Datasheet

Data Sheet

BMA456

Page 50

BST-BMA456-DS000-01 | Version 1.1 | October 2017 Bosch Sensortec

BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice.

4.10. Offset Compensation

BMA456 offers manual compensation as well as inline calibration.

Offset compensation is performed with pre-filtered data, and the offset is then applied to both, pre-

filtered and filtered data. If necessary the result of this computation is saturated to prevent any overflow

errors (the smallest or biggest possible value is set, depending on the sign).

The public offset compensation Registers OFFSET_0 to OFFSET_2 are images of the corresponding

registers in the NVM. With each image update the contents of the NVM registers are written to the

public registers. The public registers can be overwritten by the user at any time.

The offset compensation registers have a width of 8 bit using two’s complement notation. The offset

resolution (LSB) is 3.9 mg and the offset range is +- 0.5 g. Both are independent of the range setting.

Offset compensation needs to be enabled through NV_CONF.acc_off_en = 0b1

Manual Offset Compensation

The contents of the public compensation Register OFFSET_0 to OFFSET_2 may be set manually via

the digital interface. After modifying the Register OFFSET_0 to OFFSET_2 the next data sample is

not valid.

Offset compensation needs to be enabled through NV_CONF.acc_off_en.

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 manual offset compensation to determine the

proper compensation values and then storing these values permanently in the NVM.

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.