PNI CompassPoint Prime - Manual (Page 31)

Prime User Manual r08 Page 25
The calibration procedures can be executed using StudioPrime or the Prime’s binary
protocol. Sections 5.3 and 5.4 outline how to configure and perform a calibration in
StudioPrime. The steps below provide an example sequence of commands to perform a
calibration using the PNI binary protocol. (Refer to Section 7 for information on how to
implement the binary protocol commands.)
Using the kSetParam command, set the number of filter taps. (8 is typical.)
Using the kSetConfig command, set kUserCalAutoSampling. FALSE allows for
more control over the process, while TRUE may simplify the procedure.
Using the kSetConfig command again, set kUserCalNumPoints to the appropriate
number of calibration points. The recommended number of calibration points is at
least 12 for Magnetic Sensor Only Calibration and at least 18 for Accel Only
Calibration or Mag and Accel Calibration.
Initiate a calibration using the kStartCal command. Note that this command requires
indentifying the type of calibration procedure (i.e. Magnetic Sensor Only, etc.).
Follow the appropriate calibration procedure discussed in Sections 6.2.1 to 6.2.3. If
kUserCalAutoSampling is FALSE, then send a kTakeUserCalSample command when
ready to take a calibration point. If kUserCalAutoSampling is TRUE, then look for
kUserCalSampCount to confirm when a calibration point has been taken.
When the final calibration point is taken, the module will present the calibration score
using kUserCalScore.
If the calibration is acceptable (see Section 6.2.4), save the calibration coefficients
using kSave.
6.2.1 Magnetic Calibration Procedure
The following procedure is recommended for magnetic sensor calibration. Additional
sample points with the module flipped upside down are also desirable if possible.
Move the module to the following positions, noting that these are not absolute heading
directs, but rather relative headings referenced to your initial heading sample. (i.e. yaw is
relative to the starting orientation, and does not need to be North.)
Note: Once a calibration procedure is started with auto sampling enabled, pausing between
desired calibration points can cause unintentional points to be taken.