Datasheet

BMM150 Geomagnetic Sensor

Page 21

BST-BMM150-DS001-01 | Revision 1.0 | April 2013

Bosch Sensortec

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

4.6.5 High-threshold interrupt

When the data registers’ (DATAX, DATAY and DATAZ) values exceed the threshold level

defined by the “High Threshold register (0x50), the corresponding interrupt status bits for those

axes are set (“High Int X”, “High Int Y” and “High Int Z” in register 0x4A). This is done for each

axis independently.

Hereby, one bit in “High Threshold” corresponds to roughly 6µT (not exactly, as the raw

magnetic field values DATAX, DATAY and DATAZ are not temperature compensated).

The High-threshold interrupt is issued on INT pin when one or more values of the data registers

DATAX, DATAY and DATAZ exceed the threshold level defined by the “High Threshold” register

(0x50), and when the axis where the threshold was exceeded is enabled for interrupt

generation:

Result =

(DATAX > “High Threshold” x 16) AND “High Int X en” is “0” OR

(DATAY > “High Threshold” x 16) AND “High Int Y en” is “0” OR

(DATAZ > “High Threshold” x 16) AND “High Int Z en” is “0”

Note:

Threshold interrupt enable bits (“High INT [XYZ] en”) are active low and “1” (disabled) by

default.

Figure 7: High-threshold interrupt function

4.6.6 Overflow

When a measurement axis had an overflow, the corresponding data register is saturated to the

most negative value. For X and Y axis, the data register is set to the value -4096. For the Z axis,

the data register is set to the value -16384.

The “Overflow” flag (register 0x4A bit6) indicates that the measured magnetic field raw data of

one or more axes exceeded maximum range of the device. The overflow condition can be

flagged on the INT pin by setting the bit “overflow int enable” (register 0x4D bit6, active high,

default value “0”). The channel on which overflow occurred can by determined by assessing the

DATAX/Y/Z registers.

High threshold

measurements

INT pin (non-latched)

INT pin (latched)

Read interrupt status

register (0x4A)

a

a