Campbell Scientific GPS16X-HVS GPS Receiver - Manual (Page 29)

Appendix B. CR23X Wiring and Programming
The GPS16X-HVS needs to be reconfigured using the Garmin configuration
software from the Garmin website for 1200 baud, 8 data bits, 1 stop bit and no
parity (see Appendix A). The GPGGA string should be output. The 1 pulse
per second signal should be output with a pulse duration of 100 milliseconds.
The code required to read the GPS information and store it to final storage is in
Subroutine 98. Subroutine 98 is interrupt driven and triggered when a rising
edge is detected on Control port 8. The GPS16X-HVS has a 1 PPS signal
which is wired to control port 8. The transmit data line of serial port 1 on the
GPS16X-HVS is wired to control port 5. The GPS16X-HVS serial port 2
generally is not used.
When the 1 PPS signal triggers subroutine 98, P15 is executed. P15 is setup to
read ASCII serial data. Each data point is separated by a non-numeric
character or a decimal point. Fifteen input locations are used as temporary
storage for the $GPGGA string. TABLE 4-1 explains the $GPGGA string.
The input locations used for the $GPGGA string are:
1) Raw_Time, Time in hours, minutes, and seconds
2) LatDegMin, Latitude degrees and minutes
3) Lat_Frac, Latitude fractions of minute
4) LngDegMin, Longitude degrees and minutes
5) Lng_Frac, Longitude fractions of minute
6) Quality, GPS quality indicator
7) NumSats, Number of satellites in use
8) HDPWhole, Horizontal Dilution of Precision
9) HDPFrac, Horizontal Dilution of Precision, tenths
10) Elevation, Elevation in meters
11) Geoidal, Geoidal separation in meters
12) Geoidalth, Geoidal separation in meters, tenths
13) Age, Age of differential GPS data
14) Agetenth, Age of differential GPS data, tenths
15) DiffID, Differential reference station ID
Additional input locations used in the example program are:
18) Orig_TM, Copy of original time
19) Int1, Place holder for math
20) Hours, formatted hours
21) Minutes, formatted minutes
22) Seconds, formatted seconds
23) remainder, place holder for math
Before writing any datalogger code, it’s best to enter all the input locations
needed. In Edlog, open the input location editor (F5) and enter names for the
input locations listed above. When an input location is needed, use the input
location pick list (F6).
B-5