BMA255 datasheet(24/119 Pages) BOSCH

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BMA255

Data sheet

Page 24

BST-BMA255-DS004-05 | Revision 1.2 | August 2014

Bosch Sensortec

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.

correction process is reflected in the status bit (0x36) cal_rdy. Bit (0x36) cal_rdy is ‘0’ while the

correction is in progress. Otherwise it is ‘1’. Bit (0x36) cal_rdy is ´0´ when (0x36) cal_trigger is

not ´00´.

For the fast offset compensation, the compensation target can be chosen by setting the bits

(0x37) offset_target_x, (0x37) offset_target_y, and (0x37) offset_target_z according to Table 9:

Table 9: Offset target settings

(0x37)

offset_target_x/y/z

Target value

00b

01b

+1g

10b

-1g

11b

Fast compensation should not be used in combination with any of the low-power modes. In low-

power mode the conditions (availability of necessary data) for proper function of fast

compensation are not fulfilled.

4.5.3 Manual compensation

The contents of the public compensation registers (0x38, 0x39, 0x3A) offset_filt_x/y/z can be

set manually via the digital interface. It is recommended to write into these registers directly

after a new data interrupt has occurred in order not to disturb running offset computations.

Writing to the offset compensation registers is not allowed while the fast compensation

procedure is running.

4.5.4 Inline calibration

For certain applications, it is often desirable to calibrate the offset once and to store the

compensation values permanently. This can be achieved by using one of the aforementioned

offset compensation methods to determine the proper compensation values and then storing

these values permanently in the NVM. See section 4.6 Non-volatile memory for details of the

storing procedure.

Each time the device is reset, the compensation values are loaded from the non-volatile

memory into the image registers and used for offset compensation until they are possibly

overwritten using one of the other compensation methods.

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