BMA150 datasheet(22/56 Pages) BOSCH

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Data sheet

BMA150

Triaxial, digital acceleration sensor

Bosch Sensortec

Rev. 1.6

Page 22

30 October 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.

3.4 Status registers

3.4.1 St_result

This is the self test result bit (address 09h, bit 7). It can be used together with selftest_0 control

bit (section 3.3.4). After selftest_0 has been set, self-test procedure starts. At the end selftest_0

is written to 0 and microcontroller can react by reading st_result bit. When st_result=1 the self

test passed successfully.

The result of the st_result can be taken into account to evaluate the basic function of the sensor.

Note: Evaluation of the st_result bit should only be understood as one part of a wider

functionality test. It should not be taken into consideration as the only criterion.

3.4.2 Alert_phase

This status bit (address 09h, bit 4) is set when BMA150 has been set to alert mode (section

3.2.5) and an any motion criterion has been detected. During alert phase, HG_dur and LG_dur

variables are decreased to have a smaller reaction time when HG_thres and LG_thres

thresholds are crossed; the decrease rate is by 1 ms per ms.

The alert mode is reset when an interrupt generated due to a high threshold or a low threshold

event or when both HG_dur and LG_dur variables are at 0. When alert is reset, HG_dur and

LG_dur variables come back to their original values stored in image registers.

3.4.3 LG_latched, HG_latched

These status bits (address 09h, bit 3 and address 09h, bit 2) are set when the corresponding

criteria have been issued. They are latched and thus only the microcontroller can reset them.

When both high acceleration and low acceleration thresholds are enabled, these bits can be

used by microprocessor to detect which criteria generated the interrupt.

3.4.4 Status_LG, status_HG

These status bits (address 09h, bit 1 and address 09h, bit 2) are set when the corresponding

criteria have been issued; they are automatically reset by BMA150 when the criteria disappear.

3.4.5 Customer_reserved 1, customer_reserved 2

Both bytes (address 12h, bit 7-0 and address 13h, bit 7-0) can be used by customer. Writing or

reading of these registers has no effect on the sensor IC functionality.

If information has to be stored in a non-volatile memory addresses 32h and 33h have to be

used. The write access to EEPROM takes ca. 30ms. Since EEPROM has limited write cycle

lifetime special care has to be taken to this issue.

BMA150 Datasheet(PDF) 22 Page - Bosch Sensortec GmbH