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Date: Mon, 31 Jul 1995 07:14:42 +0200
To: thogard <thogard@soulcage.inmind.com>
From: ebneter@iap.unibe.ch (Daniel Ebneter)
Subject: Re: Using GPS (Garmin 45) with a Mac Powerbook
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Status: RO

Tim,

>Could you send me the details of that.  I've got a PC and it doesn't
>like the Mac compressed files.
Larry James writes the following in the MacGPS doc:
<start quote>
Hardware Interface

This is the hardest part of getting your Macintosh to talk to the GPS
receiver.  The GPS receiver must be connected to the Macintosh modem port
(or printer port if the modem port must be in use for something else).
Garmin makes a power/data cable for the GPS 45 (P/N 4520, $21.95 from James
Associates), and a data cable for the GPS 40 or GPS 45 (P/N 4042, $17.95
from James Associates) which may be wired to a Macintosh mini-DIN
connector. Connect the wires as follows (see Inside Macintosh, Volume IV,
page 248 for Macintosh connector details):

        GPS 40 or 45            Macintosh                   Macintosh
connector description with key up
  ______________  _______________     _________________
         Data Out (Brown)         Receive Data (5)        pin in same
horiz. plane as center pin, not as close
         Data In (White)             Transmit Data (3)      pin in same
horiz. plane as center pin, closest
         Ground (Black)       Ground (4)                  centermost pin
   Power(+)(Red)         No Connection            No Connection

The GPS 40/GPS 45 data out is a 0 to 5 volt signal which will drive most
RS-232 ports (RS-232 transition levels are typically about 1 to 2 volts).
The Macintosh will not respond to this signal if the Receive Data + (8)
line is grounded.  Good results are obtained on most computers by leaving
the Macintosh Receive Data + open, but this may not work with all
computers.  It may be necessary to bias the Receive Data + line at some
positive voltage (about 3 volts).

While you're at it, you can also connect a DC power supply (5 to 40 volts
DC for the GPS 45,
6 to 8 volts for the GPS 40) between the Garmin Power (red, positive) wire
and the Ground (black, negative) wire, and save your batteries. Any adapter
rated at 6 to 8 volts with an output current of 250 mA or more should work.
<end quote>

Hope it'll work out for you.

Daniel

------------------------------------------------------------------------------
Daniel Ebneter                                University of Bern
Diploma Student                               Institute of Applied Physics
                                              Sidlerstrasse 5
email       ebneter@iap.unibe.ch              CH-3012 Bern
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Fax         +41 31631 3765                    Mules succeed where horses fail.




