PNI CompassPoint Prime - Manual (Page 48)

PNI Sensor Corporation DOC# 1014177 r08
Prime User Manual – July 2011 Page 42
Below is a complete sample frame for an Accelerometer Only Calibration:
00 09 0A 00 00 00 64 5C F9
7.3.11 kStopCal (frame ID 11
d
)
This command aborts the calibration process. The prior calibration results are retained.
7.3.12 kSetParam (frame ID 12
d
)
The Prime 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. Selecting a larger number of taps can significantly slow the time for the
initial sample reading and, if “Flush Filters” is selected, the rate at which data is output.
Parameter ID Axis ID Count Value
1
Value
2
UInt8 UInt8 UInt8
ID
Specific
ID
Specific
Value
3
Value
Count
ID
Specific
ID
Specific
Payload
Parameter ID should be set to 3 and the Axis ID should be set to 1. The third payload
byte indicates the number of taps to use, which can be 0 (no filtering), 4, 8, 16, or 32.
This is followed by the tap values (0 to 32 total Values can be in the payload), with each
Value being a Float64, and suggested values given below in Table 7-6.
Note: Selecting a large number of taps will significantly slow the time for the initial heading
reading, since the filter must be fully populated before the Prime will output a heading reading.
And, if “Flush Filters” is selected the rate at which the output is updated will be inversely
proportional to the number of taps. For example, if 8 taps and flush filters are selected, the output
will be updated at ~3.5 Hz, while it will be updated at ~1 Hz if 32 taps is selected.