Making your own cables

Cable Making Instructions

GPSyTM has extensive documentation on how to create your own data cables, and if you are handy with a soldering iron (or know how to use crimp connectors), there are some instructions below (in Adobe Acrobat 3.0 PDF format) on how to make your own cable.

The GPSyTM 3.0 Getting Started Abridged Documentation, Getting Started & Appendix A -- "Connecting your Macintosh to GPS Units" (lots of schematic diagrams, assumes some technical expertise and ability to wield soldering iron)

For users interested in supplying power to their GPS using their PowerBook's ADB or GeoPort +5V supply, we have a FAQ entry on this topic (basically, we do no recommend it).

Note that we cannot provide any technical support for users making custom cables. The only cables we can support and guarantee are the ones that we sell.

Garmin Handheld Units

The Garmin 12/12CX/12XL/38/40/45/45XL/48/89/90/92/II/II+/III/III+/III Pilot/ and StreetPilot use a proprietary connector (well, so does every other GPS). You can either use a Garmin authorized data cable as your base or purchase a lookalike connector from the Purple Computing sharehardware [sic] project.
 Garmin 4-Pin Handheld Pinouts                 Mac Mini Din 8
   (looking from rear of unit)            (looking at front of cable)
        2                                      6   7   8
    1       3                                 3    4     5   (pin 5 is the odd man out)
     /  4                                       1     2
 1 = RxD                   ----------       3 = Transmit (TxD-)
 2 = Ground (Data/Power)   ----------       4 = Signal GND
 3 = TxD                   ----------       5 = Receive (RxD-)
 4 = V+                    
                                            [leave all others unconnected, especially Pin 8]

Other Garmin Units

Garmin 75: Connection diagram for a Garmin 75 (circa 1993 single-channel handheld).

Garmin 120: From Garmin 120 Power/Data Cable (see diagram above for Mac pin assignments):

     Pin 1 (red)      Power in 12V
     Pin 2 (black)    Ground          to   MiniDin8 Pin 4 GND
     Pin 3 (Blue)     NMEA out ->  to   MiniDin8 Pin 5 RxD- 
     Pin 4 (Brown)    NMEA in  <-;  from MiniDin8 Pin 3 TxD-
     Pin 5 (White)    NMEA Ground --- to   MiniDin8 Pin 4 GND
     Pin 6 (Green)    No connection    
     Pin 7 (Yellow)   Alarm Low    

Garmin 175 (GPSMap) cable diagrams courtesy of Paul Lahaye. Note that they are for PC systems, so make the adjustments for the Mac MiniDin 8 using the pin instructions above.

Garmin 195 and DeLorme TripmateTM cabling instructions courtesy of Dennis Fraser of LaserType, Inc. Be sure to not ground Pin 8 for TripMatesTM as they are not RS-232 compliant. Nor are most other GPS units (despite such claims in their documentation), so leave it ungrounded unless you are 100% positive.

Nota bene: The power requirements for V+ vary among the Garmin handhelds. While the majority accept 10V-32V, some of the lower-end handhelds (Garmin 12 for example), do not have a voltage-limiter and accept only 6-8V. Since you risk burning out your handheld if you supply it with more voltage than it can handle, it behooves you to check with your manual before supplying power to your unit. Thanks to Joe Mehaffey for reminding us of this issue.

Eagle Explorer / Explorer II

Many people have asked if we supply Eagle Explorer cables. One of the reasons that we don't recommend the EE is because of the proprietary data cable pinout. In any case, we don't have a source for the pin-plug but the pin layout is below. There is also a picture and schematic at Ron Weber's Eagle site.

Eagle Explorer 6-Pin  Pinouts                Mac Mini Din 8
  (looking from rear of unit)            (looking at front of cable)
        5                                      6   7   8
    3       1
        6                                     3    4     5   (pin 5 is the odd man out)
    4       2                                  
                                                1     2
 1 = DC+
 2 = Receive NMEA          ----------       3 = Transmit (TxD-)
 3 = Ground                ----------       4 = Signal GND
 4 = Transmit NMEA         ----------       5 = Receive (RxD-)
 5,6 = Reserved for future use              [leave all others unconnected, especially Pin 8]

If you want to connect your EE, you have two solutions:

  1. Get the EE PC-data cable from the manufacturer and then use the "generic PC-data cable"adaptor on our cable purchase page; or make your own from the instructions above.
  2. Use some female DB crimp pins and crimp them onto half of a printer cable, then slip them over the EE's male pins. Tape the cable to the EE with some electrical tape. Ugly, but it works... Brian Mork suggests over e-mail that Crayola Modelling Clay which sets to a foamlike density is perfectly suited to making one-off connectors

Magellan ColorTrack / Tracker

Most customers will want to use the pre-made cables from Magellan. You can either order just the data-only cable or the power+data cable. Either of these cables used in conjunction with our generic PC to Mac data cable adaptor (above) will work fine with your Macintosh.

Note: These must be purchased through your Magellan dealer. We do not sell Magellan cables.

If you're interested in how the Magellan data-port is wired:

 Magellan ColorTRAK/Tracker 5-Pin           Mac Mini Din 8
  (looking from rear of unit)            (looking at front of cable)
          3                                   6   7   8
    2       4
                                             3    4     5   (pin 5 is the odd man out)
    1       5                                  
                                               1     2

 1 = DC+
 2 = Receive NMEA          ----------       3 = Transmit (TxD-)
 3 = External alarm (ColorTRAK only)
 4 = Transmit NMEA         ----------       5 = Receive (RxD-)
 5 = Ground                ----------       4 = Signal GND

Magellan 3000/4000

If you have a Magellan GPS 3000/4000 (XL) unit; things are difficult since Magellan terminates the power/data unit with raw wire strands and not any sort of connector. The cable diagrams in GPSy preliminary manual above should help you, but if you are soldering-iron-phobic, things may be difficult. Try to find the Magellan PC-Kit which comes pre-made with a data cable with a DB-9 interface -- and then use our Generic PC-DB9 Adaptor, above.

Magellan Data Cable Strands                   Mac Mini Din 8
                                        (looking at front of cable)
    Black = GND                                 6   7   8
    Yellow = Transmit         
    Orange = Receive                           3    4     5   (pin 5 is the odd man out)
    Red = V+                                          
                                                 1     2

 Orange = Receive NMEA     ----------       3 = Transmit (TxD-)
 Black  = Ground           ----------       4 = Signal GND
 Yellow = Transmit NMEA    ----------       5 = Receive (RxD-)
                                            [leave all others unconnected, especially Pin 8]   


Other sites

Finally, here are some other sites that have cable diagrams:


Copyright (C) 1997-2007 by Global Mapping Systems and Karen Nakamura. All rights reserved. GPSy® and GPSy.COM® are registered trademarks and GPSy ProTM and GPSyLinkTM are trademarks of Karen Nakamura. All other trademarks are the property of their respective owners. Mention of a third-party's product does not represent endorsement of or by that product.

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