Making Your Own GPS to iPAQ Cables
1) A disassembled four pin connector from Pfranc, which is used with GPS 12 and other similar GPS receivers.  [MORE]

2) Assembled cable with GOMADIC iPAQ connector and Pfranc eTrex connector.   [MORE]

3) A disassembled GOMADIC connector. NOTE: The pinouts for the 3800+ / 3700- series iPAQs differ! Make sure you consult proper documentation before attempting to create your own cable.   [MORE]

You will need a base connector to your handheld, an appropriate connector to your GPS, and a length of wire (three conductor). The pinouts for the iPAQ 22 pin base connector are as follows:
	Pin out 22 Pin Cradle Connector iPAQ side.
	1	V_ADP
	2	V_ADP
	3	V_ADP
	4	V_ADP
	5	Reserved - Do Not Use
	6	RS232 DCD
	7*	RS232 RXD
	8*	RS232 TXD
	9	RS232 DTR
	10*	GND
	11	RS232 DSR
	12	RS232 RTS
	13	RS232 CTS
	14	RS232 RING
	15*	GND
	16	No Connect - Do Not Use
	17	USB Detect
	18	No Connect - Do Not Use
	19	USB - UDC +
	20	No Connect - Do Not Use
	21	USB - UDC -
	22*	GND
	Shell tied to GND
You will need to match the TXD, RXD, and GND from the iPAQ and GPS receiver connector. Always make sure to test your connections before connecting the devices.



There are some useful tutorials :
    Pfranc Garmin 4 pin to DB9
    Pfranc eTrex cable assembly


LINKS
    How to run Linux in the iPAQ - how did this get here?
    Compaq Parts Store - YES IT'S TRUE!
    Colored sleeves for the iPAQ!
    Have someone just make me one!