[aprssig] Kenwood/Garmin adapter update
scott at opentrac.org
Mon Sep 8 10:22:31 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
Hard to do with a QFN... you've got to take it off the tape, drop it in
with a vacuum pen, and then repackage it somehow. Much easier to ship
it to the contract manufacturer on the original tape, and then program
it once it's on the board. For this one, I'll probably machine a
fixture out of Delrin and put pogo pins in it. I just haven't had a
chance to do that yet.
> one I can probably pull a few strings for you; let me know the package
> specs. That would eliminate some of the soldering.
It's a 7mm 48QFN. The sockets tend to be really expensive, though I did
get a handful of different types at a surplus place in the Bay area for
> 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
Unfortunately, no. The nuvi won't even work as a GPS once you hook it
up to a USB host - it just becomes a dumb mass storage device to manage
waypoints and files. There's no USB-related firmware in this thing at
all. It just has to do a bunch of floating point math and some
trigonometry to convert between the Garmin 9600 baud binary stream and NMEA.
I *do* have embedded host controller chips around here that could be
used for some USB/serial applications. BUT... you've got to know
exactly how the USB device communicates (at least Garmin documents their
interface) and you've also got to have power for the host, and probably
power for the target device as well, since it's going to expect external
power when it's connected to a USB host. That rules out a simple
in-line cable adapter like this project.
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