User Manual

HMC5883
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Configuration Register A
The configuration register is used to configure the device for setting the data output rate and measurement configuration.
CRA0 through CRA7 indicate bit locations, with CRA denoting the bits that are in the configuration register. CRA7 denotes
the first bit of the data stream. The number in parenthesis indicates the default value of that bit.
CRA7
CRA6
CRA5
CRA4
CRA3
CRA2
CRA1
CRA0
(0)
(0)
(0)
DO2 (1)
DO1 (0)
DO0 (0)
MS1 (0)
MS0 (0)
Table 6: Configuration Register A
Location
Name
Description
CRA7 to CRA5
0
These bits must be cleared for correct operation.
CRA4 to CRA2
DO2 to DO0
Data Output Rate Bits. These bits set the rate at which
data is written to all three data output registers.
CRA1 to CRA0
MS1 to MS0
Measurement Configuration Bits. These bits define the
measurement flow of the device, specifically whether or
not to incorporate an applied bias to the sensor into the
measurement.
Table 7: Configuration Register A Bit Designations
The Table below shows all selectable output rates. All three channels shall be measured within a given output rate. Other
output rates with maximum rate of 116 Hz can be achieved by monitoring DRDY interrupt pin in single measurement
mode. DRDY pin is normally high and is low for 5 µsec when data is placed in the output registers.
DO2
DO1
DO0
Typical Data Output Rate (Hz)
0
0
0
0.75
0
0
1
1.5
0
1
0
3
0
1
1
7.5
1
0
0
15 (default)
1
0
1
30
1
1
0
75
1
1
1
Not used
Table 8: Data Output Rates
MS1
MS0
Mode
0
0
Normal measurement configuration (default). In normal measurement
configuration the device follows normal measurement flow. The positive and
negative pins of the resistive load are left floating and high impedance.
0
1
Positive bias configuration for X and Y axes, negative bias configuration for
Z axis. In this configuration, a positive current is forced across the resistive
load for X and Y axes, a negative current for Z axis.
1
0
Negative bias configuration for X and Y axes, positive bias configuration for
Z axis. In this configuration, a negative current is forced across the resistive
load for X and Y axes, a positive current for Z axis.
1
1
This configuration is not used.
Table 9: Measurement Modes