HMR3400 Datasheet, PDF (7/9 Pages) Honeywell Accelerometers – Digital Compass Solution

HMR3400
Resets compass to power-up condition. A one second initialization routine starts and EEPROM data (non-volatile
memory) is uploaded (shadowed) into RAM. Continuous streaming data begins after initialization and status
output.
User Calibration
*C<cr><lf>
The command to be issued to enter and exit the calibration mode. Once in the calibration mode, the device will
send one or more magnetometer data strings appended by a “C” character to indicate the Calibration Mode
operation.
Eg. 123,834,1489,C<cr><lf>
See the calibration procedure notes earlier in this datasheet. At the completion of the calibration movements,
issue another *C<cr><lf> to exit the calibration mode.
CONFIGURATION COMMANDS
Syntax: #Dev=±xxxx<cr><lf> Sets parameter value
#Dev?<cr><lf>
Queries for the parameter value
Variation Input (Declination Angle Correction)
#Var=±nnnn<cr><lf> where the variation is ± nnn.n degrees
Sets the declination angle between magnetic north and geographic north. The declination angle is subtracted
from the magnetic north heading computed to create a geographic north heading. Values typically range in the
±25 degree area. For example New York has a -14 degree declination angle, and Los Angles has a +14 degree
declination angle.
Eg: #Var=-203<cr><lf> sets the declination angle to –20.3 degrees.
Eg: #Var=?<cr><lf>returns the declination angle; –20.3
Deviation Input (Platform Angle Correction)
#Dev=±nnnn<cr><lf> where the angle is ± nnn.n degrees
Sets or returns the angle between compass forward direction and that of the mounting platform. The Deviation
angle is subtracted from the predicted heading to compensate for mechanical misalignment.
Eg: #Dev=23<cr><lf> sets the deviation angle to +2.3 degrees.
Eg: #Dev=?<cr><lf>returns the deviation angle; +2.3
User Magnetic Offset Values (X, Y and Z)
#Xof, #Yof, #Zof
Sets or returns the user offset values for each magnetic axis. These values are recomputed after a calibration
routine. Also fixed offsets can be inserted to correct for known magnetic shifts. Values are in ADC counts.
Eg: #Xof=+47<cr><lf> sets the x offset value to +47.
Eg: #Xof=?<cr><lf> returns the x offset value; +47.
Baud Rate
#Bau
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