Datasheet

Datasheet
BMM150 Geomagnetic Sensor
Page 17
BST-BMM150-DS001-01 | Revision 1.0 | April 2013 Bosch Sensortec
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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.
Table 4: Magnetometer advanced self-test control
(0x4C)
Adv.ST <1:0>
Configuration
00b
Normal operation
(no self-test), default
01b
Reserved, do not use
10b
Negative on-chip magnetic
field generation
11b
Positive on-chip magnetic
field generation
The BMM150 API/driver provided by Bosch Sensortec provides a comfortable way to perform
both self-tests and to directly obtain the result without further calculations. It is recommended to
use this as a reference.
4.5 Non-volatile memory
Some of the memory of the BMM150 magnetometer is non-volatile memory (NVM). This NVM is
pre-programmed in Bosch Sensortec fabrication line and cannot be modified afterwards. It
contains trimming data which are required for sensor operation and sensor data compensation,
thus it is read out by the BMM150 API/driver during initialization.
4.6 Magnetometer interrupt controller
Four magnetometer based interrupt engines are integrated in the BMM150: Low-Threshold,
High-Threshold, Overflow and Data Ready (DRDY). Each interrupt can be enabled
independently.
When enabled, an interrupt sets the corresponding status bit in the interrupt status register
(0x4A) when its condition is satisfied.
When the “Interrupt Pin Enable” bit (register 0x4E bit6) is set, any occurring activated interrupts
are flagged on the BMM150’s INT output pin. By default, the interrupt pin is disabled (high-Z
status).
Low-Threshold, High-Threshold and Overflow interrupts are mapped to the INT pin when
enabled, Data Ready (DRDY) interrupt is mapped to the DRDY pin of BMM150 when enabled.
For High- and Low-Threshold interrupts each axis X/Y/Z can be enabled separately for interrupt
detection in the registers “High Int Z en”, “High Int Y en”, “High Int X en”, “Low Int Z en”, “Low Int
Y En” and “Low Int X En” in register 0x4D bit5-bit0. Overflow interrupt is shared for X, Y and Z
axis.
When the “Data Ready Pin En” bit (register 0x4E bit7) is set, the Data Ready (DRDY) interrupt
event is flagged on the BMM150’s DRDY output pin (by default the “Data Ready Pin En” bit is
not set and DRDY pin is in high-Z state).
The interrupt status registers are updated together with writing new data into the magnetic field
data registers. The status bits for Low-/High-Threshold interrupts are located in register 0x4A,
the Data Ready (DRDY) status flag is located at register 0x48 bit0.
If an interrupt is disabled, all active status bits and pins are reset after the next measurement
was performed.