BMA020 datasheet(13/50 Pages) BOSCH

13 / 50 page

Data sheet

BMA020

Digital, triaxial acceleration sensor

Bosch Sensortec

Rev. 1.2

Page 13

30 May 2008

as copying and passing on to 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.

3.2 Interrupt settings

Five different types of interrupts can be programmed. When the corresponding criterion

becomes valid, the interrupt pin is triggered to a high level. All interrupt criteria are combined

and drive the interrupt pad with a Boolean <OR> condition.

Interrupt generations may be disturbed by changes of control bits because some of these bits

influence the interrupt calculation. As a consequence, no write sequence should occur when

microprocessor is triggered by interrupt or the interrupt should be deactivated on the

microprocessor side when write sequences are operated.

Interrupt criteria are using digital code coming from digital filter output. As a consequence all

thresholds are scaled with range selection (section 3.1.3.2). Timings used for high acceleration

and low acceleration debouncing are absolute values (1 LSB of HG_dur and LG_dur registers

corresponds to 1 millisecond, timing accuracy is proportional to oscillator accuracy = +/-10%),

thus it does not depend on selected bandwidth. Timings used for any motion interrupt and alert

detection are proportional to bandwidth settings (section 3.1.3).

3.2.1 Enable_LG

This bit (address 0Bh, bit 0) enables the LG_thres criteria to generate an interrupt.

3.2.2 Enable_HG

This bit (address 0Bh, bit 1) enables the HG_thres criteria to generate an interrupt.

3.2.3 Enable_adv_INT

This bit (address 15h, bit 6) is used to disable advanced interrupt control bits (any_motion,

alert). If enable_adv_INT=0, writing to these bits has no effect on sensor IC function.

3.2.4 Any_motion

This bit ((address 0Bh, bit 6)enables the any motion criteria to generate directly an interrupt. It

can not be turned on simultaneously with alert. This bit can be masked by enable_ adv_INT, the

value of this bit is ignored when enable_adv_INT=0 (section 3.2.3).

3.2.5 Alert

If this bit (address 0Bh, bit 7) is at 1, the any_motion criterion will set BMA020 into alert mode

(section 3.2.9). This bit can be masked by enable_adv_INT, the value of this bit is ignored when

enable_adv_INT=0 (section 3.2.3).

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