BMA020 Bosch Sensortec, BMA020 Datasheet - Page 19

• 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
3.3 Control registers
All single control bits are active at 1.
3.3.1 Reset_INT
This interrupt (address 0Ah, bit 6) is reset (interrupt pad goes to low) each time this bit is written
to 1.
3.3.2 Selftest_0
The self-test command (address 0Ah, bit 2) uses electrostatic forces to move the MEMS
common electrode. The result from selftest can be verified by reading st_result (section 3.4.1).
During the self-test procedure no external change of the acceleration should be generated.
3.3.3 Selftest_1
This self test bit (address 0Ah, bit3) does not generate any electrostatic force in the MEMS
element but is used to verify the interrupt function is working correctly and that microprocessor
is able to react to the interrupts.
0g acceleration is emulated at ADC input and the user can detect the whole logic path for
interrupt, including the PCB path integrity. The LG_thres register must be set to about 0.4g
while LG_dur = 0 to generate a low-g interrupt
3.3.4 Soft_reset
BMA020 is reset each time this bit (address 0Ah, bit 1) is written to 1. The effect is identical to
power-on reset. Control, status and image registers are reset to values stored in the default
setting registers (see also memory map). After soft_reset or power-on reset BMA020 comes up
in normal mode or wake-up mode. It is not possible to boot BMA020 to sleep mode.
No serial transaction should occur within 10µs after soft_reset command.
The soft_reset procedure may overwrite the SPI4 setting (section 3.1.1). Thus the correct
interface configuration may have to be updated.
3.3.5 Sleep
This bit (address 0Ah, bit 0) turns the sensor IC in sleep mode. Control and image registers are
not cleared.
When BMA020 is in sleep mode no operation can be performed but wake-up the sensor IC by
setting sleep=0 or soft_reset. As a consequence all write and read operations are forbidden
when the sensor IC is in sleep mode except command used to wake up the device or soft_reset
command. After sleep mode removal, it takes 1ms to obtain stable acceleration values (>99%
data integrity).
Rev. 1.2
Page 19
30 May 2008
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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.