BMA255 datasheet(14/119 Pages) BOSCH

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BMA255

Data sheet

Page 14

BST-BMA255-DS004-05 | Revision 1.2 | August 2014

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.

Low Power

Mode 1

Low Power

Mode 2

NORMAL

Mode

SUSPEND

Mode

DEEP-

SUSPEND

Mode

STANDBY

Mode

Low Power

Mode 1

Low Power

Mode 2

NORMAL

Mode

SUSPEND

Mode

DEEP-

SUSPEND

Mode

STANDBY

Mode

4.2 Power modes

The BMA255 has six different power modes. Besides normal mode, which represents the fully

operational state of the device, there are five energy saving modes: deep-suspend mode,

suspend mode, standby mode, low-power mode 1 and low-power mode 2.

The possible transitions between the power modes are illustrated in figure 2:

Figure 2: Power mode transition diagram

After power-up BMA255 is in normal mode so that all parts of the device are held powered-up

and data acquisition is performed continuously.

In deep-suspend mode the device reaches the lowest possible power consumption. Only the

interface section is kept alive. No data acquisition is performed and the content of the

configuration registers is lost. Deep suspend mode is entered (left) by writing ‘1’ (‘0’) to the

(0x11) deep_suspend bit while (0x11) suspend bit is set to ‘0’. The I

2C watchdog timer remains

functional. The (0x11) deep_ suspend bit, the (0x34) spi3 bit, (0x34) i2c_wdt_en bit and the

(0x34) i2c_wdt_sel bit are functional in deep-suspend mode. Equally the interrupt level and

driver configuration registers (0x20) int1_lvl, (0x20) int1_od, (0x20) int2_lvl, and (0x20) int2_od

are accessible. Still it is possible to enter normal mode by performing a softreset as described in

chapter 4.8. Please note, that all application specific settings which are not equal to the default

settings (refer to 6.2 register map), must be re-set to its designated values after leaving deep-

suspend mode.

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