The HMC5883L utilizes Honeywell’s Anisotropic
Magneto resistive (AMR) technology that provides advantages over
other magnetic sensor technologies. These anisotropic, directional sensors
feature precision in-axis sensitivity and linearity. These sensors’
solid-state construction with very low cross-axis sensitivity is designed to
measure both the direction and the magnitude of Earth’s magnetic fields,
from Milli-Gauss to 8 Gauss. Honeywell’s Magnetic Sensors are among the most
sensitive and reliable low field sensors in the industry.
Triple Axis Magnetometer:
Features
- I2C digital interface
- 3-axis magnetorestive sensors.
- Low voltage operations.
- Sensors can be used in strong magnetic field environments.
Applications
- Weapon systems positioning.
- Heart beat monitors.
- Locating objects such as submarines, sunken ships.
- Can be deployed in spacecraft.
- Weather prediction.
Working
The Honeywell HMC5883L
magnetoresistive sensor circuit is a trio of sensors and application specific
support circuits to measure magnetic fields. With power supply applied, the
sensor converts any incident magnetic field in the sensitive axis directions to
a differential voltage output. The magnetoresistive sensors are made of a
nickel-iron (Permalloy) thin-film and patterned as a resistive strip element.
In the presence of a magnetic field, a change in the bridge resistive elements
causes a corresponding change in voltage across the bridge outputs.
MODES OF OPERATION
This device has several operating
modes whose primary purpose is power management and is controlled by the Mode
Register. This section describes these modes.
Continuous-Measurement Mode
During continuous-measurement
mode, the device continuously makes measurements, at user selectable rate, and
places measured data in data output registers. Data can be re-read from the
data output registers if necessary; however, if the master does not ensure that
the data register is accessed before the completion of the next measurement,
the data output registers are updated with the new measurement. To conserve
current between measurements, the device is placed in a state similar to idle
mode, but the Mode Register is not changed to Idle Mode. That is, MD[n] bits
are unchanged. Settings in the Configuration Register A affect the data output
rate (bits DO[n]), the measurement configuration (bits MS[n]), when in
continuous-measurement mode. All registers maintain values while in
continuous-measurement mode. The I2C bus is enabled for use by other devices on
the network in while continuous-measurement mode.
Single-Measurement Mode
This is the default power-up
mode. During single-measurement mode, the device makes a single measurement and
places the measured data in data output registers. After the measurement is
complete and output data registers are updated, the device is placed in idle
mode, and the Mode Register is changed to idle mode by setting MD[n]
bits. Settings in the configuration register affect the measurement
configuration (bits MS[n])when in single-measurement mode. All registers
maintain values while in single-measurement mode. The I2C bus is enabled for
use by other devices on the network while in single-measurement mode.
Idle Mode
During
this mode the device is accessible through the I2C bus, but major sources of
power consumption are disabled, such as, but not limited to, the ADC, the
amplifier, and the sensor bias current. All registers maintain values while in
idle mode. The I2C bus is enabled for use by other devices on the network while
in idle mode.
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