PNI TCM - Manual (Page 55)

PNI Sensor Corporation DOC#1014688 r06
TCM User Manual – July 2013 Page 50
Initiate a calibration using the kStartCal command. Note that this command
requires indentifying the type of calibration procedure, for example Full-Range
Calibration or 2D Calibration.
Follow the appropriate calibration procedure, as discussed in Section 5. If
kUserCalAutoSampling was set to FALSE, send kTakeUserCalSample when
ready to take a calibration point. If kUserCalAutoSampling was set to TRUE,
then look for kUserCalSampCount to confirm when a calibration point has been
taken. During the calibration process, heading, pitch, and roll information will be
output from the TCM, and this can be monitored using kGetDataResp.
When the final calibration point is taken, the device will present the calibration
score using kCalScore and save the calibration coefficient set and coefficient
values to volatile memory, assuming the calibration was not aborted.
If the calibration was not good, either perform another calibration procedure,
reboot to restore the prior coefficients, recall another coefficient set
(kMagCoeffSet), or recall the factory coefficients (kFactoryMagCoeff).
If the calibration was good and you want to save the calibration coefficients to
non-volatile memory, send the kSave command.
7.3.11 kStopCal (frame ID 11
d
)
This command aborts the calibration process. Assuming the minimum number of sample
points for the calibration, as defined in Table 7-5, is not acquired prior to sending
kStopCal, the prior calibration results are retained. If the acquired number of sample
points prior to sending kStopCal is within the allowable range of kUserCalNumPoints,
then new calibration coefficients and a new score will be generated. For instance, if
kUserCalNumPoints is set to 32 for a Full-Range Calibration, and kStopCal is sent after
taking the 12
th
sample point, then a new set of coefficients will be generated based on the
12 sample points that were taken. They will not be saved, however, unless the kSave
command is sent.
7.3.12 kSetFIRFilters (frame ID 12
d
)
The TCM incorporates a finite impulse response (FIR) filter to provide a more stable
heading reading. The number of taps, or samples, represents the amount of filtering to be
performed, and directly affects the time for the initial sample reading, as all the taps must
be populated before data is output.
The TCM can be configured to clear, or flush, the filters after each measurement.
Flushing the filter clears all tap values, thus purging old data. This can be useful if a
significant change in heading has occurred since the last reading, as the old heading data