HMR3500 User's Guide
4.10 SELF TEST
The TEST command (see page 10) is sent to the module. The reply will be displayed in the main display scrolling text.
See the description of the command for details.
4.11 START-UP DEFAULTS
This brings up a dialog box almost identical to that for initializations (see Figure 7 above). The quantities in this box
correspond to those in the initialization dialog but with one crucial difference: Power-up defaults are the values in effect
immediately after power up or reset and before they have been set with normal initialization. The power up defaults is
stored in the compass non-volatile memory.
There is no immediate change when using this dialog. It changes only the values which will be loaded after the next reset
or power-up. Those currently in effect are not changed.
Warning: This function writes to the non-volatile memory in the compass's processor. There are a finite number of
allowable write cycles specified by the chip manufacturer so please do not change power-up defaults unnecessarily.
4.12 MAGNETIC DECLINATION
The compass will calculate and apply the local magnetic declination based on its built-in World Magnetic Model. This
model is provided by the U.S. Geological Survey and is endorsed by the Department of Defense. Four data items are
required: latitude, longitude, altitude, and date, and these are provided through the dialog shown in Figure 8. Note that
position accurate to about 1 degree is adequate.
Figure 8: Magnetic Declination Dialog Box
The current date from the host computer is supplied as a default. Choosing "Submit" closes the dialog but only starts the
calculation. Because the calculations are extensive, the compass performs them in its background mode. Nonetheless it
should finish in less than one second. When finished, the new declination is put into effect immediately and is also loaded
into flash memory as the new start-up default value.
4.13 BAUD RATE
Although the normal speed for serial communication with the compass is 9600 baud, it is possible to command the
module to use a different rate. (See Set Baud Rate, on page 9.) The Compass/Baud Rate menu item leads to a drop-
down menu with the possible speeds, and the speed currently used by CompassHost checked. Any of the speeds may be
If, for any reason, you have a module operating at a different baud rate, this menu item can be used to set