BMA150 Bosch Sensortec, BMA150 Datasheet - Page 23

• Manufacturer Part Number: BMA150
• Description: 3-AXIS ACCELEROMETER DIGITAL I/F
• Manufacturer: Bosch Sensortec

Specifications of BMA150

• Axis: X, Y, Z
• Acceleration Range: ± 2g, 4g, 8g
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g
• Voltage - Supply: 2.4 V ~ 3.6 V
• Output Type: Digital
• Bandwidth: 3kHz
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Package / Case: 12-LGA
• For Use With: DM180021 - KIT STARTER MPLAB FOR PIC18F MCU828-1013 - BMA150 TRIBOX DEMO BOARD W/USB828-1009 - BMA150 DAUGHTERCARD FOR DEV KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 0273 141 043; 828-1003-2

3.5 Data registers
3.5.1 Temp
A thermometer (address 08h, bit 7-0) is embedded in BMA150. Temperature resolution is
0.5°C/LSB. Code 00h stands for lowest temperature which is -30°C. This minimum value can be
corrected by trimming of the offset of the temperature sensor IC (not described in this
datasheet).
3.5.2 Acc_x, acc_y, acc_z
Acceleration values are stored in the following registers to be read out through serial interface.
acc_x (02h, 7-6; 03h, 7-0)
acc_y (04h, 7-6; 05h, 7-0)
acc_z (06h, 7-6; 07h, 7-0)
The description of the digital signals acc_x, acc_y and acc_z is “2’s complement”.
From negative to positive accelerations, the following sequence for the ±2g measurement range
can be observed (±4g and ±8g correspondingly):
-2.000g
-1.996g
...
-0.004g
+0.004g
...
+1.992g
+1.996g
Data is periodically updated (rate 3kHz) with values from the digital filter output. LSB
acceleration bytes must be read first. After an acceleration LSB byte read access, the
corresponding MSB byte update can optionally be blocked until it is also accessed for read.
Thus, MSB / LSB mix from different samples can be avoided (section 3.1.6).
It is not possible to read-out only MSB bytes if shadow_dis=0, an LSB byte must first be read
out. To be able to read out only MSB byte, shadow_dis must be written to 1.
new_data_* flags on bits 0 of acc_x (LSB), acc_y (LSB) and acc_z (LSB) can be used to detect
if acceleration values have already been read out (section 3.5.3).
If systematic acceleration values read out is planned (for signal processing by the
microcontroller), the interrupt pad can be programmed to flag the new data (section 3.2.10).
Every time all temperature plus three axes values have been updated, the interrupt goes high
and microcontroller can read out data. With this method, microcontroller accesses are
synchronized with internal sensor IC updates.
Rev. 1.6
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such
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.
0.000g
:
:
:
:
:
:
10 0000 0000
10 0000 0001
11 1111 1111
:00 0000 0000
00 0000 0001
01 1111 1110
01 1111 1111
Triaxial, digital acceleration sensor
Data sheet
BMA150
Page 23
Bosch Sensortec
30 October 2008