrated interrupt controller and evaluate interrupt conditions.

Once the interrupt conditions have been evaluated and no interrupt has occurred, the

chip goes back to sleep. If no interrupt is enabled, the acceleration for x-, y- and z-axes

are converted once and then the chip goes back to sleep.

4. Sleep for the programmed duration.

Figure 3: sleep and awake phases

The low-power mode can be enabled by setting the sleep_en bit in Reg. 0x0F (SPI) / 0x1E

C) and by enabling the data ready interrupt (or any other interrupt, see chapter 5). The sleep

duration can be configured via the sleep_dur bits in Reg 0x0F (SPI) / 0x1E (I

C).

Table 3: Sleep durations for low-power mode

sleep_dur setting Sleep Duration

000 2ms

001 10ms

010 25ms

011 50ms

100 100ms

101 500ms

110 1s

111 2s

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 62 63

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