O.K. I just assumed you were using a Nuvi since you mentioned Garmin protocol. If you are using a Garmin GPS puck, then you have a choice of NMEA (default) or Garmin protocol (via Garmin config software) and both are rs-232 complient TTL level outputs which would be easy to split to two outputs, one bi-directional to the T2 and one single ended.
If you are using another GPS unit that only outputs Garmin protocol through the mini-USB port, i.e. Zumo 550, then you are back to the same solution as the Nuvi. Scott can correct me, but I believe the Gtrans circuit has a USB input like the Garmin cable rather than a level shifter. In which case you need to parallel both on the USB side, again with only one of the cables being connected to the ID pin on the mini-USB going to the GPS. Larry K7YBZ --- In [email protected], "Fred Hillhouse" <fmhillho...@...> wrote: > > Personally, I don't have a Nuvi. Maybe at some point I will add it, but not > today. > > Since I just realized (again, duh!) the GTRANS connects into the Nuvi, the > GTRANS with all its cabling will not work as imagined, but, I imagine it > wouldn't take much if it doesn't. I seem to recall chatter about hardware > inside the Garmin cable, too. That is okay. The data still gets into the T2 > and it is there in two signal levels; one RS232 and the other TTL. The TTL > signal is perfect! > > If the TTL level is fed to the processor on the GTRANS then all the level > shifting stuff goes away. Since I only want NMEA out, and the GTRANS would > be inside the T2, power on/off is all the same for both. Therefore, the > timing mentioned earlier should be okay. > > Of course this is all theory. ;) > > Well, actually my ideal is more like: in addition to the T2 normal > functions, GPS data (NMEA or Garmin protocol) is passed bi-directionally > through the T2. I guess that makes it a GPS router, too. But I am not > asking! Even if it did, I am not sure how to use it right now. Hmm. > > Thanks! > > > Best regards, > Fred > > > > > > _____ > > From: [email protected] [mailto:[email protected]] On Behalf > Of k7ybz > Sent: Thursday, September 24, 2009 15:41 > To: [email protected] > Subject: [tracker2] Re: Garmin and NMEA Data from Nuvi 350? > > > > > Just make sure you only have one device with the ID resistor otherwise the > Nuvi will not recognize what device is connected. Even then, the load on the > USB side, since this is the side that needs to be in parallel, may be a bit > too much for a good signal out of the Nuvi. > > You may need to think about suppling power to the GTRANS cable from a source > other than the Nuvi too. The Nuvi can accept upto 500 ma for its own use > (battery charging through the data port), but only supplies a limited amount > of current (through current limiting circuitry) to external devices even > with power connected to the back of the unit. > > The ideal would be a serial splitter where both TX/RX would go to the T2 and > the TX out to a Garmin to NMEA converter for single ended use. > New product Scott? > > The clouds have lifted. Time to go back outside and play photographer on the > beach. > > Larry > K7YBZ > > --- In track...@yahoogroup <mailto:tracker2%40yahoogroups.com> s.com, "Fred > Hillhouse" <fmhillhouse@> wrote: > > > > It could make for an easy way to get NMEA out of a T2 while connected to a > > GPS running the Garmin protocol. It the PCB was tacked down inside, a > cable > > with a connector could come out the 'power' hole. > > > > Ok, I want just the PCB! (loaded of course). :) > > > > I haven't been following the GTRANS information really at all. Can I > select > > only the sentences I am interested in? Just curious, not a requirement. > > > > > > Thanks! >
