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On 8/28/2011 4:52 PM, Tom Russo wrote:
<blockquote cite="mid:20110828205206.GA54767@bogodyn.org"
type="cite">
There is no mention of a classic RS-232 serial port (required to
connect to a Kenwood), nor any mention of FMI support (that allows
the USB interface to "morph" into a serial port when a special
cable is attached).
<pre wrap="">
FMI and "morph to serial" are separate things.</pre>
</blockquote>
<br>
The FMI interface IS serial, but with a screwball proprietary binary
data format rather than vanilla NMEA ASCII. <br>
<br>
<blockquote cite="mid:20110828205206.GA54767@bogodyn.org"
type="cite">
<pre wrap="">
Several of the handheld usb-only Garmin GPS units will indeed "morph to serial
NMEA" with just the right cable, even though they don't talk FMI. If you look
at the Montana's spec says its interface is "USB and NEMA 0183 compatible," </pre>
</blockquote>
<br>
One can have NMEA-0183-format ASCII data over USB rather than serial
-- many USB faceless hockeypuck GPSs do exactly this . This is
what I assumed they meant in the Montana description. <br>
<br>
<br>
<blockquote cite="mid:20110828205206.GA54767@bogodyn.org"
type="cite">
<pre wrap="">
and on its "accessories" page there is a USB "Serial Data/Power" cable
<a class="moz-txt-link-freetext" href="https://buy.garmin.com/shop/shop.do?pID=26668">https://buy.garmin.com/shop/shop.do?pID=26668</a>
with bare wires to access the serial data. This cable is compatible with
several of the devices other than the Montana, including the Colorado, Oregon,
and GPSMAP 62 series.
I believe that the way these devices work (Scott Miller can correct me here
if I'm mistaken) is that they detect a certain resistance in the cable between
certain pins, and switch from USB to plain RS232 serial protocol on the data
pins. </pre>
</blockquote>
<br>
This is how the USB-to-FMI-serial interface morphing works also.
It looks as through the complexity of the Garmin USB interfaces has
just doubled, with the magic USB-data-line pullup cable on some
devices waking up FMI while the pullup wakes up generic NMEA serial
on others. <br>
<br>
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--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
=== Now relocated from Pasadena, CA back to 8-land (East Lansing,
MI) ===<br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
===== Vista & Win7 Install Issues for UI-View and Precision
Mapping =====<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7">http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7</a><br>
<br>
*** HF APRS over PSK63 ***<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRS_PSK63/index.htm">http://wa8lmf.net/APRS_PSK63/index.htm</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
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