[aprssig] Re: D700A gps interface problem

KC2MMi kc2mmi at verizon.net
Wed Jul 21 07:10:49 EDT 2004

 From what I've seen on 3 different model DeLuos, all recent, they are
shipped with a default not to use power saving, so there is no need to send
them a "wake" signal or pull a line high to wake them. Of course, it is
possible some units shipped with a different default enabled. DeLuo has some
manuals available in PDF format that explain this--but their manuals don't
always match the units exactly.
 Also, RS-232 is enabled by default, or at least it was in mine. Some of
their units are dual RS-232/USB and from the little I know, they will
respond to either interface without needing any forcing.
 I had them hooked up to a Byonics PocketTrack, which is supposed to treat
the GPS identically to their TinyTrack. Of course, since his GPS is running
and talking to his PC on a standard port--which won't exert any wakeup
signal--there's good reason to try confirming any changes in the Kenwood
before rewiring the GPS. (And, confirming the programming in the GPS, via
GPSManager, the PC stream, or other tools.)

 Maybe a simple wiring problem to the radio?? The usual pins 2/3 being
reversed? (I'm good at doing that.<G>)

----- Original Message ----- 
From: "Stephen H. Smith" <WA8LMF2 at aol.com>
To: "KC2MMi" <kc2mmi at verizon.net>
Cc: <aprssig at lists.tapr.org>
Sent: Wednesday, July 21, 2004 3:34 AM
Subject: Re: [aprssig] Re: D700A gps interface problem

My guess about this is that the new Deluo units probably either:

1)  Need the incoming RS-232 data line ( relative to the GPS ) asserted
in order to make it turn on.  This seems to be an increasingly common
feature in mouse-type GPS units to eliminate the need for a power
switch.  The RS Digitraveller was the first unit of this type
encountered on this list.  The Digitraveller needs to see either + or -
RS-232 level from the device it is connected to (PC, D700, TinyTrak,
etc) before it starts.  The default behavior of the TinyTrak (and I
think also the D700 unless waypoints are being uploaded to a GPS device)
is to have the outgoing pin of the GPS port inactive (0 volts).   I had
to provide a pullup resistor to make the TT work with the Digtraveller.

I wonder if the new Kenwood is setting the outgoing GPS serial port line
to tri-state inactive instead of driving it to either - or + RS-232
level, denying the GPS the turnon signal it needs.  Perhaps the older
D700 is activating the outgoing line.


2)  The Deluo needs RS232 handshaking lines asserted to turn on.  When
it is plugged into the PC to test with Visual GPS, etc, all the 232 pins
are asserted by the PC serial port.  When you connect to the D700 GPS
port, you only have a 3-wire basic serial port connection with TXD, RXD
and GND/COMMON.  The handshaking lines are left floating unless you make
null-modem-type cross-connects in the male DB9 on the
DB9-to-2.5MM-stereo-miniplug cable going into the Kenwood.

The standard DB9 wiring to assert local-handshake foldback are:

   Pins 1(CD), 4(DTR) and 6(DSR) connected together

   Pins 7(RTS) and 8(CTS) connected together

[ This are just cross connections on the back of the connector; they
don't leave the plug at all. ]

The three lines that actually leave the DB9 connector to go to the
device at the other end are:

   Pin 2 TX Data wire to far end

   Pin 3 RX Data wire to far end

   Pin 5 Common/GND wire to far end

Stephen H. Smith                   wa8lmf (at)  aol.com
Home Page:                            http://wa8lmf.com

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