How the GPS Intermediate Driver Uses the Registry for Configuration
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4/8/2010
The GPS Intermediate Driver uses the registry for two basic types of configuration information: connecting the GPS Intermediate Driver to GPS hardware, and providing data to applications that use the GPS Intermediate Driver.
Connecting the GPS Intermediate Driver to GPS Hardware
To connect to GPS hardware, the registry must contain one or more keys that contain all information necessary to connect to the GPS hardware's driver. This information includes the appropriate COM port and, if necessary, communication parameters like baud rate. For information about these registry entries, see GPS Intermediate Driver Input Source Registry Settings, GPS Intermediate Driver GPS Hardware Registry Settings, and GPS Intermediate Driver File Registry Settings.
The GPS Intermediate Driver supports configuring multiple GPS devices by providing the CurrentDriver registry entry, which specifies which configuration registry key to use. This enables you to, for example, connect to two different pieces of hardware by defining separate registry keys, each with all necessary connection information, and then switching between these keys by changing the value of the CurrentDriver registry entry. Changing configuration settings is discussed in more detail in Refreshing GPS Intermediate Driver Configuration using IOCTL_SERVICE_REFRESH.
Note
The GPS Intermediate Driver can only connect to a single GPS device at a time. The CurrentDriver registry entry is a convenience so that only a single registry entry has to be changed to switch GPS hardware. Without the CurrentDriver registry entry, multiple registry entries would have to change to switch between different GPS devices.
Providing Data to Applications That Use the GPS Intermediate Driver
The GPS Intermediate Driver can handle multiple application clients using internal multiplexing code that provides the same data to multiple clients.The DriverInterface registry entry defines the name of the device that applications use to connect when using ReadFile. For more information about DriverInterface, see GPS Intermediate Driver Multiplexer Registry Settings. Applications that use the parsed API do not need to be aware of a specific interface - they retrieve all information using GPSGetPosition.
See Also
Concepts
Configuring the GPS Intermediate Driver
GPS Intermediate Driver Registry Settings