HMR3500 User's Guide
The HMR3500 TruePoint compass module is a 3-axis digital compass solution with a customizable coordinate system for
mounting in any desired orientation. Three AMR sensors and three MEMS accelerometers are combined to provide
compass heading as well as pitch and roll angles.
The HMR3500 has provisions for hard and soft-iron correction algorithms to handle magnetic distortion effects. In addition
a World Magnetic Model feature is provided to add declination angle corrections for reference to true north (geographic
2.0 GETTING TO KNOW THE HMR3500 PRODUCT
2.1 IDENTIFYING THE HMR3500
The HMR3500 Compass module comes with two different options:
(1) PCB Compass Module with the RS-232 electrical interface
(2) Demonstration Kit (housed module, software and RS-232 cabling)
It is strongly suggested that your first HMR3500 purchase be the demonstration kit, to get you quickly into successfully
using the compass with a personal computer and the Compass Host demonstration software. From the kit, you will have a
known good operating condition when creating your customized interface firmware.
2.2 SETTING UP THE HMR3500
The RS-232 Interface and power supply cable for the HMR3500 digital compass module should be included in the
Electrical connections are made via a 5-pin header. Mechanical mounting uses a four-point attachment with #2-56
screws. Additionally, the cable assembly can be ordered separately.
The HMR3500 requires an external DC power supply for the red (positive) and black (ground) wires of the cable
assembly. By feeding 5 volts DC at about 60 milli-amperes into the HMR3500, the compass will begin to operate.
2.3 HMR3500 SPECIFICATIONS
Pitch and Roll
Default orientation, rotation about X-axis
Default orientation, rotation about Y-axis
(Clean Magnetic Environment)
Pitch 0° to ±30°
Roll 0° to ±30°
3 sweeps, 0º to 360º, level
Roll ±30º, Pitch ±30º
Level, 1-sigma, 100 readings