BMA020 Bosch Sensortec, BMA020 Datasheet - Page 20

• Manufacturer Part Number: BMA020
• Description: 3-AXIS ACCELEROMETER DIGITAL I/F
• Manufacturer: Bosch Sensortec

Specifications of BMA020

• Axis: X, Y, Z
• Acceleration Range: ± 2g, 4g, 8g
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g
• Voltage - Supply: 2 V ~ 3.6 V
• Output Type: Digital
• Bandwidth: 3kHz
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Package / Case: 12-LGA
• For Use With: 828-1014 - BMA020 TRIBOX DEMO BOARD W/USB828-1008 - BMA020 DAUGHTERCARD FOR DEV KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 828-1000-2

Data sheet
BMA020
Bosch Sensortec
Digital, triaxial acceleration sensor
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 BMA020 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 BMA020 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.
Rev. 1.2
Page 20
30 May 2008
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Note: Specifications within this document are subject to change without notice.