Datasheet

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