[aprssig] Kenwood/Garmin adapter update

Derek Koonce derek at dkoonce.com
Sun Sep 7 23:39:43 CDT 2008

Nice PCB Scott. For programming, there are sockets that can take the IC 
package and allow you to program off the PCB. If you need me to hunt for 
one I can probably pull a few strings for you; let me know the package 
specs. That would eliminate some of the soldering.

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.

Derek Koonce

Scott Miller wrote:
> I've got the first couple of prototypes of my Garmin <> NMEA converter 
> board build and running - beta testing will be starting soon.  This 
> board is intended to work with the nuvi and StreetPilot models that have 
> a mini-B USB connector (and support fleet management mode.)  Here's a 
> picture of my TH-D7A hooked up to a nuvi 350:
> http://n1vg.net/images/nuvi_d7.jpg
> So far only the nuvi 350 works right for waypoint display, but I think 
> Garmin's going to have a solution for that soon.  Here's another shot of 
> the converter circuit, this one with a DB9:
> http://n1vg.net/images/nmea_converter.jpg
> It'll probably get overmolded directly into the cable eventually, but 
> for now it's just encapsulated in adhesive-lined heat shrink tubing. 
> Here's the PCB itself:
> http://n1vg.net/images/nmea_pcb.jpg
> Afraid I only had my phone camera handy when I took that, so the quality 
> is bad.  The whole thing is about 2mm thick.  I probably could have made 
> it a little narrower, but I got tired of playing with the routing.  It's 
> got a 20 MHz HCS08 processor on it, a clock crystal, ESD protection, and 
> an RS-232 transceiver.  It's all powered by the nuvi (but not when the 
> nuvi is on battery power).
> I've only got a few prototypes, and I've already got beta testers lined 
> up.  I'm afraid I can't build any more until I get more USB cables 
> (they're non-standard 5-conductor cables with a custom right angle 
> overmold, and the factory is just getting started on them) and soldering 
> a 7mm, 48-contact QFN chip by hand is exceedingly tedious.  I also 
> haven't built a programming fixture yet, so loading the firmware 
> requires soldering wires to test pads and then removing them again when 
> it's done.
> But it works!  Plug it in to the nuvi and it starts spitting out GPGGA 
> and GPRMC sentences.  It'll take GPWPL and PKWDWPL (D710) waypoint 
> inputs, and in the case of the PKWDWPL format it'll pick an appropriate 
> symbol as well.
> I'm planning on a retail price of $48 for the converter cable.  I'll let 
> everyone know when it's available.
> Scott
> N1VG
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