Hard-wired Connection

This chapter describes some so called hard wired PDA ↔ GPS solutions. Make sure to also checkout the links page and/or the user reviews / example setups.

Garmin Connection

The picture below shows what pins to connect together to allow the two devices to talk to each other. With my Garmin 12XL I use a standard HotSync cable on the pilot, then I bought a Garmin data cable without a PC-type connector on it (Garmin round connector on one end, wires on the other) and put my own DB9 male connector on it with the correct pinouts. If you have another type GPS, you should be able to purchase a similar data cable and make your own.

Thanks to Dominic Sexton &
http://www.software-developing.de 1)
A more complex description of what the pin-out requirements are for connecting the GPS to a PC (including power) can be found at:

Pre-made cables

You can actually buy pre-made cables pretty cheap for connecting the PalmPilot (and most other handhelds) to Garmin GPS round and eTrex connectors at: Blue Hills Innovations. Just click on the “Pfrankly Speaking button”, then on the “Products” link, then scroll down to the “Handhelds” section.

PN Technologies also sells pre-made cables for a wide range of PDA‘s and GPS combinations. Check out their Product Selector matrix.

Palm OS Hardware for Navigation

Dale DePriest also has a lot of information on his Palm OS Hardware for Navigation site howto hookup a GPS with a Palm PDA.

if you decide for a GPS mouse, make sure to select a model that supports RS232 output.

Sony Clie Connector Description

If building your own cable for a Sony Clie, make sure to use a resistor soldered between the appropriate pins in the Clie as this activates the serial port on the Clie. The schematic below how to do this for S series Clie’s. I’m not sure about CLie’s with N series connectors but if you Google “Clie serial port” you’ll probably find what is needed. There is also a Clie users group on Yahoo where you can probably find this info.
clie_s_connector.jpg sony_clie_connector.jpg

Handspring Visor + GPS

Below is the schematic for a cable to hook a GPS to a Handspring Visor. It is specific for a round Garmin connector pin-out, but you can easily adapt it for any other GPS with ground and data-out.


The trick with GPS’s and Visors is, the Visor is looking for the +5 VDC serial voltage to permit hardware handshaking. The GPS will NOT provide this and that is why a regular serial to TLL cable will not work. In order to fix this instead of trying to pull the +5 VDC from the GPS, you just add in a separate source of power. In this case a 7805 being fed by something between +5 and +12 VDC. The regulator can handle up to +25 VDC but there is no reason to worry about that since you are trying to keep it light and portable. I use a 9 VDC battery to do the job. By feeding the +5 VDC to the MAX chip, you can permit handshaking and the Visor should start seeing data from the GPS like a normal computer would on it’s com port.

Source: http://www.ke4nyv.com/gpsstuff.htm

Handspring Links

  • More Visor specific information (page suffers from “link-rot”, but contains usefull info).
  • Pre-made cables are available at PN Technologies.
  • ATL Connect sells Handspring connectors.

Handspring Visor Pinout

With the Visor screen up and the buttons at the bottom, pin 1 is on the right-hand side. The pinout is as follows:

Pin Nr. Visor Signal
1 RX Data (Serial)
2 Keyboard Detect
3 Hotsync Interupt
4 Ground
5 USB + Data
6 USB - Data
7 VDOCK (Cradle Power)
8 TX Data (Serial)

The data signals RXD and TXD are NOT RS232 compatible! This means that without signal conversion electronic you cannot connect a GPS directly to these signals! Only the USB signals and with some models the VDOCK/Charge Pin can be used without further electronics.

Handspring Visor Edge Pinout

This pinout is ONLY for the Visor Edge, not for other Visor models!

The data signals RXD and TXD are NOT RS232 compatible! This means that without signal conversion electronic you cannot connect a GPS directly to these signals! Only the USB signals and with some models the VDOCK/Charge Pin can be used without further electronics.

A suitable RS232 converter for the Edge is f.i. a MAX3232. The Edge operates with signals of 3.15 Volt, so the logic voltage levels should be in that range too, say 3V. With higher voltage levels you could damage your Visor. The Visor Edge can be charged from an external source via the VDOCK Pin. The charge voltage should be between 4.75 and 6.2 Volt DC at ca. 500mA. The original Handspring charger outputs 5.9 Volt.

The pass through pins are reserved for suitable Springboard Modules. However, other Visors do not have these pins and I’m not aware of any springboard modules that actually use these pins.

The pin numbering is from front/bottom (screen up) at the contacts of the EDGE from left to right. RxD is thus links, Passthrough4 right

Pin Nr. Visor Edge Signal
1 RxD - input serial data for EDGE, (0-3.15V TTL level!)
2 TxD - output serial data from EDGE, (0-3.15V TTL level!)
3 /Keyb - Keyboard Detect, active low, (0-3.15V TTL level!)
4 /HS - HotSync Detect, active low, (0-3.15V TTL level!)
5 USB_D-
6 USB_D+
7 VDOCK - Cradle Power, also fed through to Springboard module
9 Passthrough 1 - see note above
10 Passthrough 2
11 Passthrough 3
12 Passthrough 4

Palm Universal 16pin Connector


Palm T/X Multi Connector

plammcpinout2ak.jpg plammcpinout25da.jpg

1) link is dead?
soarpilot/hard-wired_connection.txt · Last modified: 2007/12/19 03:53 by pgleesonuk
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