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From: Gary Hawkins (no email)
Date: Sun May 13 2001 - 22:31:25 EDT
Good GPS connector wiring diagram here if you scroll down on this page:
http://pfranc.com/projects/g45contr/assemb.htm
Notice the 9-pin serial port connector is only using one pin for transmit,
one for receive, and one for ground, but the GPS unit has one for power. If
you want to dedicate one of your computer's serial port connectors solely
for the GPS, then on the inside of the computer you can wire up an unused
pin for power and avoid having a power wire hanging there externally.
Depending on the voltage required by your unit, one way to do this is by
using an LM3171 regulator to reduce the 12 volts from the computer power
supply (wire running to motherboard). The LM3171 looks like a transistor
with three leads. The only other components needed are a resistor, cap, and
mini 5K potentiometer to vary the output voltage. With the regulator laying
on the table in front of you and leads pointing toward you, connections are
as follows:
Regulator left pin: To one side of ~220 ohm resistor and two pins of the
potentiometer (middle and one side)
Regulator right pin: To one side of a .1 uf capacitor, and to supply
voltage DC IN, up to about 27 volts I think, before you would burn it out.
Other side of resistor: To middle pin of regulator and OUT voltage
Remaining capacitor and potentiometer pins connect together and go to GROUND
for both supply and device being driven.
Makes for a very small, variable, stable DC supply for whenever you need
voltage less than your batteries provide. If it is inside the computer,
then all you need is a four conductor wire from the computer to GPS unit,
and so ordinary telephone cable would work.
-g
-----Original Message-----
From:
[mailto:]On Behalf Of Pierre Mitham
Sent: Thursday, March 15, 2001 2:58 PM
To: live-aboard list
Subject: lv-ab: Garmin GPS 128
Anyone know what the pin outs are to wire up a GPS 128 to a 9 pin serial
port so that I can run the firmware upgrade on this unit. I really don't
feel like spending the $90 to buy the gramin cable which is just a serial
cable with labels!
Pierre & Tracy Mitham
aboard Shanica J II
on The Toronto Islands "Mon!"
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