I was able to dig this up:
- Garmin Spanner (Creates a virtual serial port for use with most NMEA 0183 compliant programs)
- NMEA Sentences
- Status (GSA, GSV)
- Wpts/Route (WPL, RTE)
- GRMN Propritary
- Autopilot Mode
- Waypoint IDs
- Precision of Minutes
- MM.MM' (2 digits)
- MM.MMM' (3 digits)
- MM.MMMM' (4 digits)
- Baud
- Garmin Serial (Garmin proprietary data transfer format)
- NMEA In/Out (Use standard NMEA 0183 input and output)
- NMEA Sentences
- Status (GSA, GSV)
- Wpts/Route (WPL, RTE)
- GRMN Propritary
- Autopilot Mode
- Waypoint IDs
- Precision of Minutes
- MM.MM' (2 digits)
- MM.MMM' (3 digits)
- MM.MMMM' (4 digits)
- Text Out (Provides simple ASCII text output of location and velocity information)
- MTP (Media Transfer Protocol)
Based on the MTT4BT being able to take APRS audio, and convert it to NMEA serial waypoints ($GPWPL & $PGRMW), I think this is a go!
