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Get
your iPAQ connected to your Garmin eTrex...
The cool thing about GPS is to know where you
are ... but what use does it make without a map showing you where
that might be? The great thing about an iPAQ is that it has a lot
of memory, most of them have a colorscreen and best of all they
have sound on board. So combing this, for example with the TomTom
Navigator or TeleType
GPS software, would make an excellent navigation tool ... wouldn't
it? Ehm,... but how should we connect them?
Well, let me show you how I connected my Compaq/HP
iPAQ 3630 to my Garmin
eTrex Venture. The iPAQ 3630 (Any 3600
and 3800 series will do) can be bought pretty cheap at for
example eBay.com
or Marktplaats.nl.
The GPS receiver, a Garmin
eTrex, can be bought for app. $100 (basic model) to $170 (the
Venture model which has just that little bit of extra, and comes
with a serial cable too! See also: GPSNow).
pFranc
(Larry) designed his own eTrex connectors for both the
rectangle shaped Garmin connector and the
round Garmin connectors.
Note: read the disclaimer!
Tip: READ THE
ENTIRE ARTICLE FIRST! |
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Overview
Before we start we need to decide what type of cable
we wish to make:
Getting Connected with
a nullmodem cable
This trick assumes a Compaq/HP iPAQ 3600 (or 3800)
series PDA and a Garmin eTrex GPS receiver (any model will do).
What do we need?
- Garmin eTrex serial cable.
The connector would be sufficient too, but since these are rare and
pretty expensive, I opt for the re-use of my serial cable. My Garmin
eTrex Venture came with a suitable cable.
- A iPAQ connector.
I got mine from a $5 USB to iPAQ cable. I used the
USB cable for the serial
craddle to USB trick. The connector of the iPAQ was not used for
that ... keep in mind though that if you use a cable that this connector
should be detachable - ie. not molded to the cable!
A Serial to iPAQ cable would make things even easier. In that case rather
go to a shop and find yourself an nulmodem adapter (male DB9
on both sides).
- A male DB9 connector.
- Some cable (3 wires inside)
Basic layout of the connection


Standard Garmin Serial cable


(Our new cable)


Cables, Cables, Cables ...
So how are the wires connected then?
2 |
8 |
7 |
RX Data |
Blue |
3 |
7 |
8 |
TX Data |
Red |
5 |
4 |
10 |
GND |
Black |
Connect the 3 wires with the connectors as indicated
in the table above.
(Thanks to Jan Willem van der Hoek for the 38xx information)
After doing the soldering, you might want to try one
or two of the freeware applications for your PocketPC (Stealth
GPS for example). Make sure protocol (Garmin
vs NMEA) and baudrate (usually 4800
for NMEA) are set properly. The connection of your Compaq
iPAQ is sometimes called COM1 in the PocketPC application ...
Below you will find detailed images on the pins
to use.
Keep in mind that this cable is for GPS only!
And this cable is a NULMODEM cable!
Other equipment might need more cables to put through!
Connectors and numbers ...
As always, connectors have numbered pins,... the only
things is: WHAT numbers? Most DB9 connectors have number printed on them,
but the iPAQ connector is too small for that. So I tried to make it better
understandable which is which.
The iPAQ 3600 series connector
Front view, viewing the part that goes into the iPAQ:

This is what such a connector looks like on the backside,
ie. inside the connector:

The RS232
DB9 connector
This is a well known and well document
connector, most of them even have numbering on the connector itself.
 
Direct connected to the Garmin
eTrex
If you'd rather have a direct connected
cable, you should need the data on the Garmin eTrex connector:

The serial connector of the iPAQ (3600
and 3800 series!) will have to be connected as such:
pin 1 |
Power (+ 3 Volt) |
|
not used! |
not used! |
not used! |
pin 2 |
RXD (Data IN) |
 |
pin 8 |
pin 7 |
TXD (Data OUT) |
pin 3 |
TXD (Data OUT) |
 |
pin 7 |
pin 8 |
RXD (Data IN) |
pin 4 |
GND (-) |
 |
pin 4 |
pin 10 |
GND |
(Thanks to Jan Willem van der Hoek for the 38xx information)
Tip: If you're busy with an
eTrex connector anyways then you might want to consider adding external
power for the eTrex aswell. Use a 3V powersupply and connect it to pin
1 (+) and 4 (-) of eTrex connector.
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