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[aprssig] Kenwood/Garmin adapter update

J. Lance Cotton joe at lightningflash.net
Mon Sep 8 13:50:41 UTC 2008


on 9/7/2008 23:39 Derek Koonce said the following:
> Is this basically a USB to RS232 adapter without the PC? This is a great 
> idea and could be used in many other applications. I've been thinking 
> about how to put one together but I am an analog / power electronics 
> designer and not a digital person.

No, this interface does not use USB at all. The Garmin Nuvi series (some of
them) have a "Fleet Management Interface" or FMI mode. When a special cable
is plugged into the mini-USB plug, the Nuvi is put into FMI mode and the
mini-USB port turns into a standard serial RS232 port in "Garmin Mode" much
like all the other garmin handhelds can do.

Garmin GPS mode is a binary serial protocol that has structures/commands for
setting waypoints, obtaining the GPS location data, etc.

Scott's board converts this garmin binary protocol to standard NMEA so that
the Nuvi can be used with any device expecting RS232 NMEA at 4800 bps.

-Lance KJ5O

-- 
J. Lance Cotton, KJ5O
joe at lightningflash.net
http://kj5o.lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the
cookies.





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