Casio IT-800 Series, Руководство пользователя программного обеспечения

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2.11.2 GPS Function API
Latitude and longitude data are obtained using independent positioning to provide the following
functions.
•
Obtains positional data from user application via the GPS intermediate driver (Windows
Mobile standard GPS interface)
•
Displays satellite reception status with the GPS Information tool
Note:
Refer to “
3
GPS Information” with the GPS Information tool for detail.
The GPS intermediate driver provides GPS information in two ways.
•
NMEA Format Data Output
•
Positional Data using the GPS Intermediate Driver API
In addition, multiple user applications can simultaneously access the GPS intermediate driver to
obtain positional data.
NMEA Format Data Output
The NMEA is an abbreviation for National Marine Electronic Association which provides
electronic instrument and communication specification standards for shipping vessels. The
NMEA-0183 output protocol is a standard for GPS receiver and navigation equipment
communication via a serial port. It’s widely supported by GPS equipment.
NMEA data can be output by accessing the GPS Intermediate driver’s virtual COM port (COM8).
Note:
The integrated communication port is as follows.
Table 2.101
GPS intermediate driver virtual serial port : COM8
The procedure for using the virtual serial port is as follows.
1. Open the virtual COM port with CreateFile() .
2. Read the NMEA character string with
ReadFile()
.
3. Analyze the NMEA character string to retrieve the positional data.
4. NMEA character strings are continually output for each GPS Module measurement. Repeat
steps 2 and 3 above as required to retrieve continuous positional data.
5. Close the port with CloseHandle() .