[aprssig] APRS and Garmin Nuvi

[Greg D.]

Wow, I wonder if this would work on the other Garmin USB-based GPS's?  I see it's not listed for their service, but I have a eTrek Vista HCx in the mail, due for delivery tomorrow.  I figured I would have to keep using my GPS-III (with the display going out), or pick up a simple serial GPS module and put it in a plastic box, for attachment to my Kenwood D7.  Instead, maybe this?

Does the cable have a standard mini-USB end on it (the small kind), or is it something special?  If standard, then they must be emulating a USB host in there, because there aren't any extra pins on the connector to do anything other than USB.

Greg  KO6TH


> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Scott Miller
> Sent: Thursday, January 31, 2008 11:01 PM
> To: TAPR APRS Mailing List
> Subject: [aprssig] APRS and Garmin Nuvi
> 
> 
> I discovered something interesting today.  Here I've been telling people
> all along that the newer USB-only Garmin receivers like the Nuvi are
> worthless for APRS.  Turns out I was wrong.
> 
> When I heard about Garmin's fleet management interface, I decided it'd
> be worth checking out.  It needs a special cable, though - for the Nuvi
> 350 I picked up, it's Garmin p/n 010-10813-00.  By the looks of it, it's
> probably just got a level converter inside, but I'm not sure.
> Apparently there's a serial interface of some sort that can share the
> USB connector.
> 
> The fleet management protocol looked suspiciously like a subset of
> Garmin's regular binary serial protocol, so (once I figured out the
> cable pinouts and soldered on a DB9) I fired up the test program I'd
> written, and sure enough, it spit out a list of supported protocols.
> 
> I plugged it straight into a stock Tracker2 and the activity light
> started blinking green, showing a good fix.  I piped in some recorded
> APRS traffic and the map screen started showing APRS stations.  Here are
> some pictures I took (haven't tried the screen capture program yet):
> 
> Map screen (2D mode): http://n1vg.net/images/nuvi-map.jpg
> Waypoint list: http://n1vg.net/images/nuvi-list.jpg
> Station detail: http://n1vg.net/images/nuvi-detail.jpg
> 
> It's not perfect - the waypoint set is different, for one.  You can see
> that all of the cars are now up on lifts with the hood up!  The digis do
> show up as antenna towers, at least, and the houses are there.  I'll
> have to find out if it'll take custom symbols.  Also, it seems to have
> some quirks about showing waypoints at different zoom levels.
> 
> The Nuvi 350 has a USB port on the side and another one on the clip-on
> base, so you can power it and plug it in to the tracker at the same
> time.  When I find out how the serial interface adapter works, I'll see
> if I can power it from the tracker, or maybe vice versa.  I'll also see
> about a cheaper substitute for the cable - this one cost me $30 after
> shipping.  It probably wouldn't be hard to build an equivalent circuit
> into a DB9 shell.
> 
> The bad news is that the Tracker2 (at least the OT2m version) is totally
> sold out right now.  My only two spares are going out for CE EMC
> certification shortly.  The factory producing the boards is snowed in
> right now and hasn't even been able to get the parts for the next batch
> - DHL's had them sitting at the depot for days.  It'll probably be the
> end of February before I have any more.  The T2-135 (for the Alinco
> DR-135) is shipping, albeit slowly due to limited production capability
> here.  (The Tracker2 page has moved to
> http://www.argentdata.com/products/tracker2.html if you're looking for
> more information.)
> 
> Hopefully by the time the boards come in I'll have figured out all of
> the Nuvi's quirks and dealt with them.  I also hope to make some use of
> the fleet management interface for some new features.  Most importantly
> - it does text messaging.
> 
> Scott
> N1VG
> 
> 
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